Prenatal effects of buspirone and stress on behavioral reactions in rat pups of different sexes during period of ontogeny with low level of brain serotonin

Previously we revealed for the first time pain response exacerbation caused by inflammation in rats born to dams exposed to stress during pregnancy (prenatal stress). The present study is devoted to tinvestigation of prenatal stress effects on psychoemotional and tonic pain reactions in rat pups during the individual development period that is characterized with a dramatic reduction of the brain serotonin level. Effects of maternal buspirone before stress during pregnancy on functional indices of psychoemotional and tonic pain systems in the offspring were also investigated. Prenatal stress increased the number of pain patterns (flexing + shaking) during different phases of the time-course of formalin-induced pain in females and males to a greater extent in males. Prenatlly stressed rat pups of both sexes failed to show reliable changes in the index of psychoemotional behavior in the forced swim test. With the aim to decrease pain response exacerbation found in prenatally stressed offspring, pregnant dams were exposed to chronic injections of serotoninergic anxiolytic and antidepressant buspirone which is an agonist of 5-HT1A receptors; prenatal effect of buspirone on psychoemotional behavior in prenatally stressed rat pups was also evaluated. Maternal buspirone normalized pain behavior and decreased considerably the time of immobility, the index of depressive behavior in the forced swim test. The present results indicate analgesic and antidepressive effects of maternal buspirone in prenatally stressed 10-day old rat pups and demonstrate sexual dimorphism in effects of prenatal stress on the time-course of formalin-induced pain. Differences in effects of prenatal influences on pain respone during the interphase in males and females indicate earlier maturation of the descending serotonergic inhibitory system of afferent pain signals modulation in males than in females and demonstrate that 5-HT1A receptors are involved in this process.