OVARIAN AND ADRENAL FUNCTION IN POLYCYSTIC OVARY SYNDROME

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POLYCYSTIC OVARY SYNDROME

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OVARIAN AND ADRENAL FUNCTION IN POLYCYSTIC OVARY SYNDROME Robert L. Rosenfield, MD

Polycystic ovary syndrome (PCOS) is the prototypic form of chronic hyperandrogenic anovulation. The basis of the hyperandrogenism has been a mystery until recently. New research data indicate that PCOS results from a previously unrecognized type of disturbance of androgen secretion, abnormal regulation (dysregulation) of steroidogenesis. As a background for understanding ovarian and adrenal function in PCOS, this article reviews normal androgen physiology. The nature of the ovarian and adrenal dysfunction of PCOS is then discussed, with a focus on the common type of PCOS (primary PCOS) and not that secondary to disorders, such as extreme insulin resistance syndromes or congenital adrenal hyperplasia. NORMAL ANDROGEN PRODUCTION AND ITS REGULATION Androgen Biosynthesis

The ovary and adrenal share the core of the steroid biosynthesis pathway (Figs. 1 and 2). The initial step in the biosynthesis of all steroid

This work was supported in part by USPHS grant RR-0005.

From the Departments of Pediatrics and Medicine, The Pritzker School of Medicine, The University of Chicago, Chicago, Illinois

ENDOCRINOLOGYAND METABOLISM CLINICS OF NORTH AMERICA

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VOLUME 28 * NUMBER 2 JUNE 1999

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Figure 1. Major steroid biosynthetic pathways in the adrenal cortex. The square contains the core steroidogenic pathways also used by the gonads. The upper, lightly shaded area shows the zona fasciculata pathway to cortisol. The lower, darker shaded area shows additional zona reticularis steps to dehydroepiandrosterone sulfate (DHEA-SO,). Dashed pathways are considered to be relatively minor. Compound S = 11-deoxycortisol; the 11-deoxy intermediate to aldosterone (deoxycorticosterone) is not shown. Steroidogenic enzymes are italicized. Cytochrome P450 enzyme steps are side chain cleavage; 1701hydroxylase/l7,20-lyase; 21 hydroxylase (21);1 1p-hydroxylase/l8-hydroxylase-dehydrogenase (11,18);and aromatase. Non-P450 enzyme steps are steroidogenic acute regulatory protein (StAR), A5-isomerase-3p-hydroxysteroiddehydrogenase (3p), 17p-hydroxysteroid dehydrogenase (1 7p), sulfokinase (SK) and sulfolyase (SL).(Adapted from Rosenfield RL, Barnes RB, Cara JF, et al: Dysregulation of cytochrome P450c17a as the cause of polycystic ovary syndrome. Fertil Steril 53:785,1990; with permission.)

hormones is the conversion of cholesterol to pregnenolone. This is a two-stage process. The conversion is carried out by the cholesterol side chain cleavage enzyme. The rapidity of the process is dependent on the transport of cholesterol from the outer to the inner mitochondria1 membrane by the acute steroidogenicregulatory protein.lo2Pregnenolone subsequently undergoes a two-step conversion to the 17-ketosteroid dehydroepiandrosterone (DHEA) along the A5-steroid pathway. This conversion is accomplished via cytochrome P450c17. P450c17 is a single enzyme with both 17-hydroxylaseand 17,20-lyase activitie~?~ the former being more efficient than the latter.25Progesterone undergoes a parallel transformation to androstenedione in the A4-steriodpath. 17-Hydroxylation is accomplished by P450c17, but in humans, the quantitative importance of 17,20-lyase activity in the A4-pathway is unknown. The P450c17 gene product does not efficiently use 17-hydroxyprogesterone as a substrate, thus P450c17 does not seem to carry out 17,20-lyase activity in the A4-pathway.5,l7 Some evidence supports the existence of a P450c17-independent pathway.l7.25, lo5The metabolism of A5-3B-hydroxy-

OVARIAN AND ADRENAL FUNCTION IN POLYCYSTIC OVARY SYNDROME

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DEHYDROEPIANDROSTERONE

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Figure 2. Organization of the major steroid biosynthetic pathways in the small antral follicle of the ovary, according to the two-gonadotropin, two-cell model of ovarian steroidogenesis. Luteinizing homone (LH) stimulates androgen formation within theca cells by the steroidogenic pathway common to the gonads and adrenal glands. Follicle-stimulating hormone (FSH) regulates estradiol biosynthesis from androgen by granulosa cells. Long-loop negative feedback of estradiol on gonadotropin secretion does not readily suppress LH at physiologic levels of estradiol. Androgen formation in response to LH appears to be modulated by intraovarian feedback at the levels of 17-hydroxylase and 17,20-lyase, both of which are activities of cytochrome P450c17. The quantitative importance of androstenedione formation from 17-hydroxyprogesterone (dashed arrow) in the intact follicle is unknown. Androgens and estradiol inhibit (minus signs), and inhibin, insulin, and insulin-like growth factor-I (IGF-I) stimulate (plus signs) 17-hydroxylase and 17,204yase activities. (For italicized enzyme abbreviations, see Fig. 1 legend). (Adapted from Ehrmann DA, Barnes RB, Rosenfield RL: Polycystic ovary syndrome as a form of functional ovarian hyperandrogenism due to dysregulation of androgen secretion. Endocrin Rev 16:322, 1995; with permission.)

steroids to steroids with the A4-3-keto configuration is accomplished dehydrogenase (3f3). The type I1 3P by A5-isomerase-3~-hydroxysteroid isozyme accounts for the vast majority of the 3P activity in the human ovary and adrenal.losIn the adrenal, 17-hydroxyprogesteroneis situated at a potential branch point at which cortisol and sex hormone synthesis may diverge depending on whether 17-hydroxyprogesteroneundergoes 21-hydroxylation (pathway to cortisol) or 17,2O-lysis (pathway to 17ketosteroids). The conversion of 17-ketosteroids to 17P-hydroxysteroids by 17P-hydroxysteroid dehydrogenase (17P) is essential for the formation of the potent sex steroids testosterone, dihydrotestosterone, and

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estradiol. In the ovary, androstenedione is an intermediate both in the biosynthesis of testosterone (via 17p) and estrogens (via aromatase).

