P2X(2) receptor expression by interstitial cells of Cajal in vas deferens implicated in semen emission

Male reproduction is dependent upon seminal emission mediated by vas defere ns contraction. This drives spermatic fluid to the prostatic urethra during ejaculation. We localize interstitial cells of Cajal (ICC), which express P2X(2) receptor, subunits of ATP-gated ion channels, to rat, mouse and guin ea-pig vas deferens submucosa. Reverse transcription-polymerase chain react ion (RT-PCR) analysis of rat vas deferens resolved two functional splice va riant transcripts of the P2X(2) receptor subunit. The P2X(2) receptor mRNA was localized principally within the lamina propria (submucosal) region of the rat vas deferens using in situ hybridization (ISH) and in situ RT-PCR-I SH. Immunohistochemistry using rat, mouse and guinea-pig vas deferens tissu es confirmed expression of P2X(2) receptor protein within the lamina propri a, particularly within a dense column of small spindle-shaped cells adjacen t to the columnar epithelial cells which line the lumen. This immunoreactiv ity was co-localized with neurone-specific enolase (NSE) and c-Kit protein expression, gene markers for ICC. Mucosal mast cells were distinguished fro m ICC by toluidine blue staining. Choline acetyltransferase immunoreactivit y, a marker for post-ganglionic parasympathetic innervation, occurred on th e lateral margin of the lamina propria and extended into the inner longitud inal muscle layer. P2X(1) receptor immunolabelling was associated with symp athetic innervation of the smooth muscle in the outer longitudinal and circ ular muscle layers, but not the inner longitudinal layer. The physiological significance of the vas deferens ICC which express P2X(2) receptors remain s to be established. Possible roles include regulation of smooth muscle act ivity or mucosal secretion utilizing local ATP signaling, both of which wou ld affect semen transport. (C) 2000 Elsevier Science B.V. All rights reserv ed.