journal article
LitStream Collection
Home
ROBERGE, ANDRÉE C.; BOUCHARD, SYLVIE; LAVOIE, JOCELYNE; TREMBLAY, ROLAND R.; MAILHOT, JEAN
doi: 10.1002/j.1939-4640.1980.tb00027.xpmid: N/A
The authors found that DOPA/5‐HTP decarboxylase was present in the human seminal plasma and that its activity was lower in fertile men than in infertile men. The Km and Vmax of the enzyme were, respectively, 0.88 × 10−6 M and 19.8 pmol of serotonin/mg of protein/min. The enzyme was pyrldoxal‐5′‐phosphate (PLPHndependent, and the content of PLP in the seminal plasma was lower In fertile than in infertile subjects. A soluble, heat stable, diffusible inhibitor of DOPA/5‐HTP decarboxylase was detected in seminal plasma. This naturally occurring inhibitor was capable of reducing the activity of decarboxylase in the human seminal plasma and in cat liver. Zinc inhibited DOPA/5‐HTP decarboxylase in both human seminal plasma and cat liver, suggesting the involvement of zinc, in close relationship with PLP, in the decarboxylation mechanism. These findings suggest a relationship between the synthesis of biogenic amines and testicular function in infertile men.
D'ADDARIO, D. A.; TURNER, T. T.; HOWARDS, S. S.
doi: 10.1002/j.1939-4640.1980.tb00028.xpmid: N/A
Intraluminal fluids from the hamster seminiferous tubules and cauda, corpus, and caput epididymidis were obtained In vivo using micropuncture techniques. The effect of vasectomy on the osmolarity of these fluids was studied two weeks and four months postvasectomy. There was an overall decrease in the osmolarity of reproductive fluids at two weeks postvasectomy that was not apparent at four months postvasectomy.
PELLETIER, G.; CUSAN, G. L.; BÉLANGER, A.; SÉGUIN, C.; KELLY, P. A.; LABRIE, F.
doi: 10.1002/j.1939-4640.1980.tb00029.xpmid: N/A
Following the recent observation that chronic treatment with [D‐Ala6, des‐Gly‐NH210]LHRH ethylamide, a potent LHRH agonist, leads to an almost complete degeneration of seminiferous tubules in the rat, the time‐course of recovery of spermatogenesis after cessation of treatment was investigated. Adult rats injected with the LHRH agonist (100 ng, every second day) for four weeks were studied four, eight, and 16 weeks later. Although progressive improvement was noted from four to 16 weeks after cessation of treatment, about 25% of tubules still appeared completely degenerated at the end of the recuperation period. One month following cessation of treatment, testicular LH and prolactin receptor concentrations, testicular testosterone (T) and dihydrotestosterone (DHT) levels, and ventral prostate and seminal vesicle weights had returned to normal values. Testis weight, however, which was decreased by 40% one month after treatment with the LHRH analog, increased more slowly toward normal and was still at 85% of control value four months after treatment. Plasma LH and FSH levels, which were increased approximately 100% after treatment with the LHRH analogue, returned to within normal values between one and two months following cessation of treatment, respectively. Administration of androgens (T or DHT) concomitantly with the LHRH agonist only partially prevented the deleterious effects of the peptide on spermatogenesis. On the other hand, administration of the LHRH agonist had no effect on testicular morphology in hypophysectomized rats. These data show a rapid return to normal of the hypophyseal testicular elements responsible for androgen formation after desensitization by LHRH agonist treatment in adult rats. These results suggest that the inhibitory effect of chronic LHRH agonist administration on spermatogenesis is at least partially reversible, and that a decrease in androgen production is probably not the only factor involved in the inhibition of spermatogenesis by LHRH agonist treatment.
FREE, MICHAEL J.; JAFFE, RICHARD A.; CHENG, HSIEN‐CHEN
doi: 10.1002/j.1939-4640.1980.tb00030.xpmid: N/A
Changes in testicular vein and peripheral testosterone concentrations in mature rats were monitored during anesthesia with six different agents. Samples taken 2–3 minutes after initial disturbance of the resting animal yielded mean testicular vein testosterone levels of 59–247 ng/ml plasma in nine separate groups of rats. Sustained anesthesia under halothane, enflurane, pentobarbital, ether, urethan, or ketamine/promazine resulted in a decline in testicular vein testosterone to 10–60 ng/ml by the third hour. Luteinizing hormone levels, measured under enflurane anesthesia, also fell significantly by 1 and 2 hours after administration of anesthesia, although follicle‐stimulating hormone remained constant. Testes of the enflurane‐anesthetized rat were still able to respond to gonadotropins, but withdrawal of the anesthetic did not reverse the downward trend in testosterone. No changes in testicular blood flow were detected during anesthesia, although flow under urethan anesthesia was consistently slower than with other agents. The first 90 minutes of urethan anesthesia were characterized by severe fluctuations in testicular vein testosterone. Halothane, enflurane, and pentobarbital resulted in a larger ratio of peripheral to testicular vein testosterone compared with ether or rapid sampling, suggesting a reduction in turnover rate under these three agents. Conclusions were that different anesthetic agents can distort hormone levels and endocrine function of the testes in various ways, and that the production rate of testosterone by rat testes is higher than has been previously suggested.
FALVO, RICHARD E.; VINCENT, DOUGLAS L.
doi: 10.1002/j.1939-4640.1980.tb00031.xpmid: N/A
Studies were carried put to determine the effect of various numbers of testosterone‐filied polydimethylsiloxane (PDS) capsules on plasma concentrations of testosterone and FSH in acutely orchidectomized dogs. Dogs were implanted with either one empty PDS capsule or one, three, or five testosterone‐filled PDS capsules. Blood samples were collected daily prior to implantation, following implantation, following castration, with capsules left in situ, and following capsule removal. Replacement of testosterone, using one testosterone‐filled capsule, did not prevent the postcastration rise of FSH. Replacement of testosterone, using three and five testosterone‐filled capsules, maintained both FSH and testosterone in castrated dogs at concentrations similar to those observed in intact animals. Removal of testosterone‐filled capsules from castrated dogs resulted in hypersecretion of FSH. These studies indicate that testosterone replacement within physiologic limits will maintain FSH in the acutely orchidectomized dogs at concentrations similar to those observed in intact, untreated animals.
WEAKER, F. J.; SHERIDAN, P. J.
doi: 10.1002/j.1939-4640.1980.tb00032.xpmid: N/A
The nuclear uptake and retention of 3H‐dihydrotestosterone (3H‐DHT) were studied in the reproductive organs of the male hamster by autoradiography. Castrated adult male hamsters were infected with 0.2/μg of 3H‐DHT (107 Cl/mmole/100 g body weight) and sacrificed 1 1/2 hours later. The epididymides, prostate glands, and seminal vesicles were removed and processed for autoradiography. Localization of the androgen was observed in the nuclei of the secretory cells of all three organs. The nuclei of the smooth muscle cells of the muscularis and the connective tissue cells of these organs also demonstrated varying degrees of nuclear labeling. In addition, nuclear uptake was observed in the smooth muscle of the tunica media of the blood vessels of all three organs. In comparison to other studies, the results demonstrate species variation in the uptake of androgens in the accessory reproductive organs and support recent data that suggest that the cardiovascular system is a target organ for androgens.
Showing 1 to 8 of 8 Articles