BEHAVIOURAL CHANGES INDUCED BY N,N‐DIMETHYLTRYPTAMINE IN RODENTS

In rodents pretreated with pargyline, DMT caused a dose-dependent set of behaviors including hyperactivity, prostration, hindlimb abduction, mild tremor, Straub tail, retropulsion, and jerking. Unlike l-tryptophan or quipazine, DMT did not produce forepaw treading or head-weaving and caused only mild tremor. The hyperactivity component was potentiated by cyproheptadine, methergoline, and mianserin; inhibited by cinanserin, haloperidol, pimozide, methiothepin, and propranolol; and unaffected by 501C67-sulphate and methysergide. Other behavioral changes were mostly unaffected by these drugs, except propranolol reduced most effects and methergoline decreased prostration duration. Phenoxybenzamine and haloperidol enhanced prostration. DMT did not induce circling in mice with unilateral 6-hydroxydopamine lesions. The syndrome appears to have two components: hyperactivity, possibly mediated by dopamine, and other behaviors that are not.

Study at a glance

Abstract

N,N‐Dimethyltryptamine (DMT) in pargyline pretreated rodents induced a dose‐dependent behavioural syndrome consisting of hyperactivity, prostration and hindlimb abduction, mild tremor, Straub tail, retropulsion and jerking. In rats pretreated with pargyline, the behavioural syndrome induced by DMT differed from that induced by l‐tryptophan or quipazine, in the lack of forepaw treading and head‐weaving and in the presence of only mild tremor. The hyperactivity component of the DMT‐induced behavioural syndrome in pargyline‐pretreated mice was potentiated by cyproheptadine, methergoline, and mianserin, inhibited by cinanserin, haloperidol, pimozide, methiothepin and propranolol, and not affected by 501C67‐sulphate and methysergide. The maximal behavioural changes induced by DMT in rats, other than hyperactivity, were unaffected by pretreatment with cyproheptadine, methysergide, and cinanserin. However, propranolol reduced the intensity of all behavioural effects apart from body jerking, and methergoline decreased the duration of prostration. Phenoxybenzamine and haloperidol, in contrast, enhanced prostration. DMT plus pargyline did not induce circling behaviour in mice with a unilateral 6‐hydroxydopamine lesion of the nigro‐striatal pathway. The DMT‐induced behavioural syndrome appears to consist of two components, (a) hyperactivity and (b) other behavioural changes. They differ in their response to drugs affecting brain monoamines. The hyperactivity component may be expressed via dopamine mechanisms, but the other behavioural changes are not. The two behaviours do not respond consistently to drugs believed to alter brain 5‐hydroxytryptamine function.