1,721,133 research outputs found
Nitric oxide in follicle development and oocyte competence
Full text linkApart from its well-known role in regulating endothelial function, in mammals, nitric oxide (NO) is an important signaling molecule involved in many processes, regulating different biological functions. It has been demonstrated that NO plays a role in the physiology of the reproductive system, where it acts in controlling the activity of reproductive organs in both sexes. In the female of several animal species, experimental data suggest the presence of an intraovarian NO-generating system, which could be involved in the control of follicular development. The role of NO in regulating follicular atresia by apoptosis is still controversial, as a dual action depending mostly on its concentration has been documented. NO also displays positive effects on follicle development and selection related to angiogenic events and it could also play a modulatory role in steroidogenesis in ovarian cells. Both in monovulatory and poliovulatory species, the increase in PGE2 production induced by NO via a stimulatory effect on COX-2 activity appears to be a common ovulatory mechanism. Considerable evidence also exists to support an involvement of the NO/NO synthase system in the control of meiotic maturation of cumulus-oocyte complexes
Melatonin role in ovarian function
No full textMelatonin is a hormone mainly produced by the pineal gland in the absence of light stimuli. The light, in fact, hits the retina, which sends a signal to the suprachiasmatic nucleus which inhibits the synthesis of the hormone by the epiphysis. Mostly by interacting with MT1/MT2 membrane receptors, melatonin performs various physiological actions, among which the regulation of the sleep-wake cycle and the control of the immune system. One of its best known functions is the non-enzymatic antioxidant action, which is independent from binding with receptors and occurs by electron donation. The hormone also represents an indicator of the photoperiod in seasonally reproducing mammals, which are divided into long days and short days breeders according to the time of year in which they are sexually active and fertile. It is known that melatonin acts at hy-pothalamic pituitary gonadal axis level in many species. In particular, it inhibits the hypothalamic release of GnRH with consequent alteration of FSH and LH levels. Present paper is mainly ad-dressed to review the ovarian effect of melatonin
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
Sanguinarine inhibits VEGF-induced endothelial cell growth in a three dimensional fibrin gel matrix.
No full textEffetti dell'insulina sulla produzione basale di progesterone e sulla risposta al testosterone in cellule della granulosa bovine.
No full textEffetti dell’insulina sulla produzione basale di progesterone e sulla risposta al testosterone in cellule della granulosa suine.
No full textSwine granulosa cells vascular endothelial growth factor production in inhibited by epigallocatechin-3-gallate
No full textAngiogenic activity of swine granulosa cells: effects of hypoxia and Vascular Endothelial Growth Factor Trap R1R2, a VEGF blocker
No full textThe possible role played by hypoxia and vascular endothelial growth factor (VEGF) in the
regulation of follicular angiogenesis was studied in a three-dimensional fibrin gel model. Granulosa
cells from follicles >5mm were subjected to normoxia (19% O2), partial (5% O2) or total (1% O2)
hypoxia and their culture media were collected and used to stimulate porcine Aortic Endothelial
Cells (AOC) included in the fibrin matrix. A suspension of AOC on microcarrier beads was pipetted
in a fibrinogen solution (1 mg/ml PBS) before the addition of 1250 IU thrombine (250 microl) to
catalize the gel formation. Granulosa cell conditioned media were tested in the presence or absence
of VEGF Trap R1R2 (150 ng/ml), a potent VEGF inhibitor, that had its efficacy tested by adding
VEGF (100 ng/ml) to AOC culture. Endothelial cell proliferation was measured at 48, 96, 144, 192
h by means of Scion Image Beta. A significant (p < 0.01) increase of AOC proliferation at each
time of measurement was induced by culture media from granulosa cells subjected to partial (except
at the end of the first 48 h) and total hypoxia compared to control and normoxia conditions, and by
VEGF. VEGF Trap significantly (p < 0.01) inhibited the stimulatory effect of media conditioned by
granulosa cells cultured in hypoxic conditions. These data suggest that hypoxia stimulates
angiogenic activity of granulosa cells possibly by means of VEGF which could represent the main
effector in promoting endothelial cell proliferation
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