Journal of Pharmacology, 222 (1992)7-12 0 1992ElsevierSciencePublishersB.V. All rights reserved0014-2999/92/$05.00
European
JZJP52706
Multidimensional behavioral analyses show dynorphin A-( 1-13) modulation of methamphetamine-induced behaviors in mice Makoto Department
of Chemical
Ukai, Tohru
Pharmacology,
Faculty
Toyoshi
and,Tsutomu
of Pharmaceutical
Sciences,
Kameyama Meijo
University,
Nagoya
468, Japan
Received29 May 1992,revisedMS received14 July 1992,accepted28 July1992 The effects of intracerebroventricular (i.c.v.) injection of dynorphin A-(1-13) on methamphetaniine-induced behavioral alterationi in mice were determined by using multidimensional behavioral analyses. Methamphetamine (0.3, 1.0 and 3.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing and/or grooming behaviors. The behavioral effects of methamphetamine (1.0 mg/kg s.c.) were almost completely antagonized by pretreatment with the dopamine D, receptor antagonist, S(-)-sulpiride (3.0 and/or 10.0 mg/kg i.p.), but not with the dopamine D, receptor antagonist, SCH 23390 (0.01 or
0.03 mg/kg i.p.). Although dynorphin A-(1-13) (3.0 or 12.5 pg i.c.v.) alone did not produce any significant effects on behavior, the methamphetamine (1.0 mg/kg s.c.)-induced increase in circling ipsilateral to the injection side was markedly enhanced by dynorphin A-(1-13) (12.5 pg i.c.v.). In contrast, the peptide (12.5 pg i.c.v.) inhibited the methamphetamine (1.0 mg/kg s.c.)-induced increase in rearing, whilst the increase in grooming remained unchanged. The effects of dynorphin A-(1-13) (12.5 pg i.c.v.) were fully reversed by the opioid antagonist, Mr 2266 (5.6 mg/kg s.c.). These results suggest that the unilateral administration (i.c.v.) of dynorphin A-(1-13) inhibits the activity of dopamine-elicited neurotransmission, resulting in an increase
in ipsilateral circling and in a decrease in rearing. Dynorphin A-(1-13); Methamphetamine; Mr 2266; Circling; Rearing; (Mouse) 1. Introduction Opioid receptors in the central nervous system can be divided into at least three different types such as p, 6 and K (Wiister et al., 1981; Paterson et al., 1983; Martin, 1984). Dynorphins in particular have potent agonistic properties at K-Opioid receptors in gUinea pig ileum, mouse vas deferens (Chavkin et al., 1982; Corbett et al., 1982) and guinea pig brain homogenates (James et al., 1982). Dynorphins have been reported to exhibit a specific behavioral profile, according to multidimensional behavioral analyses based on a capacitance system in which nine different classes of movement frequency were recorded, some of these classes corresponding to discrete elements of the animal’s behavior (Ukai and Kameyama, 1984; Ukai et al., 1984). For example, dynorphin A-cl-131 (0.3 and 1.0 pg i.c.v.1 produces a marked increase in linear locomotion, while higher doses (3.0 and 10.0 pg i.c.v.) of the peptide have no significant effects on various behaviors.
Correspondenceto: M. Ukai, Department of Chemical Pharmacology, Faculty of PharmaceuticalSciences,Meijo University, Nagoya 468,Japan. Tel. (81) 52-832-1781ext. 344, fax (81) 52-834-8780.
Previous reports have demonstrated the pharmacological interaction of K-SekCtiVe opioid peptides with dopamine neurons. For instance, a lO.O-pg i.c.v. dose of dynorphin A-cl-131 produces an inhibitory effect on the apomorphine (0.56 and 1.0 mg/kg s&induced increase in rearing behavior (Ukai et al., 1989a), whereas the selective dopamine D, receptor agonist RU 24213 (3.0 mg/kg s.c.)-induced increase in linear locomotion and circling behaviors is almost completely reversed by the peptide (12.5 pg i.c.v.1 (Ukai et al., 1992). Furthermore, the i.c.v. injection of E-2078, a metabolically resistant analog of dynorphins, produces a marked decrease in dopamine release in the nucleus accumbens (Spanagel et al., 1990). The amphetamineor methamphetamine-induced behavioral model is perhaps considered the best known approach to the experimental study of schizophrenia (McKinney, 1988). This model is particularly based upon the clinical effects of amphetamine or methamphetamine in humans (McKinney, 1988). Thus, it is of great interest to determine whethdr dynorphin A-cl-131 affects behaviors induced by amphetamine or methamphetamine in experimental animals. In the present study, the effects of dynorphin A-(l13) on methamphetamine-induced behavioral alterationS were examined by using multidimensional analy-
a
ses (Kameyama and Ukai, 1981; 1983; Ukai and Kameyama, 1984; Ukai et al., 1989b; 1991; Toyoshi et al., 1991). In addition, the effects of dynorphin A-0-13) were characterized with the opioid antagonist, Mr 2266 (Roemer et al., 1980; Ukai and Kameyama, 1985; Ukai et al., 1988). 2. Materials
and methods
2.1. Animals
Male ddY mice (Japan SLC, Inc.) weighing between 20-30 g were used. The animals were randomly assigned to groups of eight or ten. Before the experiments, the mice were given free access to food and water, and mice were housed individually in a cage in a constantly illuminated room at a temperature of 23 f 1°C and a relative humidity of 55 f 2.5%. The mice were used only once and were unfamiliar with the test box. The experiments were conducted between 10:00 a.m. and 6 : 00 p.m. in a sound-attenuating room. 2.2. Multidimensional
analysis
Immediately before multidimensional analyses, mice were selected according to the number of revolutions (range from 125 to 150 per 10 min for meeting criterion) in wheel cages to exclude individual differences of animals as much as possible. About 30% of the mice purchased were discarded for failing to meet the criterion in the first measurement. The mice discarded were repeatedly put into wheel cages for selection on different days. Finally, we could use almost all of the mice purchased. Behavior was observed over a period of 15 min. The Animex II, equipped with a personal computer, was used for measuring behaviors (Kameyama and Ukai, 1981; 1983; Ukai and Kameyama, 1984; 1985; Ukai et al., 1989a). The sensor consisted of three pairs of electrodes and formed a capacitor bridge. Once a mouse was placed in the space (150 x 210 x 140 mm) between the electrodes connected to field detectors, the value of the capacitor then depended upon the location of the mouse within this space. When converting the analog signal received by the detectors to digital form, the d.c. voltage movement spectrum analyser classified the movement into nine degrees (l/l, l/2, l/4, l/8, l/16, l/32, l/64, l/128 and l/256). The surface areas of the cage in which mice could show behavioral responses (ambulation, circling, rearing and grooming) were 490 mm in distance. The 490 mm distance consisted of the length of the cage bottom (210 mm) and the cage walls (140 mm X 2). Thus, the counters corresponded to the following sizes of movements: l/l (X490.0 mm> = 490.0 mm, l/2 (X 490.0 mm> = 245.0 mm, l/4 ( x 490.0 mm>
