[show abstract][hide abstract] ABSTRACT: Follicular fluid steroid content and theca and granulosa cell steroidogenesis in pelvic congestion cystic ovaries were compared with steroidogenic function in both normal and polycystic ovaries. Ovaries were obtained at oophorectomy for benign gynaecological conditions, and classified according to gross morphology at dissection. Individual follicles were dissected out, follicular fluid aspirated, and granulosa and theca cells cultured in vitro. Androstenedione, progesterone and oestradiol content of the follicular fluid and overlying culture medium were measured by radioimmunoassay. There was a significant elevation of both basal and LH-stimulated androstenedione production by theca from both polycystic ovaries (n = 10; P < 0.005) and pelvic congestion cystic ovaries (n = 8; P < 0.05 and < 0.01 respectively) as compared with normal ovaries (n = 5). Granulosa cells from pelvic congestion ovaries (n = 7) had a diminished oestradiol response to FSH as compared with those from normal ovaries (n = 8). Follicular fluid from the majority of follicles in the pelvic congestion cystic ovaries had a high androgen:oestrogen ratio consistent with atresia. For the first time, pelvic congestion ovaries characterized by predominantly atretic follicles scattered throughout the stroma in a normal volume ovary are reported. Follicular atresia was reflected by reduced granulosa cell responsiveness to FSH, theca cell hyperplasia and increased basal and LH-stimulated androgen production. These ovaries are functionally distinct from polycystic ovaries, which do not have a higher proportion of atretic follicles than normal ovaries.
Human Reproduction 01/2001; 15(12):2570-6. · 4.67 Impact Factor
[show abstract][hide abstract] ABSTRACT: Dehydroepiandrosterone sulphate (DHEAS) is the most abundant androgen in the circulation and in ovarian follicular fluid. A steroid sulphatase accepting DHEAS as a substrate has been identified in the follicle, but the cellular location has not been determined. As DHEAS is also a potential source of oestrogen for endocrine-dependent tumours, a potent steroid sulphatase inhibitor oestrone-3-O-sulphamate (EMATE) has been developed which inhibits this activity in rat liver and mammary tumour. The aim of this study was to investigate human granulosa cells as a site of steroid sulphatase activity, to determine whether DHEAS can be utilized as a precursor for oestrogen synthesis and to investigate the inhibitory capacity of EMATE in these cells. Conversion of DHEAS to DHEA was assessed in luteinized granulosa cells by tritiated steroid assay following incubation with or without LH or insulin and steroid accumulation in the medium measured by RIA. The effects of EMATE were assessed by addition of a range of doses during the measurement of conversion of DHEAS to DHEA. Cells from three sizes of small follicles from an unstimulated ovary were also assessed for their ability to produce oestradiol from DHEAS. Sulphatase enzyme activity was present in all cells; the mean conversion of tritiated DHEAS to DHEA was 50% (range 4-65%). LH and EMATE inhibited and insulin stimulated this activity. Addition of DHEAS to granulosa cells caused a dose-dependent increase in oestradiol and androstenedione production with no change in progesterone concentration. LH increased the accumulation of oestradiol in the medium. DHEAS also stimulated oestradiol production by granulosa cells from small follicles. This is the first demonstration that granulosa cells are a site of sulphatase activity and that DHEAS can be utilized as a substrate for androstenedione and oestrogen production. This may be of physiological importance for both normal folliculogenesis and oestrogen-dependent tumour growth.
Journal of Endocrinology 01/2001; 167(3):465-71. · 4.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: Insulin has a stimulatory effect on steroidogenesis by granulosa cells of normal and polycystic ovaries and interacts with gonadotropins in an additive or, as in the case of LH, a synergistic manner. These actions seem to be mediated specifically by the insulin receptor rather than by cross-reaction with the type I IGF receptor, even in tissue obtained from women with PCOS with biochemical evidence of insulin resistance. The authors suggest that hyperinsulinemia makes a significant contribution to premature arrest of follicle growth, which is characteristic of anovulation in women with PCOS, and that the interaction of insulin with LH is a key element in this process. Insulin may also have a role in amplifying LH-induced androgen production by theca cells, which may help explain the prominence of symptoms of hyperandrogenism in obese subjects with PCOS. The results of recent clinical studies of insulin-sensitizing agents such as metformin and the thiazoladinedione troglitazone in PCOS have provided encouragement that improvement of insulin sensitivity and consequent lowering of circulating insulin levels by these agents may be of therapeutic value in the management of both anovulation and hirsutism.
