EJP 57771

Antiepileptic effects of CN 6024 a novel thyrotropin-releasing hormone analog, on absence-like and tonic seizures of spontaneously epileptic rats Xie

Renming, Kumatoshi Ishihara, Masashi Sasa, Hisamitsu Ujihara, Toshihiko Momiyama, Yasuhiko Fujita, Naoyuki Todo, Tadao Serikawa “, Junzo Y:lmada ” and Shuji Takaori

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Received IO June IYYZ. revised MS rrceivsd 75 August 1901. accepted1 Seplemher lYY7

The cffccts of CNK-602A IN~[~6-mcthyl-S-oxo-3-thiomorpholinyl~ carhonyll-L-histidyl-L-prolinamido). a novel thyrotropin-rclcasing hormone rclatcd analog. wcrc invcstigatcd on abscncc-like scizurc and sonic convulsion in the spontanconsly epileptic rat ISER), which is :I gcncticaliy dcfincd double-mutant. When CNK-6O2A of 0.2-l mg/kg was given intravenously to the animal, thcrc wcrc no changes in the background EEG cxccpt for an incrcasc in low-voltage fast waves concomitant with behavioral alcrtncss. Howcvcr. CNK-602A supprcsscd ahscncc-like scizurc and tonic convulsion in a dose-dcpcndcnt manner for oc’cr I IL Thcsc anticpilcptic cffccts of CNK-6OiA on hoth scizurcs wcrc antagonized by prctrcatmcnt with halopcridol (I mg/kg. i.p.). It was found, using iI brain in viva microdialysis method. that CNK-WA at a dose of I mg/kg, which inhihits the scizurcs. incrcnscd the rclcasc ofdopaminc in the caudatc nucleus. Thcsc results suggest that CNK-602A inhibits the seizures of SER in a similar manner to thyrotropin-rclcasing hormone (TRH), prohahly hy increasing the rclcnsc of dopaminc in the central nclvous system. In addition. ~hc anticpilcptic cffccts of CNK402A wcrc more potent and I;l:itcd iongcr than those r:l’ TRI 1.

Sponlancously

cpilcptic rat (SER); Thyrotropin-rclcasing hormone a~nalogs:

1. Introduction

Thyrotropin-releasing hormone (TRH) and its rcarc known to be widely distrihutcd in the central nervous system (Winokur and Utigcr, 1974; ccptors

Manaker et al., 10X5; Mantyh and Hunt, 1c)HSI . TRH is also known to modulate the rcleasc of ncurotransmitters such as dopamine and noradrenaline (Horita ct al., 1086; Lamour ct al., 1085; Takatani et al., 1087: Keller et al.. 1074). In addition, TRH rcportcdly has anticpilcptic activity in cxperimcntal animals, such as the kindling model of epilepsy C&to et sl., 1084: Sakai ct al., 1991), as well as in human epilepsy, such as the Lennox-Gastaut syndrome (Ucda ct al., IOX3) and scvcrc childhood epilepsy !Matsumoto et al., 1087). Prcviously, we also found that TRH supprcsscd abscncclike scizurcs and tonic convulsions in the spontu-

C’orrcspondcncc to: M. SilSiIa Dep;u?tncnt Al’ I’ll;lrln;lrology. r(jshitn;l University School ol’ Mcdicinc, Iliro41in~ 7.34. J;I~xII~.

I li-

C’NK-WA;

Anticpilcptic

cl’f’cct; Dnpaminc

ncously cpilcptic rat (SER) (Ujihara ct al.. 1991). This animal is a gcnctically defined double mutant (zi/zi, Im/tm) and is useful for the evaluation of anticpilcptic action of the drugs, since cthosuximide and trimcthadion suppress absence-like scizurc and phcnytoin inhibits tonic convulsion:;, while valproatc and phcnobarbital suppress both types of scizurc in this animal (Scrikawa and Y:;mada. 19x6; Sass cl al., 1988). However, tbc effects of TRH arc weak and short, compared with those of conventional anticpilcptics. prob;lbly due to the fast metabolism ot this drug. TRH itnalogs. QN-1417 and YM-14073. wcrc reported lo h::vc a more potent and longer action on scizurcs in the kindled animal than did TRH (S:tto ct al., 1084: Yatsugi and Yalllilnlol0, 1091). Thcrcforc. wc cxamincc! tiic cftccts of a novel TRH analog, CNK-hO2A (N-[(O-methyl-Soxo-.3-thiomorpliolinyl)carbonyl]-L-histidyl-L-pr~~linilmidc), on cpilcptic seizures in SER. Furthcrmorc, using an in viva Inicrodialyhis nettled, WC attcmptcd to dctcmminc whcthcr or not the cffu% of CNK-hO2A arc due to an increase in the rcleiisc 01 dopitt?litlc.

