Immunohistochemical localization of two angiotensin I-converting isoenzymes in the reproductive tract of the male rabbit

The male reproductive tract contains two different isoenzymes of angiotensin I-converting enzyme (ACE), i.e., pulmonary and testicular ACE. The present study shows selectively the cellular distribution of the ACE isoenzymes in the reproductive tract of male rabbit, using indirect immunofluorescence or immunoperoxidase methods. Testicular ACE was found in the seminiferous tubules of the testes in spermatocytes containing mature spermatids, and in spermatids within the epididymal tubular lumen in sexually mature, but not in immature, rabbits. Epididymal tubular cells contained pulmonary ACE. In the young rabbit, epididymal tissue contained more ACE than that in adult rabbit, since ACE was observed in principal cells in addition to basal cells. In mature rabbit, ACE was observed in basal cells only. Strong staining for pulmonary ACE was observed in cells of the vas deferens in both young and adult rabbit. Therefore, synthesis of epididymal ACE, unlike the testicular isoenzyme, was not stimulated by sexual maturation. Enzymatically active ACE in seminal fluid corresponds to the pulmonary isoenzyme. The present study indicates that this seminal fluid ACE may originate from cells of the epididymal tubules, particularly those of the vas deferens. Endothelial cells of blood vessels lying in the interstitium of both testicular and epididymal tissue contained the pulmonary isoenzyme.

[Studies on gamma-glutamyl transpeptidase (gamma-GTP) in seminal plasma]

The significance of gamma-GTP (gamma-glutamyl transpeptidase) in seminal plasma was examined by measuring the gamma-GTP activity in ejaculate, seminal plasma, prostatic secretion, testis, epididymis, vas deferens, prostate and sperm. The gamma-GTP activity was measured spectrophotometrically (405 nm) using L-gamma-glutamyl-p-nitroanilide as a substrate. One unit of enzyme activity was defined as the amount liberating 1 mumol of p-nitroaniline per min. The mean gamma-GTP activity was 9,094 +/- 4,351 mU/ml in ejaculate and 7,487 +/- 4,286 mU/ml in seminal plasma of 76 men visiting the infertility clinic. There is a positive correlation between gamma-GTP activity in ejaculate and in seminal plasma. The gamma-GTP activity was 15,044 +/- 6,422 mU/ml in prostatic secretion and twice as high as the activity in seminal plasma. There was no significant correlation between gamma-GTP activity in seminal plasma and volume of ejaculate, sperm density or sperm motility. The gamma-GTP activity in testicular tissues was 72 +/- 25 mU/mg protein except for two cases in which its activity was not detected (3 years old; retentio testis, 71 years old; prostatic carcinoma, was administered with hormonal medicine). The gamma-GTP activity in prostatic tissues was 133 +/- 68 mU/mg protein. The relationship between the gamma-GTP activity in testicular tissues and Johnsen's mean score count. Judging from the present results together with the previous reports of Rosalki et al (1977) and Simon et al (1978) the prostate seemed to be the major source of gamma-GTP in human semen.

The inactivation of [Met5]-enkephalin by bestatin-sensitive aminopeptidase, captopril-sensitive peptidyl dipeptidase A and thiorphan-sensitive endopeptidase-24.11 in mouse vas deferens

The enkephalin-hydrolyzing peptidases in mouse vas deferens were studied and compared with those in guinea pig ileum which had been characterized in the previous study. The present results showed that three distinct peptidases, bestatin-sensitive aminopeptidase, captopril-sensitive peptidyl dipeptidase A, and thiorphan-sensitive endopeptidase-24.11, played a critical role in the inactivation of enkephalin in mouse vas deferens, being consistent with the previous results obtained with guinea pig ileum. However, the data in both previous and present studies showed that the activity of the bestatin-sensitive aminopeptidase relative to that of either the captopril-sensitive peptidyl dipeptidase A or the thiorphan-sensitive endopeptidase-24.11 in guinea pig ileum was higher than that in mouse vas deferens, while the activity of either peptidyl dipeptidase A or endopeptidase-24.11 relative to that of aminopeptidase in mouse vas deferens was higher than that in guinea-pig ileum. In contrast to these three enzymes, both L-tyrosyl-L-tyrosine-sensitive dipeptidyl aminopeptidase and D-phenylalanine-sensitive carboxypeptidase were suggested not to be involved significantly in the inactivation of enkephalin in mouse vas deferens as well as guinea pig ileum.

