A histological and immunohistochemical study of neuropeptide containing somatic nerves in the levator ani muscle of women with genitourinary prolapse

Background. To evaluate the changes occurring in the somatic innervation throughout the levator ani muscle in women with genitourinary prolapse and stress urinary incontinence (SUI). Methods. Thirty-four patients with genital prolapse entered the study and ten subjects with non-malignant pathologies acted as a control group. All patients were evaluated by urodynamic investigation and an electromyographic study of pelvic floor muscles to define the type of urinary incontinence. Biopsy samples were obtained from both groups of patients: the site of muscle biopsies were left and right part of perirectal pubococcygeus muscle. The evaluation of immunoreactivity was semiquantitative and based on staining intensity and distribution. Results. In all cases, S-100 protein and NSE immunoreactivities were found in nerve fascicles running throughout the striated muscle. NPY and VIP positivities were more intense and diffuse, whereas SP immunoreactivity was quite scanty. The different patterns of NPY and VIP expression changed in relation to degree of genital prolapse and to the presence of SUI. Conclusions. Our immunohistochemical study shows the presence in the pelvic floor of neurons that are able to synthesize neuropeptides. The lower immunoreactivity score of same neuropeptides (VIP, NPY) observed among patients with third degree genital prolapse and with SUI could be related to biochemical damage of the neurons with subsequent lower production of chemical messengers.