Is there visceral adipose tissue (VAT) intracellular hypercortisolism in human obesity?

The fact that obesity is a prominent feature of Cushing's syndrome (systemic hypercortisolism of adrenocortical origin) stimulated a 40-year search for evidence of systemic hypercortisolism in human obesity. That search has failed to find such evidence. For the past 15 years, however, studies have been done to evaluate a possible alternative type of hypercortisolism in obesity, namely visceral adipose tissue (VAT) intracellular hypercortisolism. The current review summarizes the evidence published so far about this possibility. There have been three types of evidence studied: direct measurement of the VAT levels of 11ß-hydroxysteroid dehydrogenase type I (11-HSD-1), which converts biologically inactive cortisone to biologically active cortisol; direct measurement of splanchnic cortisol production; and evaluation of the effect of a specific inhibitor of 11-HSD-1 on metabolic abnormalities associated with obesity, particularly diabetes mellitus. The results are complex and difficult to interpret. Our conclusion is that the presence of VAT intracellular hypercortisolism in human obesity is possible but unlikely.

Estradiol metabolism in cirrhosis.

Abnormal estrogen metabolism has been found in cirrhosis after administration of intravenous tracers of estradiol-(3)H to 6 patients and 23 healthy controls. The major abnormalities observed involved estrogen metabolites other than the 3 "classic" ones, i.e., estrone (E1), estradiol (E2), and estriol (E3). Urinary recovery of radioactivity was regularly elevated in the patients, to an average of 71% of the dose compared to 51% in normals. This is considered to reflect the component of intrahepatic cholestasis in cirrhosis. The per cent dose recovered as urinary glucosiduronates (42%) was normal in cirrhotics in contrast to impaired glucuronidation of cortisol metabolites in this disease. E1 and E2 were present in normal amounts, and E3 was slightly elevated to 21% of the extract compared to 14% in controls. There were strikingly decreased excretion of 2-hydroxyestrone (3% compared with normal 20%) and 2-methoxyestrone (2% compared with 5%) and increased excretion of 16alpha-hydroxyestrone (12% compared with normal 6%). Thus cirrhosis, too, is characterized by the reciprocal relationship between decreased 2-hydroxylation and increased 16alpha-hydroxylation previously described in hypothyroidism and male breast cancer. However, unlike these latter, the increase of 16alpha-hydroxy metabolites was less than the decrease of 2-hydroxy metabolites. The data indicate clearcut impairment of 2-hydroxylation, suggestive impairment of 16alpha-hydroxylation, and a definite depression of the reaction 16alpha-hydroxyestrone-->estriol, the latter finding so far unique to cirrhosis. Demonstration of abnormal peripheral metabolism of estrogen in cirrhosis provides a new approach to the origin of the hyperestrogenic syndrome in this disease.

Cortisol metabolism in cirrhosis.

The production and peripheral metabolism of cortisol have been studied in 10 cirrhotics and 11 controls after i.v. tracers of cortisol-(14)C. The findings were as follows: (a) Total urinary excretion of radioactivity was normal (81% of the dose) but a decreased fraction was present as glucosiduronates: 18-47% of the dose (average 34%) compared to a normal average of 54%. (b) There was a distinctively abnormal pattern of cortisol metabolites, not previously observed in other illnesses: tetrahydrocortisone was decreased to 14% of the enzyme hydrolysate (normal 26%); cortolones were increased to 34% (normal 19%), owing entirely to an increase in cortolone (20alpha) formation, since beta-cortolone (20beta) was not significantly increased; Reichstein's substances U and epi-U were increased, averaging 2.6% for the former and 4.7% for the latter; tetrahydrocortisol, allotetrahydrocortisol and cortols were normal. This pattern was independent of the degree of decreased glucosiduronate formation and also independent of the presence or absence of a portacaval shunt. (c) Cortisol production, determined by isotope dilution, was normal in each of six cirrhotic patients. From these data, taken in conjunction with our previously reported findings concerning the influence of norethandrolone on cortisol metabolism, the following conclusions were drawn: (a) Cirrhotic patients have decreased A-ring reduction of cortisone to tetrahydrocortisone and correspondingly increased 20-ketone reduction of cortisone to Reichstein's substances U and epi-U and then to the cortolones. (b) Intrahepatic cholestasis, a regular pathophysiological feature of cirrhosis, may be responsible for the observed abnormal cortisol metabolite pattern in this disease. (c) The slowed metabolic turnover rate of cortisol in cirrhosis may be due to decreased transport and/or binding of cortisol to its intracellular metabolic sites rather than to abnormalities of any specific metabolizing enzymes.

