Nerve growth factor (
NGF) has been recently proposed as one of the key factors responsible not only for promotion of nerve fiber growth but also for the onset and maintenance of
pain in a variety of diseases. The aim of this study was to investigate the role of
NGF in the
pelvic pain associated with
endometriosis. Tissue and peritoneal fluid samples were collected from 95 women with laparoscopically and histopathologically confirmed
endometriosis and 59 control women without
endometriosis. Expression levels of
NGF mRNA and
protein were examined using real-time RT-PCR and immunohistochemistry, respectively. Concentration of
NGF in the peritoneal fluid (PF-
NGF) was measured using ELISA. The degree of
dyspareunia and
dysmenorrhea was evaluated using a verbal rating scale. Real-time RT-PCR analysis revealed that
NGF mRNA was significantly more abundant in the ovarian
endometriomas and peritoneal
endometriosis than in the normal control endometrium. Immunohistochemical analyses demonstrated that
NGF was prominently expressed and preferentially localized to the glands of the ovarian
endometriomas and peritoneal
endometriosis, whereas it was only weakly detectable in the normal endometrium. Although PF-
NGF was undetectable in some normal subjects and
endometriosis patients, elevated PF-
NGF in the peritoneal fluid was more frequently observed in
endometriosis patients with severe
pain than in those with less severe
pain. Our results suggest that
NGF produced locally in the peritoneal cavity may be involved in the generation of
endometriosis-associated
pelvic pain.