Effects of prenatal stress on anxiety- and depressive-like behaviours are sex-specific in prepubertal rats.

The foetal brain is highly susceptible to stress in late pregnancy, with lifelong effects of stress on physiology and behaviour. The present study aimed to determine the physiological and behavioural effects of prenatal stress during the prepubertal period of female and male rats. We subjected pregnant Sprague-Dawley rats to a restraint stress protocol from gestational day 14 to 21, a critical period for foetal brain susceptibility to stress effects. Male and female offspring were subsequently assessed at postnatal day 24 for anxiety- and depressive-like behaviours, as well as spontaneous social interaction. We also assessed maternal behaviours and 2 stress markers: basal vs acute-evoked stress levels of serum corticosterone and body weight gain. Prenatal stress did not affect the maternal behaviour, whereas both female and male offspring had higher body weight gain. On the other hand, lower levels of corticosterone after acute stress stimulation, as well as anxiety- and depressive-like behaviours, were only evident in stressed males compared to control males. These results suggest that prenatal stress induced sex-specific effects on hypothalamic-pituitary-adrenal (HPA) axis activity and on behaviour during prepuberty. The HPA axis of prenatally stressed male rats was less active compared to control males, and they were also more anxious and experienced depressive-like behaviours. These results are useful with respect to studying the neurobiological basis of childhood depression at a preclinical level.