= 122.5 mm, l/8 (x490.0) = 61.3 mm, l/16 (X490.0 mm) = 30.6 mm, l/32 (x490 mm) = 15.3 mm, l/64 (X490.0 mm) = 7.7 mm, l/128 (X490.0 mm> = 3.8 mm and l/256 ( X 490.0 mm) = 1.9 mm. The movement of greatest magnitude was mostly recorded on the l/l counter and the movement of the smallest magnitude, such as tremor, on the l/256 counter. Specific patterns of behavior induced by a drug were registered on the counters as follows, linear locomotion on l/l, circling on l/4, rearing on l/16 and grooming on l/64 (Kameyama and Ukai, 1983). Additionally, the circling behaviors mentioned above include movement of the animal along every nook and corner of the testing cage. The sensitivity (%o) of the device was adjusted according to body weight (g) as follows, 20-21 g = 27%, 22-23 g = 26%, 24-25 g = 25%, 26-28 g = 24% and 29-30 g = 23%. Each value in the figures was labeled as mean f S.E. ratio after calculation of the ratios for each of the animals. The ratios for each of the animals = (each of the actual values for drug-treated animals)/(mean actual values of controls). Additionally, the behaviors (behavioral traces) were recorded continuously with X-Y recorders (Watanabe Inc., Nagoya, Japan) connected to the field detectors of the Animex II. 2.3. Drugs
Methamphetamine hydrochloride (Dainippon Pharmaceutical Co., Japan), SCH 23390 (7-chloro-2,3,4,5tetrahydro-3-methyl-5-phenyl-lH-3-benzazepine-7-ol maleate) (Schering Corp., U.S.A.), S(-)-sulpiride (Research Biochemicals Inc., U.S.A.), dynorphin A-0-13) (Peptide Institute Inc., Japan) and Mr 2266 ((-I(lR,5R,9R)-5,9-diethyl-2-(3-furyl-methyl)-2’-hydroxy6,7-benzomorphan) (Boehringer Ingelheim KG, Germany) were used throughout. Methamphetamine was dissolved in isotonic saline (0.9% NaCl, pH 7.5). Mr 2266 was dissolved in 1.0 ml 5% w/v ( f )-tartaric acid and the volume was made up with 0.9% saline. The vehicle for SCH 23390 and SC-)-sulpiride was 8.5% lactic acid and 1.0 N sodium hydroxide in a 3 : 2 ratio. Methamphetamine (s.c.), SCH 23390 (i.p.1, St-)sulpiride (i.p.1 and Mr 2266 (s.c.1 were administered 40, 75, 75 and 30 min before the start of behavioral observations, respectively. Dynorphin A-(1-13) dissolved in sterile isotonic saline in polypropylene containers was injected i.c.v. 25 min before the start. The unilateral injection site was 2 mm from either side of the midline on a line drawn through the anterior roots of the ears (Haley and McCormick, 1957). The injection was made with a 4-mm long needle attached to a 50-~1 Hamilton microsyringe. The needle was inserted perpendicularly through the skull and into the lateral ventricle of the brain. The mouse was anaesthetized locally with XyloCaine (8% lidocaine) spray (Fujisawa Pharmaceutical
9
Co., Ltd., Osaka, Japan). Solutions were injected in a volume of 10 ~1 per mouse over a period of 20 s as previously described (Kameyama and Ukai, 1981; 1983). The site was checked by injecting a 1: 10 dilution of India ink in isotonic saline (0.9% NaCI, pH 7.5). Histological examination revealed particles of ink in the lateral and 3rd ventricles but not in the others. As previously described (Kameyama and Ukai, 19831, neither insertion of the needle nor injection of 10 ~1 of isotonic saline solution had a significant influence on behaviors as measured by multidimensional behavioral analyses. 2.4. Data analysis
The actual values were analyzed statistically by means of a one-factor analysis of variance (ANOVA). Post hoc analysis for betweenigroup differences was carried out by the Newman-Keuls method for multiple comparisons (Zar, 1984). -Effects were considered statistically significant if P < 0.05. The data in figures indicate ratios derived from actual values for clearer presentation of the results.
3. Results 3. I. Effects on behavioral traces
The traces in A and B in the upper left-hand part of fig. 1 indicate horizontal and vertical movements, respectively. SCH 23390 (0.03 mg/kg i.p.), S(-I-sulpiride (10.0 mg/kg i.p.), dynorphin A-cl-131 (12.5 pg i.c.v.1,
Mr 2266 (5.6 mg/kg s.c.) and their combinations had no marked effects on the behavioral traces (fig. 1). Methamphetamine (1.0 mg/kg s.c.) produced a marked increase in both horizontal and vertical movements. Not only dynorphin A-cl-131 (12.5 pg i.c.v.1 but SC-)sulpiride (10.0 mg/kg i.p.) also, unlike SCH 23390 (0.03 mg/kg i.p.1, antagonised the methamphetamine (1.0 mg/kg s.c.)-induced increase in vertical movements. In contrast, the increase in horizontal movements induced by methamphetamine (1.0 mg/kg s.c.) was maikedly enhanced by dynorphin A-Q-13) (12.5 pg i.c.v.1. The effects of dynorphin A-(1-13) (12.5 pg i.c.v.1 on the two components of movements induced by methamphetamine (1.0 mg/kg s.c.) were fully antagonized by Mr 2266 (5.6 mg/kg s.c.) which alone did not markedly affect horizontal or vertical movements (fig. 1). 3.2. Effects of methamphetamine
Methamphetamine (0.3-3.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing and/or grooming behaviors, although a 0.1 mg/kg dose of the drug failed to affect the behaviors (fig. 2A). However, the patterns of circling induced by methamphetamine were qualitatively similar to those observed in mice treated with 0.9% saline (i.c.v.1. 3.3. Effects of dopamine antagonists phetamine-induced behaviors
on metham-
SCH 23390 (0.01 or 0.03 mg/kg i.p.1 (fig. 2B) or S(-)-sulpiride (3.0 or 10.0 mg/kg i.p.1 (fig. 2C) had no significant effects on the behaviors, whilst a l.O-mg/kg
MAP * SAL
u¶P * SUL
UslAp. DYN
W
+ Mr2266
t SAL
K4P
l
Hr2266
. DYN
Fig. 1. Behavioral traces for each of the mice treated with SCH 23390, St-I-sulpiride, dynorphin A-(1-13), methamphetamine, Mr 2266 or their combinations within 15-30 min after the start of behavioral measurements. Top left-hand part of the figure shows: A, cagebottom; B, cage walls; SAL, 0.9% saline S.C. and i.c.v.; SCH, SCH 23390 0.03 mg/kg i.p.; SUL, S(-)-sulpiride 10.0 mg/kg i.p.; DYN, dynorphin A-(1-13) 12.5 kg/mouse i.c.v.; Mr 2266 5.6 mg/kg S.C.and MAP, methamphetamine 1.0 mg/kg S.C.
