Localization of Nitric Oxide Synthase in the Reproductive Organs of the Male Rat1

Abstract

Nitric oxide synthase (NOS), which catalyzes the production of nitric oxide (NO), was characterized within the reproductive tract of adult male Sprague-Dawley rats by means of biochemical and immunohistochemical techniques. Tissues examined included the testis, epididymis (caput, corpus, and cauda regions), vas deferens, ejaculatory duct, seminal vesicle, and coagulating gland. NOS activity was measured by use of an assay based on the stoichiometric conversion of [3H]-L-arginine to [3H]-L-citrulline and NO, catalyzed by NOS. Low levels of NOS activity were detected in the testis and seminal vesicle (< 0.5 fmol [3H]-L-citrulline formed/min/mg protein in each tissue). The highest levels of NOS activity were present in the cauda segment of the epididymis and in the vas deferens, each having a sevenfold greater amount of NOS activity than the testis (p < 0.05). Intermediate levels of NOS activity were detected in the coagulating gland (0.863 +/- 0.248 fmol [3H]-L-citrulline formed/min/mg protein), caput epididymidis (0.457 +/- 0.180 fmol [3H]-L-citrulline formed/min/mg protein), and corpus epididymidis (0.631 +/- 0.215 fmol [3H]-L-citrulline formed/min/mg protein). NADPH diaphorase histochemistry and NOS immunohistochemistry localized NOS to neuronal fibers coursing throughout the smooth musculature and subepithelial regions of the epididymis, vas deferens, and ejaculatory duct. Endothelial cells and nerve plexuses within the adventitia of blood vessels supplying reproductive tissues were also positive for NOS. Additional localizations of NOS were within epithelial cells of the epididymis and coagulating gland.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of the testis in the response of the pituitary-testicular axis to nitric oxide-related agents

“…In the last few years, however, several studies have reported that testicular nonandrogenic factors are also involved in the regulation of LH secretion (13)(14)(15). In the testis, NO can be produced by several cell types closely related to androgen-producing cells such as endothelial cells, autonomic nerve endings, macrophages, mast cells or Leydig cells themselves (5,16,17). Previous studies have found that NO-related agents modify serum LH concentrations, although the mechanisms involved and the role of the testis are not clear.…”

Sıçan Testisinde 3-Metil-4-Nitrofenol İle Oluşturulan Hasara Karşı Morinda citrifolia (Noni)’nın Koruyucu Etkisi

“…NOS, which is expressed also in male reproductive system under physiological conditions is essential for the maintenance of spermatogenesis and testicular androgen concentrations [36,37] . Pathogenic agents cause an enormous increase in both iNOS and eNOS activities, which lead to oxidative stress and thus increase apoptotic activity in germ cells [15,38] .…”

Immunolocalisation of nitric oxide synthase isoforms in the ductuli efferentes and epididym

“…NO functions as an atypical neurotransmitter in the central nervous system and as a non-adrenergic and non-cholinergic mediator in the control of different reproductive tract organs [2]. NOS exists in two forms: constitutive, Ca 2+ -dependent forms that are rapidly activated by agonists that elevate intracellular free Ca 2+ , including neuronal NOS (nNOS) and endothelial NOS (eNOS); and a Ca 2+ -independent inducible form (iNOS) [8].…”