Distribution of P2X receptor subtypes in the rat female reproductive tract at late pro-oestrus/early oestrus

Using immunohistochemistry techniques, we have examined the female reproductive organs of the rat in late pro-oestrus/early oestrus for the presence of purine nucleotide P2X(1-7) receptors. In contrast to the male genital organs and the urinary tract, P2X(1) receptors were present weakly, if at all, on smooth muscle membranes, except in blood vessels, whereas P2X(2) immunoreactivity in smooth muscle was present in ovary and uterus as well as in blood vessels. Neither P2X(1) nor P2X(2) receptors were present in fallopian tubes. P2X(5) receptors were seen in the differentiating cell layers of the stratified squamous vaginal epithelium and also in the very early stages of ovarian follicular development; P2X(6) receptors were present in secondary follicles. P2X(7) receptors, markers for programmed cell death, were present in the keratinised vaginal epithelium and also in the exfoliating superficial endometrial cells. The possible biological significance of these signalling molecules in the female reproductive tract is discussed.