Expression of 5-HT3 receptors in primary sensory neurons of the petrosal ganglion of adult rats.

By using a specific antiserum, expression of the 5-HT3 receptor was examined in the petrosal ganglion (PG) of adult male rats. We found that the 5-HT3 receptors are widely distributed in the PG. This finding was confirmed by RT-PCR detection of the 5-HT3 receptor mRNA in the tissue. Unlike the distribution patterns of tyrosine hydroxylase (TH), which occurred in limited regions of PG, the 5-HT3 receptors seemed to distribute throughout the ganglion. As many TH-positive neurons in PG innervate type I cells in the carotid body, the coexistence of 5-HT3 receptor and TH in some neurons suggests that this receptor may play a role in carotid body chemoreception.