Normal Regulation of Androgen Production Plasma androgens are produced directly by secretion and indirectly by peripheral metabolism of secreted precursors. Androgens and androgen precursors are secreted by both the ovaries and adrenal glands in response to their respective trophic hormones, luteinizing hormone (LH) and adrenocorticotropic hormone (ACTH). Thus, they undergo about twofold episodic, diurnal, and cyclic variation. Androgens in women are not specifically under negative feedback control by these pituitary hormones because they are by-products of estradiol and cortisol secretion. The rate-determining step in steroidogenesis is the formation of pregnenolone from cholesterol, which is regulated by trophic hormones. The rate-limiting step in androgen formation is the regulation of P450c17 gene expression. P450c17 gene expression is absolutely dependent on the concentration of trophic hormones, LH in the ovary2,80, 86 and ACTH in the adrenal cortex.21,56 The 17,20-lyase activity of P450c17 is selectively upregulated by interaction with electron-donor enzymes5and by serine pho~phorylation.'~~ In addition, the steroidogenic response to ACTH and LH is modulated by a multitude of small peptides, of which insulin and insulin-like growth factors (IGFs) are best characterized.

Ovary Regulation of the intraovarian androgen concentration is critical to ovarian function. Androgens are a "necessary evil" in the ovary. On the one hand, androgens are obligate substrates for estradiol biosynthesis and promote the growth of small follicles.&,130, 13* When in excess, they seem to interfere with the process of follicular maturation, preventing the emergence of the dominant follicle and committing the follicle to atresia,&,47, 49 as well as interfering with LH action on luteinized granulosa cells.1o1Therefore, androgen synthesis must be kept to the minimum necessary to optimize follicular development. This means that the synthesis of ovarian androgens must be coordinated with the needs of the follicle. Normal ovarian function depends on the combined action of LH on theca-interstitial-stromal (thecal) cells and follicle-stimulating hormone (FSH) on granulosa cells.25According to the two-cell model of ovarian function (Fig. 2), steroidogenesis through the middle of the follicular phase is organized such that the thecal cell compartment secretes androstenedione in response to LH and the androstenedione formed by the thecal cells is converted within granulosa cells to estrogen by aromatase under the influence of FSH. As a dominant follicle emerges, both increased amounts of androstenedione and estradiol are secreted, but

OVAlUAN AND ADRENAL FUNCTION IN POLYCYSTIC OVARY SYNDROME

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estradiol comes to predominate. LH secretion, and consequently androgen secretion, is not very sensitive to long-loop negative feedback by the modest changes in plasma estradiol or testosterone levels that occur during the normal menstrual cycle. Intraovarian modulation of androgen synthesis in response to LH seems to be a critical aspect of the regulation of androgen biosynthesi~.~~ As LH stimulation increases, desensitization of the response to LH (homologous desensitization) sets in (Fig. 3). The mechanism of desensitization has been worked out in detail in Leydig cells. Overstimulation by LH in a time- and dose-related manner initially causes downregulation of LH receptors and cholesterol side chain cleavage activity, later causes downregulation of 17,20-lyase activity, and finally causes downregulation of 17-hydroxylase activity. In the course of this process, the ratio of 17-hydroxyprogesterone to androgen production increases as LH rises into the upper portion of the stimulatory range. The coordination of thecal cell androgen biosynthesis and granulosa cell function seems to be critically dependent on modulation of 17hydroxylase/ 17,20-lyase activities by specific autocrine, paracrine, and hormonal factors such as those shown in Figure 2. Some of these factors are LH-dependent, whereas other are FSH-dependent. The processes mediating downregulation of 17-hydroxylase/17,20-lyase activities in response to LH are counterbalanced by processes upregulating these activitie~.~~ Androgens and estrogens seem to be negative modulators of the androgenic response to LH, possibly through both receptor-dependent and receptor-independent mechanisms. The IGF system within the

120,

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PCO ’ ANDROSTENEDIONE

40 17-HYDROXYPROGESTERONE

0

5 LH DOSE ng/mL

10

Figure 3. LH-steroid dose-response curves of human theca cells in culture. Low doses of LH stimulate steroid secretion, 17-hydroxyprogesterone more than androstenedione. In normals no further stimulation of the secretion of these respective steroids occurs beyond LH doses of 2.5 and 5.0 ng/mL (1 ng LH = 12.7 mlU first IRP-hLH, WHO 68/40). Doseresponse curves of theca cells from polycystic ovaries seem shifted to the left and upwards. (Data from Gilling-Smith C, Willis DS, Beard RW, et al: Hypersecretion of androstenedione by isolated theca cells from polycystic ovaries. J Clin Endocrinol Metab 79:1158, 1994.)

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ovary seems to have an important role in positively modulating the ovarian response to LH. In the rat, IGFs act by increasing thecal levels of side chain cleavage enzyme mRNA and by augmenting the ability of LH to increase P-450~17 mRNA levels. Insulin augments LH-stimulated androgen production similarly through several potential mechanisms. Insulin may act via its own receptor, the IGF-I receptor, atypical IGF-I receptors, or a hybrid receptor, which contains a combination of a- and P-subunits of both receptors. It has also been postulated that, by lowering levels of IGFbinding protein-1, insulin may raise the fraction of IGF-I that is bioavailable.96Either insulin or IGF causes escape from homologous desensitization to LH (Fig. 4).14 Inhibin stimulates ovarian androgen production,5° whereas androgens, in turn, stimulate ovarian inhibin produ~tion.~~, 45 Activin opposes the inhibin effect.46A variety of other ovarian peptides are also capable of modulating thecal androgen synthesis.25Stimulators include prostaglandin and angiotensin. Inhibitors include corticotropinreleasing hormone,3O transforming growth factor$, epidermal growth factor, tumor necrosis factor, and cytokines. Granulosa cell development is another important determinant of ovarian androgen p r o d u ~ t i o n Follicles .~~ develop both high numbers of granulosa cells and high aromatase activity as they mature; healthy follicles 8 mm or more in diameter efficiently convert androstenedione to estradiol. On the other hand, granulosa cell number and aromatase activity are low in atretic or cystic follicles such that follicles have a high

5

50

LUTElNlZlNG HORMONE (IU/L) Figure 4. Effect of insulin or IGF on LH-steroid dose-response curves in thecal cells. LH in the physiologic range stimulates thecal steroid secretion. LH doses above the physiologic range completely desensitize the ability of thecal cells to respond to further increases in LH. The addition of insulin or IGF-I to LH causes escape from this decrease and markedly augments steroid production, in response to LH. (From Ehrmann DA, Barnes RB, Rosenfield RL: Polycystic ovary syndrome as a form of functional ovarian hyperandrogenism due to dysregulation of androgen secretion. Endocrin Rev 16:322,1995; with permission.)