Endocrinology & Metabolism Clinics of North America 07/1999; 28(2):361-78. · 3.79 Impact Factor
[show abstract][hide abstract] ABSTRACT: Polycystic ovary syndrome is the most common cause of anovulatory infertility. Anovulation in polycystic ovary syndrome is characterized by the failure of selection of a dominant follicle with arrest of follicle development at the 5-10 mm stage. In an attempt to elucidate the mechanism of anovulation associated with this disorder we have investigated at what follicle size human granulosa cells from normal and polycystic ovaries respond to LH. Granulosa cells were isolated from individual follicles from unstimulated human ovaries and cultured in vitro in serum-free medium 199 in the presence of LH or FSH. At the end of a 48-h incubation period, estradiol (E2) and progesterone (P) were determined in the granulosa cell-conditioned medium by RIA. In ovulatory subjects (with either normal ovaries or polycystic ovaries), granulosa cells responded to LH once follicles reached 9.5/10 mm. In contrast, granulosa cells from anovulatory women with polycystic ovaries responded to LH in smaller follicles of 4 mm. Granulosa cells from anovulatory women with polycystic ovaries were significantly more responsive to LH than granulosa cells from ovulatory women with normal ovaries or polycystic ovaries (E2, P < 0.0003; P, P < 0.03). The median (and range) fold increase in estradiol and progesterone production in response to LH in granulosa cell cultures from size-matched follicles 8 mm or smaller were E2, 1.0 (0.5-3.9) and P, 1.0 (0.3-2.5) in ovulatory women and E2, 1.4 (0.7-25.4) and P, 1.3 (0.3-7.0) in anovulatory women. Granulosa cells from anovulatory (but not ovulatory) women with polycystic ovaries prematurely respond to LH; this may be important in the mechanism of anovulation in this common endocrinopathy.
[show abstract][hide abstract] ABSTRACT: In experimental animal models, insulin-like growth factors (IGFs) have been found to be more potent stimulators of ovarian function than insulin. In human theca cells, however, insulin, IGF-I, and IGF-II have similar effects on androgen production. The relative effects of insulin and IGFs on human granulosa cell steroidogenesis is unknown. Furthermore, it is unclear whether effects of IGF-II on steroidogenesis are mediated by the type-I or type-II IGF receptor. The effects of insulin, IGF-I, and IGF-II on human granulosa cell steroidogenesis were compared in vitro. As expected, insulin, IGF-I, and IGF-II enhanced steroidogenesis. Previously, IGF-II has been shown to enhance granulosa cell steroid production after insulin preincubation. In this study, an effect of IGF-II, independent of insulin priming, also was observed. In granulosa cell cultures from small antral follicles (< or = 13 mm), insulin and IGF-I stimulated steroid production to a similar degree, whereas IGF-II was less effective. In contrast, IGFs were more effective than insulin (IGF-I > IGF-II > insulin) in granulosa cells isolated from preovulatory follicles. IGF-I and IGF-II actions were mediated via the type-1 IGF receptor. The increased responsiveness of mature granulosa cells to IGFs may be an important mechanism by which granulosa cells increase their steroidogenic output in the preovulatory follicle.
[show abstract][hide abstract] ABSTRACT: This study analysed the effect of oestradiol on basal and LH-stimulated production of androstenedione and progesterone by human theca cells in monolayer culture. Incubations were carried out for either 2 days (seven experiments) or 4 days (four experiments), in the presence or absence of luteinizing hormone (LH), oestradiol (10(-9)-10(-6) M) or inhibin. Medium collected at 48 and 96 h was stored until radioimmunoassay for steroid content. Theca pooled from small follicles (<10 mm) was used in all but two experiments; in these, ovaries were obtained from ovulatory women in the mid-follicular phase of their cycle and theca from small and large follicles was pooled. Oestradiol inhibited progesterone production in a dose-dependent manner in all experiments, irrespective of follicle size, ovulatory status and ovarian morphology, with maximum effect at 10(-6) M. At this dose, oestradiol had no effect on androstenedione production by theca from four anovulatory women with polycystic ovaries but produced a significant augmentation of both basal and LH-stimulated androstenedione production in theca from five of the seven ovulatory women, with maximal response in theca from the two pre-ovulatory subjects. During the 48-96 h period of incubation, oestradiol augmented androstenedione production in all four experiments and had a greater stimulatory effect than the physiological dose of inhibin (10 ng/ml). This is the first report of oestradiol regulating human theca cell steroidogenesis in a dose-dependent manner.
