Aromatase activity in human granulosa cells during follicular development and the modulation by follicle-stimulating hormone and insulin

Garzo, V. Gabriel; Dorrington, Jennifer H.

doi:10.1016/0002-9378(84)90769-5

Cited by 189 publications

(67 citation statements)

References 13 publications

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“…Insulin interacts positively with the reproductive systems of both sexes, enhancing or directly stimulating production of estradiol and progesterone by ovarian cells (Garzo and Dorrington, 1984;Greisen et al, 2001;Willis et al, 1996), testosterone by testicular cells (Pasquali et al, 1995), and prolactin by pituitary cells (Prager et al, 1988). These hormones in turn can have positive effects on insulin release (testosterone: Morimoto et al, 2001;prolactin: Nielsen, 1982).…”

Section: Discussionmentioning

confidence: 99%

Urinary C-peptide tracks seasonal and individual variation in energy balance in wild chimpanzees

Thompson

Muller

Wrangham

et al. 2009

Hormones and Behavior

105

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C-peptide of insulin presents a promising new tool for behavioral ecologists that allows for regular, noninvasive assessment of energetic condition in wild animals. C-peptide is produced on an equimolar basis with insulin, thus is indicative of the body's response to available glucose and, with repeated measurement, provides a biomarker of energy balance. As yet, few studies have validated the efficacy of C-peptide for monitoring energy balance in wild animals. Here, we assess seasonal and interindividual variation in urinary C-peptide concentrations of East African chimpanzees (Pan troglodytes schweinfurthii). We assayed 519 urine samples from 13 adult male chimpanzees in the Kanyawara community of Kibale National Park, Uganda. Cpeptide levels were significantly predicted by the total amount of fruit and the amount of preferred fruit in the diet. However, chimpanzees had very low C-peptide titers during an epidemic of severe respiratory illness, despite highly favorable feeding conditions. Kanyawara males had significantly lower C-peptide levels than males at Ngogo, a nearby chimpanzee community occupying a more productive habitat. Among Kanyawara males, low-ranking males had consistently higher C-peptide levels than dominant males. While counterintuitive, this result supports previous findings of costs associated with dominance in male chimpanzees. Our preliminary investigations demonstrate that C-peptide has wide applications in field research, providing an accessible tool for evaluating seasonal and individual variation in energetic condition, as well as the costs of processes such as immune function and reproduction.

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Section: Discussionmentioning

confidence: 99%

Urinary C-peptide tracks seasonal and individual variation in energy balance in wild chimpanzees

Thompson

Muller

Wrangham

et al. 2009

Hormones and Behavior

105

View full text Add to dashboard Cite

show abstract

“…While physiological insulin levels synergise with FSH in their action on granulosa cells (49), high levels of insulin amplify the action of LH in stimulating androgen synthesis in adult ovarian stroma (50). The concomitant aromatisation of the excess androgen to oestrogen in the granulosa cells is likely to increase oestrogen production also (51) so that both androgen and oestrogen levels are modified.…”

Section: Pubertal Adiposity Hyperinsulinaemia and Sex Steroid Profilementioning

confidence: 99%

Does Early Physical Maturity Influence Breast Cancer Risk?

1994

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“…In fact, insulin increases 17a-hydroxylase and 17 -20 lyase (both components of the P450c17 enzyme system) activity 8 and stimulates the expression of 3b-hydroxysteroid dehydrogenase in human luteinized granulosa cells. 9 Conversely, the role of insulin on aromatase activity is rather discordant, in vitro studies having demonstrated either a stimulatory 10 or a lack of effect. 9 In addition, insulin appears to increase the sensitivity of pituitary gonadotropes to gonadotropin releasing hormone (GnRH) action 7 and to potentiate the ovarian steroidogenic response to gonadotropins, by mechanisms probably related to an increase of the luteinizing hormone (LH) receptor number.…”

mentioning

confidence: 99%

Obesity and the polycystic ovary syndrome

et al. 2002

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The polycystic ovary syndrome (PCOS) is a condition characterized by hyperandrogenism and chronic oligo-anovulation. However, many features of the metabolic syndrome are inconsistently present in the majority of women with PCOS. Approximately 50% of PCOS women are overweight or obese and most of them have the abdominal phenotype. Obesity may play a pathogenetic role in the development of the syndrome in susceptible individuals. In fact, insulin possesses true gonadotrophic function and an increased insulin availability at the level of ovarian tissue may favour excess androgen synthesis. Obesity, particularly the abdominal phenotype, may be partly responsible for insulin resistance and associated hyperinsulinemia in women with PCOS. Therefore, obesity-related hyperinsulinemia may play a key role in favouring hyperandrogenism in these women. Other factors such as increased estrogen production rate, increased activity of the opioid system and of the hypothalamic-pituitary-adrenal axis, decreased sex hormone binding globulin synthesis and, possibly, high dietary lipid intake, may be additional mechanisms by which obesity favours the development of hyperandrogenism in PCOS. Irrespective of the pathogenetic mechanism involved, obese PCOS women have more severe hyperandrogenism and related clinical features (such as hirsutism, menstrual abnormalities and anovulation) than normal-weight PCOS women. This picture tends to be more pronounced in obese PCOS women with the abdominal phenotype.Body weight loss is associated with beneficial effects on hormones, metabolism and clinical features. A further clinical and endocrinological improvement can also be achieved by adding insulin-sensitizing agents and=or antiandrogens to weight reduction programmes. These obviously emphasize the role of obesity in the pathophysiology of PCOS.

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Aromatase activity in human granulosa cells during follicular development and the modulation by follicle-stimulating hormone and insulin

Cited by 189 publications

References 13 publications

Urinary C-peptide tracks seasonal and individual variation in energy balance in wild chimpanzees

Urinary C-peptide tracks seasonal and individual variation in energy balance in wild chimpanzees

Does Early Physical Maturity Influence Breast Cancer Risk?

Obesity and the polycystic ovary syndrome

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