Abstract
Although it has been well established that oxytocin (OXT) in the blood during lactation accelerates milk ejection in a pregnant woman, a recent study has indicated that OXT secreted in the brain of both male and female, plays an important role in the hyporesponsiveness to stress. There are many human and animal experiments, demonstrating that increased brain OXT exerts inhibitory effects on the hypothalamo-pituitary–adrenal axis (HPA axis) through a suppression of CRF neurons in the hypothalamus. Factors facilitating OXT secretion in the brain are lactation, social touch with aesthetic relaxation, attachment between parents and children, romantic love, and social grooming behaviors including drinking with friends after work and talk with intimate persons while drinking teas. On the other hand, serotonergic neurons (5-HT neurons) in the dorsal raphe nuclei express oxytocin (OXT) receptors, indicating that OXT secreted in the brain may also produces anxiolytic effect by activating 5-HT neurons.