Human Reproduction 08/1997; 12(8):1621-8. · 4.67 Impact Factor
[show abstract][hide abstract] ABSTRACT: Anovulation in polycystic ovary syndrome (PCOS) is associated with hyperinsulinemia and insulin resistance, but it has been unclear whether the ovary is insulin resistant in women with PCOS. The aims of this study were, firstly, to determine whether human granulosa cells respond to physiological concentrations of insulin and, secondly, to investigate insulin and gonadotropin interactions in vitro in granulosa cells obtained from normal (N) and polycystic ovaries (PCO). Granulosa cells were incubated with insulin with or without gonadotropins for 48 h. Insulin augmented not only basal production of estradiol and progesterone, but also LH-stimulated steroid accumulation in granulosa cell cultures from N and PCO. Insulin enhanced FSH-stimulated progesterone production by granulosa cells from N and PCO, but the effect on FSH-stimulated estradiol production was variable, ranging from no effect for granulosa cells from N to synergistic for granulosa cells from PCO of anovulatory subjects. Preincubation with insulin for 48 h increased subsequent basal and LH-induced, but not FSH-stimulated, steroid production. These data demonstrate that granulosa cells from PCO respond to insulin despite the association, in vivo, of PCOS with peripheral insulin resistance. Insulin preincubation enhances the subsequent response of human granulosa cells to LH. We propose that in anovulatory women with PCOS, elevated levels of insulin interacting with LH may contribute to the mechanism of anovulation.
[show abstract][hide abstract] ABSTRACT: The adverse effects of obesity on reproductive function in women are well recognized, but women with polycystic ovary syndrome (PCOS), the most common cause of anovulatory infertility, seem particularly vulnerable to the effects of excessive intake of calories. Polycystic ovary syndrome is associated with hyperinsulinaemia and insulin resistance, the causes of which remain unclear. These metabolic abnormalities are, in turn, related to a disorder of energy expenditure, characterized by reduced post-prandial thermogenesis. It is proposed that these closely interlinked phenomena that, particularly in overweight subjects, are associated with anovulation, may confer a biological advantage for women with PCOS at times of food deprivation, when such women may reproduce more successfully than those without PCOS. A possible causal link between hyperinsulinaemia and ovulation is explored by reference to the interaction of insulin and LH in granulosa cells.
[show abstract][hide abstract] ABSTRACT: In order to account for the effects of insulin on the polycystic ovary (PCO), despite peripheral insulin resistance in women with polycystic ovary syndrome (PCOS), it has been suggested that insulin may act through the type-I insulin-like growth factor (IGF) receptor and not the insulin receptor. We have tested this hypothesis by investigating the effect of anti-insulin receptor and anti-type-I IGF receptor antibodies on insulin-stimulated steroidogenesis in human granulosa cells in vitro from normal (N) and PCO. Insulin-stimulated estradiol and progesterone production was inhibited by an anti-insulin receptor antibody. In contrast, anti-type-I IGF receptor antibodies had no effect on insulin-stimulated steroidogenesis in granulosa cell cultures from N or PCO. Hence insulin acts via its own receptor in human granulosa cells from both N and PCO.