Relationship of obesity to blood estrogens.

It has become conventional wisdom that estrogenic stimulation of breast tissue has something to do with the causation of breast cancer and that the reason obesity is a risk factor for breast cancer is that obese women are hyperestrogenized. However, it has been very difficult to demonstrate that excessive exogenous estrogen increases the incidence of breast cancer, that endogenous estrogen excess is present in breast cancer, or that obese women are hyperestrogenized. We have examined the last question by measuring 24-hr mean plasma estrone and estradiol levels in the midfollicular phase in 18 healthy, regularly cycling, very obese (53 to 218% above ideal weight) women and 16 regularly cycling, age matched, nonobese control women. Unlike obese men, the obese women showed no significant elevation of either estrone or estradiol. Their average estrone level was 72 compared with 64 pg/ml in controls; their average estradiol level was 65 compared with 57 pg/ml in controls. In the combined group (obese plus nonobese), there was a significant correlation of percentage of deviation from ideal weight with plasma estrone (y = 63 + 0.12x; p less than 0.05) but not with estradiol. This correlation supports the current hypothesis that there is increased androstenedione leads to estrone conversion (i.e., increased aromatase activity) in obesity. The reason plasma estrone levels are not significantly elevated in obese women is that the small amount derived from androstenedione is swamped by the much larger amount derived from ovarian secretion, which is apparently unaffected by obesity. Unless there is increased local formation of estrogens in the breast tissue of obese women, the absence of elevated plasma estrogens in them means that their breasts are not "seeing" increased estrogen levels. Thus, endogenous hyperestrogenization is unlikely to be a causative factor of breast cancer in obese women.U

Influence of obesity and malnutrition on the metabolism of some cancer-related hormones.

It has been suggested that the well-documented relationship of dietary composition to the incidence of human breast cancer is mediated by the effects of dietary constituents on hormone levels. There is fairly good evidence for diet-hormone relationships in animals, but the evidence in humans is unconvincing. In this paper, we describe three of our findings relating nutrition to hormone levels: (a) that obesity causes retention of a tracer of estradiol in women but not in men, a finding we attribute to the presence of specific estrogen receptor in the adipose tissue of women but not men; (b) that obese men have elevated plasma estrone and estradiol levels but obese women do not, a finding we attribute to greater androstenedione-to-estrone conversion in the adipose tissue of men than in that of women; and (c) that cachectic girls with anorexia nervosa fail to have the normal nocturnal surge of prolactin secretion, a finding that we attribute to deficiency of tryptophan, which is an adequate stimulus for prolactin secretion. These findings give support to the concept that dietary factors affect hormone secretion and/or metabolism in humans.

Paradoxical effects associated with supranormal urinary testosterone excretion in premenopausal women with breast cancer: increased risk of postmastectomy recurrence and higher remission rate after ovariectomy.

Urinary testosterone excretion was measured in 18 normal premenopausal women, 80 women studied shortly after mastectomy for primary operable breast cancer, and 93 women with either metastatic breast cancer (77) or primary inoperable breast cancer (16) who were to be ovariectomized. Forty-two of the 93 were restudied after the ovariectomy. The control women showed a normal distribution of testosterone excretion, up to 12 micrograms daily; the postmastectomy patients showed a bimodal distribution, with 14 patients (17.5%) having values above 12 micrograms (up to 39 micrograms) daily. In the metastatic group, 24 of 77 patients (31.1%) had urinary testosterone excretion greater than 12 micrograms daily (up to 77 micrograms). The difference in percentage of high excretors was significant (p less than 0.02). Of the patients treated by ovariectomy, 27 had supranormal testosterone excretion preoperatively, and 16 of these (59.2%) had remissions; 66 had normal excretion preoperatively, and 21 of these (31.8%) had remissions. The difference was significant (p less than 0.02). Urinary testosterone excretion was restudied postoperatively in 42 of the 93 ovariectomized patients. Values were normal preoperatively in 31, and these were unchanged postoperatively. Values were supranormal preoperatively in 11; all of these fell significantly after ovariectomy, to normal in 8 cases. These findings appear to confirm the ovarian source of the excessive urinary testosterone. The following conclusions were drawn. There is a subgroup of premenopausal women with primary operable breast cancer who have supranormal urinary testosterone excretion; the incidence of this abnormality in women with recurrent metastatic disease after mastectomy is nearly twice as high. It can be calculated that the finding of supranormal urinary testosterone shortly after mastectomy represents virtually a 100% risk of recurrence, in contrast to a recurrence rate of about 38% in women with normal testosterone excretion. Patients with supranormal testosterone excretion prior to therapeutic ovariectomy have nearly twice as high a remission rate as do those with normal testosterone excretion.

