Suppressive Effects of Various Amino Acids Against Ouabain-Induced Seizures in Rats
Total Page：16
File Type：pdf, Size：1020Kb
THE CANADIAN JOURNAL OF NEUROLOGICAL SCIENCES is Suppressive Effects of Various Amino Acids against Ouabain-Induced Seizures in Rats Y. TSUKADA, N. INOUE, J. DONALDSON, and A. BARBEAU SUMMARY: The suppressive effect of thionic acid showed increases in inci INTRODUCTION various amino acids against ouabain- dence of running and leaping seizures induced seizures was investigated in while L-arginine in high concentrations Recent investigations on the young female rats. The amino acids caused aggravation in clonic-tonic biochemistry of convulsive seizures were injected into the left lateral ven seizures. L-cysteine, even in low concen have revealed the existence of ab tricle 10 minutes prior to the intra trations, also brought about an increase normalities in the metabolism or ventricular administration of 5 jj.g. of in the occurrence and incidence of brain content of various amino ouabain. Animals receiving 1.9 x 10A M clonic-tonic seizures. The ED^of hypo acids. For example, an accumulation solutions of hypotaurine and of fir taurine was 10.11 x 10~2 M for running 3, of alanine and decreased citrate alanine were almost completely protected seizures and 4.63 x 10- M for clonic- levels were observed in the precon from the ouabain seizures. Administra tonic seizures; that of fi -alanine was tion of L-alanine and of glycine was also 14.01 x 10~2 M for running seizures and vulsive stage; on the other hand, effective, although running and leaping 5.50 x 10-2 M for clonic-tonic seizures. GABA increased in rat brain during seizures still occurred to some extent. However, hypotaurine and fi-alanine, tonic seizures as well as during Betaine reduced only clonic-tonic and the most effective compounds tested in post-convulsive stages (Nahorski et whole body flexion and extension the present studies, provided less protec al, 1970). According to some au seizures. In contrast, L-proline exclu tion than taurine previously examined thors, electroconvulsive shocks sively suppressed clonic-tonic and focal by us under similar conditions (Izumi markedly inhibit the conversion of clonic seizures. Rats injected with ise- et al., 1973). 14C-glucose to amino acids and the incorporation of 14C into pro teins in mouse brain (Dunn and RESUME: Nous avons etudie I'effet ayant regu I'acide isethionique mont- Giudetta, 1971) and in rat neo- suppresseur de plusieurs acides amines rerent une augmentation de Yincidence cortical slices (Jones and Mcllwain, contre les convulsions induites par la des convulsions cursives et des sauts. 1971). These findings were chal ouabaine chez lajeune rate. Les acides La L-arginine, en forte concentration, lenged by others (Barkulis et al., amines furent injectes dans le ventricule aggravait les convulsion tonico- 1960; Orrego and Lipmann, 1967). lateral gauche 10 minutes avant Vad cloniques. II enfut egalement ainsi pour ministration intraventriculaire de 5/j.g. la L-cysteine, meme en faibles concen Recently, van Gelder et al. (1972) de ouabaine. Les animaux recevant des trations. La DEgo de I'hypotaurine est reported lower levels of GABA and solutions de concentration 1.9 x 10-1 M de 10.11 x 10~2 M pour les convulsions aspartic acid in all regions of epilep d'hypotaurine et de fi -alanine etaient cursives et de 4.63 x 10-2 M pour les tic human cortex sampled and lower presque completement proteges contre convulsions tonico-cloniques; celles de concentrations of glutamic acid and les convulsions induites. L'administra la fi-alanine sont de 14.01 x 10-2 M et taurine together with very high tion de L-alanine et de glycine etait de 5.50 x 10-2 M, respectivement. Ce- glycine levels in human cortical egalement efficace, meme si les de- pendant il faut noter que Yhypotaurine epileptic foci. Koyama (1972) ob charges cursives et les sauts etaient et la fi -alanine, les composes les plus served similar decreased concentra encore presents. La betaine ne reduisait efficaces dans la presente etude, offrent tions of taurine, glutamate, asparate que les convulsions tonico-cloniques ou tous deux une protection moindre contre celles se manifestant par une flexion et les convulsions induites par la ouabaine and GABA during the period pre une extension du corps. Par contraste, que la taurine que nous avions pre- ceding cobalt induced convulsions la L-proline supprimait exclusivement alablement etudie en detail (Izumi et al., in cats. However, Reynolds and Gal les convulsions tonico-cloniques oupure- 1973). lagher (1973) found neither changes ment cloniques localisees. Les rates in amino acid levels nor alterations of U-14C-glucose incorporation into amino acids during any of the stages of the seizure induced by Flurothyl. Department of Neurobiology, Clinical Research Some amino acids have been Institute of Montreal, 110 Pine Avenue West, shown to be neurotransmitter candi Montreal, Quebec, Canada. dates with inhibitory or excitatory Reprint address: Dr. Andre Barbeau, Clinical Research Institute of Montreal, 