抄録
Oxytocin (OT) serves as a neurotransmitter in the hypothalamic paraventricular nucleus (PVN). OT neuronal networks are thought to be involved in the regulation of male sexual behavior since administration of OT to males caused sexual behavior and this was reduced by an OT receptor antagonist. Recently, sexual behavior is mainly provoked by olfactory stimuli, possibly volatile pheromones released by the estrus female. We examined whether OT neurons in the PVN were activated by estrus female odor and sexual contact in sexually naïve and experienced Long-Evans rats. Male rats were not presented to anesthetized estrus females (control) or presented to the females without (exposure to the female odor without sexual contact) or with direct contact (exposure to the female odor with sexual contact). Exposure to the female odor with sexual contact significantly increased OT neurons with Fos expression in both males. Exposure to the female odor without contact increased OT neurons with Fos in sexually experienced males but not in naïve males, suggesting that the female odor without sexual contact activated the OT neuron in the PVN in the experienced males. Therefore, exposure to the estrus female odor itself may exert different effects on sexually naïve and experienced males. It is possible that female odors induce sexual arousal in males and the arousal is mediated by OT neurons in the PVN. [Jpn J Physiol 54 Suppl:S224 (2004)]
