CNS region-specific oxytocin receptor expression: Importance in regulationof anxiety and sex behavior

The oxytocin receptor (OTR) is differentially expressed in the CNS. Because there are multiple mechanisms by which the OTR can be transcriptionally in duced, we hypothesized that differences in OTR expression may be explained by activation of distinct signal transduction pathways and may be critical for the control of anxiety and sex behaviors. To determine the regulation a nd functional significance of this expression, we infused female rats with modifiers of protein kinases before assaying for behavior and oxytocin rece ptor binding. In the ventromedial nucleus of the hypothalamus (VMH), estrog en-dependent induction of oxytocin receptors required protein kinase C acti vation, and oxytocin infused here promoted female sex behavior but had no e ffect on anxiety. In contrast, dopamine controlled tonic oxytocin receptor expression in the central nucleus of the amygdala (cAmyg) through activatio n of protein kinase A, and oxytocin infused here was anxiolytic but had no effect on female sex behavior. Therefore, we have identified brain region-s pecific regulation of the OTR in the VMH and cAmyg. Distinct signal transdu ction pathways regulating receptor expression and binding in each brain reg ion may mediate in part the ability of oxytocin to exert these differential behavioral effects.