Linear IommoUon
Circling
Rearing
Grooming
20 72
(B)
Linear lommotion
Linear locomotion
Circling
Rearing
Grooming
Fig. 3. Movements of mice after the administration of methamphetamine (MAP) (1.0 mg/kg s.c.), dynorphin A-cl-131 (DYN) (12.5 pg i.c.v.) or their combinations. - - - Saline S.C.+ saline i.c.v.; q saline s.c.+ DYN 3.0 pg i.c.v.; •U saline S.C.+DYN 12.5 pg i.c.v.; 0 MAP 1.0 mg/kg s.c.+saline i.c.v.; q MAP 1.0 mg/kg S.C.+DYN 3.0 pg 1.c.v.; q MAP 1.0 mg/kg s.c.+DYN 12.5 pg i.c.v. Values represent the meansfS.E. for 10 mice. Significant difference from saline control, *P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.) alone, ’ P < 0.05.
Circling
Rearing
Grooming
0.03 mg/kg i.p.> (fig. 2B), inhibited the methamphetamine (1.0 mg/kg s.c.)-induced increase in behaviors. 3.4. Effects of phetamine-induced
dynorphin behaviors
A-(1-13)
on
metham-
Methamphetamine (1.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing
Linear lowmolion
Circling
Rearing
Grooming
Fig. 2. Movements of mice after the administration of methamphetamine (MAP) (0.1, 0.3, 1.0 and 3.0 mg/kg s.c.) alone (A), MAP (1.0 mg/kg s.c.) plus SCH 23390 (SCH) (0.01 and 0.03 mg/kg i.p.1 (B) and MAP (1.0 mg/kg s.c.) plus S(-)-sulpiride (SUL) (3.0 and 10.0 mg/kg i.p.) (C). (A) --Saline s.c.; t?dMAP 0.1 mg/kg s.c.; •t MAP 0.3 mg/kg s.c.; 0 MAP 1.0 mg/kg s.c.; S MAP 3.0 mg/kg S.C. (B) - - - Saline s.c. +saline i.p.; tZt saline S.C.+ SCH 0.01 mg/kg i.p.; GUIsaline s.c.+SCH 0.03 mg/kg i.p.; 0 MAP 1.0 mg/kg s.c.+saline, i.p.; q MAP 1.0 mg/kg s.c.+SCH 0.01 mg/kg i.p.; 8 MAP 1.0 mg/kg s.c.+SCH 0.03 mg/kg i.p. (0 --saline s.c.+saline i.p.; gt saline s.c.+SUL 3.0 mg/kg i.p.; III saline s.c.+ SUL 10.0 mg/kg i.p.; 0 MAP 1.0 mg/kg s.c.+saline i.p.; q MAP 1.0 mg/kg s.c.+SUL 3.0 mg/kg i.p.; 8 MAP 1.0 mg/kg S.C.+SUL 10.0 mg/kg i.p. Values represent the means* S.E. for S-10 mice. Significant difference from saline control, *P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.) alone, ‘P < 0.05.
S.C. dose of methamphetamine again produced a marked increase in linear locomotion, circling, rearing and grooming (fig. 2BC). S(-)-Sulpiride (3.0 and/or 10.0 mg/kg i.p.3 (fig. 2C), but not SCH 23390 (0.01 or
Linear locomotion
Cirding
Rearing
Grooming
Fig. 4. Movements of mice after the administration of methamphetamine (MAP) (1.0 mg/kg s.c.), dynorphin A-(1-13) (DYN) (12.5 Fg i.c.v.), Mr 2266 (5.6 mg/kg s.c.) or their combinations. - - Saline S.C.+saline S.C.+saline i.c.v.; r?~ saline s.c.+ Mr 2266 5.6 mg/kg S.C.+saline i.c.v.; •tl saline s.c.+saline S.C.+DYN 12.5 pg i.c.v.; 0 saline S.C.+ Mr 2266 5.6 mg/kg S.C.+ DYN 12.5 pg i.c.v.; q MAP 1.0 mg/kg s.c.+saline S.C.+saline i.c.v.; KI MAP 1.0 mg/kg s.c.+Mr 2266 5.6 mg/kg s.c.+ saline i.c.v.; q MAP 1.0 mg/kg s.c.+saline s.c.+DYN 12.5 pg i.c.v.; 0 MAP 1.0 mg/kg s.c.+Mr 2266 5.6 mg/kg s.c.+DYN 12.5 pg i.c.v. Values represent the meansfS.E. for 10 mice. Significant difference from saline control, *P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.) alone, ‘P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.)+ DYN (12.5 pg i.c.v.), s P < 0.05.
11
and grooming behaviors, although dynorphin A-(1-13) (3.0 or 12.5 ,ug i.c.v.) alone did not affect the behaviors (fig. 3). The peptide (12.5 pg i.c.v.) had an inhibitory effect on the methamphetamine (1.0 mg/kg s.c.)-induced increase in rearing behaviors (fig. 3). In contrast, the increase in circling behaviors induced by methamphetamine (1.0 mg/kg s.c.) was markedly enhanced by dynorphin A-(1-13) (12.5 pg i.c.v.), although the increase in grooming behaviors remained unchanged (fig. 3). In addition, the circling behaviors were ipsilateral to the side injected. 3.5. Effects of Mr 2266
The effects of dynorphin A-(1-13) (12.5 pg i.c.v.) on the methamphetamine (1.0 mg/kg s.c.)-induced behavioral changes were almost completely reversed by Mr 2266 (5.6 mg/kg s.c.), although Mr 2266 (5.6 mg/kg s.c.) alone did not affect any behavioral patterns (fig. 4).