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androstenedione to estradiol ratio, that is, they are relatively androgenic.25 What factors determine the proliferation and health of the granulosa cell population? The growth of antral follicles beyond the 2 to 5 mm stage requires FSH action on granulosa and FSH is concentrated by the emerging dominant follicle.88FSH actions on granulosa cells are mediated, at least in part, by the IGF system.1,92,136 In synergy with FSH, IGF-I and insulin (in physiologic but generally greater concentrations than IGF-1) stimulate estradiol production in cultured granulosa cells.81 On the other hand, IGF-binding proteins inhibit FSH bioactivity, whereas transforming growth factor-a and epidermal growth factor inhibit aromatase.81IGF-binding proteins are strongly expressed in granulosa cells targeted for a t r e ~ i a .Although ~~ activin inhibits thecal androgen secretion, it promotes granulosa cell estrogen ~ e c r e t i o n . ~ ~ Adrenal

Adrenal 17-ketosteroid secretion is low in childhood. It gradually increases in midchildhood as a result of adrenarche, the "adrenal puberty" during which the adrenal cortex develops the ability to secrete 17-keto~teroids."~ During adrenarche, DHEA sulfate becomes as prominent an adrenocortical secretion as cortisol. Adrenarche represents a change in the pattern of adrenal secretory response to ACTH that is characterized by striking increases in 17-hydroxypregnenolone and DHEA responsiveness to ACTH, whereas cortisol responsiveness remains unchanged.lWThe development of adrenarche seems to be related to the development of the zona reticularis of the adrenal This zone forms in concert with adrenarche, expresses little 3p 34 and has sulfokinase activity that conjugates DHEA to form DHEA sulfate.57Both in vitro and in vivo data suggest that this zone undergoes maturational increases in 17-hydroxylase and 17,20-lyase activities.22, lo9, lZ2 Insulin and IGF-I stimulate the expression of adrenal 3p and 67 with lesser effects on other steroidogenic steps.66 P450c17 activitie~.~~, Although adrenarche is unrelated to true puberty (gonadotropindependent "gonadal puberty"), gonadal function may have a role in supporting adrenal DHEA sulfate production. Ovarian failure and ovariectomy precipitate an early decline in DHEA sulfate levels, yet estrogen replacement has no beneficial effect on the DHEA sulfate de~line.'~ Plasma DHEA sulfate levels in women are two thirds those in men.2o Androgens may regulate DHEA sulfate levels because testicular secretion of DHEA sulfate is modest.68 Considerable controversy exists regarding the existence and nature of an "adrenarche This factor has been postulated to be a pituitary, ACTH-related hormone distinct from ACTH because adrenal androgen production is more sensitive to glucocorticoid suppression than is cortisol production.110Leading candidates for this factor include a proopiomelanocortin product and corticotropin-releasing hormone. Corticotropin-releasing hormone was recently reported to stimulate

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DHEA sulfate secretion preferentially by human fetal adrenocortical cells125in contrast to its reported inhibitory effect on ovarian thecal DHEA ~ e c r e t i o n .Currently, ~~ the only established adrenal androgenstimulating hormone in postnatal life is ACTH and it is necessary and sufficient to do so. Because the adrenarchal secretion pattern represents a change in the pattern of steroidogenic response to ACTH, an adrenarche factor need only control the growth and differentiation of the zona reticularis or regulate steroidogenic enzymes, such as by decreasing 3p activity or increasing the 17,20-lyase activity of P450c17. Serine phosphorylation is a potential mechanism by which the 17,20-lyase activity of P450c17 is selectively increased.89 Peripheral Metabolism of Secreted Precursors

The 17-ketosteroids are proandrogens. Peripheral conversion to the 17P-hydroxysteroids testosterone and dihydrotestosterone is required for androgenic activity. Approximately half of plasma testosterone is derived from the peripheral conversion of secreted androstenedione. The remainder is derived from direct ovarian and adrenal secretion. The major clinically important sites of this peripheral conversion are lung, liver, adipose tissue, and skin.13,16, 85, 112 The factors controlling these conversions are poorly understood. Under conditions of gonadotropin hyperstimulation, plasma DHEA sulfate becomes a major substrate for ovarian testosterone biosynthesi~.~~ Plasma dihydrotestosterone arises virtually entirely by 5a-reductase activity in the periphery. Plasma androstenedione is the major precursor of dihydrotestosterone in women, accounting for more than 60% of circulating levels.61,84, 131 Adipose tissue also forms estrone from andro~tenedi0ne.l~~ Obesity, therefore, causes a state of mild estrogen

OVARIAN FUNCTION IN POLYCYSTIC OVARY SYNDROME

The presence of enlarged polycystic ovaries has suggested that the ovaries are the primary site of the abnormality in PCOS. Several studies have indicated that the ovaries usually produce excess androgen. Ovarian vein catheterization showed a prominent gradient between ovarian and peripheral venous androgen levels.62Suppression of ovarian function by estrogen-progestin (birth control pills)6oor by long-term administration of gonadotropin-releasing hormone (GnRH) ag~nists’~, typically suppresses the elevated androgen levels. In addition, suppression of adrenal function by dexamethasone administration seldom corrects the plasma free testosterone level, although it often improves it.M)These findings have indicated that PCOS is a form of functional ovarian hyperandr~genism.~