Origin of alkaline phosphatase of canine seminal plasma

The tissular origin of alkaline phosphatase was evaluated in canine seminal plasma. Alkaline phosphatase activity was most concentrated in the first fraction of the split ejaculate and was virtually undetectable in the third and fourth fractions. By contrast, arginine esterase, a known marker of dog prostatic secretion, was present in similar concentrations in all fractions of the split ejaculates analyzed by SDS gel electrophoresis. Similarly, arginine esterase was very abundant in secretory granules prepared from dog prostate homogenates, whereas these granules contained virtually no alkaline phosphatase. Among male sex accessory organs, alkaline phosphatase activity was very high in the epididymis and much lower in the testis and prostate. Furthermore, the specific activity in epididymal fluid collected from the cauda epididymis was about 10 times higher than in the corresponding epididymal homogenates. These results show that the major portion of alkaline phosphatase in dog seminal plasma does not come from the prostate but from the epididymis.

Inhibition of smooth muscle 5'-nucleotidase by imidazole and its reversal by magnesium

Imidazole, commonly used as an effective pH-buffering reagent in aqueous media maintained at pH 7-8, was found to depress the 5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) activity of microsomal membrane fraction isolated from rat vas deferens smooth muscle in a dose-dependent manner in the absence of added Mg2+. Such an inhibitory effect of imidazole on the smooth muscle 5'-nucleotidase was not dependent upon the purity or integrity of the membrane fractions used and could be fully reversed by the inclusion of 5-10 mM Mg2+ in the assay medium. Of the five different pH-buffering reagents tested, imidazole was specific in exerting inhibitory effect on the 5'-nucleotidase in the absence of Mg2+ and this inhibition could not be accounted for by the impurities present in the imidazole. Differential effects of chelating reagents and other divalent metal ions on the 5'-nucleotidase activity were also observed in imidazole and Tris buffer solutions. The 5'-nucleotidase activity was not affected if the membranes were preincubated and washed with a large volume of 50 mM imidazole and subsequently assayed in 50 mM Tris in the absence of Mg2+. Similar findings were obtained with EDTA treated membrane. These results suggest that imidazole does not act by removal of the activating metal ion but rather interacts directly with 5'-nucleotidase and alters the metal-enzyme interactions.

Target size of 5'-nucleotidase in smooth muscle

Target size of the 5'-nucleotidase in six different smooth muscles was determined by radiation inactivation. The enzyme in the soluble fraction of rat myometrium and vas deferens gave a target size of approximately 80,000 daltons. The plasma membrane bound 5'-nucleotidase however, gave target size of 80,000 to 110,000 daltons in rat gastric fundus and vas deferens and dog stomach and ileum, 135,000 daltons in rat mesenteric artery and 210,000 daltons in rat myometrium.

Proenzyme to urokinase-type plasminogen activator in the mouse in vivo

We have investigated whether urokinase-type plasminogen activator (u-PA) is present in the mouse in vivo as the proenzyme or as the active enzyme. u-PA in extracts of various murine tissues was of a one-polypeptide chain form with an electrophoretic mobility indistinguishable from purified proenzyme (pro-u-PA), as demonstrated by SDS-polyacrylamide gel electrophoresis under reducing conditions followed by immunoblotting. No 2-chain u-PA was detected in any of the extracts (detection limit 10% of that of one-chain u-PA). In bladder urine more than half of the u-PA was of the one-chain form. Together with previous immunocytochemical studies of the normal murine tissues and studies of the Lewis lung carcinoma, the present results indicate that in these tissues the one-chain proenzyme is the predominant form of u-PA in intracellular stores and for the first time demonstrates that at least in some cases the one-chain form constitutes a sizeable fraction of the u-AP in extracellular fluids in the intact organism.

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.

