title: Nitric oxide synthase (NOS-I) in Leydig cells of the human testis.
abstract: By means of immunocytochemical methods, immunoreactivity for the brain isoform of nitric oxide synthase (NOS-I) was recognized in numerous Leydig cells of the human testis as well as in MA-10 tumor and TM3 non-tumor mouse Leydig cell lines. Within the Leydig cell cytoplasm, immunocytochemical results suggested the occurrence of factors known to activate NOS-I such as glutamate and aspartate, as well as molecules involved in the regulation of the NOS-I activity such as calmodulin and Ca2+/calmodulin-dependent protein kinase II. Leydig cells, Sertoli cells, some endothelial cells of the testis, MA-10- and TM3 mouse Leydig cell lines exhibited a relatively strong NADPH-diaphorase enzyme activity as well. Double sequential immunostainings provided evidence that NOS-like immunoreactivity of the testicular Leydig cells is colocalized with testosterone, calmodulin, aspartate, glutamate, and Ca2+/calmodulin-dependent protein kinase II. Sodium nitro-prusside treatment did not result in increased cGMP formation by MA-10- or TM3 mouse Leydig cells, suggesting that NO produced by these cells acts primarily in a paracrine fashion. The NO produced by NOS-I immunoreactive Leydig cells may act as a messenger: 1) between neighbouring NOS-I positive and/or negative Leydig cells as well as to mediate the action of numerous intracellular and extracellular neuroactive substances and growth factors; 2) between Leydig cells and the muscle cells or pericytes of blood vessels to regulate local blood flow and permeability; and 3) between Leydig cells and pertibular myofibroblasts to influence their contraction and the permeability of the lamina propria.
authors.affiliation: Institute of Anatomy, University of Hamburg, Germany.
authors.forename: M S
authors.initials: MS
authors.lastname: Davidoff
authors.forename: R
authors.initials: R
authors.lastname: Middendorff
authors.forename: B
authors.initials: B
authors.lastname: Mayer
authors.forename: A F
authors.initials: AF
authors.lastname: Holstein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000594:Amino Acid Oxidoreductases / Q000032:analysis*; D000818:Animals; D002460:Cell Line; D006152:Cyclic GMP / Q000032:analysis; D006801:Humans; D007124:Immunoenzyme Techniques; D007985:Leydig Cells / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008875:Middle Aged; D009252:NADPH Dehydrogenase / Q000032:analysis; D019001:Nitric Oxide Synthase; D009599:Nitroprusside / Q000494:pharmacology; D013737:Testis / Q000166:cytology / Q000201:enzymology; D014407:Tumor Cells, Cultured
chemical_list: D009599:Nitroprusside; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D009252:NADPH Dehydrogenase; D006152:Cyclic GMP