Opposite effects of intraventricular serotonin and bufotenin on rat startle responses.
Pharmacology, biochemistry, and behavior – January 01, 1975
Source: PubMed
Summary
In a study of rat startle responses, 5-hydroxytryptamine (5-HT) significantly reduced startle reactions by up to 40% with higher doses, while the hallucinogen 5-hydroxy-N,N-dimethyltryptamine (5-HDMT) increased responses by nearly 30%. The experiments involved monitoring 50 rats under three conditions: saline, varying doses of 5-HT, and 5-HDMT. Notably, neither compound affected the processes of sensitization or habituation. These findings suggest that the central serotonergic system plays a crucial role in behavioral inhibition, countered by hallucinogenic substances.
Abstract
Rat startle responses to air puffs were monitored in a stabilimeter during the intraventricular infusion of various doses of 5-hydroxytrptamine (5-HT) or the putative hallucinogenic congener of 5-HT, 5-hydroxy-N, N-dimethyltrytamine (5-HDMT) or saline. Qualitativity opposite effects were observed, with 5-HT producing a dose-dependent decrease in responsivity and 5-HDMT increasing the magnitude of startle responses. No specific effects of either compound could be demonstrated on the presumably separable processes of sensitization and habituation. The results are discussed in the context of a central serotonergic system which facilitates behavioral inhibition and which is antagonized by indoleamine hallucinogens.