Cellular localization of TRPC5 in the substantia nigra of rat.

Transient receptor potential channels (TRPC) are plasma membrane, non-selective cationic channels and have been proposed as candidates involved in the regulation of cellular Ca2+ influx. TRPC are involved in metabotropic glutamate receptor (mGluR)-mediated excitatory post-synaptic currents (EPSCs) in the dopaminergic neurons of the substantia nigra. We previously observed several subtypes of TRPC to be expressed at an mRNA level in the substantia nigra dopamine neurons. In particular, TRPC1 and TRPC5 are most frequently expressed in the substantia nigra. Our recent immunohistochemical findings showed that TRPC1 are mainly distributed in the dendrites of dopamine neurons. In the present study we have investigated, by means of immunohistochemistry and dual label immunofluorescence, the anatomical distribution of TRPC5 in the substantia nigra, and we have shown their preferential localization into the neuronal nuclei. Our findings suggest a role of TRPs in the calcium signaling system of the nucleus, although its physiological meaning needs further investigations.