Expression of connexin36 mRNA in adult rodent brain

A new member of the connexin gene family, named Connexin36 (Cx36) has, recently, been identified in rodents and shown to be preferentially, if not exclusively, expressed in neurones of the adult CNS. In this study we present a detailed in situ hybridization analysis of the expression pattern of mouse Connexin 36 (mCx36) mRNA in the adult mouse brain, with particular regards to the correlation of mCx36 expression to specific neuronal cell classes and systems. We found that mCx36 was strongly and widely expressed in the brain, including areas where the presence of gap junctions was never detected before. Quantitative analysis of the hybridization signal indicated varying levels of expression in different areas. In particular mCx36 was highly expressed in the neurones at different levels of the motor pathway, the olfactory pathway, the hippocampus, and areas related to the generation of respiratory rhythm. On the contrary, mCx36 was more heterogeneously expressed in nuclei of the sensory pathways. These findings show that mCx36 is the first connexin specifically expressed in neuronal cells in the adult rodent brain. The profiles of expression clearly indicate that mCx36 might play specific roles within different neuronal systems.