110 Pine Avenue functions. Micro-electrophoretic West, Montreal, Quebec, Canada H2W 1R7. techniques to substantiate this 214 - NOVEMBER 1974 Downloaded from https://www.cambridge.org/core. IP address: 170.106.33.14, on 30 Sep 2021 at 00:59:18, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S031716710001979X # LE JOURNAL CANADIEN DES SCIENCES NEUROLOGIQUES nypothesis were reviewed by Curtis administration of amino acid and sons of seizure incidence and of la and Crawford (1969). Uptake studies ouabain solutions which were in tency in onset of the first seizure. have been carried out in central jected through the cannula at a rate nervous system tissue or retina (Bal- of 25nl./min. Two different doses of RESULTS car and Johnston, 1973; Ehinger, each amino acid (9.5 x 10-2 M or 1.9 J Occurrence and incidence 1972; Kaczmarek and Davison, x 10 M) were administered 10 mi Pretreatment of the animals with 1972; Snyder, Young et al., 1973; nutes prior to the injection of 5^g. in hypotaurine (the main precursor of Snyder, Yamamura et al., 1973). 50 p.1. ouabain. Moreover, various taurine), /3-alanine, L-alanine and Finally, some authors have ap concentrations of hypotaurine and glycine caused a dose dependent de proached the problem with the help j3-alanine were used to investigate crease in seizure occurrence and in of autoradiography (Ehinger and median effective doses (ED50) for cidence (Tables 1 and 2). Test rats Falek, 1971; Iversen and Schon, running and clonic-tonic seizures. receiving hypotaurine at 10 minutes 1973). These investigations con The control animals received an in prior to the ouabain injection were cluded that 7-aminobutyric acid jection volume of 50 1. of buffered kept free from all seizure activities at (GABA), glycine, 0 -alanine and saline. The effects of amino acids high concentrations (1.9 x 10-1 M). taurine may be inhibitory neuro against the different types of Moreover, even in low concentra transmitters, while glutamic acid and ouabain-induced seizures previously tions (9.5 x 10-2 M), the compound aspartic acid have excitatory func described in rats (Izumi et al., 1973) completely suppressed clonic-tonic, tions. were observed for fifteen minutes whole body flexion and extension after the administration of ouabain. On the other hand, once recom seizures (WBFE), and to a lesser mended trials of treatment with Preparation of solutions extent, focal clonic seizures. This amino acids in human epilepsy no Ouabain solutions were prepared concentration of hypotaurine also longer appear useful today, except at a concentration of 5ju,g./50/il. in decreased the incidence of running possibly with gamma-amino-beta- warm 0.85% saline. The amino acids and leaping seizures. hydroxybutyric acid (GABOB) were dissolved in a NaCl solution Intraventricular administration of (Hahashi, 1972). Recently, however, containing 5 mM phosphate buffer, 1.9 x 10*1 Mf3 -alanine showed sig some antiseizure effects of taurine to obtain an osmotic pressure of 290 nificant protective effects against all have been reported (Barbeau and to 300 mosm. and the solutions were types of ouabain-induced seizures. Donaldson, 1974; Izumi et al, 1973; checked by osmometry. The pH of At low concentrations (9.5 x 10-2 M) van Gelder, 1972). van Gelder (1972) the amino acid solutions was ad the compound completely abolished first demonstrated the suppressive justed to 7.0-7.2. The control solu focal clonic and WBFE seizures and effect of taurine administered sys- tion contained 5mM. phosphate buf significantly decreased clonic-tonic temically against cobalt-induced fer in a NaCl solution. seizures. seizures in cat and mouse. Izumi et al. (1973) then found that the in Ouabain, betaine and isethionic Animals injected with high con traventricular injection of taurine acid were purchased from Sigma centrations of either L-alanine or revealed more marked antiseizure Chemical Co., glycine, L-alanine glycine were protected from WBFE, effects than GABA against ouabain- and L-arginine from California clonic-tonic and focal clonic seizures induced seizures in rats. Moreover, Biochemical Research, hypotaurine and to a lesser extent from running Barbeau and Donaldson (1974) re and L-cysteine from Calbiochem, and leaping seizures. Low concen ported that taurine also possessed L-proline from Nutritional Biochem trations of these two amino acids also anticonvulsant activity against cer ical Corporation and /3-alanine from completely suppressed WBFE and tain types of human epilepsy. Eastman Kodak Co. clonic-tonic seizures. Furthermore, glycine had some suppressive effect The present studies were carried STATISTICS against leaping and running seizures out to investigate the activity against at a low concentration. Administra Median effective doses (EDso ± 2 1 ouabain-induced seizures in rats of 95% confidence limits) of tion of 9.5 x 10- M or 1.9 x 10- M various amino acids, including some hypotaurine and /3 -alanine against betaine protected rats from WBFE precursors, a metabolite and various clonic-tonic and running seizures and clonic-tonic seizures only.