Soundararajan Regunathan

Learn More
The possible inhibitory effect of prolactin on serum cholinesterase activity has been examined. Prolactin given to mice inhibited the enzyme's activity in a dose-related fashion. This inhibition was not reversed by naloxone. A significant correlation was observed between the anticholinesterase and analgesic activity of prolactin. The findings suggest that(More)
The activities of lipoyl dehydrogenase, aspartate transaminase, and alanine transaminase, and levels of lactate were estimated in cerebral cortex, cerebellum, and brainstem of rats intoxicated acutely with tetraethyl lead and chronically with lead acetate. A significant inhibition of lipoyl dehydrogenase was observed in both groups of animals, whereas(More)
Chemical changes in central glutamate neurotransmission were assessed by measuring synaptic membrane receptor binding, the uptake and release by synaptosomes of glutamate in rats treated acutely with tetraethyl lead and chronically with lead acetate. The activity of Na+, K+-ATPase in synaptosomes was measured to correlate with the changes in uptake/release(More)
Agmatine (l-amino-4-guanidino-butane), a metabolite of L-arginine through the action of arginine decarboxylase, is a novel neurotransmitter. In the present study, effects of agmatine on cognitive functions have been evaluated by using one trial step-down passive avoidance and three panel runway task. Agmatine (20, 40, 80 mg/kg i.p.) was administered either(More)
The effect of induction of adrenal tyrosine hydroxylase (TH) by various centrally acting drugs on catecholamine levels in adrenal and plasma was investigated in rats. All the drugs tested, namely oxotremorine, Piribedil, B-HT 920, and HA-966, produced significant increases in adrenal dopamine content and plasma epinephrine level. Denervation of the adrenal(More)
It has been previously demonstrated that nigrostriatal dopaminergic fibres participate in the neural regulation of the activity of adrenal tyrosine hydroxylase, specifically in its induction. To determine whether activation or inhibition of these fibres is responsible for this induction, the role of presynaptic dopamine receptors was investigated.(More)
?-Methylserotonin, an analogue of serotonin formed in vivo from ?-methyltryptophan, is able to stimulate phosphoinositide turnover (up to 190% of the basal rate) in slices of rat cerebral cortex in vitro. Desensitization of the cortical slices by ?-methylserotonin or serotonin significantly decreases serotonin-stimulated (but not norepinephrine-stimulated)(More)
We have assessed the effect of arginine vasopressin (AVP) on adrenal tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) activities. Both enzymes show marked increases after systemic administration of AVP in the range of 66 and 100 micrograms/day. To determine whether the pituitary gland plays a role in these inductions, the effect(More)
The synthesis of glutamate and its conversion to glutamine and GABA were studied using labelled glucose in cerebral cortex, cerebellum and brainstem of rats intoxicated acutely with tetraethyl lead and chronically with lead acetate. To assess the interconversion and the synaptosomal accumulation of these amino acids, the labelling of glutamate, glutamine(More)