Effects of Neonatal Stress on Ovarian Follicular Reserve and Initial Follicular Waves in Rats

The study tested the hypothesis that stress experienced during neonatal life alters follicular reserve and onset of initial follicular waves. Rat pups immediately after their birth (postnatal day 1) were randomly segregated into three groups and the first group pups were autopsied on postnatal day 1, second group served as controls and those in third group were exposed to a stressor (maternal separation 6 hours/ day) from postnatal day 1 to 3. Five pups in control and stress group were autopsied on postnatal day 4, 6 and 8. There was a significant increase in blood corticosterone level in stressed rats on postnatal day 4. Neonatal stress did not delay the timing of folliculogenesis and onset of initial follicular waves. However, mean number of oocytes, primordial and primary follicles on postnatal day 4, 6 and 8 was significantly lower in stressed rats compared to controls. Reduction in follicular number was due to increased rate of atresia which was assessed by TUNEL and caspase-3 assay. The results, for the first time, reveal that neo-natal stress has dire consequence as it reduces the number of oocytes and primordial follicles (follicular reserve) which might curtail the reproductive lifespan of neo-natally stressed rats.