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There are experimental data demonstrating the presence and actions of various neurotransmitters in the ovary, thus supporting the view that they might play a role in intraovarian regulatory mechanisms, although their exact function in the regulation of ovarian hormone secretion is unclear. The objective of the present study was to investigate the direct action of catecholamines, acetylcholine and histamine on progesterone secretion of human granulosa cells in a superfused cell system. Human granulosa cells were isolated from preovulatory follicular fluid using a Percoll gradient centrifugation method. Approximately 2 × 106 cells were mixed with Sephadex G-10 and were transferred into two chambers of the superfusion apparatus. The system was perfused with a culture medium and test materials were added to the system at a dose of 100 pmol/ml. The progesterone concentration of samples was measured using an 125I radioimmunoassay. Administration of epinephrine (adrenaline), norepinephrine (noradrenaline), dopamine and histamine had no effect on progesterone release. However, acetylcholine produced a significant progesterone release, which could be blocked by atropine. The observed effect of acetylcholine on progesterone release of superfused human granulosa cells may reflect a physiological role of acetylcholine in the regulation of granulosa cell function during the menstrual cycle.

The aim of this study was to explore the direct action of melatonin (Me) on basal and gonadotropin-stimulated progesterone (PG) and estradiol (E2) secretion of human granulosa cells (GCs) cultured in serum-free medium and in a superfused GC system. Human GCs were isolated from preovulatory follicular fluid aspirated from 34 women undergoing in vitro fertilization at the University Women’s Hospital of Tübingen. PG and E2 production was measured in the presence and absence of Me, propranolol, LH or FSH using radioimmunoassay. Statistical analysis of the data was performed by ANOVA and Newman-Keuls test. Me stimulated E2 secretion in a dose-dependent manner. Propranolol did not cause any change in E2 secretion, and when given with Me, it only partially blocked but could not entirely prevent E2 output. There was no statistically significant effect of Me on PG production when Me was administered at concentrations between 10–4 and 10–8 M. However, at 10–3 MMe significantly suppressed PG output of granulosa cells. LH and FSH significantly stimulated the secretion of both steroid hormones. Me significantly reduced LH- and FSH-induced E2 secretion, as well as LH-stimulated PG output, while it caused only a slight, yet significant decrease in PG secretion. In the superfused GC system, FSH and LH resulted in a significant stimulatory effect on PG release. Me did not modify the stimulatory effect of FSH on PG, while it caused some delay in LH-stimulated PG release. Propranolol and Me had no stimulatory effect on PG release. On the basis of our results we suggest that Me has a direct modulatory effect on basal E2 and gonadotropin-stimulated E2 and PG secretion of human GCs. The observed effect may play a physiological role in the regulation of GC function during the menstrual cycle.

The aim of this study was to explore the direct action of acetylcholine on gonadotropin-stimulated progesterone (P) and estradiol (E2) secretion of human granulosa cells (GCs) cultured in serum-free medium. Human GCs were isolated from preovulatory follicular fluid aspirated from 22 women undergoing in vitro fertilization at the University Women’s Hospital of Tübingen. The production of progesterone and E2 was measured in the presence and absence of acetylcholine, carbachol, atropine, luteinizing hormone (LH) or follicle-stimulating hormone (FSH) using radioimmunoassay. Statistical analysis of the data was performed by ANOVA and Newman-Keuls test. Administration of acetylcholine or carbachol (10–5M) resulted in a significant increase in P and E2 secretion. This response was specifically blocked by the muscarinic receptor antagonist atropine. Similarly, carbachol resulted in a significant increase in P and E2 output, though the response to it was somewhat reduced when compared to that evoked by acetylcholine. Acetylcholine did not show any additive effect on LH-stimulated P secretion, while it augmented the stimulatory effect of FSH on P release. In contrast, carbachol markedly diminished the stimulatory effect of LH on P secretion, while it caused no change in FSH-induced P output. When administered together, acetylcholine did not modify the stimulatory effect of FSH on E2 secretion, however, it markedly elevated LH-induced E2 output. Similar to this, carbachol significantly increased LH-induced E2 release, however it decreased FSH-stimulated E2 secretion. We suggest that acetylcholine has a direct modulatory effect on gonadotropin-stimulated steroid production of GCs, an effect that is mediated via muscarinic receptors. This effect may have a physiological role in the regulation of GC function during the menstrual cycle.