Hormone profiles in hormone-dependent cancers.

Studies on the relationship of urinary excretion of androgen metabolites and estrogens to the natural history of breast cancer are reviewed. The importance of distinguishing between "within-population" studies (i.e., cancer patients versus normal controls) and "between populations" studies (i.e., low-risk versus high-risk populations) is emphasized, and it is pointed out that "qualitative" agreement (i.e. the same direction of differences) between the two types of studies must be present in order to implicate a hormonal parameter as a determinant of the natural history of breast cancer. For reasons detailed in this paper, it is concluded that the reported relationship of low urinary androgen metabolite excretion to increased risk of developing breast cancer and poor response to adrenalectomy or hypophysectomy and the validity of the "estriol hypothesis," namely, that a high urinary ratio of estriol to estrone-plus-estradiol in early life is protective against subsequent development of breast cancer, are both dubious. A new hypothesis concerning the relationship of estrogens to breast cancer risk is presented: "A period of of time, prior to age 30, during which the amount of biological availability of active estrogens' (i.e., estrone and estradiol) is diminished, protects against subsequent development of cancer." This hypothesis is shown to be compatible with the epidemiological and biochemical data. Reports concerning the influence of nutrition on endocrine parameters are reviewed. Inanition and obesity have been shown to alter steroid metabolism but it is not known whether nutritional "microdifferences" (i.e., differences between populations or individuals that are due to cultural, geographic, or socioeconomic factors, but that fall within the range of "normal" or adequate nutrition) can also alter steroid metabolism.

Abnormal 24-hr mean plasma concentrations of dehydroisoandrosterone and dehydroisoandrosterone sulfate in women with primary operable breast cancer.

The 24-hr mean plasma concentrations of dehydroisoandrosterone (DHA) and dehydroisoandrosterone sulfate were measured in 11 women with primary operable breast cancer, ages 31 to 78 years, and in 37 normal women, ages 21 to 75 years. In contrast to the marked and progressive decline of DHA and dehydroisoandrosterone sulfate concentration with age in the normal women, the concentrations of both steroids were age invariant in the cancer patients. The premenopausal patients had subnormal plasma DHA and dehydroisoandrosterone sulfate levels, while the post menopausal patients had supranormal levels. Since the plasma DHA/androsterone ratio was normal in the premenopausal patients and significantly elevated in the postmenopausal patients, it is postulated that the subnormal plasma adrenal androgen levels in the premenopausal patients were due principally to diminished production of these steroids, while the elevated plasma levels in the postmenopausal patients were due principally to slowed metabolic removal. Reports in the literature that DHA inhibits the development of breast cancer in mice suggest that the subnormal plasma DHA levels in premenopausal breast cancer may have clinical significance.

Cortisol secretion in endogenous depression. I. Basal plasma levels.

Plasma levels of cortisol were sampled for 24 hours in 32 endogenously depressed (ED) patients and 72 normal controls who also underwent the dexamethasone suppression test. The ED patients had significantly higher mean 24-hour plasma levels of cortisol (means 24h PC). However, means 24h PC values of subjects in both groups were normally distributed, with a marked overlap between the two. Only seven ED patients had means 24h PC values higher than 2 SDs from the normal mean (greater than 10 micrograms/dL). An abnormal dexamethasone suppression test result was only partially related to basal cortisol levels. The mean plasma level of cortisol between 1 and 4 PM was found to be highly correlated with the means 24h PC value in ED patients, as has been previously reported in normal subjects and patients with various other diseases (in which it also powerfully discriminated between hypersecretors and normosecretors). This finding supports the use of mean cortisol levels between 1 and 4 PM as a reliable and convenient indication of cortisol secretion.