4. Discussion It has been reported that the apomorphine (0.56 and 1.0 mg/kg s.c.)-induced increase in rearing behaviors is completely inhibited by dynorphin A-(1-13) (10.0 pg i.c.v.) (Ukai et al., 1989a). Additionally, dynorphin A-(1-13) (3.0 and 12.5 pg i.c.v.) has been shown to produce an inhibitory effect on the RU 24213 (3.0 mg/kg s.c.)-induced increase in linear locomotion and circling behaviors (Ukai et al., 1992). In contrast, this peptide (3.0 or 12.5 pg i.c.v.) did not affect the behavioral effects induced by the dopamine D, receptor agonist, SKF 38393. These findings suggest that Kopioid peptides play an inhibitory role in the behaviors induced by the selective activation of dopamine D, receptors. In the present study, methamphetamine (1.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing and grooming behaviors. The behavioral effects of methamphetamine (1.0 mg/kg s.c.) seem to be indirectly mediated through dopamine D, receptors, since the selective dopamine D, receptor antagonist, S(-)-sulpiride, unlike the selective dopamine D, receptor antagonist, SCH 23390, fully antagonized the effects of methamphetamine. In addition, the effects of higher doses of SCH 23390 were not examined in the present study because, at doses over 0.03 mg/kg, the antagonist has an inhibitory effect on behaviors induced by the dopamine D, agonist, RU 24213, in mice (unpublished data). Dynorphin A-(1-13) (3.0 or 12.5 pg i.c.v.) alone did not produce any significant effects on the behaviors, whereas the peptide (12.5 pg i.c.v.) caused an inhibitory effect on the methamphetamine (1.0 mg/kg
s.c.)-induced increase in rearing. In contrast, the increase in circling behaviors induced by methamphetamine (1.0 mg/kg s.c.) was markedly enhanced by unilateral dynorphin A-(1-13) (12.5 pg i.c.v.). Additionally, these behaviors were ipsilateral to the side injected. However, the bilateral administration of dynorphin A-(1-13) (12.5 pg i.c.v.) has been shown to produce an inhibitory effect on the methamphetamine (1.0 mg/kg s.c.)-induced increase in circling (unpublished data). These observations indicate that dynorphin A-(1-13) inhibits the behavioral activation through the mediation of dopamine D, receptors, resulting in the increase in circling ipsilateral to the side injected. Since the present results indicate that the unilateral injection of dynorphin A-(1-13) (12.5 pg) increased circling in response to methamphetamine and decreased rearing, it is possible that the behavioral interaction between circling and rearing is merely reciprocal. However, the bilateral injection of dynorphin A(1-13) inhibits circling without influencing rearing (unpublished data), suggesting that dynorphin A-(1-13) specifically inhibits circling due to methamphetamine. The site of dynorphin A-(1-13) action for the inhibitory effects on methamphetamine-induced behaviors seems to be postsynaptic in the brain, because dynorphin A-(1-13) fails to affect the decrease in behaviors induced by a presynaptic dose of apomorphine (unpublished data) and the intrastriatal injection of dynorphin A-(1-13) inhibits the behavioral sensitization induced by a lower dose of apomorphine in 6-hydroxydopamine-treated mice (Toyoshi et al., 1992). The effects of dynorphin A-(1-13) (12.5 pg i.c.v.) were fully reversed by the opioid antagonist, Mr 2266 (5.6 mg/kg s.c.). Our previous study has demonstrated that the increase in linear locomotion, circling, rearing and/or grooming behaviors induced by the dopamine D, receptor agonist, RU 24213 (3.0 mg/kg s.c.) is almost completely inhibited by the CL-opioid agonist, DAMGO ([D-Ala2,NMePhe4,Gly5-ollenkephalin) (0.003 and/or 0.01 pg i.c.v.), and dynorphin A-(1-13) (3.0 and/or 12.5 kg i.c.v.), but not by the &opioid agonist, DPLPE ([D-Pen*,L-Pen5]enkephalin) (0.3 or 1.0 pg i.c.v.) (Toyoshi et al., 1991). The effects of DAMGO are reversed by the p-selective alkylating agent, p-funaltrexamine (Toyoshi et al., 1991), although the effects of dynorphin A-(1-13) are insensitive to the agent (unpublished data). These findings suggest that dynorphin A-(1-13) plays an inhibitory role in behaviors induced by the indirect activation of dopamine D, receptors through the mediation of Kopioid receptors. There is, however, a discrepancy concerning the behavioral effects of dynorphin A-(1-13) on dopamine D, receptor-related behaviors. For example,mdynorphin A-(1-13) enhanced methamphetamine-induced circling in the present experiments and conversely was found to
12
decrease RU 24213-induced circling (Ukai et al., 1992). Although there is not yet a clear-cut explanation for the discrepancy, the neuropharmacological difference between methamphetamine and RU 24213 may play a role in the effects of dynorphin A-(1-13). Particularly, it has been reported that methamphetamine, unlike RU 24213, affects neuronal systems other than dopamine neurons (Cooper et al., 1991). In view of the various findings, dynorphin A-O-13) may be useful for the development of potentially effective drugs in the treatment of schizophrenic patients, because the amphetamine- or methamphetamine-induced behavioral model appears to be appropriate for the experimental study of schizophrenia (McKinney, 1988).
Acknowledgements The authors thank Boehringer Ingelheim KG and Schering Corp. for the generous gifts of Mr 2266 and SCH 23390, respectively. We also thank Tetsuya Kobayashi for secretarial assistance.
References Chavkin, C., I.F. James and A. Goldstein, 1982, Dynorphin is a specific endogenous ligand of the k-opioid receptor, Science 215, 413. Cooper, J.R., F.E. Bloom and R.H. Roth, 1991, The Biochemical Basis of Neuropharmacology (Oxford University Press, New York). Corbett, A.D., S.J. Paterson, A.T. M&night, J. Magnan and H.W. Kosterlitz, 1982, Dynorphin (I-8) and dynorphin (l-9) are ligands for the kappa subtype of opiate receptor, Nature (London) 299, 79. Haley, T.J. and W.G. McCormick, 1957, Pharmacological effects produced by intracerebral injection of drugs in the conscious mouse, Br. J. Pharmacol. 12, 12. James, I.F., C. Chavkin and A. Goldstein, 1982, Preparation of brain membranes containing a single type of opioid receptor highly selective for dynorphin, Proc. Natl. Acad. Sci. U.S.A. 79, 7570. Kameyama, T. and M. Ukai, 1981, Multi-dimensional analyses of behavior in mice treated with cy-endorphin, Neuropharmacology 20, 247. Kameyama, T. and M. Ukai, 1983, Multi-dimensional analyses of behavior in mice treated with morphine, endorpliins and [destyrosine’l-y-endorphin, Pharmacol. Biochem. Behav. 19, 671.
