EXTRINSIC INNERVATION OF THE CAT PROSTATE-GLAND - A COMBINED TRACING AND IMMUNOHISTOCHEMICAL STUDY

Purpose: The purpose of the present study was to determine the periphe ral neural pathways, spinal distribution, sizes, and peptide transmitt er content of primary afferent and autonomic efferent neurons that inn ervate the prostate gland. Methods: Retrograde transport of the fluore scent dye ''fast blue'' (injected into the prostate gland) was combine d with neurotransmitter immunohistochemistry. Lesions of the pelvic an d pudendal nerve were used to determine the peripheral neural pathways . Results: The majority of the afferent innervation arose from the sac ral dorsal root ganglia (DRG) and was equally comprised of small, subs tance P- and calcitonin gene-related peptide-immunoreactive (IR) neuro ns and large, non-IR neurons. The majority (70%) of the afferent axons traversed the pelvic nerve with the remainder traversing the pudendal nerve. Fewer afferent neurons were located in lumbar DRG; nearly all of these were small, peptidergic neurons. Efferent autonomic neurons w ere located in the inferior mesenteric ganglia (IMG), sympathetic chai n ganglia (SCG), and pelvic plexus ganglia (PPG). Nearly all efferent neurons in the IMG and SCG, but only 2/3 of the PPG neurons, contained dopamine-beta-hydroxylase. Substantial neuropeptide Y innervation was derived from the SCG but not the IMG or PPG. Conclusions: First, clin ical reports suggested that sensory innervation of the prostate would be purely nociceptive in nature (implied by small, peptide-IR neurons) . However, the present study suggests that there may also be a substan tial, presumably non-nociceptive, afferent innervation (implied by fin dings of large, non-IR neurons). Second, 3 sources of autonomic effere nt innervation exist, each being different in the distribution of tran smitter phenotypes. Understanding the physiological role of putative n on-nociceptive primary afferent neurons, and the differential roles of the various autonomic neurons, is likely to be important in developin g therapies for the treatment of prostatic diseases, such as benign pr ostatic hyperplasia and prostatodynia.