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Thecal Cell Dysfunction

The recent development of a specific test of the combined function of the ovarian follicular compartments identified a specific type of ovarian dysfunction in the great majority of patients with classic PCOS. When normal women are given a single dose of a potent GnRH agonist, such as nafarelin or leuprolide, a premature LH and FSH surge takes place that is of preovulatory magnitude (Fig. 5).1°,25 In response to this, plasma estradiol and estrone rise threefold within 24 hours. The process is fairly efficient because there is relatively little elevation in the blood level of estradiol precursors. Patients with classic PCOS (hyperandrogenism with LH or ultrasonographic abnormality or both) characteristically respond to a GnRH agonist challenge test with hyperresponsiveness of plasma 17-hydroxyprogesterone and, to a lesser extent, androstenedione.l0!25 The pattern of steroid responses is not consistent with any known enzyme block (Fig. 5). The intermediates from 17-hydroxypregnenolone and androstenedione onward hyperrespond; testosterone rises slightly yet significantly and estrone and estradiol marginally. The 3P-hydroxy intermediates pregnenolone, 17-hydroxyprogesterone, and DHEA rise only slightly. This pattern of steroid secretion suggests that there is generalized dysregulation of ovarian androgen secretion, which is particularly prominent at the level of 17-hydroxylase and 17,20-lyase activities. The biochemical basis of this dysregulation is unclear. Current opinion favors l7 If this is true, 17P450c17 as the major source of 17,20-lyase a~tivity.~, hydroxyprogesterone is simply a passive marker of P450c17 dysregulation accumulating in a “metabolic cul-de-sac,” whereas androstenedione is formed predominantly from 17-hydroxyprogesteronevia DHEA. A PCOS-like type of ovarian dysfunction is found in more than half of hyperandrogenic patients, even in many who lack the classic criteria for the diagnosis of PCOS. The author and his colleagues enrolled 40 hyperandrogenic women who consecutively presented to reproductive endocrinology, medical endocrinology, or pediatric endocrinology clinics with oligomenorrhea, hirsutism, or acne and who consented to undergo GnRH agonist, dexamethasone, and ACTH testingz6 Hyperprolactinemia and Cushing’s syndrome were excluded. An elevated plasma 17hydroxyprogesterone response to GnRH agonist was found in 23 of the 40 women (58%).Twenty-two of these 23 women (96%)had an abnormal dexamethasone androgen-suppression test. The dexamethasone test was abnormal in 27 women; of these, 22 (81%) had an abnormal response to the GnRH agonist test. The peak response of 17-hydroxyprogesterone to GnRH agonist correlated well with the free testosterone level after dexamethasone suppression of adrenal function (Y = 0:75), with 85% concordance between the two tests. It was concluded that the correlation between the responses to GnRH agonist and dexamethasone indicated that these tests reflect closely related aspects of ovarian function. Functional ovarian hyperandrogenism is found in 70% of hyperandrogenic

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Figure 5. Patterns of response to GnRH agonist (nafarelin) testing in patients with classic polycystic ovary syndrome (PCOS). All subjects were pretreated with dexamethasone to suppress coincident adrenal androgen production. Baseline (0 min) for LH and FSH is the mean of four samples taken over 1 hour. Nafarelin 100 pg was administered subcutaneously after obtaining the baseline samples. The time scale for the LH and FSH graphs is expanded to demonstrate the early (30-60 min) hyperresponsiveness of LH in PCOS. Substantial and prolonged release of gonadotropins stimulates ovarian steroid secretion within 24 hours. PCOS patients had 17-hydroxyprogesterone (8/8cases) and androstenedione (6/8cases) hyperresponsiveness, with no evidence of a steroidogenic block on the pathway to estrogens. PCOS patients differed significantly from normal at designated time points (*) and in peak incremental responses (t). Solid circle = PCOS; open circle = normal. (Adapted from Ehrmann DA, Barnes RB, Rosenfield RL: Polycystic ovary syndrome as a form of functional ovarian hyperandrogenism due to dysregulation of androgen secretion. Endocrin Rev 16:322, 1995; with permission.)

women when either the GnRH agonist test or the dexamethasone androgen-suppression test are used as diagnostic criteria (Table 1). Half of the hyperandrogenic women were found to have a nonclassic type of PCOS in which the PCOS-type of ovarian dysfunction was Of the 23 not associated with LH excess or sonographic abn~rmalities."~ hyperandrogenic patients with abnormal responses to GnRH agonist in

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275

Table 1. SOURCE OF ANDROGEN IN 40 CONSECUTIVELY PRESENTING HYPERANDROGENIC WOMEN Adrenal Testst Ovarian Tests*

Abnormal Normal

Abnormal

Normal

35% 25%$

35% 10%

*Ovarian tests evaluated the plasma 17-hydroxyprogesterone response to gonadotropin releasing hormone agonist (nafarelin) and the plasma free testosterone response to dexamethasone. tAdrenal tests evaluated dehydroepiandrosterone and androstenedione responses to adrenocorticotropic hormone. Seventy percent of the patients had functional ovarian hyperandrogenism (one or both ovarian tests abnormal), and 60% had functional adrenal hyperandrogenism. *One of the 23 patients with isolated functional adrenal hyperandrogenism had nonclassic congenital adrenal hyperplasia owing to 21-hydroxylase deficiency. Results rounded to nearest 5%. Data from Ehrmann DA, Rosenfield RL, Barbes RB, et a1 Detection of functional ovarian hyperandrogenism in women with androgen excess. N Engl J Med 327157,1992.

the author’s prospective study, only 11 (48%) had elevated baseline serum LH concentrations.26Thus, functional ovarian hyperandrogenism occurred equally often with or without LH excess. Of the 13 women with abnormal responses to GnRH agonist who underwent ultrasonography, 7 (54%)had polycystic ovaries. Subsequent prospective study of an additional 20 hyperandrogenic women showed similar relationships among the peak 17-hydroxyprogesteroneresponse to the GnRH agonist, LH, and polycystic o ~ a r i e s . ” ~ Both in vivo and in vitro data indicate that thecal cells from PCOS patients have generalized overactivity of thecal steroidogenesis. During GnRH agonist testing, patients had increased levels or responses of all estradiol precursors studied beyond pregnenolone, although for each precursor, the increases were inconsistent (e.g., DHEA), only marginally significant (e.g., progesterone), or modest (e.g., 17-hydroxypregnenolone) (Figs. 5 and 6) (Table 2).25,118When theca cells from polycystic ovaries are subjected to primary culture, they produce the elevated basal and LH-stimulated amounts of 17-hydroxyprogesteroneand androstenedione expected from clinical studies (Fig. 5)?, This occurs on a per cell basis. Furthermore, the cultured thecal cells produce excessive amounts of all steroids examined, including progesterone and DHEA. Granulosa CelI Dysfunction At baseline, there is a tendency toward a mild estradiol excess for the stage of follicular maturation; this may be partly the consequence of excess androgenic substrate for estradiol secretion. Patients with PCOS also secrete slightly excessive amounts of estrone and estradiol in response to the slightly subnormal FSH response to an acute GnRH agonist challenge test.1° Frank hyperestrogenism is prevented by an apparent decrease in aromatase activity, which is apparently mediated by negative

