Expression of TRPV1 in sensory and sympathetic neurons innervating kidney

Abstract

The transient receptor potential vanilloid 1 (TRPV1) receptor is a ligand-gated cation channel activated by capsaicin, heat, protons and cytosolic lipids. TRPV1 is expressed primarilyin sensory nerves and functions as a molecular integrator for multiple types of sensory input. Recent reports suggest that TRPV1 plays an important role in regulating salt sensitivity during development of hypertension. Our study determined the expression of TRPV1 in the neurons supplying the kidney, which regulates salt balance. We used Fast Blue (FB) to label retrogradely sympathetic and sensory neurons innervating the kidney. In T12 to L4 segments, 4% and 6% or neurons were labeled by FB in dorsal root ganglia (DRG) and paravertebral ganglia (PVG) respectively. Labeled neurons were not found in celiac or nodose ganglia. We used antibodies raised against CGRP and tyrosine hydroxylase (TH) to mark sensory and sympathetic neurons respectively. Immunocytochemical studies showed that TRPV1 was expressed in FB-CGRP labeled DRG neurons and in FB-TH labeled PVG neurons. Whole cell recordings revealed that capsaicin caused in inward current in FB labeled DRG neurons. FB labeled neurons in PVG did not respond to capsaicin. Our data indicate that TRPV1 is expressed in DRG and PVG neurons supplying the kidney. The electrophysiological properties of TRPV1 in PVG differ from that in DRG.