Summary. The medial preoptic nucleus is critically involved in the social type of behavior regulation, such as parental behaviour, social recognition, sexual behaviour, ect.. A big amount of studies are focused on the role of glutamate, GABA, serotonin, and dopamine systems of medial preoptic area (mPOA) in the social types of behaviour regulation. However, the role of glycinergic system in this nucleus has not been investigated.