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Biomedical subjects

M R Prasad

Publications and source records attributed to M R Prasad.

At least 109 records · Page 6Linked to original sources
PubMed1976

Regional differences between nuclear concentration of (3H) estradiol and (3H) progesterone and their action on the uterus of rat during delayed implantation.

The cellular and subcellular localization of radioactivity by dry-mount autoradiography was studied at 5, 15 and 30 minutes after intraluminal or at 5, 15, and 60 minutes after subcutaneous administration of (3H) estradiol or (3H) progesterone to rats in which implantation was delayed by ovariectomy on day 3 post-coitum, followed by treatment with progesterone. After intraluminal instillation of (3H) estradiol or (3H) progesterone, radioactivity was cleared from the uterine lumen at 5 minutes. After intraluminal as well as subcutaneous injection of (3H) estradiol, radioactivity was concentrated at all time intervals in the nuclei of cells of the substantia propria, glands and muscularis, but not in the luminal epithelium. White blood cells and endothelial cells were unlabeled, while perivascular cells showed concentration of radioactivity. After intraluminal instillation of (3H) progesterone, radioactivity was retained in the cytoplasm of the luminal epithelium at 5 and 15 minutes, while no such concentration appeared after subcutaneous injection. No selective nuclear retention was observed in the luminal epithelium, in contrast to the substantia propria and muscularis. The autoradiographic results indicate that progesterone treatment simulating the conditions of early pregnancy, changes the uptake affinity of uterine tissues for (3H) estradiol. The lack of a detectable concentration of estrogen within nuclei of the luminal epithelium does not preclude hormone action. Possible mechanisms of metabolic activation of the uterine luminal epithelium in the apparent absence of concentration of (3H) estradiol to nuclei of the luminal epithelium are discussed.

Animals↗
PubMed1976

Metabolism of testosterone by the epididymis and ventral prostate of rat and its inhibition by cyproterone acetate.

The metabolism of 3H-testosterone by the epididymis and accessory organs of adult male rats exposed continuously to microdoses of cyproterone acetate from subcutaneous capsules were studied. The major metabolite of 3H-testosterone in the epididymis, vas deferens and ventral prostate of control rat was dihydrotestosterone while the formation of androstanediol by these tissues was low. The highest percentage of DHT was formed by the ventral prostate and cauda epididymis. In rats exposed to cyproterone acetate for four months, the conversion of testosterone to DHT was inhibited in all the tissues but maximally in the ventral prostate and cauda epididymis. In these rats, the secretory function of the ventral prostate was normal while that of the epididymis was markedly decreased. These data are discussed based on the differential thresholds of androgens required to regulate the functions of the accessory organs.

Animals↗
PubMed1976

Stimulation of nucleic acid and protein synthesis in the epididymis and accessory organs of the rat by testosterone.

The effects of a single dose to testosterone on the content of DNA, RNA and protein and the incorporation of [3H]phenylalanine into protein in the epididymis, vas deferens and ventral prostate of the rat were studied. A single dose of testosterone did not increase the weights of the accessory organs but restored the incorporation of [3H]phenylalanine into proteins in the catput, corpus and cauda epididymides, vas deferens and ventral prostate to the normal level. Within 1 h of hormone administration, significant increases in the content of DNA, RNA and protein were noticed in the cauda epididymidis and ventral prostate. The catput and corpus epididymides and was deferens whoed decreasing order to responsiveness to testosterone. These data are discussed with respect to the relative responsiveness of these organs to reinitiation to their function by administration of a single dose of testosterone. The new protein(s) synthesized in response to hormonal stimulation associated with growth and secretory activity of the cells may be different from the new protein macromolecules synthesized after hormone withdrawal or inhibition of hormone action which are involved in autolytic processes.

Animals↗
PubMed1976

Target sites for suppressing fertility in the male.

The present status and perspectives in the control of fertility in the male have been reviewed. There are two potential sites in the male reproductive processes that can be used as targets for regulation of fertility in the male: (1) inhibition of spermatogenesis, and (2) interference with sperm maturation in the epididymis. A variety of compounds tested for their antispermatogenic action in laboratory animals have no future for the control of fertility in the human male because of a number of undesirable side effects (cf. Prasad, 1973). Progestational compounds inhibit spermatogenesis by affecting the hypothalamo-hypophysial system and result in impairment of libido. The possibility of adjustment of the minimal dose of progestational compounds required to induce suppression of spermatogenesis and reduction of plasma testosterone to a level compatible with the maintenance of normalcy of libido and potency needs to be studied. A new approach to contraception in the male involves the use of a combination of progestational compounds for suppression of spermatogenesis along with testosterone (administered through silastic capsule implants or as intramuscular injections) for maintenance of libido and accessory sex gland function. A number of such combinations have been tested clinically with some success. However, the limitations of side effects, such as weight gain, gynecomastia, and psychological complications preclude their long-term use for contraception in man. Short-term use of these combination regimens by the male for 1 year followed by use of a contraceptive method by the female may be desirable to encourage partnership in family planning. Although testosterone and other androgens suppress spermatogenesis in man, the feasibility of their use for contraception depends on the establishment of a dosage and mode of adminstration that provide antispermatogenic action without causing more general metabolic alterations. Inhibition of spermatogenesis by selective interference with the action of FSH on the Sertoli cells by active or passive immunization or by selective suppression of synthesis and release of FSH by administration of "Inhibin" offers exciting possibilities in the control of fertility in the male. Studies on the physiology of the rete testis highlight its importance as a post-tubular site of action of antifertility agents in conveying (to the epididymis) compounds interfering with epididymal functions and/or viability of spermatozoa. A new approach to the induction of functional sterility in the male by selective alteration of epididymal function by a local androgen deprivation effect has been successfully tested in clinical trials. Small doses of cyproterone acetate, administered orally, result in maintenance of libido and accessory sex gland function accompanied by a decrease in the motility of ejaculated spermatozoa and incomplete inhibition of spermatogenesis...

Androgen Antagonists↗