Tripeptidyl carboxypeptidase activity of angiotensin-converting enzyme in human tissues of the urogenital tract

The tripeptidyl carboxypeptidase activity of angiotensin-converting enzyme (EC 3.4.15.1) has been determined in several human tissues of the urogenital tract. Benzoyl-glycyl-L-seryl-L-prolyl-L-phenylalanine was used as substrate. The cleaved benzoyl-glycine was measured by means of high-performance liquid chromatography. Results obtained showed a high enzymatic activity for seminal plasma, vesicula seminalis and benign prostatic hyperplasia. Normal prostate and in particular prostatic adenocarcinoma have low enzymatic activity. The activity of the enzyme is sensitive to inhibition by the angiotensin-converting enzyme inhibitor captopril.

Distribution of steroid sulfotransferase in the male hamster reproductive tract

Steroid sulfotransferase activity has been assayed in cytosol extracts obtained from the male hamster reproductive tract. Dehydroisoandrosterone and desmosterol were used as substrates in the presence of phosphoadenosine phosphosulfate-35S as sulfate donor. No significant sulfotransferase activity was found in the testis. In the epididymis, a severalfold increase in activity was found in the tissue from the caput to the caudal regions. A lower but significant activity was detected in the vas deferens. The enzyme appears to be secreted into the luminal fluid while little activity is associated with the spermatozoa. This increase in activity along the epididymis is undoubtedly responsible for the accumulation of sterol sulfates reported previously. In view of the fact that sterol sulfates are potent and specific inhibitors of acrosin, as reported for the porcine and confirmed herein for hamster acrosin, the epididymal production of steroid and sterol sulfates may represent a protective mechanism against the premature release of proteolytic activity within the male reproductive tract.

Cholinesterases and choline acetyltransferase in the ductus deferens of the guinea-pig

Several authors have reported that longitudinal and circular muscle layers of the guinea-pig ductus deferens possess a rich adrenergic innervation. Cholinergic innervation has been doubted by several authors, especially its presence in the longitudinal muscle layer. Acetylcholinesterase and butyrylcholinesterase were demonstrated, by electron-microscopic examination of both muscle layers of the guinea-pig ductus deferens, to be localized on the axolemma of the nerve endings and in smooth-muscle fibres, on sarcolemma, in the intracellular caveolae and in the intercellular space. Activity of cholinesterases and choline acetyltransferase was measured by the radiometric method and was found in both muscle layers. The activity of butyrylcholinesterase was higher than that of acetylcholinesterases in the homogenates of the whole ductus deferens and in the longitudinal muscle layer. In the circular muscle layer, the activity of acetylcholinesterase was higher than the activity of butyrylcholinesterase. In both muscle layers, we also found choline acetyltransferase, the activity being stronger in the circular layer. The localization of cholinesterases in smooth-muscles in the same places as the calcium and muscarinic acetylcholine receptors is discussed, together with the possibility that the enzyme is in some way involved in the excitation-contraction mechanism of smooth muscle.

Carbonic anhydrase activity of the reproductive tract tissues of aged male fowls and its relationship to semen production

A significant positive correlation was found between the carbonic anhydrase activity of the testes or ductus deferens and the volume of semen, spermatozoa or seminal plasma per collection. No relationship was found between the carbonic anhydrase activity of tissue from the epididymal region and semen production. The intramuscular injection of greater than 25 mg acetazolamide/kg body weight, a known carbonic anhydrase inhibitor, significantly reduced the carbonic anhydrase activity in the testes, epididymides and ductus deferens. As the dose was increased, the carbonic anhydrase activity of the reproductive tract tissues decreased in a linear manner. The reduction in carbonic anhydrase activity was associated with significantly lower volumes of semen, spermatozoa and seminal plasma per collection.

Genital tract proteins in the male rabbit: II. Alkaline phosphatase--enzyme action and site of synthesis

An alkaline phosphatase was isolated from rabbit seminal plasma by ion-exchange chromatography, gel-filtration and preparative isoelectric focusing. Enzyme inhibition with Na2-EDTA was mostly effectively reverted by means of Mg2+, Zn2+ and Ca2+ in the incubation medium. The use of a monospecific antiserum against the seminal plasma alkaline phosphates permitted to identify through immunofluoresceine the ductus epididymis, deferens and its ampullae as the main site of synthesis of this protein.

