Distribution and developmental changes in vasopressin V2 receptor mRNA in rat brain

The extrarenal presence of vasopressin V2 receptors (V2Rs) has been suggested but never been demonstrated. We investigated the distribution of V2R mRNA expression in the brain of newborn and adult rats using the reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH). RT-PCR assay revealed V2R mRNA in the cerebellum of both newborn and adult rats, and in the cerebrum of newborn but not adult rats. Further examination of the newborn rat brain by ISH showed dense localization of that V2R mRNA in the choroid plexus, and the neurons of the hippocampus and granular layer of the cerebellum. Epithelial cells and vascular endothelial cells were strongly stained in the choroid plexus. Moreover, expression of V2R mRNA in the hippocampus of the newborn rat decreased with age and could not be detected in rats more than 2 weeks old, while in the cerebellum V2R mRNA expression was stable and did not change with development. The results of our study have demonstrated the presence and distribution of V2R in the brain for the first time, and also show that expression of V2R mRNA in the hippocampus changes dynamically during the process of development. V2R may play an important role in the development of the central nervous system.