McKinney, W.T., 1988, Models of Mental Disorder (Plenum Publishing Corporation) p. 132. Martin, W.R., 1984, Pharmacology of opioids, Pharmacol. Rev. 35, 283. Paterson, S.J., L.E. Robson and H.W. Kosterlitz, 1983, Classification of opioid receptors, Br. Med. Bull. 39, 31. Roemer, D., H. Buscher, R.C. Hill, R. Maurer, T.J. Petcher, H.B.A. Welle, H.C.C.K. Bake1 and A.M. Akkerman, 1980, A potent, long-acting opiate kappa-agonist, Life Sci. 27, 971. Spanagel, R., A. Herz and T.S. Shippenberg, 1990, The effects of opioid peptides on dopamine release in the nucleus accumbens: an in vivo microdialysis study, J. Neurochem. 55, 1734. Toyoshi, T., M. Ukai and T. Kameyama, 1991, [D-Ala2,NMePhe4, Gly-ol’]enkephalin, but not [D-Pen’,L-Per?]enkephalin specifically inhibits behaviors induced by the dopamine D, agonist RU 24213, Eur. J. Pharmacol. 201, 41. Toyoshi, T., M. Ukai and T. Kameyama, 1992, Effects of intrastriatal injections of dynorphin AU-131 on the apomorphine-induced behavioral alterations in 6-hydroxydopamine-treated mice, using multi-dimensional behavioral analyses, Jap. J. Pharmacol. 58, Suppl. I, 322P. Ukai, M. and T. Kameyama, 1984, The antagonistic effects of naloxone on hypermotility in mice induced by dynorphin-(l-13) using a multi-dimensional behavioral analysis, Neuropharmacology 23, 165. Ukai, M. and T. Kameyama, 1985, Multi-dimensional analyses of behavior in mice treated with U50,488H, a purported kappa (non-mu) opioid agonist, Brain Res. 337, 352. Ukai, M., S. Nakayama and T. Kameyama, 1988, The opioid antagonist, Mr 2266, specifically decreases saline intake in the mouse, Neuropharmacology 27, 1027. Ukai, M.;T. Toyoshi and T. Kameyama, 1989a, Dynorphin AU-13) modulates apomorphine-induced behaviors using multidimensional behavioral analyses in the mouse, Brain Res. 499, 299. Ukai, M., T. Toyoshi and T. Kameyama, 19894 Multi-dimensional analyses of behavior in mice treated with the delta opioid agonists DADL (D-Ala2-D-Let?-Enkephalin) and DPLPE (D-Pen2L-Per?-Enkephalin), Neuropharmacology 28, 1033. Ukai, M., T. Toyoshi and T. Kameyama, 1991, DAGO ([D-Ala2,NMelPhe4,Gly-ol]enkephalin) specifically reverses apomorphineinduced increase in rearing and grooming behaviors in the mouse, Brain Res. 557, 77. Ukai, M., T. Toyoshi and T. Kameyama, 1992, Dynorphin A(l-13) preferentially inhibits behaviors induced by the D, dopamine agonist RU 24213 but not by the D, dopamine agonist SK&F 38393, Pharmacol. Biochem. Behav. 42, 755. Ukai, M., S. Yamada and T. Kameyama, 1984, Naloxone reverses the inhibitory effects of dynorphin A on motor activity in the mouse, Pharmacol. Biochem. Behav. 20,815. Wiister, M., R. Schulz and A. Hen, 1981, Multiple opiate receptors in peripheral tissue preparations, Biochem. Pharmacol. 30, 1883. Zar, J.H., 1984, Biostatistical Analysis (Prentice-Hall, Englewood Cliffs) p. 190.
European
JZJP52706
Multidimensional behavioral analyses show dynorphin A-( 1-13) modulation of methamphetamine-induced behaviors in mice Makoto Department
of Chemical
Ukai, Tohru
Pharmacology,
Faculty
Toyoshi
and,Tsutomu
of Pharmaceutical
Sciences,
Kameyama Meijo
University,
Nagoya
468, Japan
Received29 May 1992,revisedMS received14 July 1992,accepted28 July1992 The effects of intracerebroventricular (i.c.v.) injection of dynorphin A-(1-13) on methamphetaniine-induced behavioral alterationi in mice were determined by using multidimensional behavioral analyses. Methamphetamine (0.3, 1.0 and 3.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing and/or grooming behaviors. The behavioral effects of methamphetamine (1.0 mg/kg s.c.) were almost completely antagonized by pretreatment with the dopamine D, receptor antagonist, S(-)-sulpiride (3.0 and/or 10.0 mg/kg i.p.), but not with the dopamine D, receptor antagonist, SCH 23390 (0.01 or
0.03 mg/kg i.p.). Although dynorphin A-(1-13) (3.0 or 12.5 pg i.c.v.) alone did not produce any significant effects on behavior, the methamphetamine (1.0 mg/kg s.c.)-induced increase in circling ipsilateral to the injection side was markedly enhanced by dynorphin A-(1-13) (12.5 pg i.c.v.). In contrast, the peptide (12.5 pg i.c.v.) inhibited the methamphetamine (1.0 mg/kg s.c.)-induced increase in rearing, whilst the increase in grooming remained unchanged. The effects of dynorphin A-(1-13) (12.5 pg i.c.v.) were fully reversed by the opioid antagonist, Mr 2266 (5.6 mg/kg s.c.). These results suggest that the unilateral administration (i.c.v.) of dynorphin A-(1-13) inhibits the activity of dopamine-elicited neurotransmission, resulting in an increase
in ipsilateral circling and in a decrease in rearing. Dynorphin A-(1-13); Methamphetamine; Mr 2266; Circling; Rearing; (Mouse) 1. Introduction Opioid receptors in the central nervous system can be divided into at least three different types such as p, 6 and K (Wiister et al., 1981; Paterson et al., 1983; Martin, 1984). Dynorphins in particular have potent agonistic properties at K-Opioid receptors in gUinea pig ileum, mouse vas deferens (Chavkin et al., 1982; Corbett et al., 1982) and guinea pig brain homogenates (James et al., 1982). Dynorphins have been reported to exhibit a specific behavioral profile, according to multidimensional behavioral analyses based on a capacitance system in which nine different classes of movement frequency were recorded, some of these classes corresponding to discrete elements of the animal’s behavior (Ukai and Kameyama, 1984; Ukai et al., 1984). For example, dynorphin A-cl-131 (0.3 and 1.0 pg i.c.v.1 produces a marked increase in linear locomotion, while higher doses (3.0 and 10.0 pg i.c.v.) of the peptide have no significant effects on various behaviors.
Correspondenceto: M. Ukai, Department of Chemical Pharmacology, Faculty of PharmaceuticalSciences,Meijo University, Nagoya 468,Japan. Tel. (81) 52-832-1781ext. 344, fax (81) 52-834-8780.