[show abstract][hide abstract] ABSTRACT: The underlying cause of anovulation in polycystic ovary syndrome is unknown. Circulating levels of immuno- and bioactive FSH are within the normal range, and the follicles contain measurable levels of bioactive FSH. The aim of this study was to compare estradiol (E2) production in response to FSH by granulosa cells from normal ovaries with those from polycystic ovaries derived from both anovulatory (anovPCO) and ovulatory subjects (ovPCO). Intrafollicular levels of immunoactive FSH, E2, and androstenedione in follicles of less than 12 mm were also measured. Follicular fluid steroid concentrations were obtained from 41 pairs of normal ovaries and 23 pairs of polycystic ovaries (8 anovPCO and 15 ovPCO). In size-matched follicles from each group there were no significant differences in follicular fluid FSH or E2 concentrations, but androstenedione levels were significantly higher in 5- to 11-mm follicles from ovPCO than in corresponding follicles from normal ovaries. Dose responses to FSH were determined in granulosa cells derived from 9 pairs of normal ovaries, 7 anovPCO, and 8 ovPCO. Cells from anovPCO produced 6- to 10-fold more E2 in response to FSH than normal cells, although there was no significant difference in the ED50 values. The response in cells from ovPCO was reduced compared to normal, but this difference did not reach significance. In summary, as judged by their FSH and E2 contents, polycystic ovaries do not have a higher proportion of atretic follicles than normal. Indeed, cells from anovPCO are hyperesponsive to FSH in vitro. This could be explained by stimulation of aromatase in vivo by either paracrine or, more probably, by endocrine factors, of which insulin is an arguable candidate.
[show abstract][hide abstract] ABSTRACT: The aim of this study was to examine the hypothesis that hypersecretion of ovarian androgens in polycystic ovary syndrome results from an intrinsic abnormality of androgen biosynthesis by thecal cells. Steroid accumulation by human thecal cells from normal and polycystic ovaries (PCO-theca) was examined under basal and LH-stimulated conditions. A method for dispersing and culturing human thecal cells as primary monolayers in serum-free medium was developed. LH increased androstenedione (A), progesterone (P), 17 alpha-hydroxyprogesterone, dehydroepiandrosterone, and estradiol accumulation in the overlying medium in a dose-dependent manner at a maximum effective dose of 2.5 ng/mL. The principal variables affecting the magnitude of steroid accumulation were plating density, duration of incubation, and follicle size. Using only theca from follicles less than 10 mm and keeping plating density constant, 48-h steroid production by theca from five normal ovaries was compared to that from nine polycystic ovaries isolated from both anovulatory and ovulatory women. There was a significant increase in both basal (median, 32.1 pmol/1000 cells.48 h; range, 18.7-250) and LH-stimulated (56 pmol/1000 cells; range, 40.7-406) A accumulation by PCO-theca compared to basal (1.7 pmol/1000 cells; range, 1.1-4.3) and LH-stimulated (2.8 pmol/1000 cells; range, 2.0-8.1) A accumulation by normal theca, with no overlap in values between the two. Although P production was also increased in the PCO-theca, the A to P ratios under both basal and LH-stimulated conditions were significantly higher in the PCO-theca [A/P ratio normal; PCO basal, 0.1 and 0.53 (P < 0.01); LH-stimulated, 0.04 and 0.65 (P < 0.001)], suggesting increased conversion of P to A. The steroid response to LH was similar in both groups. This is the first report of a difference in thecal androgen production between normal and polycystic ovaries and supports the hypothesis that there is a primary abnormality in the regulation of androgen production in PCOS.
[show abstract][hide abstract] ABSTRACT: Although abundant mRNA for IGF-II has been detected in the human ovary, a role for IGF-II in steroidogenesis has not yet been established. In rat adipocytes, incubation with insulin greatly increases cell-surface IGF-II receptor (5-fold) and the receptor is rapidly internalised in the absence of insulin. We have therefore investigated the effects of insulin preincubation on the response of granulosa cells from unstimulated ovaries to a range of doses of IGF-II. In the absence of insulin, IGF-II stimulated steroidogenesis in only one of three experiments. After incubation with 10 ng/ml insulin, there was a dose-dependent response to IGF-II in all experiments. Cells incubated with insulin produced 5-10 fold more estradiol in response to IGF-II than those incubated without. In contrast, insulin produced only a small increase of estradiol in response to IGF-I. These results demonstrate a synergistic interaction of insulin with IGF-II in human granulosa cells and suggest that there is an important role for IGF-II in human ovarian steroidogenesis.
