Participation of different 5-HT receptors in the memory process in rats and its modulation by the serotonin depletor p-chlorophenylalanine.

The memory effects of agonists and antagonists of some serotonin (5-HT) receptor subtypes were examined in experiments on rats using an active avoidance method (shuttle-box). The 5-HT receptor antagonists NAN 190 (1 mg/kg i.p.) and pindolol (6 mg/kg i.p.) improved some indices for memory; the 5-HT2 and 5-HT3 receptor antagonists ritanserin (1 mg/kg i.p.) and ondansetron (0.1 mg/kg i.p.) exerted a favourable effect on the mastering of active avoidance performance. The tryptophan hydroxylase inhibitor para-chlorophenylalanine (300 mg/kg i.p.) alone produced no significant changes in the indices for retention of learned behaviour but in combination with the 5-HT-receptor agonists and antagonists influenced some of their effects. The results obtained show different participation of 5-HT1A, 5-HT2 and 5-HT3 receptors in the mechanisms of the memory process; the nature of this involvement is modulated by the brain level of serotonin.