Possible mechanism of referred pain in the perineum and pelvis associated with the prostate in rats

Purpose: Since persistent pain in the perineum and pelvic floor associated with chronic prostatitis/chronic pelvic pain syndrome has been hypothesized to be referred pain, it might also be explained by neural mechanisms. Materials and Methods: Dual retrograde fluorescent labeling and immunohistochemistry were identified as methods with which to investigate the neurogenic aspect of this status. The dual distribution of dorsal root ganglia (DRG) cells was determined after double retrograde fluorescent staining of the prostate and pelvic floor, and the prostate and perineum somatic nerves. Calcitonin gene-related peptide (CGRP) and substance P (SP) in dual labeled cells were determined by immunohistochemistry, giving possible insight into the cause of pelvic pain. Results: Fluorescent double labeled cells were found in the lumbar and sacral DRG, while double labeled cells were distributed predominantly in L6 to S1 and L1 to L2 segment DRG in groups 1 and 2, respectively. On immunohistochemistry some of them were confirmed to contain CGRP and SP. Thus, there are crossover pathways between the prostate and pelvic floor. Conclusions: The findings that we present confirm that the peripheral process of DRG cells dichotomizes to the prostate, sphincter and somatic parties simultaneously. Some of these cells contain CGRP and SP, which indicate that referred pain in the perineum and pelvic floor may be caused by an axon reflex in the peripheral process of DRG neurons.