Smooth muscle metaplasia and innervation in interstitium of endometriotic lesions related to pain

Possible involvement of nerve growth factor in dysmenorrhea and dyspareunia associated with endometriosis

“…Notably, NGF can increase the number of sensory neurons and is selectively trophic for the small fiber sensory neurons and sympathetic ganglion neurons, which participate in mediating pain sensation [10,33]. Based on these observations, the nerve fibers present in endometriotic lesions are most likely a mixture of sensory Ad, sensory C, cholinergic and adrenergic nerve fibers, as determined by the staining pattern sion was up-regulated in artificially induced endometriotic lesions [22,23]. We have shown for the first time that these lesions exhibit an abundance of NGF transcripts, which explains the elevated levels of its protein.…”

“…Recently, it has been reported that nerve fiber density and expression levels of NGF in deep infiltrating endometriosis are much higher than in superficial peritoneal endometriotic lesions [31]. Also, in rodent models of endometriosis, NGF expression is up-regulated with resulting development of numerous nerve fibers within the endometriotic lesions [22,23,32]. Notably, NGF can increase the number of sensory neurons and is selectively trophic for the small fiber sensory neurons and sympathetic ganglion neurons, which participate in mediating pain sensation [10,33].…”

Dating Endometriotic Ovarian Cysts Based on the Content of Cyst Fluid and its Potential Clinical Implications

“…The increased reactive oxygen species in the cyst fluid (summarized in 36 ) may facilitate EMT. 57,58 The reported metaplastic changes into smooth muscle cells in endometrioma 59 and the ovarian smooth muscle cell metaplasia 60,61 may result from the activation of myofibroblasts in the lesions, which produce large amount of collagens in the process. In addition, the activation of the coagulation system due to cyclic hemorrhage of the ectopic endometrium results in the activation of the extrinsic coagulation pathway with resultant elevation of plasminogen activator inhibitor 1 (PAI-1) levels in cyst fluid, as reported.…”

Nerve fibers in ovarian endometriomas

“…One study has reported that there were no myelinated nerve fibers stained with neurofilament (NF) in ovarian endometriomas or in the endometrioma-containing ovaries, whereas nerve fibers stained with NF were detected in dermoid cysts (5). However, other studies have reported that the expression of nerve growth factor (NGF) and neural cell adhesion molecule (NCAM) was greater in ovarian endometriomas than in peritoneal endometriotic lesions (6). We have studied innervation with a range of different types of specific neuronal markers as well as the expression of neurotrophins and their receptors in the endometriotic deposits in ovarian endometriomas.…”