Biomedical subjects
Publications and source records attributed to N M Biswas.
Blinding decreases spermatogenesis along with Leydig cell degeneration in toad. Pinealectomy decreases spermatogenesis with an increase in Leydig cell activity. Melatonin decreases spermatogenesis as well the Leyding cells. Possibly pineal and melatonin possess an inverse relationship with light and inhibit testis.
Long term Prostaglandin E2 treatment stimulates adrenal weight and steroid output. Indirect studies with histochemical localization of steroidogenic enzymes and hepatocyte glycogen content revealed that in state of adrenal suppression, PGE2 fails to elicit a positive change in steroid output from adrenal cortex, although apparently increases the enzymatic staining reactions. This suggests that the action of Prostaglandin on adrenal steroidogenesis is a pharmacologic one rather than a physiologic response.
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The enzymes delta5-3beta-hydroxysteroid dehydrogenase delta5-3beta-HSD) and glucose-6-phosphate dehydrogenase (G-6-PDH) were demonstrated histochemically in the adrenal cortex of female rat. The activities of these enzymes were increased significantly in the alloxan-treated rats kept in LD (light: darkness) cycles of 10:14 h. Continuous light exposure to diabetic animals appeared to decrease delta5-3beta-HSD and g-6-PDH in comparison to the diabetic rats kept in 10 h illumination. The evidence indicates that suppression of adrenal steroidogenesis in diabetic rats after exposure to continuous light is due to the alteration of pentose phosphate pathway.
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Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.
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A quantitative study of changes in the seminiferous tubule and the measurement of Leydig cell area were performed in the testis of toads exposed to 48 degrees C for 8 days. The frequency of occurrence of stages I and II was not affected whereas stages III and IV were influenced by the exposure to heat. The number of primary spermatocytes and secondary spermatocytes in stages III and IV were significantly decreased. The spermatocytes in stages III and IV were injured in the exposed toads. The area of Leydig cells including their nuclei was also decreased in the testes of heat exposed toads. It is concluded that the exposure to high temperature may have arrested spermatogenesis and affected Leydig cell function.
A quantitative study of seminiferous tubules in toad treated with a single subcutaneous injection of cadmium chloride, showed that 7 days after cadmium injection some stages of spermatogenesis consisting of secondary spermatogonia and primary spermatocytes were decreased significantly.
The enzyme diphosphopyridine nucleotide diaphorase (DPND) was demonstrated histochemically in both the tubular and Leydig cells of the toad testis. Addition of 200 mug of dehydroascorbic acid (DHA) to 100 mg of testicular slices in the incubating medium increased the activity of DPND, while a similar dose of ascorbic acid failed to do so. The evidence indicates that DHA is involved in the oxidation of reduced DPND in toad testis.
A histochemical study of testicular delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-OHD) and a quantitative study of seminiferous tubules in hibernating toad following the administration of HCG revealed stimulation in the activity of the enzyme delta 5-3 beta-OHD and the spermatogenesis by increasing spermiation, meiotic division and the maturation of secondary spermatogonia.
The hepatic synthesis of the androgen-dependent urinary protein in the rat, called alpha2u globulin, is strongly inhibited by estrogens. In mature male rats, treatment with estradiol-17beta (0.5 mug/g body weight) completely inhibits alpha2u synthesis within 6-7 days. Following withdrawal of estrogen treatment alpha 2u synthesis is not reinitiated for approximately 20 days. Parabiotic joining of estrogen-suppressed male rats with their normal littermates within this lag period fails to change the preparabiotic pattern of alpha2u synthesis in the respective partners. Besides estradiol-17beta, other estrane derivatives such as estrone, estriol and estradiol-17alpha were also found to inhibit the synthesis of alpha2u globulin. All of the above estrane derivatives which inhibit alpha2u synthesis are also found to inhibit the uptake of 5alpha-dihydrotestosterone by the hepatic cytosol androgen binding protein of the mature male rat. Unlike cycloheximide, a known translational inhibitor, estradiol-17beta does not inhibit alpha 2u synthesis in the perfused rat liver.
In contrast to our previous observation of increased activity of testicular delta5-3beta-hydroxysteroid dehydrogenase in toad with relation to the moderate rise of external temperature (40 degrees C), the present observation, however, shows a significant fall of this enzyme in the testis of toads exposed to a considerably high temperature (48 degrees C). The possible mechanism of action of heat on testicular steroid hormone synthesis has been discussed.
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Explore the source record for details and available documents.
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Explore the source record for details and available documents.