Transient expression of oxytocin receptor mRNA in the central nervous system during development

Abstract

Our previous study demonstrated a wide localization of oxytocin receptor mRNA in the adult rat brain (Yoshimura et al., 1993), and present study further revealed the developmental profiles of oxytocin receptor mRNA expression in the central nervous system. The development of oxytocin receptor mRNA in the rat brain was studied by in situ hybridization histochemistry using antisense RNA probe. The positive hybridization signal was firstly found in a dorsal part of the medulla corresponding to the primordium of the dorsal motor nucleus of vagus, and other positive regions progressively appeared after this time. The developmental profile of oxytocin receptor mRNA expression seen in various regions was classified in two types, which were transiently abundant and constantly expressing types. The regions belonging to the first type were the caudate putamen, cingulate cortex, hippocampus, the dorsal subiculum and the anterior thalamic nucleus, whereas the regions belonging to the second type were tenia tecta, olfactory tubercle, the anterior olfactory nuclei, amygdaloid nuclei, the dorsal motor nucleus of vagus and the ventromedial nucleus of hypothalamus. These finding concurred well with those of the ontogenical studies demonstrated by receptor binding autoradiography using oxytocin specific ligand (Tribollet et al., 1989). Taking the results into consideration, oxytocin seems to have functions not only as a neurohypophysial hormone but also as a substance which could be involved in neuronal maturation or a synaptogenesis in some part of the brain.