Previous reports have demonstrated the pharmacological interaction of K-SekCtiVe opioid peptides with dopamine neurons. For instance, a lO.O-pg i.c.v. dose of dynorphin A-cl-131 produces an inhibitory effect on the apomorphine (0.56 and 1.0 mg/kg s&induced increase in rearing behavior (Ukai et al., 1989a), whereas the selective dopamine D, receptor agonist RU 24213 (3.0 mg/kg s.c.)-induced increase in linear locomotion and circling behaviors is almost completely reversed by the peptide (12.5 pg i.c.v.1 (Ukai et al., 1992). Furthermore, the i.c.v. injection of E-2078, a metabolically resistant analog of dynorphins, produces a marked decrease in dopamine release in the nucleus accumbens (Spanagel et al., 1990). The amphetamineor methamphetamine-induced behavioral model is perhaps considered the best known approach to the experimental study of schizophrenia (McKinney, 1988). This model is particularly based upon the clinical effects of amphetamine or methamphetamine in humans (McKinney, 1988). Thus, it is of great interest to determine whethdr dynorphin A-cl-131 affects behaviors induced by amphetamine or methamphetamine in experimental animals. In the present study, the effects of dynorphin A-(l13) on methamphetamine-induced behavioral alterationS were examined by using multidimensional analy-
a
ses (Kameyama and Ukai, 1981; 1983; Ukai and Kameyama, 1984; Ukai et al., 1989b; 1991; Toyoshi et al., 1991). In addition, the effects of dynorphin A-0-13) were characterized with the opioid antagonist, Mr 2266 (Roemer et al., 1980; Ukai and Kameyama, 1985; Ukai et al., 1988). 2. Materials
and methods
2.1. Animals
Male ddY mice (Japan SLC, Inc.) weighing between 20-30 g were used. The animals were randomly assigned to groups of eight or ten. Before the experiments, the mice were given free access to food and water, and mice were housed individually in a cage in a constantly illuminated room at a temperature of 23 f 1°C and a relative humidity of 55 f 2.5%. The mice were used only once and were unfamiliar with the test box. The experiments were conducted between 10:00 a.m. and 6 : 00 p.m. in a sound-attenuating room. 2.2. Multidimensional
analysis
Immediately before multidimensional analyses, mice were selected according to the number of revolutions (range from 125 to 150 per 10 min for meeting criterion) in wheel cages to exclude individual differences of animals as much as possible. About 30% of the mice purchased were discarded for failing to meet the criterion in the first measurement. The mice discarded were repeatedly put into wheel cages for selection on different days. Finally, we could use almost all of the mice purchased. Behavior was observed over a period of 15 min. The Animex II, equipped with a personal computer, was used for measuring behaviors (Kameyama and Ukai, 1981; 1983; Ukai and Kameyama, 1984; 1985; Ukai et al., 1989a). The sensor consisted of three pairs of electrodes and formed a capacitor bridge. Once a mouse was placed in the space (150 x 210 x 140 mm) between the electrodes connected to field detectors, the value of the capacitor then depended upon the location of the mouse within this space. When converting the analog signal received by the detectors to digital form, the d.c. voltage movement spectrum analyser classified the movement into nine degrees (l/l, l/2, l/4, l/8, l/16, l/32, l/64, l/128 and l/256). The surface areas of the cage in which mice could show behavioral responses (ambulation, circling, rearing and grooming) were 490 mm in distance. The 490 mm distance consisted of the length of the cage bottom (210 mm) and the cage walls (140 mm X 2). Thus, the counters corresponded to the following sizes of movements: l/l (X490.0 mm> = 490.0 mm, l/2 (X 490.0 mm> = 245.0 mm, l/4 ( x 490.0 mm>
= 122.5 mm, l/8 (x490.0) = 61.3 mm, l/16 (X490.0 mm) = 30.6 mm, l/32 (x490 mm) = 15.3 mm, l/64 (X490.0 mm) = 7.7 mm, l/128 (X490.0 mm> = 3.8 mm and l/256 ( X 490.0 mm) = 1.9 mm. The movement of greatest magnitude was mostly recorded on the l/l counter and the movement of the smallest magnitude, such as tremor, on the l/256 counter. Specific patterns of behavior induced by a drug were registered on the counters as follows, linear locomotion on l/l, circling on l/4, rearing on l/16 and grooming on l/64 (Kameyama and Ukai, 1983). Additionally, the circling behaviors mentioned above include movement of the animal along every nook and corner of the testing cage. The sensitivity (%o) of the device was adjusted according to body weight (g) as follows, 20-21 g = 27%, 22-23 g = 26%, 24-25 g = 25%, 26-28 g = 24% and 29-30 g = 23%. Each value in the figures was labeled as mean f S.E. ratio after calculation of the ratios for each of the animals. The ratios for each of the animals = (each of the actual values for drug-treated animals)/(mean actual values of controls). Additionally, the behaviors (behavioral traces) were recorded continuously with X-Y recorders (Watanabe Inc., Nagoya, Japan) connected to the field detectors of the Animex II. 2.3. Drugs
Methamphetamine hydrochloride (Dainippon Pharmaceutical Co., Japan), SCH 23390 (7-chloro-2,3,4,5tetrahydro-3-methyl-5-phenyl-lH-3-benzazepine-7-ol maleate) (Schering Corp., U.S.A.), S(-)-sulpiride (Research Biochemicals Inc., U.S.A.), dynorphin A-0-13) (Peptide Institute Inc., Japan) and Mr 2266 ((-I(lR,5R,9R)-5,9-diethyl-2-(3-furyl-methyl)-2’-hydroxy6,7-benzomorphan) (Boehringer Ingelheim KG, Germany) were used throughout. Methamphetamine was dissolved in isotonic saline (0.9% NaCl, pH 7.5). Mr 2266 was dissolved in 1.0 ml 5% w/v ( f )-tartaric acid and the volume was made up with 0.9% saline. The vehicle for SCH 23390 and SC-)-sulpiride was 8.5% lactic acid and 1.0 N sodium hydroxide in a 3 : 2 ratio. Methamphetamine (s.c.), SCH 23390 (i.p.1, St-)sulpiride (i.p.1 and Mr 2266 (s.c.1 were administered 40, 75, 75 and 30 min before the start of behavioral observations, respectively. Dynorphin A-(1-13) dissolved in sterile isotonic saline in polypropylene containers was injected i.c.v. 25 min before the start. The unilateral injection site was 2 mm from either side of the midline on a line drawn through the anterior roots of the ears (Haley and McCormick, 1957). The injection was made with a 4-mm long needle attached to a 50-~1 Hamilton microsyringe. The needle was inserted perpendicularly through the skull and into the lateral ventricle of the brain. The mouse was anaesthetized locally with XyloCaine (8% lidocaine) spray (Fujisawa Pharmaceutical
9
Co., Ltd., Osaka, Japan). Solutions were injected in a volume of 10 ~1 per mouse over a period of 20 s as previously described (Kameyama and Ukai, 1981; 1983). The site was checked by injecting a 1: 10 dilution of India ink in isotonic saline (0.9% NaCI, pH 7.5). Histological examination revealed particles of ink in the lateral and 3rd ventricles but not in the others. As previously described (Kameyama and Ukai, 19831, neither insertion of the needle nor injection of 10 ~1 of isotonic saline solution had a significant influence on behaviors as measured by multidimensional behavioral analyses. 2.4. Data analysis
The actual values were analyzed statistically by means of a one-factor analysis of variance (ANOVA). Post hoc analysis for betweenigroup differences was carried out by the Newman-Keuls method for multiple comparisons (Zar, 1984). -Effects were considered statistically significant if P < 0.05. The data in figures indicate ratios derived from actual values for clearer presentation of the results.