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Serum Luteinizing Hormone Level (IU/L) Figure 6. Apparent dose-response relationships between LH and steroids in PCOS during dexamethasone-pretreated nafarelin tests in comparison with normal. PCOS defined here as hyperandrogenic females with LH excess, versus nonclassic PCOS defined as those without LH excess. Baseline and peak blood levels of LH are plotted against these respective parameters for steroids. Baseline 17-hydroxyprogesterone, androstenedione, and testosterone levels differ among groups independently of LH excess according to analysis of covariance (*). In addition, the apparent slopes of the LH-17-hydroxyprogesterone and LH-testosterone dose-response curves (AsteroidIALH) are significantly greater in both types of PCOS than normal (**). (Adapted from Rosenfield RL, Barnes RB, Ehrmann DA: Studies of the nature of 17-hydroxyprogesterone hyperresponsiveness to gonadotropin releasing hormone agonist challenge in functional ovarian hyperandrogenism. J Clin Endocrinol Metab 79:1686, 1994; with permission.)

feedback inhibition of FSH.IIs FSH therapy induces a larger cohcrt of follicles to develop in women with PCOS when compared with other infertile women (hyperstimulation syndrome).48,121 Granulosa cells from polycystic ovaries in vitro also secrete excessive estradiol in response to FSH.s2Granulosa cells from polycystic ovaries have been reported to lose FSH-responsiveness prematurely and to produce low amounts of

NS

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AD = androstenedione; DHEA = dehydroepiandrosterone; E2 = estradiol; FROG = progesterone; 17I'ROG = 17-hydroxyprogesteronc; T = testosterone; LH = lutemzing hormone; FOH = functional ovarian hyperandrogenism; ANOVA = analysis of variance; NS = not significant. Significant differences exist among values designated by same superscript for a given parameter: a and b, P <0.05, c and d, P ~ 0 . 0 1 e; and f, P <0.001. Adnptrd from Rosenfield RL. Barnes RB, Ehrmann D A Studies of the nature of 17-hydroxyprogesterone hyperresponsiveness to gonadotropin-releasing hormone agonist challenge in functional ovarian hyperandrogenism. J Clin Endocrinol Metal 79.1686, 1994; with permission.

Normal (n = 18) PCOS, classic (LH high) (n = 19) PCOS, nonclassic (LH normal) ( n = 18) ANOVA

Group

Basal nmollL

Progesterone

Table 2. STEROID INTERMEDIATES AND STEROID RATIOS DURNG DEXAMETHASONE-SUPPRESSED NAFARELIN TESTS (MEAN 5 SEM)

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progester~ne.~~ In addition, granulosa cells, along with theca cells from PCOS ovaries, express mRNAs for IGF-I, IGF-11, and IGF-binding proteins in a pattern consistent with follicular maturation arrest.27 Pathogenesis of Ovarian Dysfunction

Primary LH excess has long been considered the cause of the excess ovarian androgen secretion in patients with PCOS. This concept arises from the known stimulatory effect of LH on thecal function and the elevation of serum LH levels at baseline and in response to GnRH in classic PCOS. A primary role of LH excess is arguable, however. Theca cells from polycystic ovaries secrete abnormal amounts of steroids in culture, both before and after LH ~timulation.~~ Furthermore, when patients with PCOS are given a fixed dose of the LH analogue human chorionic gonadotropin (hCG), they have 17-hydroxyprogesterone and androstenedione hyper response^.^^, 74 In addition, patients with PCOS continue to manifest 17-hydroxyprogesterone hyperresponsiveness to hCG despite correction of their baseline LH abnormality by 1 month of GnRH agonist treatment.35Nevertheless, these data are not adequate to resolve the question of whether the abnormality is simply related to residual thecal cell hyperplasia from antecedent LH stimulation.116, I2O An additional line of evidence against a primary role of LH excess is that the PCOS type of ovarian dysfunction occurs at the same frequency with or without the classic PCOS feature of LH excessz6;however, it could be argued that these patients may secrete an LH molecule with enhanced bioa~tivity,3~, 5z or, since recent data suggest, that serum gonadotropin levels inversely correlate with the adiposity of patients with PCOS,4. lz8 that the hyperinsulinemia of obesity amplifies the effect of normal gonadotropin levels. Perhaps the most important factor weighing against a primary role of LH excess as a cause of hyperandrogenism is the desensitization process (see Fig. 3). Normal thecal cells are very sensitive to the downregulating effect of LH levels within the physiologic range.14,36 Maximal stimulation of 17-hydroxyprogesterone and androstenedione in culture normally occurs at LH concentrations approximating the upper portion of the normal range for follicular phase serum LH levels, and a further increase in LH dosage leads to no further rise. Nevertheless, the possibility exists that the disproportionate 17-hydroxyprogesterone response to stimulation by gonadotropins in patients with PCOS and functional ovarian hyperandrogenism might be explained by their being positioned on the LH-steroid dose-response curve at the point where there is incipient downregulation of 17,20-lyase at LH levels stimulatory to 17hydroxylation. To test this possibility, the author and his colleagues analyzed apparent LH-steroid dose-response relationships during GnRH agonist tests performed with concurrent dexamethasone administration to suppress coincidental adrenal steroid secretion.118The pattern of steroid secretion was similarly abnormal in patients with functional ovarian

