Estrogen suppresses the stress response of prolactin-releasing peptide-producing cells

Prolactin-releasing peptide (PrRP) is known to be produced in A1/A2 noradrenergic neurons and to mediate the stress response. Our preliminary experiment showed that PrRP neurons in the A2 region differed between males and females in terms of c-Fos expression. In addition it has been reported that estrogen receptor α is detectable in A2 PrRP neurons. Therefore, we speculated that the stress response of PrRP neurons is modified by estrogen. We, therefore, examined c-Fos expression in A2 PrRP neurons during the estrous cycle and found that c-Fos accumulation in PrRP neurons was significantly decreased in estrus compared with in proestrus, metestrus and diestrus. This suggests that estrogen suppresses the activation of PrRP neurons. We thus administered diethylstilbestrol (DES) to ovariectomized rats and then added restraint stress. The data clearly showed that PrRP cells in DES-administered rats significantly suppressed c-Fos accumulation induced by stress.