Abstract

Seventy-three rabbits were used for an electro-graphic analysis of the effects of bufotenin and 5-hydroxytryptophan (5-HTP). In animals with intact brains, both substances produced EEG alerting. In order to ascertain a site of EEG alerting, a series of transections immediately above the midbrain, below the midbrain or at the level of the first cervical vertebra were made. Drugs were administered via intracarotid and intravenous routes.

Bufotenin produced sustained alerting in animals transected at the first cervical segment after the drug-induced EEG alert pattern was evoked. However, the arousal reaction was abolished by transections caudad to the midbrain indicating an effective locus for bufotenin between these planes. In contrast, 5-HTP evoked alerting following transections posterior to the midbrain, while sections above the midbrain abolished the drug-induced arousal. Thus, a potent site of action for 5-HTP was found in the midbrain region. This EEG activation is ascribed to the accumulation of 5-HT in the mesencephalon-diencephalon area as previously noted by Costa etal. (1960).

In general, bufotenin and 5-HTP, which have similar chemical relationships in regard to the N,N-dimethyl group as do MP-809 and psiocin, have revealed similar differences in their loci of action in producing EEG alerting.