We have investigated the role of m- and k-opioid receptors in the central control of preovulatory LH and FSH release in the proestrous rat. Animals were anesthetized with chloral hydrate at 14:00 h on proestrus day. Following femoral artery cannulation, they were mounted in a stereotaxic apparatus. Morphine and U-50488H (benzene-acetamide methane sulphonate) were infused intracerebroventricularly either alone or in combination with naloxone and MR1452, respectively. Controls received sterile saline alone. Blood samples were obtained at hourly intervals between 15:00 h and 17:00 h. Plasma LH and FSH levels were measured by radioimmunoassay. Morphine did not significantly change plasma LH levels at 15:00 h and 16:00 h sampling intervals. A significant increase was observed at 17:00 h compared to the controls (p<0.05). U-50488H significantly increased LH levels at 16:00 h and 17:00 h (p<0.05). The co-administration of naloxone and MR1452 with m- and k-agonist had no significant effect on LH levels at any sampling interval. In all groups, LH levels showed a linear rise over the sampling period between 15:00 h and 17:00 h. None of the treatments significantly altered plasma FSH levels which however, declined towards the end of the afternoon surge. In conclusion, we suggest that the secretion of LH and FSH is differentially regulated by m- and k-opioid receptors. It is thought that in all groups chloral hydrate interfered with the LH surge secretory systems., S. Kumru, M. Şimşek, B. Yilmaz, E. Sapmaz, S. Kutlu, S. Sandal, S. Canpolat., and Obsahuje bibliografii
The involvement of the mTOR system/enzyme sirtuin 1 (SIRT1) intracellular signaling system in the control of ovarian functions and its role in mediating hormonal action on the ovary has been proposed, but this hypothesis should be supported by a demonstrated influence of hormones on mTOR/SIRT1. Therefore, the aim of our in vitro experiments was to examine the effect of the known hormonal regulators of ovarian functions, such as follicle-stimulating hormone (FSH), oxytocin (OT) and insulin-like growth factor I (IGF-I), on mTOR/SIRT1. The accumulation of SIRT1 in porcine ovarian granulosa cells cultured with and without these hormones (at doses of 1, 10 or 100 ng.ml-1 ) was evaluated using immunocytochemistry. It was observed that the addition of FSH (at 10 ng.ml-1 but not at 1 or 100 ng/ml) and OT (at all tested doses) increased the expression of SIRT1 in ovarian cells. In addition, 100 ng.ml-1 , but not at 1 or 10 ng.ml-1 , of IGF-I decreased SIRT1 accumulation. Our observations are the first demonstration that hormones can directly regulate the ovarian mTOR/SIRT1 system and that this system could mediate the action of hormonal regulators on the ovary.
This study aimed at examining the secretion activity of steroid hormones progesterone and 17β-estradiol by porcine ovarian granulosa cells after addition of green tea extract. Granulosa cells were incubated with green tea extract (at doses of 0.01, 0.1, 1, 10 and 100 μg.ml-1). Another set of cells were incubated with green tea extract at the above doses along with additional supplementation of follicle stimulating hormone (FSH) at 10 μg.ml-1. Release of hormones by granulosa cells was assessed by EIA after 24 h exposure. Secretion of steroid hormones was not affected either by green tea extract alone or after FSH supplementation with green tea extract. Results indicate that ovarian steroidogenesis is not affected by green tea under conditions used in the experiment.
In the present in vitro experiments we examined FSH- and ghrelin-induced changes in ovarian hormone secretion by transgenic rabbits. Fragments of ovaries isolated from adult transgenic (carrying mammary gland-specific mWAP-hFVIII gene) and non-transgenic rabbits from the same litter were cultured with and without FSH or ghrelin (both at 0, 1, 10 or 100 ng/ml medium). The secretion of progesterone (P4), estradiol (E2) and insulin-like growth factor I (IGF-I) was assessed by RIA. It was observed that ovaries isolated from transgenic rabbits secreted much less P4, E2 and IGF-I than the ovaries of non-transgenic animals. In control animals FSH reduced E2 (at doses 1-100 ng/ml medium) and IGF-I (at 1-100 ng/ml), but not P4 secretion, whereas ghrelin promoted P4 (at 1 ng/ml) and IGF-I (at 100 ng/ml), but not E2 output. In transgenic animals, the effects were reversed: FSH had a stimulatory effect on E2 (at 100 ng/ml) and ghrelin had an inhibitory effect on P4 (at 10 ng/ml). No differences in the pattern of influence of FSH on P4 and IGF-I and of ghrelin on E2 and IGF-I were found between control and transgenic animals. The present observations suggest that 1) both FSH and ghrelin are involved in rabbit ovarian hormone secretion, 2) transgenesis in rabbits is associated with a reduction in ovarian secretory activity, and 3) transgenesis can affect the response of ovarian cells to hormonal regulators., A. V. Sirotkin, P. Chrenek, K. Darlak, F. Valenzuela, Ž. Kuklová., and Obsahuje bibliografii a bibliografické odkazy
The effect of hormonal stimulation with FSH injection in the doses of 18 mg (360 IU) and 24 mg (480 IU FSH) on the levels of plasma catecholamines (dopamine, norepinephrine and epinephrine) was studied by radioenzymatic methods during synchronized oestrous cycles of the sheep. Catecholamines were determined in the blood plasma before and 24, 48, 96 and 120 hours after application of FSH. It follows from the results that the levels of plasma dopamine increased significantly (p<0.001) 24 and 48 hours after FSH application. Furthermore, the levels of dopamine (DA) during the other time intervals observed, compared with those of controls before hormonal stimulation, remained at a higher level. A lower dose of the hormone (18 mg) had a more pronounced effect on changes in the levels of plasma dopamine. Norepinephrine (NE) did not exhibit any significant changes in comparison with the plasma levels of dopamine in the sheep after hormonal stimulation with FSH. A statistically significant increase in plasma norepinephrine was recorded 24 hours after administration of 18 or 24 mg FSH. During the other time intervals observed, its levels did not differ from the control values. Plasma epinephrine (E) showed a significant increase 24 and 48 hours after FSH application but not later. The effect of FSH on plasma catecholamine levels was not dose-dependent and their increase was pronounced especially in the period of ovulation.