Control of Rat Testicular Prostaglandin Dehydrogenase, δ13-Prostaglandin Reductase, and Total Prostaglandin Hypophysectomy, Follicle Stimulating Hormone, Luteinizing Hormone, Prolactin, Growth Hormone, and Testosterone

Carbonyl reductases from rat testis and vas deferens. Purification, properties and localization

Three enzyme forms (T1, T2, T3) from rat testis and two from rat vas deferens (V1, V2) of carbonyl reductase have been highly purified to apparent homogeneity. These carbonyl reductases from rat reproductive organs have several similarities in terms of molecular mass (32-33 kDa), isoelectric point (pI 5.9-6.4), immunochemical properties, cofactor requirement (NADPH dependency) and sensitivity to sulfhydryl reagents. The isoenzymes from the vas deferens (V1, V2) have similar catalytic activities, whereas those from the testis (T1, T2, T3) showed different catalytic activities from each other. All enzymes, however, reduced quinones, aromatic aldehydes and ketones, while T3, V1 and V2 were characterized as possessing high affinity towards prostaglandins. An immunoinhibition study using a specific antibody indicated that these enzymes were solely responsible for the overall catalytic activities of 13, 14-dihydro-15-oxo-prostaglandin F2 alpha, 4-benzoylpyridine, and 4-nitroacetophenone reduction and prostaglandin F2 alpha oxidation in both testis and vas deferens cytosol. The immunohistochemical staining revealed a positive immunoreactivity to antibody only in the Leydig cells of the testis, but neither the germ cells nor Sertoli cells in the seminiferous tubule. The staining also showed that the enzymes in the vas deferens were primarily localized in mucosal epithelium cells.

Prostaglandin dehydrogenase activity of rat and rabbit testicular tissues and accessory glands before and after castration

Rat reproductive tissues contained both 15-hydroxy-prostaglandin dehydrogenase (PGDH) and delta 13-reductase activities, while rabbit tissues exhibited only PGDH activity. In the rat, delta 13-reductase activity was absent in those tissues that had a high specific activity of PGDH and was present in those tissues with a low specific activity. Total specific activity of PGDH was greatest in the testicular capsule, whereas total activity was greatest in the testicular parenchyma of both species. Total PGDH activity was highest in rat seminal vesicles, where it was second only to the testicular parenchyma. Castration significantly increased PGDH activity of the epididymis, prostate, and seminal vesicles of rats, while delta 13-reductase activity disappeared from those tissues. The specific activity of PGDH was greater in the rat than in the rabbit, except for the testicular parenchyma of the rabbit. The greater PGDH activity in rat testicular capsules, compared to those of the rabbit, correlated well with diminished contractility of the rat capsule. PGDH activity of the interstitial cells correlated well with the role of prostaglandins in androgen synthesis.

Indomethacin decreases both luteinizing hormone binding and fluidity of testicular microsomal membranes in rat

The objective of these studies was to examine the effects of in vivo treatment with indomethacin, a prostaglandin synthesis inhibitor, on luteinizing hormone receptors and fluidity in microsomal membrane preparations of rat testis. Adult male rats were treated with vehicle or either of two doses of indomethacin (3.8 micrograms/g body weight or 7.5 micrograms/g body weight) every 8 h for 1, 2 and 3 days. Indomethacin treatment decreased human luteinizing hormone (hLH) binding in rat testis in a time-dependent fashion. The lower dose of indomethacin decreased hLH binding by 19%, 35% and 50%, respectively, after 1, 2 and 3 days of treatment. The higher dose of indomethacin decreased hLH binding at these respective times by 21%, 44% and 56%. Scatchard analysis of the hLH binding of testicular membrane preparations indicated that indomethacin treatment decreased the number of hLH binding sites rather than the apparent affinity constant. Testicular membrane fluidity was estimated by a fluorescence polarization technique. The effects of indomethacin on apparent fluidity of microsomal membrane paralleled that of LH binding. The values of apparent microviscosity, inversely related to the fluidity, also increased in a time-dependent fashion. These simultaneous effects of indomethacin on testicular LH binding and fluidity suggest that these phenomena are interrelated and that prostaglandins are involved in the maintenance of LH receptors in vivo.