3. Results 3. I. Effects on behavioral traces
The traces in A and B in the upper left-hand part of fig. 1 indicate horizontal and vertical movements, respectively. SCH 23390 (0.03 mg/kg i.p.), S(-I-sulpiride (10.0 mg/kg i.p.), dynorphin A-cl-131 (12.5 pg i.c.v.1,
Mr 2266 (5.6 mg/kg s.c.) and their combinations had no marked effects on the behavioral traces (fig. 1). Methamphetamine (1.0 mg/kg s.c.) produced a marked increase in both horizontal and vertical movements. Not only dynorphin A-cl-131 (12.5 pg i.c.v.1 but SC-)sulpiride (10.0 mg/kg i.p.) also, unlike SCH 23390 (0.03 mg/kg i.p.1, antagonised the methamphetamine (1.0 mg/kg s.c.)-induced increase in vertical movements. In contrast, the increase in horizontal movements induced by methamphetamine (1.0 mg/kg s.c.) was maikedly enhanced by dynorphin A-Q-13) (12.5 pg i.c.v.1. The effects of dynorphin A-(1-13) (12.5 pg i.c.v.1 on the two components of movements induced by methamphetamine (1.0 mg/kg s.c.) were fully antagonized by Mr 2266 (5.6 mg/kg s.c.) which alone did not markedly affect horizontal or vertical movements (fig. 1). 3.2. Effects of methamphetamine
Methamphetamine (0.3-3.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing and/or grooming behaviors, although a 0.1 mg/kg dose of the drug failed to affect the behaviors (fig. 2A). However, the patterns of circling induced by methamphetamine were qualitatively similar to those observed in mice treated with 0.9% saline (i.c.v.1. 3.3. Effects of dopamine antagonists phetamine-induced behaviors
on metham-
SCH 23390 (0.01 or 0.03 mg/kg i.p.1 (fig. 2B) or S(-)-sulpiride (3.0 or 10.0 mg/kg i.p.1 (fig. 2C) had no significant effects on the behaviors, whilst a l.O-mg/kg
MAP * SAL
u¶P * SUL
UslAp. DYN
W
+ Mr2266
t SAL
K4P
l
Hr2266
. DYN
Fig. 1. Behavioral traces for each of the mice treated with SCH 23390, St-I-sulpiride, dynorphin A-(1-13), methamphetamine, Mr 2266 or their combinations within 15-30 min after the start of behavioral measurements. Top left-hand part of the figure shows: A, cagebottom; B, cage walls; SAL, 0.9% saline S.C. and i.c.v.; SCH, SCH 23390 0.03 mg/kg i.p.; SUL, S(-)-sulpiride 10.0 mg/kg i.p.; DYN, dynorphin A-(1-13) 12.5 kg/mouse i.c.v.; Mr 2266 5.6 mg/kg S.C.and MAP, methamphetamine 1.0 mg/kg S.C.
Linear IommoUon
Circling
Rearing
Grooming
20 72
(B)
Linear lommotion
Linear locomotion
Circling
Rearing
Grooming
Fig. 3. Movements of mice after the administration of methamphetamine (MAP) (1.0 mg/kg s.c.), dynorphin A-cl-131 (DYN) (12.5 pg i.c.v.) or their combinations. - - - Saline S.C.+ saline i.c.v.; q saline s.c.+ DYN 3.0 pg i.c.v.; •U saline S.C.+DYN 12.5 pg i.c.v.; 0 MAP 1.0 mg/kg s.c.+saline i.c.v.; q MAP 1.0 mg/kg S.C.+DYN 3.0 pg 1.c.v.; q MAP 1.0 mg/kg s.c.+DYN 12.5 pg i.c.v. Values represent the meansfS.E. for 10 mice. Significant difference from saline control, *P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.) alone, ’ P < 0.05.
Circling
Rearing
Grooming
0.03 mg/kg i.p.> (fig. 2B), inhibited the methamphetamine (1.0 mg/kg s.c.)-induced increase in behaviors. 3.4. Effects of phetamine-induced
dynorphin behaviors
A-(1-13)
on
metham-
Methamphetamine (1.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing
Linear lowmolion
Circling
Rearing
Grooming
Fig. 2. Movements of mice after the administration of methamphetamine (MAP) (0.1, 0.3, 1.0 and 3.0 mg/kg s.c.) alone (A), MAP (1.0 mg/kg s.c.) plus SCH 23390 (SCH) (0.01 and 0.03 mg/kg i.p.1 (B) and MAP (1.0 mg/kg s.c.) plus S(-)-sulpiride (SUL) (3.0 and 10.0 mg/kg i.p.) (C). (A) --Saline s.c.; t?dMAP 0.1 mg/kg s.c.; •t MAP 0.3 mg/kg s.c.; 0 MAP 1.0 mg/kg s.c.; S MAP 3.0 mg/kg S.C. (B) - - - Saline s.c. +saline i.p.; tZt saline S.C.+ SCH 0.01 mg/kg i.p.; GUIsaline s.c.+SCH 0.03 mg/kg i.p.; 0 MAP 1.0 mg/kg s.c.+saline, i.p.; q MAP 1.0 mg/kg s.c.+SCH 0.01 mg/kg i.p.; 8 MAP 1.0 mg/kg s.c.+SCH 0.03 mg/kg i.p. (0 --saline s.c.+saline i.p.; gt saline s.c.+SUL 3.0 mg/kg i.p.; III saline s.c.+ SUL 10.0 mg/kg i.p.; 0 MAP 1.0 mg/kg s.c.+saline i.p.; q MAP 1.0 mg/kg s.c.+SUL 3.0 mg/kg i.p.; 8 MAP 1.0 mg/kg S.C.+SUL 10.0 mg/kg i.p. Values represent the means* S.E. for S-10 mice. Significant difference from saline control, *P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.) alone, ‘P < 0.05.
S.C. dose of methamphetamine again produced a marked increase in linear locomotion, circling, rearing and grooming (fig. 2BC). S(-)-Sulpiride (3.0 and/or 10.0 mg/kg i.p.3 (fig. 2C), but not SCH 23390 (0.01 or
Linear locomotion
Cirding
Rearing
Grooming
Fig. 4. Movements of mice after the administration of methamphetamine (MAP) (1.0 mg/kg s.c.), dynorphin A-(1-13) (DYN) (12.5 Fg i.c.v.), Mr 2266 (5.6 mg/kg s.c.) or their combinations. - - Saline S.C.+saline S.C.+saline i.c.v.; r?~ saline s.c.+ Mr 2266 5.6 mg/kg S.C.+saline i.c.v.; •tl saline s.c.+saline S.C.+DYN 12.5 pg i.c.v.; 0 saline S.C.+ Mr 2266 5.6 mg/kg S.C.+ DYN 12.5 pg i.c.v.; q MAP 1.0 mg/kg s.c.+saline S.C.+saline i.c.v.; KI MAP 1.0 mg/kg s.c.+Mr 2266 5.6 mg/kg s.c.+ saline i.c.v.; q MAP 1.0 mg/kg s.c.+saline s.c.+DYN 12.5 pg i.c.v.; 0 MAP 1.0 mg/kg s.c.+Mr 2266 5.6 mg/kg s.c.+DYN 12.5 pg i.c.v. Values represent the meansfS.E. for 10 mice. Significant difference from saline control, *P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.) alone, ‘P < 0.05. Significant difference from MAP (1.0 mg/kg s.c.)+ DYN (12.5 pg i.c.v.), s P < 0.05.