[show abstract][hide abstract] ABSTRACT: The effects of recombinant human follicle stimulating hormone (rFSH; Org 32489) have been examined in human granulosa cells from ovaries obtained from women with spontaneous menses. In the first series of experiments the actions of rFSH on production of oestradiol and progesterone were compared with those of urinary-derived gonadotrophins. Recombinant FSH induced dose-dependent increases in production of both oestradiol and progesterone which were similar to the effects of 'pure' FSH (Metrodin) and the International Standard IS 71/223. In further studies, the actions of rFSH on oestradiol production by individual preovulatory follicles were investigated; rFSH increased oestradiol accumulation from cells obtained from follicles before the luteinizing hormone (LH) surge. In contrast, rFSH inhibited oestradiol production by granulosa cells derived from a follicle after the onset of the LH surge, whereas the gonadotrophic action of growth hormone was maintained. Following preliminary reports of the in-vivo effects of rFSH in women, these findings provide further validation of the efficacy of rFSH in the human ovary. The results of studies of the preovulatory follicle illustrate the experimental importance of the availability of recombinant preparations of pure gonadotrophins, produced by recombinant technology, in the understanding of human ovarian function.
Human Reproduction 12/1993; 8(11):1823-7. · 4.67 Impact Factor
[show abstract][hide abstract] ABSTRACT: Insulin insensitivity is a recognized feature of polycystic ovary syndrome (PCOS) but previous studies have suggested that circulating insulin concentrations are normal in hyperandrogenaemic women with regular cycles. The aim of this study was to examine the relationship between insulin sensitivity and menstrual pattern in women with PCO.
A cross-sectional study of insulin sensitivity in a cohort of PCO subjects with oligomenorrhoea compared to women with PCO and regular menstrual cycles and a group of normal control subjects.
Seventy-two women with polycystic ovaries on ultrasonography were studied. PCO subjects had clinical and/or biochemical evidence of hyperandrogenism; 53 had oligo/amenorrhoea (olig) and 19 had regular menses (reg). Results were compared with 31 control subjects. The groups were matched for age, weight and ethnic origin.
Glucose and insulin responses to 75 g oral glucose were measured. Insulin sensitivity was assessed by the decline in plasma glucose following intravenous insulin (0.05 U/kg).
Glucose area (mean +/- SEM) after oral glucose was increased slightly in both PCO groups compared with controls (olig 37.6 +/- 1.4, reg 36.0 +/- 1.8, control 33.7 +/- 0.9 mmol/l h, both P < 0.01). Insulin area median (interquartile range) in response to glucose was significantly greater in the oligomenorrhoeic group (346 (239-734) mU/l h), compared with both PCO with regular cycles (246 (148-355), P < 0.01) and controls (221 (147-277), P < 0.01). Insulin sensitivity was reduced (P < 0.01) in the oligomenorrhoeic group (147 +/- 9.2 mumol/l min) compared to controls (185 +/- 7.4) but was normal in PCO with regular cycles (182 +/- 12.5). Insulin sensitivity did not correlate significantly with plasma testosterone or with SHBG levels, but plasma insulin concentrations correlated negatively with SHBG levels (fasting insulin vs SHBG, r = -0.47, P < 0.01; insulin area vs SHBG, r = -0.41, P < 0.01).
Insulin insensitivity in polycystic ovary syndrome occurs when there is oligo/amenorrhoea but not when the menstrual cycle is regular. This is consistent with PCO and insulin insensitivity being separate abnormalities which when combined are associated with anovulation.
[show abstract][hide abstract] ABSTRACT: The effects of insulin-like growth factor-binding proteins (IGFBPs) 1 and 3 on steroidogenesis by human granulosa cells has been examined. Both IGFBP-1 and IGFBP-3 produced a dose-related inhibition of IGF-I-stimulated oestradiol accumulation in granulosa cell-conditioned medium with complete reversal of the effects of IGF-I in the presence of a molar excess of binding protein. IGFBPs 1 and 3 also exerted a small (25-40%) but significant and consistent inhibition of oestradiol secretion in response to follicle-stimulating hormone (FSH) alone. The progesterone response to IGF-I was inhibited by IGFBPs 1 and 3 but there was no effect on FSH-stimulated progesterone production. These data support the concept of a physiologically important intraovarian IGF system in the human ovary and demonstrate an unequivocally inhibitory effect of IGFBPs 1 and 3 on IGF-I-stimulated granulosa cell steroidogenesis.
Molecular and Cellular Endocrinology 12/1992; 89(1-2):R1-4. · 4.04 Impact Factor