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hyperandrogenism with or without elevated serum LH levels (Fig. 6). Following GnRH agonist administration, the responses of estradiol fell along the normal LH-steroid dose-response slope, but those of estradiol precursors did not. The apparent slope of the LH-steroid dose-response relationship was markedly abnormal for 17-hydroxyprogesterone, above but parallel to normal for androstenedione, and slightly increased for testosterone. These data suggest that although 17,20-lyase efficiency is increased, it is increased less than that of 17-hydroxylation. Clinical research results suggest that patients with functional ovarian hyperandrogenism, regardless of whether they have classic or nonclassic PCOS, have an LH-17-hydroxyprogesterone dose-response curve that is shifted upward and to the left. Cultured individual theca cells from polycystic ovaries also seem to have LH-steroid dose-response curves that are displaced upward and leftward (see Fig. 3).,, Because both lines of evidence suggest that the steroid responses do not fall along the normal LH-steroid dose-response curve, the defect in steroidogenesis seems to be the result of escape from normal downregulation of thecal cell secretion rather than overstimulation by LH. The author favors the concept that the fundamental defect underlying the androgen excess of PCOS with functional ovarian hyperandrogenism is ovarian hyperresponsiveness to gonadotropin action because of escape from downregulation. The ovarian dysfunction seems indepenl z 3 LH dent of LH excess, although gonadotropins are permis~ive.~~, excess may intensify the intrinsic ovarian hyperandrogenic dysfunction. The cause of the apparent escape of thecal cells from downregulation is unclear. The cause could be extrinsic or intrinsic to the ovaries. It is tempting to link the dysregulation to the insulin excess so frequent in PCOS. The abnormality of the dose-response curves in PCOS resembles the escape from desensitization when normal cells are treated with insulin or IGF (Fig. 4).14 The ovaries in PCOS behave as if they are responsive to excess insulin or IGFs in a state of resistance to the glucose-metabolic effects of insulin. An intriguing study indicates that suppression of insulin secretion by a somatostatin analogue lowers serum LH and androgen levels in PC0S.'O4 Recent evidence suggests that insulin is indeed capable of acting through its own receptor in polycystic ovaries?4, although it is doubtful whether it is capable of acting on thecal cells at the concentrations typically found in patients. IGFs may also contribute to the thecal proliferation of polycystic ovaries.23 The granulosa cell may be the site of the defect. FSH-inducible paracrine factors affect thecal cell differentiation and regulate ovarian androgen production. In rats, treatment with FSH increased P-450~17 mRNA, and media from FSH-treated granulosa cells increased thecal cell mRNA for LH receptors79and thecal cell androgen production in response to LH.lZ6The importance of FSH for thecal cell function is indicated by the finding that women with isolated FSH deficiency have no clinical evidence of hyperandrogenism despite high levels of LH.72, 83* lo6The author and his colleagues found that the 17-hydroxyprogesterone response to an hCG test was significantly less than the response to

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a GnRH agonist test in women with functional ovarian hyperandrogenism.74Because the hCG test is essentially a challenge with LH and because the GnRH agonist test is a challenge with LH plus FSH, the different results with hCG versus GnRH agonist suggest that FSHinducible factors contribute to the steroidogenic defect in functional ovarian hyperandrogenism. Other investigators using a different study design and differently defined patient populations have found no differences in steroid responses to hCG compared with GnRH a g ~ n i s t . ~ ~ Inhibin is a candidate as an FSH-inducible factor capable of interfering with the downregulation of steroidogenesis. Plasma inhibin and androstenedione levels correlate.100Recent clinical studies found elevated serum inhibin-B levels in patients with PCOS, which is compatible with the excess numbers of developing ovarian follicles?, 76 Because inhibin stimulates androgen synthesis and androgen stimulates inhibin production, there is the potential for a vicious cycle developing within the ovary that could cause androgen excess and inhibit follicular development. Alternatively, a defect in the IGF system could account for the altered set-point for the granulosa cell response to FSH because ovarian IGF receptor mRNA is stimulated and IGF-binding protein production inhibited by FSH.37Mason and co-workers82recently proposed that LH action on granulosa cells can be advanced by insulin leading to premature luteinization, which makes small follicles prematurely sensitive to LH134and large follicles prematurely subject to downregulation by LH.70,135 Any cause of granulosa cell maturation arrest can ultimately be expected to contribute to androgen excess. The atretic follicle becomes an androgenic follicle by default because atretic follicles are deficient in aromatase activity. Although the mechanism is unclear, the consequence of the dysregulation of androgen synthesis is that the normal coordination of ovarian androgen secretion with granulosa cell function is disturbed, with grave consequences for follicular function. There is generalized ovarian hyperresponsiveness to gonadotropins. Thecal cell hyperresponse to LH accounts for the androgen excess. Granulosa cells are hyperresponsive to FSH, but frank hyperestrogenism is prevented by a compensatory reduction in FSH levels.

ADRENOCORTICAL FUNCTION IN POLYCYSTIC OVARY SYNDROME

Functional adrenal hyperandrogenism, glucocorticoid-suppressible ACTH-dependent 17-ketosteroid excess, is found in approximately one half of hyperandrogenic women and patients with functional ovarian Most functional adrenal hyperandrogenhyperandrogenism (Table 1).26 ism is idiopathic (primary). Less than 10% of adrenal hyperandrogenism can be incontrovertibly assigned to any well-established pathophysio115 The logic entity, such as nonclassical congenital adrenal hyperplasia.26,

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cause of primary functional adrenal hyperandrogenism has fostered considerable debate. Exaggerated adrenarche was originally proposed as the basis of the supranormal adrenocortical capacity for adrenal androgen synthesis by ~ ~ that the single Yen and co-workers.6,69 Lucky and c o - w ~ r k e r sfound most common adrenal steroid secretory pattern of hyperandrogenic women was compatible with this concept; however, the data could alternatively be interpreted as resulting from dysregulation of adrenal androgen ~ecretion."~ The author and his colleagues subsequently defined functional adrenal hyperandrogenism as hyperresponsiveness to ACTH of either DHEA or androstenedione from the dexamethasone-suppressed basal state in a study of 40 consecutive hyperandrogenic women who consented to undergo ACTH, dexamethasone, and GnRH agonist testingz6Sixty percent of the group (23 patients) had functional adrenal hyperandrogenism and 70% functional ovarian hyperandrogenism as indicated by an abnormal GnRH agonist or dexamethasone androgen-suppression test. The adrenal and ovarian abnormalities occurred alone or together as summarized in Table 1. Approximately 35% of hyperandrogenic women had functional ovarian hyperandrogenism alone, 35% had functional ovarian hyperandrogenism plus functional adrenal hyperandrogenism, 25% had functional adrenal hyperandrogenism alone, and less than 10% of cases were idiopathic. One of the 23 women (2.5%) had clear-cut nonclassic 21-hydroxylase deficiency, and none had a dexamethasone-resistantform of functional adrenal hyperandrogenism. Dehydroepiandrosterone hyperresponsiveness to ACTH was the most common adrenal abnormality in functional adrenal hyperandrogenism. This group of patients contained 18 of the 22 17-ketosteroid hyperresponders. Only 20% of this group had an elevated DHEA sulfate level. Abnormality of DHEA was concordant with abnormality of 17hydroxypregnenolone in 18 of 19 cases. Hyperresponsiveness to ACTH of androstenedione was found in half and of 17-hydroxyprogesterone in three patients. Cortisol responses were also significantly increased in this group (Fig. 7). Indexes of 17,20-lyase activity, the ratios of DHEA or androstenedione to cortisol, were significantly increased ( P <0.001). Gonzalez and c o - ~ o r k e r sfound ~ ~ evidence compatible with 17,20-lyase hyperactivity in patients with chronic hyperandrogenic anovulation and demonstrated that it persisted after gonadal suppression. DHEA sulfate may3s or may fall slightly during gonadal suppression by GnRH agonist therapy. Although DHEA hyperresponders have previously been considered to have mild 3p deficiency,28,75, 98,lZ4this now seems unlikely. The author and his co-workers analyzed in detail the steroid responses to the GnRH agonist nafarelin in eight women whose DHEA responses to ACTH met one or more criteria previously proposed for nonclassic 3p deficiency." It was thought that if these subjects had 3p deficiency in the adrenal gland, it would also be present in the ovary and be revealed by GnRH agonist testing. After nafarelin administration, in contrast to the ovarian