11
and grooming behaviors, although dynorphin A-(1-13) (3.0 or 12.5 ,ug i.c.v.) alone did not affect the behaviors (fig. 3). The peptide (12.5 pg i.c.v.) had an inhibitory effect on the methamphetamine (1.0 mg/kg s.c.)-induced increase in rearing behaviors (fig. 3). In contrast, the increase in circling behaviors induced by methamphetamine (1.0 mg/kg s.c.) was markedly enhanced by dynorphin A-(1-13) (12.5 pg i.c.v.), although the increase in grooming behaviors remained unchanged (fig. 3). In addition, the circling behaviors were ipsilateral to the side injected. 3.5. Effects of Mr 2266
The effects of dynorphin A-(1-13) (12.5 pg i.c.v.) on the methamphetamine (1.0 mg/kg s.c.)-induced behavioral changes were almost completely reversed by Mr 2266 (5.6 mg/kg s.c.), although Mr 2266 (5.6 mg/kg s.c.) alone did not affect any behavioral patterns (fig. 4).
4. Discussion It has been reported that the apomorphine (0.56 and 1.0 mg/kg s.c.)-induced increase in rearing behaviors is completely inhibited by dynorphin A-(1-13) (10.0 pg i.c.v.) (Ukai et al., 1989a). Additionally, dynorphin A-(1-13) (3.0 and 12.5 pg i.c.v.) has been shown to produce an inhibitory effect on the RU 24213 (3.0 mg/kg s.c.)-induced increase in linear locomotion and circling behaviors (Ukai et al., 1992). In contrast, this peptide (3.0 or 12.5 pg i.c.v.) did not affect the behavioral effects induced by the dopamine D, receptor agonist, SKF 38393. These findings suggest that Kopioid peptides play an inhibitory role in the behaviors induced by the selective activation of dopamine D, receptors. In the present study, methamphetamine (1.0 mg/kg s.c.) produced a marked increase in linear locomotion, circling, rearing and grooming behaviors. The behavioral effects of methamphetamine (1.0 mg/kg s.c.) seem to be indirectly mediated through dopamine D, receptors, since the selective dopamine D, receptor antagonist, S(-)-sulpiride, unlike the selective dopamine D, receptor antagonist, SCH 23390, fully antagonized the effects of methamphetamine. In addition, the effects of higher doses of SCH 23390 were not examined in the present study because, at doses over 0.03 mg/kg, the antagonist has an inhibitory effect on behaviors induced by the dopamine D, agonist, RU 24213, in mice (unpublished data). Dynorphin A-(1-13) (3.0 or 12.5 pg i.c.v.) alone did not produce any significant effects on the behaviors, whereas the peptide (12.5 pg i.c.v.) caused an inhibitory effect on the methamphetamine (1.0 mg/kg
s.c.)-induced increase in rearing. In contrast, the increase in circling behaviors induced by methamphetamine (1.0 mg/kg s.c.) was markedly enhanced by unilateral dynorphin A-(1-13) (12.5 pg i.c.v.). Additionally, these behaviors were ipsilateral to the side injected. However, the bilateral administration of dynorphin A-(1-13) (12.5 pg i.c.v.) has been shown to produce an inhibitory effect on the methamphetamine (1.0 mg/kg s.c.)-induced increase in circling (unpublished data). These observations indicate that dynorphin A-(1-13) inhibits the behavioral activation through the mediation of dopamine D, receptors, resulting in the increase in circling ipsilateral to the side injected. Since the present results indicate that the unilateral injection of dynorphin A-(1-13) (12.5 pg) increased circling in response to methamphetamine and decreased rearing, it is possible that the behavioral interaction between circling and rearing is merely reciprocal. However, the bilateral injection of dynorphin A(1-13) inhibits circling without influencing rearing (unpublished data), suggesting that dynorphin A-(1-13) specifically inhibits circling due to methamphetamine. The site of dynorphin A-(1-13) action for the inhibitory effects on methamphetamine-induced behaviors seems to be postsynaptic in the brain, because dynorphin A-(1-13) fails to affect the decrease in behaviors induced by a presynaptic dose of apomorphine (unpublished data) and the intrastriatal injection of dynorphin A-(1-13) inhibits the behavioral sensitization induced by a lower dose of apomorphine in 6-hydroxydopamine-treated mice (Toyoshi et al., 1992). The effects of dynorphin A-(1-13) (12.5 pg i.c.v.) were fully reversed by the opioid antagonist, Mr 2266 (5.6 mg/kg s.c.). Our previous study has demonstrated that the increase in linear locomotion, circling, rearing and/or grooming behaviors induced by the dopamine D, receptor agonist, RU 24213 (3.0 mg/kg s.c.) is almost completely inhibited by the CL-opioid agonist, DAMGO ([D-Ala2,NMePhe4,Gly5-ollenkephalin) (0.003 and/or 0.01 pg i.c.v.), and dynorphin A-(1-13) (3.0 and/or 12.5 kg i.c.v.), but not by the &opioid agonist, DPLPE ([D-Pen*,L-Pen5]enkephalin) (0.3 or 1.0 pg i.c.v.) (Toyoshi et al., 1991). The effects of DAMGO are reversed by the p-selective alkylating agent, p-funaltrexamine (Toyoshi et al., 1991), although the effects of dynorphin A-(1-13) are insensitive to the agent (unpublished data). These findings suggest that dynorphin A-(1-13) plays an inhibitory role in behaviors induced by the indirect activation of dopamine D, receptors through the mediation of Kopioid receptors. There is, however, a discrepancy concerning the behavioral effects of dynorphin A-(1-13) on dopamine D, receptor-related behaviors. For example,mdynorphin A-(1-13) enhanced methamphetamine-induced circling in the present experiments and conversely was found to
12
decrease RU 24213-induced circling (Ukai et al., 1992). Although there is not yet a clear-cut explanation for the discrepancy, the neuropharmacological difference between methamphetamine and RU 24213 may play a role in the effects of dynorphin A-(1-13). Particularly, it has been reported that methamphetamine, unlike RU 24213, affects neuronal systems other than dopamine neurons (Cooper et al., 1991). In view of the various findings, dynorphin A-O-13) may be useful for the development of potentially effective drugs in the treatment of schizophrenic patients, because the amphetamine- or methamphetamine-induced behavioral model appears to be appropriate for the experimental study of schizophrenia (McKinney, 1988).
Acknowledgements The authors thank Boehringer Ingelheim KG and Schering Corp. for the generous gifts of Mr 2266 and SCH 23390, respectively. We also thank Tetsuya Kobayashi for secretarial assistance.
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