2. Mlterinfs

and nlrtheds

2. i. :flr.‘rt!rrh SEK

wcrc hrcd in our instilutc

iIs :q3orU

prcvi-

oualy (Scrikawa and Yi~m;d;~. 19Hh). ‘fhc anirnds kcpr individually

in shot-box

wcrc’

type cages in the animal

7’ WC and 5O--h5% humidity. Commcrquartcrs al __-_ cial fooJ pcflcts (F-_.7 f%naflashi f“arm. Japiln) rlnJ wrrtcr wcrc y&n id fibitum. ‘l’hc room hild 12-h lightdark. with lights on from X:(HI to 2O:OOh.

Under urcthanc (I.5 g/kg $1 ancsrhcsia. the SEK wHS fixed in the stcrcotaxic i\pparatus. and it microdialysis pmhc with a dialyzing mcmhranc 2.0 mm in length

and 0.S mm in diamctcr (CMA/fO.

Carncgic Mcdicin.

Swcdon) was then insertcd stcnanaxicafly &tc

into \hc au-

nucleus (P. 0.3: I,. 3.0; H. 5.0 from cortical SUT-

filcc) (Paxinos and Watson. IWO). Kingcr solution was continuously pcrfuscd ill a flow t?llC of 2 pf/min. using im injection pump (CMA/ J-en m;blc and twclvc fcmnlc SF.K wcrc USC~ for the EEC, cupcrimcnl. Under sadium pcntihiirl~ital iIllCS(llcSiia [_30

mg/kg

i.p_1.

il

sifvcr

hall-tippcd

and an cn;m~cl-~OillCJ SlilinlCsS-SbXl &rrrrlically

into

impfilntCd

clcctrodc

clcctrodc

rllc ICfr flIMltill cortcs

wcrc’ illld

tor iI stabilization callcctcd

Io[), Carncgic Mcdicin).

Af-

period of over I h. the didysatc

wils

cvcry 20 min using il microsamplcr

200. Carncgic Mcdicin). for

I h and thcrcaftcr the drug was injcctcd into the f3ICll dialysis Silmpk WZi automatically

Cillldill vein.

from hrcpma).

injcctcd into HPLC.

using iIn injcclion

rcspcctivdy. according to the iIlliIs c)f Paxinos id Watson ( IOXh). An indiffcrcnt &Xtrodlc WJS placed on

UAS. Japan). Afkr

separation

cholamincs

ihc frt)nl;ll

tcclor

I&t

hippttciimpus

(P.

1.5:

1,. 2.41: kj.

2.5

cranium.

Scvcn days ;rftcr implantation of Ihc clcclrodcs. each animal was placed ill iI sk)und-altcnuittcd BOX (40 x 40 x 40 cm) with ;I small window for olwx-ving t!lc 5sh;lvior of tfic animal ;tnd recording the EEG

(CMA/

B~~slrl rclctlsc wiis dctcrmincd

pump (PM-ho,

of the sample

catc-

wcrc dctoctcd with an elcctrochcmical

(LC-46,

RAS.

Jitpan).

dopaminc and its mcldditcs

and

the

contents

dcof

wcrc rhcn rccordcd in

thu chr~m~a~ogriun. 7%~’ dopaminc peak was t;ofcd 3.X min ihfkr injection.

with a pen-writing pr~lygraph (Nihtm Kohdcn. KMfQOII). Frcqucncy ilnillysis of’ EEG wits done using ;I trend

monitor

(Nihon

Kohdcn.

OEE-7102).

