Expression of connexin30.2 in interneurons of the central nervous system in the mouse.

Electrical synapses, particularly gap junctions composed of connexin (Cx) 36, have been suggested to synchronize neuronal network oscillations. Recently, we generated Cx30.2-deficient mice which express beta-galactosidase under control of Cx30.2 gene regulatory elements. In the central nervous system beta-galactosidase activity representing Cx30.2 expression was restricted to NeuN-positive cells, thus identifying Cx30.2 as new neuronal connexin. In the hippocampus, co-immunofluorescence analyses revealed beta-galactosidase/Cx30.2 expression in GABAergic inhibitory interneurons such as parvalbumin- and somatostatin-positive basket, axo-axonic, bistratified or oriens lacunosum-moleculare cells. approximately 94% of the Cx30.2 expressing parvalbumin-positive interneurons also expressed Cx36. Performing field potential recordings from hippocampal slices we found no differences in basal excitation and excitation-inhibition balance between Cx30.2+/+ and Cx30.2LacZ/LacZ)mice. Furthermore, frequency and power of gap junction dependent gamma and ripples oscillations were similar in these animals. This suggests that the lack of Cx30.2 in interneurons can be largely compensated by other connexins, most likely Cx36.