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W AD 0 17-PROG

H

T

.as

[9 CmpdS

T

CORTISOL T

Normal Women

DHA Elevated

DHA Normal

Figure 7. Responses to adrenocorticotropic hormone (ACTH) of two groups of 17-ketosteroid hyperresponders and of eumenorrheic normal women. All were studied while amenorrheic, or in the early follicular phase of the menstrual cycle, and after dexamethasone preparation. In a prospective series of 40 hyperandrogenic women, 23 were identified as 17-ketosteroid hyperresponders. One patient had nonclassic 21-hydroxylase deficiency congenital adrenal hyperplasia and her data are not shown. Eighteen of these patients had DHEA hyperresponses, and 4 without DHEA hyperresponses had androstenedione hyperresponses. Numerical P values show comparisons of hyperandrogenic groups to normal; asterisks indicate significant ( R 0 . 0 5 ) differences between hyperandrogenic groups. AD = androstenedione; 17-PROG = 17-hydroxyprogesterone; and Cmpd S = 11deoxycortisol. (From Ehrmann DA, Barnes RE, Rosenfield RL: Polycystic ovary syndrome as a form of functional ovarian hyperandrogenism due to dysregulation of androgen secretion. Endocrin Rev 16:322, 1995; with permission.)

steroid responses in a previously reported case of well-defined 3p deficiency,'O. lo8 none of these patients had elevations of A5/A4 steroid ratios. Furthermore, all had much higher responses of 17-hydroxyprogesterone and androstenedione than of 17-hydroxypregnenolone and DHEA. Thus, ovarian steroidogenic responses to nafarelin did not support the diagnosis of 3p deficiency. Rather, they were consistent in most cases with dysregulation of 17-hydroxylase and 17,20-lyase activities in both the ovaries and adrenal glands. These data are compatible with the proposal that dysregulation of P450c17 activity accounts for most functional adrenal hyperandrogenism. This conclusion is supported by recent genotyping studies. 3P mutations have not been found in DHEA hyperresponders unless 17-hydroxypregnenolone or DHEA responses are 7 or more standard deviations above n ~ r m a l . ~ , ~ ~ , ' ~ *

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Significantly increased 17-hydroxyprogesterone and ll-deoxycortisol responses, with rises threefold above the upper limits of normal at most, were found in a smaller group of four androstenedione hyperresponders who had normal DHEA responses to ACTH (Fig. 7). Isolated 17-hydroxyprogesterone responses in the range of persons heterozygous for 21-hydroxylase deficiency were found in another five patients. In total, 25% of patients had this type of 17-hydroxyprogesteroneabnormality, and this has been found in many series?, 28, 75, lz4,lZ9 Although such patients have often been considered to have nonclassic forms or to be “manifesting heterozygotes” of congenital adrenal hyperplasia, it now seems unlikely that they carry significant steroidogenic enzyme mutations. When patients with functional ovarian hyperandrogenism with such 17-hydroxyprogesterone responses to ACTH were compared as a group with known carriers for 21-hydroxylase deficiency, the former group of patients differed in having higher ratios of A5- to A4-steroid levels in response to ACTH;17 yet elevation of A5-3P-hydroxysteroidsis not characteristic of 21-hydroxylase deficiency137Genetic studies to date indicate that carriers of 21-hydroxylase deficiency do not have an increased incidence of hyperandrogenism, although heterozygosity for 21hydroxylase deficiency cannot be ruled out as a predisposing factor.63 Modest hyperresponsiveness of ll-deoxycortisol to ACTH suggestive of an 11P-hydroxylase enzyme defect has been reported in as many as 8% of hyperandrogenic women.28The association of ll-deoxycortisol with 17-hydroxyprogesterone hyperresponses in some cases has raised the possibility that 11P-hydroxylase is inhibited secondarily by high intraadrenal androgen concentrations arising from heterozygosity for 21hydroxylase deficiency2*There is a marked difference in the reported incidence of ll-deoxycortisol abnormalities among series, which raises the question of whether the differences are methodologic or populationdependent (homozygous 11P-hydroxylase deficiency is rare outside of Semitic population^'^^). Mutations of the 11P-hydroxylase gene have not been found in the few hirsute patients with mildly elevated levels of 11deoxycortisol who have undergone molecular genetic At this time, nonclassic congenital adrenal hyperplasia is a serious consideration only when the steroids prior to the suspected block are 7 or more standard deviations above normal. What then is the nature of the adrenal hyperandrogenism observed in hyperandrogenic women in general and in PCOS with functional ovarian hyperandrogenism in particular? The author favors the concept that there is more widespread dysregulation of adrenal function and corticosteroid metabolism than in the P450c17 steps, just as there seems to be more widespread dysregulation of ovarian steroidogenesis than in the 17-hydroxylase and 17,20-lyase steps. Thus, 3p or other steroidogenic steps may be abnormally regulated. Indeed, a growing body of evidence suggests that patients with PCOS sometimes have mild increases in plasma ACTH and cortisol responsiveness to corticotropin-releasing hormone,7l spontaneous ACTH and cortisol ~ecretion,5~ cortisol responsiveness to ACTH (Fig. 7), and urinary free cortisol e x c r e t i ~ nExcessive .~~

