1
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. 2 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. 3 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. 4 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. 5 DMT plus
pargyline did not induce circling behaviour in mice with a unilateral 6-hydroxy-dopamine lesion of the nigro-striatal pathway. 6 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.