Effect of selective monoamine oxidase A and B inhibitors on footshock induced aggression in paired rats.

Effects of a selective monoamine oxidase (MAO)--A inhibitor, clorgyline, a selective MAO-B inhibitor, deprenyl, and a non-selective MAO inhibitor, nialamide, were investigated on footshock-induced aggression (FIA) in paired rats. The doses and pretreatment times of the inhibitors used were based on an earlier reported in vivo dose-response and time-course study. In addition, apomorphine, a dopaminergic receptor agonist, and beta-phenylethylamine, a preferred substrate for MAO-B, were also used to garner corroborative evidence. The results of the study indicate that selective MAO-A inhibitors are likely to attenuate FIA by augmenting central serotonergic activity, while selective MAO-B inhibitors accentuate the behaviour by facilitating dopaminergic activity. A permissive role for noradrenaline could not be delineated by the available data.

Investigation of some effects of levamisole on dog blood pressure.

The effects of levamisole were investigated on the blood pressure of anaesthetized dog. Levamisole (0.5 to 4.0 mg/kg) elicited a biphasic effect, an initial brief depressor response followed by a pressor response. The pressor response was dose-related and was blocked by phenoxybenzamine. The residual depressor response was blocked by propranolol. Repeated administration of a high dose of levamisole produced tachyphylaxis. The pressor response to levamisole was not modified by either reserpinization, acute bilateral adrenalectomy or pretreatment with cocaine, whereas pretreatment with dexamethasone, nialamide or pyroaallol shifted the dose-response curve to the right. Levamisole potentiated the pressor responses to noradrenaline, angiotensin and acetylcholine. The effects of levamisole are ascribed to inhibition of monoamine oxidase, catechol-O-methyl transferase, catecholamine uptake2 mechanism and cholinesterase.