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adrenocortical uptake of iodocholesterol 131 has also been reported in PCOS.40The author has seen a patient with functional ovarian hyperandrogenism with an adrenal incidentaloma, which has been reported to be a manifestation of insulin ~esistance.’~~ Thus, some patients with PCOS can have findings suggestive of Cushing’s syndrome or adrenal tumor. Several lines of evidence support the concept that primary functional adrenal hyperandrogenism is caused by dysregulation of adrenal steroidogenesisrather than exaggerated adrenarche. First, overactivity of 17-hydroxylase/17,20-lyase in the adrenal cortex seems to be frequently associated with overactivity of these steps in the ovaries. Second, the adrenal overproduction of 17-ketosteroids is associated with increased levels of the adrenarche marker DHEA sulfate in a small minority of cases (approximately 20%). Third, there is evidence of widespread but variable dysregulation of a number of aspects of corticosteroid secretion, leading to a tendency for hypercortisolism. In addition, evidence is accumulating that hyperinsulinemia is related to both adrenal dysregulation and ovarian dysregulation, and that there are peripheral disturbances of corticosteroid metabolism. Pathogenesis of Adrenocortical Dysfunction As is true in the ovary, insulin may affect the regulation of adrenal steroidogenesis.Insulin infusion has recently been reported to potentiate modestly the 17-ketosteroid response to ACTH in a pattern compatible with increases in 17-hydroxylase and 17,20-lyase activities, the former more prominentlyg1Insulin excess might explain the effects of simple obesity on enhancing the responsiveness of 17-ketosteroids to ACTH64 and 17-ketosteroid clearance.32Suppression of insulin secretion by somatostatin treatment improves ACTH and cortisol secretory dynamics in PCOS.71Recent in vitro studies have directly shown that insulin and 67 IGF-I upregulate adrenal 17-hydroxylase and 17,20-lyase activities.29, Other factors are involved in the intra-adrenal modulation of the response to ACTH.24Interleukin-6 is strongly expressed in the zona reticularis of the adrenal cortex and is capable of stimulating DHEA secretion. Thus, stress-induced increases in cytokine secretion may contribute to functional adrenal hyperandrogenism, as a means of diverting steroidogenesis away from cortisol. ROLE OF DISTURBED PERIPHERAL STEROID METABOLISM IN POLYCYSTIC OVARY SYNDROME Peripheral steroid metabolism is altered in PCOS. Rodin and cow o r k e r ~ ”reported ~ evidence supporting the dysregulation of 11p-hydroxysteroid dehydrogenase in PCOS. They found significantly increased urinary excretion of cortisol metabolites, and ratios of 11-keto to

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11-hydroxy metabolites of corticosteroids were elevated above normal in 40% of subjects. Although they corrected the results for obesity, an effect of fat distribution on steroid metabolism could not be ruled The data are compatible with an accelerated turnover of cortisol causing a resetting of ACTH secretion, with consequent generalized adrenocortical overactivity. Insulin excess has been suggested as the cause of the increased clearance of cortisol. Evidence of marginally increased 513reductase activity has been reported.l13,lZ7This may be attributable to androgen e~cess.9~ Obesity may contribute to androgen excess in PCOS. Adipose tissue has the capacity to form testosterone and estrone from inactive precurs o r ~ Weight . ~ ~ reduction normalizes androgen levels in some cases of chronic hyperandrogenic anovulation.12, 58, 59, 65 In part, this seems to be related to the improvement in ovarian function that results from lowered insulin levels.54,95 Body fat distribution has weight-independent effects on the clinical, hormonal, and metabolic features of women with PCOS.99 The insulin excess of obesity may mediate the effects of adiposity on steroidogenesis. CONCLUSIONS

Generalized dysregulation of steroid biosynthesis and metabolism s e e m to be associated with most functional hyperandrogenism (Fig. 8). The most likely cause of the major steroid secretory abnormalities in both ovaries and adrenal glands seems to be dysregulation of 17-hydroxylase and 17,20-lyase activities, which are both properties of P450c17, the rate-limiting enzyme in androgen biosynthesis. This dysregulation

Extrinsic Trophic Hormone Intrinsic Regulatory Excess AutocrineParacrine Peptide J Imbalance Excess

I

I

Dysregulation of Steroidogenesis

/ FUNCTIONAL OVARIAN HYPERANDROGENISM

I FUNCTIONAL ADRENAL HYPERANDROGENISM

Figure 8. Model of factors causing the common types of functional ovarian and adrenal hyperandrogenism. A mild degree of androgen excess can arise from excess trophic hormone (LH or ACTH) stimulation. Either extrinsic or intrinsic disturbances to these endocrine glands can amplify the effect of normal levels of trophic hormones. Extrinsic regulatory peptide excess is exemplified by hyperinsulinemia. Intrinsic peptides capable of inappropriately increasing steroidogenesis include insulin, IGFs and, in the ovary, inhibin.

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may be apparent as functional ovarian hyperandrogenism alone, functional adrenal hyperandrogenism alone, or both together. Dysregulation may result from imbalance among various extrinsic and intrinsic factors involved in the modulation of trophic hormone action. Insulin excess seems to be an important extrinsic factor. Intrinsic intraglandular modulation of androgen secretion within the ovary is probably important for the coordination of ovarian synthesis of androgens with that of estrogens so as to optimize fertility and prevent hyperestrogenism. Similarly, intraadrenal modulation of the pattern of steroidogenesis in response to ACTH is conceptualized to be one of several autoregulatory processes safeguarding against hypercortisolism.

SUMMARY

Androgens are secreted by both the ovaries and adrenal glands in response to their respective trophic hormones LH and ACTH. Androgens in women are not specifically under negative feedback control by these pituitary hormones because they are by-products of estradiol and cortisol secretion. Rather, androgen secretion seems to be regulated mostly by intraglandular mechanisms. Functional ovarian hyperandrogenism is found in about 70% of patients with PCOS. It is characterized by excessive secretion of 17-hydroxyprogesteronein response to GnRH agonist or hCG stimulation. Failure of dexamethasone to suppress plasma free testosterone normally in the presence of normal adrenocortical suppression is also typical. Functional adrenal hyperandrogenism is found in about half of patients with PCOS. It is most often characterized by moderately increased secretion of the 17-ketosteroid DHEA in response to ACTH. The most likely cause of the excessive androgen secretion by both glands seems to be abnormal regulation (dysregulation) of the 17-hydroxylase and 17,20-lyase activities of P-450~17,the rate-lim’iting step in androgen biosynthesis. There are also subtle generalized disturbances of steroid metabolism, including tendencies toward excessive estrogen and cortisol secretion. The cause of dysregulation of steroidogenesis is unknown. The hyperinsulinemia that is compensatory for resistance to the glucose-metabolic effect of insulin seems to have a role in many cases. In most cases, intrinsic intraovarian or intra-adrenal autocrine or paracrine regulatory mechanisms are most likely malfunctioning.

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