An analysis of the gross behavioural changes induced by tetraethylammonium and a comparison with other substances affecting the autonomic and central nervous system after intraventricular injections to conscious cats

Abstract

Tetraethylammonium (TEA) in doses from 0.2 to 3.0 mg (0.016–0.24 m, in volumes of 0.1–0.2 ml) injected intraventricularly in conscious cats caused emotional behaviour, autonomic changes and motor phenomena, as well as clonic-tonic convulsions. The gross behavioural effects of various single doses of TEA are dose-dependent. Atropine and scopolamine, when injected intraventricularly, abolished the emotional behaviour, but did not antagonize the autonomic and motor changes nor the clonic tonic convulsions of intraventricular TEA. Ganglionic and neuromuscular blocking agents, adrenergic blocking drugs, a 5-hydroxytryptamine antagonist, an antihistamine, antiepileptic drugs, calcium chloride, magnesium chloride, chlorpromazine, glycine and noradrcnaline, failed to block the gross behavioural effects of intraventricular TEA. It is concluded that the emotional behaviour caused by intraventricular injections of TEA in conscious cats is mediated through central muscarinic cholinoceptive sites. probably by enhanced release of acetylcholine. On the other hand, the autonomic changes, motor phenomena and convulsions elicited by TEA are most likely the consequence of its direct actions on the nerve cells. The gross behavioural changes of other substances affecting the autonomic and central nervous system, when injected intraventricularly can be classified into three groups. In the first group hexamethonium, nicotine, (+)-tubocurarine, gallamine, atropine, scopolamine and propranolol evoked excitant behavioural changes similar to those of TEA. Antazoline and magnesium chloride elicited excitant autonomic and motor phenomena followed by sedation and sleep. Finally, noradrenaline and calcium chloride produced only depressant behavioural effects.