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The purinergic receptor P2X ligand-gated ion channel 3 (P2X3) is crucially involved in peripheral nociceptive processes of somatic and visceral pain. Endometriosis pain is considered as a kind of inflammatory and neuropathic pain. However, whether P2X3 is involved in endometriosis pain has not been reported up to date. Here, we aimed to determine whether P2X3 expression in endometriotic lesions is involved in endometriosis pain, which is regulated by inflammatory mediators through extracellular regulated protein kinases (ERK) signalling pathway. We found that P2X3 expressions in endometriosis endometrium and endometriotic lesions were both significantly higher as compared with control endometrium (P<0.05), and both positively correlated with pain (P<0.05). The expression levels of phosphorylated –ERK (p-ERK), phosphorylated-cAMP-response element binding protein (p-CREB), and P2X3 in endometriotic stromal cells (ESCs) were all significantly increased in comparison to the initial levels after treated with interleukin (IL)-1β (P<0.05) or adenosine triphosphate (ATP) (P<0.05), respectively, and did not increase after the ESCs were pre-treated with ERK1/2 inhibitor. Additionally, P2X3 and calcitonin gene related peptide (CGRP) were co-expressed in endometriotic lesions. These obtained results suggest that P2X3 might be involved in endometriosis pain signal transduction via ERK signal pathway. [ABSTRACT FROM AUTHOR]

Background: Although nerve fibres are present in eutopic and ectopic endometrium, it is unclear whether they appear in ovarian endometriotic lesions. We investigated the presence of nerve fibres in ovarian endometriotic lesions and its correlation with clinical parameters in women with ovarian endometriosis.Methods: Histological sections of ovarian endometriotic lesions from 61 women with ovarian endometriosis (Stages II-IV) who underwent laparoscopic endometrioma cystectomy were stained immunohistochemically using a specific polyclonal rabbit anti-protein gene product 9.5 (PGP9.5) antibody to demonstrate myelinated and unmyelinated nerve fibres.Results: Nerve fibres stained with PGP9.5 were detected in ovarian endometriotic lesions in 31.1% of women, and most appeared in fibrotic interstitium of ovarian endometriotic lesions. The density of PGP9.5-immunoactive fibres in ovarian endometriotic lesions in women with pain symptoms (n = 35) was higher than in women with no pain symptoms (n = 26, P = 0.039), although the percentage (positive cases/total) of PGP9.5-positive fibres did not differ. In women with pain symptoms, PGP9.5-positive fibres appeared in 40.0% of cases and the density of PGP9.5-immunoactive fibres in ovarian endometriotic lesions was correlated with severity of pain symptoms (r = 0.466, P = 0.005). In women with no pain, PGP9.5-positive fibres were detected in only 5 (19.2%) women. Both the percentage and the density of PGP9.5-positive fibres in ovarian endometriotic lesions were associated with pelvic adhesions (chi2 = 6.833, P = 0.009; Z = 2.442, P = 0.015, respectively) but not with disease severity.Conclusions: PGP9.5-immunoactive nerve fibres in ovarian endometriotic lesions may be involved in the pathophysiology of pain generation and pelvic adhesion formation in women with ovarian endometriosis. [ABSTRACT FROM AUTHOR]

Objective: To determine whether nerve fibers can be detected in the endometrium and myometrium in women with painful uterine fibroids and adenomyosis.Design: A retrospective immunohistochemical study.Setting: An academic training hospital.Patient(s): Thirty-seven women with uterine fibroids and 29 women with adenomyosis.Intervention(s): Histologic sections of contiguous endometrial and myometrial tissues were stained immunohistochemically using the highly specific polyclonal rabbit antiprotein gene product 9.5 (PGP9.5) and monoclonal mouse antineurofilament protein (NF).Main Outcome Measure(s): Results were determined through immunohistochemical staining using PGP9.5 and NF.Result(s): We detected PGP9.5-immunoactive nerve fibers in the functional layer of the endometrium in women with pain but not in women without pain. PGP9.5-immunoactive nerve fiber density in the basal layer of the endometrium or myometrium significantly increased in women with pain, however, PGP9.5-immunoactive nerve fiber density had no statistical differences between women with adenomyosis and uterine fibroids. We identified NF-immunoactive nerve fibers in the basal layer of the endometrium and myometrium in women with adenomyosis and uterine fibroids, but found no significant differences.Conclusion(s): These results suggest that PGP9.5-immunoactive nerve fibers appearing in the endometrium and myometrium of women with painful adenomyosis and uterine fibroids may play a role in pain generation in these two disorders. [ABSTRACT FROM AUTHOR]