Localization of membrane-bound catechol-O-methyltransferase

Previous studies of the distribution of catechol-O-methyltransferase (COMT) have concentrated on the soluble enzyme activity. In this study the activity of the membrane-bound enzyme was determined in different brain regions and peripheral tissues of the rat. Membrane-bound COMT, like the soluble enzyme, has a general distribution with high levels in liver, kidney, and vas deferens. However, the ratio of membrane-bound to soluble activity varies almost 30-fold in different tissues, with the highest ratio in brain. Membrane-bound activity varies twofold within brain. In view of their different localization and kinetic properties, it seems likely that the two forms of COMT have different functions in vivo.

Subcellular distribution of oxidoreductases in genital organs of the male rat

The subcellular distribution of alcohol and aldehyde-dehydrogenases in selected endocrine tissues of the adult male rat is reported. Certain kinetics and developmental aspects of these enzymes were also investigated. Aldehyde dehydrogenase (ALDH) was measurable in nuclear, mitochondrial, and cytoplasmic preparations of rat testis (T), ductus deferans (DD), and the penis (P). This enzyme was also present in nuclear and mitochondrial but not in cytoplasmic-fractions of the seminal vesicles (SV). Alcohol dehydrogenase (ADH) was measurable in cytoplasmic preparations of the rat testis, ductus deferans, and of the penis, in addition to that of the nuclear fraction of the rat testis. Testicular nuclear and mitochondrial-aldehyde dehydrogenase as well as cytoplasmic alcohol dehydrogenase increased as a function of age. The kinetics of the study indicate that nuclear ALDH in seminal vesicles possessed greater Vmax than corresponding ALDH in reproductive tissues studied. Mitochondrial ALDH of penis preparation showed a higher velocity of the enzymatic reaction than that assayed in T, DD, or SV-preparations, and these organs possessed similar Km. Testicular cytoplasmic ALDH displayed a marked high affinity towards the substrate, and DD-ALDH showed a similar Km to that of hepatic cytoplasmic ALDH. The Vmax of ADH determined in cytoplasmic fraction of the rat testis was greater than that assayed in the nuclear fraction with both preparations demonstrating equal Km value. The kinetics suggest that the velocity of the enzymatic reaction and the apparent Km values of these enzymes depends on the tissue and on the subcellular component fractionated.

Histochemical localization of prostaglandin synthetase in human exocrine glands

Prostaglandin synthetase activity is histochemically detected in the epithelial cells of the human prostate, seminal vesicle, and deferential ampulla. The addition of the specific inhibitor indomethacin to the incubating medium strongly reduces the staining reaction. The presence of exogenous substrate in the medium is not required for the reaction, since identical results are observed following incubation with and without arachidonic acid. The presence of the enzyme appears to be related to the secretion of prostaglandins into the seminal fluid, but there is a possibility that some prostaglandins influence the metabolism of the secreting cells themselves. The localization of prostaglandin synthetase in the ductal epithelia of human salivary glands is related to a possible regulatory role of the prostaglandins upon the reabsorptive activity of the ductal cells.

Localization of delta 5-3 beta- and 17 beta-hydroxysteroid dehydrogenase activity in the efferent ducts, epididymis and vas deferens of the rabbit, hamster and marmoset monkey

The presence and distribution of delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD: EC 1.1.1.51) and 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD: EC 1.1.1.51) were studied histochemically in the excurrent ducts of the rabbit, hamster and marmoset monkey. Dehydroepiandrosterone (DHEA) and testosterone were used as substrates for delta 5-3 beta-HSD and 17 beta-HSD respectively, while phenanthroline monohydrate was used to eliminate non-specific staining due to other tissue dehydrogenases. The rabbit possessed least enzyme activity, which was confined to tubules in the middle segment of the epididymis. Enzyme activity was demonstrable throughout the excurrent ducts of the hamster and marmoset, with maximal staining occurring in the middle segment of the epididymis in both species. The region of maximum activity of hydroxysteroid dehydrogenase is where spermatozoa first develop their fertilizing capacity.