‘fhc

‘f’hc numb

of scizurcs

and the duration

of catch

recording prtlccdurc for fhc EEG itnLl the method of ;ipplic;ltion of !hc drugs wcrc similar to Ihosc dcscrihcd

scizurc wcrc nntcd for 5 min. and the Iotal duration of

previously (Ujiharn ct al.. IV11 1. Hricfly. ‘f’hc frcqucncy of the occurrcncc of ahscncc-like sburcs and tonic convulsions. as well ils the duration of cilch scizurc. wcrc mcasurcd on lhc EEG. sine the chibngcs in l+G

WiIS then Ci~lCUl~tCd cvcry 5 min before and after injection of the drug. ‘I‘hc mc;Ln total duration of

during

the

abscntdikc

scizurc

and tonic convulsion

alwitys cr)rrclihtcd with the rcspcclivc hchavitrrnl changes. as dcscrihcd previously (SilsiI Ct al.. I98H). When

;I S-7

Hz

spike-wavefikc

the sciznrcs

(summation

of duration

of each scizurc)

sci7urrs during il S-min grcriod WilS CiliCUliltCd hy IIVCTilgillg h! V;dll~s ohtilind CVCly 5 min (1S- IO, 10-S ilnd S-0

min hcforc drug administration).

CllilIlgCS ilftcr

drug idministr;dion

The pcrccnt

wcrc tIlliS d~lihN!d

from the mean value.

complch in corlicitl

and hipptwitmpid EEG fiislcd for (:vcr I S, this wits regarded as an ahscncc-liks scizurc. I’hc compfcxcs with ;I short lime interval (Icss than I s) bctwccn two spike-wavefikc compfcxcs WC’T(: rcgardcd its iI sin& scizurc. ‘I’0 iriilucc an arousal state and ;I consistsnl

CNK-602A

ionic scizurc. cacli animal rcccivcd a mild tiu3ilc slimu-

CO

CONI+

lus on the hack cvcry 5 min. One dose of CNK-MEA was injcclcd (i.v.1 inlo the tail vein of each zlnirnal. alone or in combnation with halopcridol (i.p.1. l’hc second &)SC trf CNK-OOZA or Ihc comhinittian wits given to rhc animal at Icast I week after the final in,iicction. CNK-ho3A or hillopcridol WBF injcctcd after

30 min

reading of it control EEG following I-h hahiiuabon of the imimi lo the box. When CNK4I12A

wils lipplied in combination with hEA wiIS administcrcd 3O min

h&~pcridol. CNKirflcr itljcclion of

TRH

0

C3NHa H

IS7

The pcrccnt change in dopaminc rclcasc induced by CNK-MEA

or TRH

was obtained by dividing the value

after drug treatment

by the basal rclcasc for the I-h

period before drug injection.

CNK-601A (1 mg/kg) was dctcrmincd by Student’s t-tat. Antagonism by haloperidol of the effects 01 CNK-MEA statistical

was dotermincd significance

with Student’s

t-test. ‘l‘hc

of increases in the rclcasc of

dopaminc was compared with the value bcforc drug administration using ;1 paired t-test. The statistical significance of the diffcrcncc between the means of the total duration saline-treated wits

dctcrmincd

(ANOC’A! significance

for the physiological

group and the CNK-607A-trcatcd by

one-way

followed by Student’s of the time

analysis

of

t-test. The

group variance

statistical

course of the inhibition

A Conrrof

CNK-602A

lmglkg i.v. ldmin

-0-1

6 Control Cl

t

s

CNK-602A

lmg/kg i.v. 15min

by

CNK-hO2A

(Nippon

Shinyaku.

Kyoto.

Japan; CG-

370.7, Gruncnthar. GmbH, Aachcn, F.R.G.. fig. I) was dissolved in saline and injected into the caudal vein iit doses of 0.04, 0.2 and 1 mg/kg with ;1 volume of 0.1

or gr(~oming. No ~ilt~r~lti(~ns of b~ckgr~)un~ EEG obscrvcd with 1 mg/kg of the drug. Tahlc 1 shows the offccts of CNK-602A i.v.1 on abscncc-like scizurcs

male itnd female SEK.

and fcmafc SEfi

Inhibitory

-fXH

like seizures

f(JgiciIf saline was itIS~x!cI> Md.

vicwb ol 0.

I IO.

ItIc

all;l~og(I)N_lJ17) ,111 hI* 31.

K. Ifl;lllil!il. IOHZ.(‘linkil

Cl’lCCIhOl 7 RI

1

I.~mIox syndrome. .I. J:IP. ~Pilcp~Y SOL

Antiepileptic effects of CNK-602A, a novel thyrotropin-releasing hormone analog, on absence-like and tonic seizures of spontaneously epileptic rats.

The effects of CNK-602A (N-[(6-methyl-5-oxo-3-thiomorpholinyl) carbonyl]-L-histidyl-L-prolinamide), a novel thyrotropin-releasing hormone related anal...
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