Effects of phenobarbital on monoamine levels of rat brains and convulsion induced by procaine hydrochloride.

Abstract

The role of monoamines was examined by measuring noradrenaline(NA), dopamine (DA) and serotonin(5-HT) in brain of male albino rats weighing 200-250g administered with the hydrochloride of procaine at 190 mg/kg (i.p) and pretreated with phenobarbital at 25 mg/kg (s.c), producing 100% anticonvulsant action against procaine-induced convulsion. In addition, effects of doperminergic agents on procaine-induced convulsion in rats were invesigated, and the role of brain monoamines in the anticonvulsant action of phenobarbital against procaine-induced convulsion was examined. Brains were dissected into hypothalamus, midbrain (included striatum, hippocampus), cortex, cerebellum (included pons, medullaoblongata) according to Glowinsky. Brain monoamines analyses were carried out by high pressure liquid chromatography with electrochemical detection. The following results were obtained : 1) When convulsive doses of procaine hydrochloride were administered to the rats, an increase of NA, DA and 5-HT was observed in each of the brain regions, phenobarbital treatment caused a little increse of 5-HT and significant increse of DA. Procaine with pretreatment of phenobarbital caused a significant decrease of DA levels in cerebellum, compared to procaine treatment. 2) The onset time of procaine-induced convulsion was shortened apparently by pretreatment of L-DOPA (200mg/kg) and slightly by pretreatment of apomorphine (0.5 mg/kg). However, it was delayed markedly by pretreatment with haloperidol (5 mg/kg) and chlorpromazine (2 mg/kg). However, reserpine (5mg/kg) pretreated rats produced no effect. The results suggest that the anticonvulsant action of phenobar bital against procaine induced convulsion is dependent on deple tion of brain DA.