Psychopharmacoiogy 54, 241
Psychopharmacology
242 1977)
9 by Springer-Verlag 1977
Passive Avoidance Learning in the Rat as Functions of d-Amphetamine Dosage and Shock Intensity DEBORAH LEVY SELIGER Department of Psychology, Rutgers
The State University, Camden, New Jersey~ U.S.A.
Abstract. The effects of d-amphetamine dosage (0, 1, 3, and 5 mg/kg) and shock intensity (0.2, 0.5, and 0.8 ma) on the learning of a passive avoidance response were assessed in rats. A curvilinear dose-response relationship was found at al! shock levels, showing slower learning under moderate doses of d-amphetamine. The lowest shock level produced slower learning, especially in conjunction with the lowest dose of d-amphetamine. Results are discussed in terms of freezing behavior.
passive avoidance 1earning at all shock levels, presumably through the mechanisms of increased activity and reduced freezing, and that high doses of the drug would facilitate such behavior, presumably through the mechanism of amphetamine stereotypy. It was also hypothesized that increased shock would facilitate passive avoidance performance, presumably through the mechanism of increased freezing, thereby making it easier for the animai to withhold an active response.
Key words: d-Amphetamine -
Passive avoidance learning - Shock intensity - Freezing behavior
MATERIALS AND METHODS Subjects. The experimental animals were 96 male Sprague-Dawley
Although moderate doses of d-amphetamine have been shown to improve active avoidance (Stein, 1964; Kulkarni, 1968), these same moderate doses have also been shown to impair passive avoidance learning (Seliger, !975). The primary interpretations of these results have been in terms of increased activity or the reduction of freezing behavior produced by d-amphetamine. Cicala and Kremer (1969) found that active avoidance learning was facilitated by d-amphetamine and inversely related to shock intensity. They state that their findings strongly supported those of Moyer and Korn (1964), who suggest that high levels of shock increase freezing tendencies, which impair active avoidance learning. The present study was an attempt to elaborate further the relationship between dosage of d-amphetamine and the learning of a passive avoidance response by varying levels of shock. It was hypothesized that moderate doses of d-amphetamine would impair Address for offprint requests': Dr. Deborah Levy Seliger, Department of Psychology, Rutgers--The State University, Camden, New Jersey 08102, U.S.A.
rats with an average weight of 307 g at the start of testing. They were housed individually in standard colony cages with food and water continuously avaiIable.
Apparatus. The apparatus for testing passive avoidance beha;v-ior followed that used by Seliger (I975). Current was supplied by means of a Lafayette Instrument Company Grid Scrambler, No. A615C, with the current set at 0.2, 0.5, or 0.8 ma.
Drug. Solutions of d-amphetamine in 0.9~ physiological saiine were prepared to yield dose levels of 1, 3, and 5 mg/kg body weight. Appropriate dosages were injected s.c. in a volume of 0.5 ml/I00 g body weight over a 30-s period. Animals in the control groups received only saiine injections of the same volume as the d-amphetamine animals. All animals were injected 45 min before a test trial.
Procedure. The 96 experimental animals were randomly placed into 12 treatment conditions. Forty-five minutes after injection the subject was placed on the low platform in the shock box. Daily training continued unti] the subject reached the criterion of remaining on the platform for an entire 5-min test period without receiving a shock.
RESULTS Analysis of variance indicated a high degree of significance for both factors, dosage ( F = i4.60; d f = 3/84; P < 0.01) and shock ( F ~ 22.77; dr= 2/84; P < 0.01). The interaction just fell short of significance (F = 2.02; dr= 6/84; P < 0.08).
242
Psychopharmacology 54 (1977) 0.2ma
o
9 0.5ma .8ma
Psychopharmacology
242 1977)
9 by Springer-Verlag 1977
Passive Avoidance Learning in the Rat as Functions of d-Amphetamine Dosage and Shock Intensity DEBORAH LEVY SELIGER Department of Psychology, Rutgers
The State University, Camden, New Jersey~ U.S.A.
Abstract. The effects of d-amphetamine dosage (0, 1, 3, and 5 mg/kg) and shock intensity (0.2, 0.5, and 0.8 ma) on the learning of a passive avoidance response were assessed in rats. A curvilinear dose-response relationship was found at al! shock levels, showing slower learning under moderate doses of d-amphetamine. The lowest shock level produced slower learning, especially in conjunction with the lowest dose of d-amphetamine. Results are discussed in terms of freezing behavior.
passive avoidance 1earning at all shock levels, presumably through the mechanisms of increased activity and reduced freezing, and that high doses of the drug would facilitate such behavior, presumably through the mechanism of amphetamine stereotypy. It was also hypothesized that increased shock would facilitate passive avoidance performance, presumably through the mechanism of increased freezing, thereby making it easier for the animai to withhold an active response.
Key words: d-Amphetamine -
Passive avoidance learning - Shock intensity - Freezing behavior
MATERIALS AND METHODS Subjects. The experimental animals were 96 male Sprague-Dawley
Although moderate doses of d-amphetamine have been shown to improve active avoidance (Stein, 1964; Kulkarni, 1968), these same moderate doses have also been shown to impair passive avoidance learning (Seliger, !975). The primary interpretations of these results have been in terms of increased activity or the reduction of freezing behavior produced by d-amphetamine. Cicala and Kremer (1969) found that active avoidance learning was facilitated by d-amphetamine and inversely related to shock intensity. They state that their findings strongly supported those of Moyer and Korn (1964), who suggest that high levels of shock increase freezing tendencies, which impair active avoidance learning. The present study was an attempt to elaborate further the relationship between dosage of d-amphetamine and the learning of a passive avoidance response by varying levels of shock. It was hypothesized that moderate doses of d-amphetamine would impair Address for offprint requests': Dr. Deborah Levy Seliger, Department of Psychology, Rutgers--The State University, Camden, New Jersey 08102, U.S.A.
rats with an average weight of 307 g at the start of testing. They were housed individually in standard colony cages with food and water continuously avaiIable.
Apparatus. The apparatus for testing passive avoidance beha;v-ior followed that used by Seliger (I975). Current was supplied by means of a Lafayette Instrument Company Grid Scrambler, No. A615C, with the current set at 0.2, 0.5, or 0.8 ma.
Drug. Solutions of d-amphetamine in 0.9~ physiological saiine were prepared to yield dose levels of 1, 3, and 5 mg/kg body weight. Appropriate dosages were injected s.c. in a volume of 0.5 ml/I00 g body weight over a 30-s period. Animals in the control groups received only saiine injections of the same volume as the d-amphetamine animals. All animals were injected 45 min before a test trial.
Procedure. The 96 experimental animals were randomly placed into 12 treatment conditions. Forty-five minutes after injection the subject was placed on the low platform in the shock box. Daily training continued unti] the subject reached the criterion of remaining on the platform for an entire 5-min test period without receiving a shock.
RESULTS Analysis of variance indicated a high degree of significance for both factors, dosage ( F = i4.60; d f = 3/84; P < 0.01) and shock ( F ~ 22.77; dr= 2/84; P < 0.01). The interaction just fell short of significance (F = 2.02; dr= 6/84; P < 0.08).
242
Psychopharmacology 54 (1977) 0.2ma
o
9 0.5ma .8ma
