Expression and distribution of the transient receptor potential cationic channel ankyrin 1 (TRPA1) in the human seminal vesicles

Background and Aims The transient receptor potential cationic channel ankyrin 1 (TRPA1), a channel protein permeable to most divalent cations, has been suggested to play a role in mechano‐afferent/efferent signaling (including the release of neurotransmitters) in the human urinary tract (bladder, prostate, and urethra). To date, only a few studies have addressed the expression of this receptor in male and female reproductive tissues. The present study aimed to evaluate human seminal vesicles (SVs) for the expression and localization of TRPA1. Methods SV tissue was obtained from 5 males who had undergone pelvic surgery due to malignancies of the prostate or urinary bladder. The expression of messenger ribonucleic acid (mRNA) specifically encoding for the TRPA1 protein was elucidated by means of reverse transcriptase polymerase chain reaction (RT‐PCR). Using immunohistochemical methods, the distribution of TRPA1 was examined in relation to the endothelial and neuronal nitric oxide synthases (eNOS, nNOS) and the neuropeptides calcitonin gene‐related peptide (CGRP) and vasoactive intestinal polypeptide (VIP). Results RT‐PCR revealed signals related to the expected molecular size of 656 bp. Immunohistochemistry demonstrated that TRPA1 is located in nerves running through the smooth muscle portion of the SV. Here, the protein is in part co‐localized with nNOS and CGRP, whereas no co‐localization with VIP was registered. Dot‐like signals specific for TRPA1 were observed in the cytoplasm of epithelial cells lining the lumen of glandular spaces. The epithelial layer also presented staining for eNOS. The smooth musculature appeared free of immunosignals for TRPA1. Conclusion The results convincingly show the expression of TRPA1 in nerve endings as well as in epithelial cells of the SV. Based on its location in epithelial cells, TRPA1 might be involved in the mechanism of the NO/cyclic guanosine monophosphate (GMP)‐mediated signaling and also the control of secretory function (mediated by cyclic GMP) in the human SV.