1,721,192 research outputs found
Selenium stimulates estradiol production in bovine granulosa cells: possible involvement of nitric oxide
No full textReduction in fertility is well known to be possibly related to selenium deficiencies, even if target organ for selenium action is, at present, unclear. The present study was aimed to examine whether selenium directly influences granulosa cells. Bovine granulosa cells from different size follicles were used to investigate the effect of selenium (5 ng/ml), with or without bovine follicle-stimulating hormone (bFSH) (100 ng/ml), on proliferation and steroidogenesis. In addition, we sought to determine if selenium modulates the production of nitric oxide, which is known to play an important role in ovarian activity. Our data demonstrate that selenium significantly (P < 0.001) stimulates the proliferation of the cells from small follicles; moreover, it further potentiates the stimulatory effect of the gonadotropin in the same cells. Furthermore, selenium significantly (P < 0.01) augments E2 output by cells from both kinds of follicles. bFSH increases E2 production (P < 0.01) by cells from large follicles, whereas it exerts a stimulatory (P < 0.01) effect only in the presence of selenium in the cells from the small ones. The production of nitric oxide is significantly increased (P < 0.001) by bFSH, but only in cells from small follicles. Selenium inhibits (P < 0.001) nitric oxide production in cells from both kinds of follicles and significantly decreases (P < 0.001) bFSH-induced nitric oxide production in cells from the small ones. We conclude that selenium acts on granulosa cells by modulating their proliferation and E2 synthesis; moreover, its effect could be mediated, at least in part, through an inhibition of nitric oxide. (C) 2000 Elsevier Science Inc. All rights reserved
EFFECT OF MELATONIN ON THE INVITRO SECRETION OF PROGESTERONE AND ESTRADIOL 17-BETA BY OVINE GRANULOSA-CELLS
No full textThis study was undertaken to determine the effect of melatonin on steroid hormone production by ovine granulosa and luteal cells in vitro. Granulosa and luteal cells from ovine ovaries were cultured for nine days either in D-MEM only or in the presence of melatonin (0.86, 8.6, 86 nmol/l), ovine luteinizing hormone (oLH, 2 mug/l) or a combination of both these hormones. Progesterone (P4) and estradiol 17beta (E2) were determined by validated RIAs. Melatonin stimulation began at either day 1 or day 5 of culture. Melatonin (0.86 nmol/l) significantly increased (p < 0.001) progesterone secretion by granulosa cells both when administered alone and when administered in combination with oLH; the more marked response was observed in the latter case, When the stimulation began at day 5, at a more advanced degree of differentiation of the cells, higher levels of P4 were observed. Higher concentrations of melatonin did not further increase progesterone production. Melatonin alone did not have a significant effect on the production of estradiol 17beta; neither did melatonin stimulate progesterone production in either long-term cultured luteal cells or in short-term (1-2 h) cultured luteal and granulosa cells. The results of this study document a direct effect of melatonin in stimulating granulosa cells to produce progesterone, a synergistic activity between melatonin and luteinizing hormone and a different ability of granulosa cells to secrete P4 depending on the degree of differentiation
Effect of melatonin on the in vitro secretion of progesterone and estradiol 17 ß by ovine granulosa cells
No full textSecrezione di LH (tonica e indotta dalla stimolazione con GnRH) durante le ultime fasi della gravidanza ed il post-partum nella cavalla: influenza della stagione di parto.
No full textTestosterone modulates estradiol 17 beta production in bovine granulosa cells cultured in vitro.
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