Abstract
TRPV2 (transient receptor potential channel vanilloid subfamily 2) was shown to receive noxious thermal stimuli more than 52°C, and to be expressed in a subgroup of myelinated sensory afferents. However, TRPV2 mRNA signals have been detected in many peripheral tissues of the rat in subsequent studies. We further investigated the expression of TRPV2 in rat peripheral nervous system by immunohistochemistry and transcriptase-polymerase chain reaction (RT-PCR). TRPV2 immunoreactive neurons seen in dorsal root ganglion (DRG) did not contain Parvalbumin, which is included in proprioceptive sensory neurons, and fluoro gold, a retrograde tracer, injected into dorsal column nuclei. TRPV2 immunoreactive neurons were also observed in nodose ganglion (vagal sensory neurons) and superior cervical ganglion (postganglionic sympathetic neurons), but these neurons were rare. On the other hand, many TRPV2 immunoreactive neurons were seen in intermuscular (Auerbach's) and submucosal (Meissner's) plexus of the intestine. Some of these neurons were positive to Calbindin D-28k, a marker of intrinsic afferent neurons in enteric nervous system. An analysis by RT-PCR also showed a gene expression of TRPV2 in the intestine. These findings show that TRPV2 is expressed not only in somatic and visceral afferent neurons, but also in enteric afferent and efferent neurons. [Jpn J Physiol 54 Suppl:S170 (2004)]
