Effect of reserpine on behavioural responses to agonists at 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT2C receptor subtypes

Rats were given a single dose of reserpine (5 mg/kg s.c.) and behavioural responses to agonists at 5-HT receptor subtypes compared with those of control animals 21 days later. The following effects of activating postsynaptic 5-HT(1A) receptors by the agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) were significantly increased: tail-flick, reciprocal forepaw treading, fiat body posture. The hyperphagic effect of activating presynaptic 5-HT(1A) receptors by 8-OH-DPAT tended to increase and hypothermia on activating postsynaptic 5-HT(1A) sites tended to decrease. The hyperlocomotor effect of activating 5-HT(1A) sites also tended to decrease possibly as a result of a dependence of this response on the known depletion of catecholamines by reserpine. Head shakes on activating 5-HT(2A) receptors by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOT) and two effects of activating 5-HT(2C) receptors by 1-(3-chlorophenyl) piperazine (mCPP) were significantly increased (hypophagia, anxiety) and a third effect, hypolocomotion tended to increase but hypophagia on activating postsynaptic 5-HT(1A) receptors by CP-94, 253 was significantly attenuated. The results are discussed with particular reference to altered 5-HT function in depression. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.