Distribution of serotonin‐immunoreactive paraneurons in the lower urinary tract of dogs

Abstract

Morphological and quantitative studies were made on serotonin-containing paraneurons throughout the lower urinary tract in male and female dogs. Using an anti-serotonin antiserum, the cells were consistently demonstrated to be dispersed in the epithelium from the vesico-urethral junction to the external urethral ostium. They occurred most frequently in the urethra proximal to the urogenital diaphragm in both sexes. The total number of the serotonin-immunoreactive cells in the urethra was estimated to be 36.2 X 10(4) (SD 9.9 X 10(4] in the male (n = 3) and 15.6 X 10(4) (SD 2.1 X 10(4] in the female (n = 3). Besides the urethra, the prostate and vaginal vestibule contained several serotonin-immunoreactive cells. The urethral serotonin cells were basically bipolar basal-granulated cells that extended the basal cytoplasm to the basement membrane and reached the lumen with an apical process. Modified cell shapes were, however, also frequent, and included bifurcated apical and/or basal processes or a laterally directed basal process. Occasional serotonin cells possessed a threadlike basal process with varicosities and a terminal bouton, reminiscent of a neuronal process. Immunoreactivity for chromogranin A, a carrier protein common to endocrine paraneurons, was demonstrated in all of the urethral serotonin cells. The chromogranin A-immunoreactive granules accumulated more densely in the basal and perinuclear regions of the cell. It is hypothesized that the serotonin-immunopositive paraneurons may receive chemical and/or physical information from urine and, in response to it, secrete serotonin which presumably causes the contraction of the musculature of the urethra.

Pharmacology for the Treatment of Premature Ejaculation

“…There are very few arguments in favor of the implication of peripheral 5-HT in ejaculation. Serotonergic neural fibers have been detected in prostate, seminal vesicle, vas deferens, and urethra in different species (Hanyu et al, 1987;Di Sant'Agnese et al, 1987). mRNAs for 5-HT1A, -1B, and -2C receptor subtypes were found in rat seminal vesicles and vas deferens (Kim and Paick, 2004), although their precise location (pre-or postsynaptic) is unknown.…”

Expression of Orexin A and Its Receptor 1 in the Vestibular Glands of the Cattle Genital Tract

“…The peptide oxA has recently been found in NE cells of the cattle urethra (Russo et al, 2008), where 5-HT is widespread diffused. The amine, in fact, is the main product of the NE cells scattered along the urogenital tract of humans of both sexes (Fetissof et al, 1983), dog (Hanyu et al, 1987), and sheep (Vittoria et al, 1990). Furthermore, 5-HT and oxA have been found in Leydig cells of hamster (Frungieri et al, 1999) and rat (Barreiro et al, 2005) testis, where they regulate steroidogenesis through an antagonistic mechanism of action.…”

Calcitonin Gene-Related Peptide (CGRP)-Immunoreactive Nerve Terminals in the Whole Mount Preparations of the Dog Urethra.

“…HANYU et al (1987) reported the frequency of the occurrence of the serotonin-immunoreactive cells in the canine urethra of both sexes. The "clear cells" in the urethra comprise the cells to be categorized into paraneurons according to their cell-biological features.…”