Effects of an agonist and an antagonist of 5-HT _(1A) serotonin receptors on learning in female rats during the ovarian cycle

摘要

The experiments reported here addressed comparative analysis of the role of 5-HT _(1A) serotonin receptors in the mechanisms mediating cognitive processes during natural cyclical changes in sex hormone levels in adult female rats. The effects of chronic (14 days) administration of the 5-HT _(1A) serotonin receptor agonist 8-OH-DPAT (0.05 mg/kg, s.c.) and the 5-HT _(1A) serotonin receptor antagonist NAN-190 (0.1 mg/kg, i.p.) to females at different phases of the ovarian cycle on conditioned reflex responses were studied. A conditioned passive avoidance reaction and the Morris water maze were used as behavioral tests. Chronic administration of NAN-190 to females led to the appearance of the conditioned passive avoidance response in the proestrus and estrus phases, in contrast to control females, but had no effects on the dynamics of spatial learning in the Morris water test. Chronic administration of 8-OH-DPAT consistently impaired the processes of non-spatial and spatial learning in females regardless of the phase of the ovarian cycle. The results obtained in these experiments evidenced the modulatory role of 5-HT _(1A) serotonin receptors in learning processes in rats in key phases of the ovarian cycle.