Distribution of TRPC1 receptors in dendrites of rat substantia nigra: a confocal and electron microscopy study

Abstract

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. The expression, at mRNA level, of several TRPCs has been demonstrated recently in dopaminergic neurons of the substantia nigra (SN). The aim of the present study was to characterize the expression of TRPC1, at a protein level, in the substantia nigra neurons and non-excitable cells of Wistar rats. Single-label immunohistochemistry and double-label immunofluorescence were used to study the expression of TRPC1 among substantia nigra dopamine neurons and cellular processes using antibodies against tyrosine hydroxylase (TH), substance P (SP), enkephalin, synaptophysin, vesicular glutamate transporter-2 (Vglut-2), microtubule associated protein-2 and metabotropic glutamate receptor 1 (mGluR1). Moreover, the ultrastructural localization of TRPC1 was investigated by means of electron microscopy. A set of dual label experiments was also performed to investigate the presence of TRPC1 among glial cells. Our results showed that TRPC1 is localized mainly in dendritic processes of dopamine neurons, whereas a relatively small percentage of neuronal somata display a light TRPC1 immunoreactivity. Such results were confirmed by our electron microscopy observations. Our study demonstrates, for the first time, a coexpression of TRPC1 and mGluR1 receptors in dendrites of the substantia nigra dopaminergic neurons. Such observation reinforces the concept of an involvement of TRPC1 in mGluR1-mediated excitatory inputs in rat dopamine neurons.

Distribution of TRPC4 in developing and adult murine brain

“…In the mouse hippocampus, cells expressing TRPC4 protein can be found together with neurons expressing TRPC1 and TRPC5 (von Bohlen und Halbach et al 2005;Chung et al 2006). TRPC1 and TRPC5 protein have also been found to be expressed in neurons in other areas of the rat brain, such as the substantia nigra (De March et al 2006;Martorana et al 2006). TRPC3 protein has further been observed to be expressed in the substantia nigra, although TRPC3 protein in this brain area is mainly expressed by oligodendrocytes (Fusco et al 2004).…”

Corticolimbic Expression of TRPC4 and TRPC5 Channels in the Rodent Brain

“…Although a few reported studies have examined TRPC channels in select brain regions, an extensive and comprehensive description of the brain-wide expression of TRPC4 and 5 channels is lacking [17],[18],[19],[20],[21],[22],[23]. In this study we sought to identify the expression pattern and suggest a possible function of the TRPC4 and 5 channels in the rodent brain.…”

TRPC6 channels promote dendritic growth via the CaMKIV-CREB pathway

“…Some TRPC proteins are expressed in the CNS and function as important regulators during development (Jia et al, 2007;Li et al, 1999). TRPC1 is mainly localized to dendritic processes of dopaminergic neurons (Martorana et al, 2006), whereas TRPC6 is localized to proximal dendrites and the axon hillock (Giampa et al, 2007). Interestingly, TRPC5 is preferentially localized to the neuronal nuclei in the substantia nigra (De March et al, 2006), and TRPC3 is mainly found in oligodendrocytes (Fusco et al, 2004).…”