Long lasting supersensitivity to 5-HT mediated behaviour following monoamine depletion in the rat brain.

The effects of the depletion of 5-hydroxytryptamine (5-HT) in the rat brain upon the 5-HT behavioural syndrome (ejaculatory response, abduction of hind-limbs, forepaw treading, and Straub tail) induced by 5-methoxy-N,N-dimethyltryptamine (1 mg/kg intraperitoneally) were investigated. The 5-HT depletion was produced by p-chlorophenylalanine (PCPA 2 X 200 mg/kg intraperitoneally) or by reserpine (5 mg/kg subcutaneously). It resulted in rapidly developing and long-lasting supersensitivity of the behavioural responses which were enhanced between 2 and 14 days after the PCPA injections and between 1 and 42 days after a single dose of reserpine. The depletion of catecholamines by alpha-methyltyrosine (250 + 125 mg/kg intraperitoneally) had no effect. These results underline the usefulness of the 5-HT mediated behavioural models for studies of changes in 5-HT receptor activity.