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Biomedical subjects

A V Nalbandov

Publications and source records attributed to A V Nalbandov.

At least 19 recordsLinked to original sources
PubMed1979

Testosterone synthesis by chicken follicular cells.

The roles of theca and of granulosa cells in the synthesis of testosterone (T) in ovarian follicle of hens have been studied. Theca cells alone synthesized no progesterone (P), and no or only negligible amounts of T. Granulosa cells, in contrast, without stimulation produced large amounts of P and small amounts of T. When incubated with ovine gonadotrophins, theca cells showed greater response than granulosa cells in synthesizing more T (2- to 2.5-fold increase). Combination of the two follicular cell types decreased synthesis of P, but increased that of T (9- to 17-fold). When 0.1 microgram of ovine luteinizing hormone (oLH) was added to the combined cells, T concentrations increased most dramatically, a 83-fold increase was seen after 12 h of incubation. Theca cells incubated with exogenous P also produced large amounts of T. These results indicated that in hens, theca cells may be the major site of follicular T synthesis, however, theca cells alone cannot synthesize T unless granulosa cells or P were added. It is suggested that granulosa cells may use P as a precursor, and that P is converted to T in the theca cells.

Animals↗
PubMed1977

Sex steroids in follicular fluid and blood plasma during the estrous cycle of pigs.

Concentrations of estrogen (E), progestin (P),and androgen (A) were determined in follicular fluid (FF), and concentrations of E and P were measured in peripheral plasma and perifollicular plasma during the estrous cycle in the pig. Also, concentrations of E, P,and A were determined in the utero-ovarian vein (U-OV) plasma every 2h during estrus period in pigs. It was observed that as follicles increased in size, the concentration of E, P, andA in the FF rises from 13,32 and 1 ng/ml at day 8 of the cycle to 180, 754, and 21 ng/ml at day 20 of the cycle, respectively. Approximately 12 h before ovulation there is a significant (P less than 0.01) drop of E, P, and A in the FF to 27, 120, and 0.77 ng/ml, respectivley. Concentrations of E and P in FF and peripheral plasma do not correlate during the second half of the estrous cycle. At day 20 of the cycle, E and P concentrations in the plasma were 20 pg/ml and 0.4 ng/ml, respectively. Concentration of P in the U-OV plasma started increasing 18 to 24 h after the onset of estrus, which is coincident with the drop of P concentration in the FF. As estrus progressed there was a linear drop of E concentration (r = 0.90) in the U-OV plasma. E and P concentrations in the FF were found to be about 1000 times greater than those in the peripheral blood and 5 times greater than in the blood obtained from the perifollicular capillary network at the end of the cycle.

Androgens↗
PubMed1976

Plasma steroid concentrations in conscious and anesthetized rabbits.

The ovarian steroids, estrogen, androgen, and progestin, were measured in the peripheral plasma of adult female rabbits that were either conscious or anesthetized with sodium pentobarbital (nembutal) or halothane. Concentrations of estrogen, androgens, and progestin were determined before and at 10 and 45 min after systemic injection of either buffer or LH. In the controls androgen levels were significantly different between animals anesthetized with nembutal and halothane. However, the greatest treatment effect was noted in plasma progestin concentrations which were significantly elevated in halothane-anesthetized animals in comparison to the conscious and nembutal-anesthetized animals. Following LH, the androgen and progestin levels were significantly elevated over basal levels. Most likely the treatment effect observed in the controls was still present but was overridden by the increased release of steroids following gonadotrophin stimulation. This study suggests that halothane, in contrast to nembutal, does significantly elevate peripheral progestin and androgen levels.

Androgens↗