Members of the transient receptor potential (TRP) cation channel
family play important roles in several neuronal functions. To
understand the precise role of these channels in information
processing, their presence on neuronal elements must be
revealed. In this study, we investigated the localization of
TRPC6 channels in the adult hippocampal formation.
Immunostainings with a specific antibody, which was validated in
Trpc6 knockout mice, showed that in the dentate gyrus, TRPC6
channels are strongly expressed in granule cells. Immunogold
staining revealing the subcellular localization of TRPC6
channels clarified that these proteins were predominantly
present on the membrane surface of the dendritic shafts of
dentate granule cells, and also in their axons, often associated
with intracellular membrane cisternae. In addition, TRPC6
channels could be observed in the dendrites of some
interneurons. Double immunofluorescent staining showed that
TRPC6 channels were present in the dendrites of hilar
interneurons and hippocampal interneurons with horizontal
dendrites in the stratum oriens expressing mGlu(1a) receptors,
whereas parvalbumin immunoreactivity was revealed in TRPC6-
expressing dendrites with radial appearance in the stratum
radiatum. Electron microscopy showed that the immunogold
particles depicting TRPC6 channels were located on the surface
membranes of the interneuron dendrites. Our results suggest that
TRPC6 channels are in a key position to alter the information
entry into the trisynaptic loop of the hippocampal formation
from the entorhinal cortex, and to control the function of both
feed-forward and feed-back inhibitory circuits in this brain
region. (c) 2012 Wiley Periodicals, Inc.
