[ effect of gender and number of pups on postpartum depressive-like behaviors in rats]

ABSTRACT

Postpartum depression [PPD] is the most common complication of childbearing women. According to the effect of alterations of estrogen, progesterone, beta-endorphins, CRH and hCG on the etiology of PPD and considering the effect of fetal gender on some maternal hormone levels, the effect of fetal gender on PPD [due to hormonal mechanisms] is a ponderable hypothesis. Because of the interaction between cultural, social and economical factors with occurrence of PPD, study on the correlation between gender or number of infants and PPD is difficult in human populations. We purposed to study the correlation between gender or number of pups and PPD-like behaviors in rats. In this study postpartum depressive-like behaviors were assessed in 30 Wistar rats by Forced Swim Test [FST]. Behaviors observed in the FST such as increased immobility and decreased active behaviors [struggling, swimming and diving] are depression symptoms. On postnatal days 3 and 4 dams were placed in a swim tank and their behaviors [struggling, swimming and immobility time and diving number] were recorded and assessed. The correlation between postpartum depressive like behaviors and pups sexual ratio [females/males] or pups number was analyzed by the Bivariate Correlation [Pearson's test]. A significant positive correlation between pups number and immobility time was observed [r = 0.641, p<0.05]. However increase in pups number decreased the struggling and swimming time and diving numbers, the correlations were not significant [p>0.05]. There was not any significant correlation between pups sexual ratio and behaviors observed in FST [p>0.05]. Results of this study imply that PPD-like behaviors are affected by pups number but are independent to pups gender in rats