Abstract
Oxytocin is known as a peptide hormone that causes uterine contruction and facilitates the delivery of the newborn, and stimulates the milk ejection during motherhood. Abundant oxytocin receptors also appear in central nervous system (CNS), especially in limbic system. Oxytocin is involved in the regulation of social behaviors, including maternal care, affiliation and social behaviors in CNS. Moreover, recent studies have shown that oxytocin has anti-anxietic effect during motherhood. However, the exact molecular mechanism is unclear. In the present study, we identified a crucial molecule involved in the regulation of anti-anxiety by oxytocin and regulated the expression by oxytocin. Oxytocin induced the expression of regulator of G-protein signaling2 (RGS2), which is known as a modulator of anxiety, in the amygdala slices of female mice. RGS2 expression in the amygdala of lactating mice was significantly higher than that of virgin mice. Moreover, the expression of RGS2 in virgin mice undergone restraint stress was facilitated compared with that of control mice. And the expression of RGS2 of the group that injected oxytocin antagonist into mice amygdala was significantly lower than that of placebo control group. In addition, RGS2 expression in virgin mice undergone restraint stress with oxytocin antagonist treatment was obviously lower than that with placebo treatment. These results suggest that oxytocin may downregulate anxiety through the induction of the expression of RGS2 gene. [J Physiol Sci. 2008;58 Suppl:S148]