Angiotensin I converting enzyme in rat testis, epididymis and vas deferens under different conditions

Angiotensin I converting enzyme (ACE) was found in the testis, epididymis and vas deferens of rats. In tissue specimens without a prior washout of seminal fluid the highest specific ACE activity was measured in the testis. The enzyme activity was significantly lower towards the end of the excurrent ducts, suggesting that the enzyme is synthesized in the testis and secreted into the seminal fluid there. An ACE inhibiting substance may be secreted by the epididymal epithelium. Enzyme synthesis and enzyme inhibition are probably under simultaneous endocrine control. In-vitro inhibition, pH- and temperature-dependence of gonadal ACE correspond with that of lung and blood plasma. However, the physiological function of the enzyme on sperm motility and fertility remains unsolved.

Studies of the deferent ducts from the testis of the African elephant, Loxodonta africana. III. Ultrastructure and cytochemistry of the ductuli efferentes

The epithelium of the ductuli efferentes is composed of ciliated, principal, halo and basal cells. The supranuclear cytoplasm of ciliated cells is penetrated by particularly long cilial rootlets which are surrounded by numerous elongate mitochondria. Microtubules are arranged along the longitudinal axis of the cells. The spaces between the microvilli of principal cells form canaliculi which penetrate the apical cytoplasm and appear to be involved in endocytotic activity. The supranuclear cytoplasm contains oval mitochondria and numerous vacuoles. Both ciliated and principal cells contain poorly developed Golgi and endoplasmic reticulum, but numerous supranuclear dense bodies are usually present. Supranuclear and basal accumulations of dense bodies were identified as lipofuscin; they were the source of brown pigmentation in the proximal two thirds of the ductuli efferentes. The halo cells were probably macrophages. They occurred quite frequently and contained crescent shaped nuclei and large accumulations of lipofuscin material.

Stimulation by phospholipid of calcium-dependent phosphorylation of endogenous proteins from mammalian tissues

The occurrence of endogenous substrate proteins for calcium-dependent protein kinase, augmented by either phospholipid or calmodulin, was examined in extracts of several rat tissues. Pancreas, vas deferens, adrenal and liver were found to contain substrate proteins for phospholipid-sensitive protein kinase. Under the conditions utilized, only vas deferens exhibited substrate proteins for calmodulin-sensitive protein kinase. Phosphorylation of pancreatic substrate protein for phospholipid-sensitive protein kinase was rapid and highly sensitive to Ca2+, being detectable within 15 s following exposure to Ca2+ and phosphatidylserine and at concentrations of Ca2+ as low as 0.5 muM. These findings suggest that phospholipid-sensitive protein kinase system may serve to mediate some effects of Ca2+ in a variety of mammalian cell types.

Histochemistry of some steroid-dehydrogenases in epithelia of human seminal vesicle, deferential ampulla, and prostate gland

The cytochemical localization of 17 beta-SDH, 3 beta-SDH, and 3 alpha-SDH was made in human seminal vesicle, deferential ampulla and prostate. The enzymes showed a remarkable activity in the epithelial cells of all glands. The epithelia of prostate, seminal vesicle, and deferential ampulla were able to metabolize androgens through the reductive pathway, characteristic of target tissues.

The presence and longitudinal distribution of the glutathione S-transferases in rat epididymis and vas deferens

The presence of the glutathione S-transferases, enzymes that catalyse the conjugation of glutathione with a variety of compounds, is reported here, for the first time, in the mammalian epididymis-vas deferens. These glutathione S-transferases, approx. 50% of those from rat liver on a per-mg-of-protein basis, are resolved by isoelectric focusing into six peaks, each with a characteristic isoelectric point and substrate specificity. By these same criteria, the first three peaks (pI 8.9, 8.2 and 7.8) can be identified as transferases B, A and C respectively. The fifth peak (pI7.2) may correspond to transferase M; the fourth (pI7.5) and sixth (pI7.0) peaks do not correspond to previously described transferases. The distribution of transferase activity towards any one substrate studied differs in sequential sections of the epididymis and vas deferens; in addition, the longitudinal-distribution pattern differs for each of the three substrates studied. Isoelectric focusing of the cytosol fractions of the different sections further substantiates these observations. The potential significance of these enzymes and of their distribution in terms of epididymal function, maturation of spermatozoa, is discussed.