Cortisol secretion in endogenous depression. II. Time-related functions.

Plasma levels of cortisol were sampled for 24 hours in 32 endogenously depressed (ED) patients and 72 controls to examine mean 24-hour plasma levels of cortisol, intervention in the feedback mechanism of the hypothalamic-pituitary-adrenal system (the dexamethasone suppression test), the circadian rhythm of cortisol secretion and its magnitude, and the ultradian rhythm of cortisol secretion. The main difference in the pattern of cortisol secretion in ED patients, as compared with controls, was in the ultradian rhythm. No acrophase or nadir advance of cortisol secretion in endogenous depression was found when age was controlled, but there was an earlier timing of first secretory episode of cortisol (during night). Only some ED patients have abnormalities in each of the functions studied, and they only partially overlap each other. The results suggest that abnormal cortisol secretion in depression should not be viewed as a monolithic malfunction characteristic of endogenous depression.

Sex difference in the metabolism of dehydroisoandrosterone sulfate.

The metabolism of a tracer of [3H]dehydroisoandrosterone sulfate ([3H]DHAS) was studied in five normal women and six normal men. Two major sex differences were found. 1) The total urinary recovery of radioactivity was considerably greater in women (73 +/- 5.5% of the dose vs. 51 +/- 3.5; P less than 0.01), principally due to higher excretion of nonglucuronide, nonsulfate conjugates (35 +/- 2.2% of the dose vs. 21 +/- 3.9%; P less than 0.025). This finding is analogous to the sex difference in estradiol metabolism we have reported and is hypothesized to represent diversion of excretion of these conjugates in women from the biliary to the urinary excretion route because of the known lower biliary excretory capacity of women, which is a consequence of their higher estrogen levels. 2) The recovery of androsterone and etiocholanolone was considerably higher in the women (15.4 +/- 1.4% of the dose vs. 10 +/- 1.8%; P less than 0.05). Since conversion of DHAS to etiocholanolone and androsterone in vivo entails prior cleavage of DHAS to DHA, this sex difference in the recovery of androsterone and etiocholanolone is interpreted to mean that DHAS leads to DHA cleavage is considerably greater in women than in men. It is predicted that the plasma DHA to DHAS ratio should be substantially greater in women then in men.

Acidic metabolites. V. Isosteroids as intermediates in cortoic acid formation.

The role of steroid-17-aldols, 20 beta-isocortisol (11 beta, 17,20 beta-trihydroxy-3-oxo-pregn-4-en-21-al) or 20 beta-iso THE (3 alpha,17,20 beta-trihydroxy-11-oxo-pregnan-21-al), as preferred intermediates for the biosynthesis of cortoic acids was studied in human subjects. The results demonstrated that the isosteroids were converted moe efficiently than cortisol to cortoic acids and hexahydro neutral metabolites. In all cases, the oxidation state at C-11 was largely conserved. After the administration of the 20 beta compounds both 20 alpha and 20 beta epimers of the acidic and neutral metabolites were isolated. This inversion occurred without oxidation at C-20 and provided evidence for the mediation of an epimerase in this transformation. The results further indicate that reversion of the isosteroids to ketolic intermediates (i.e. cortisol, tetrahydrocortisol, and tetrahydrocortisone did not occur.

Metabolism of cortisol-21 glucosiduronate in man.

The metabolism of cortisol-21-glucosiduronate has been studied in two subjects. Urinary excretion was about 65% in both subjects, with cortisol glucosiduronate as the principal metabolite accompanied by small amounts of 11 beta, 17,21-trihydroxypregnane-3,20-dione (THF) glucosiduronate. The absence of the other normal metabolites of cortisol [17,21-dihydroxypregnane-3,11-20-trione (THE), 3 alpha, 11 beta, 17, 20xi, 21-pentahydroxypregnane, and 3 alpha, 17, 20xi, 21-tetrahydroxypregnan-11-one] indicates that negligible hydrolysis at C-21 occurred and that an unoccupied C21 position is required for oxidation at C-11 and reduction at C-20. The limited conversion to THF suggests that a pathway through cortisol-21-glucosiduronate does not contribute significantly to the differences in specific activity of urinary THF and THE observed after administration of labeled cortisol.

Extraadrenal effects of metyrapone in man.

[14C]Cortisol was injected iv into three subjects during a control period and while receiving metyrapone. The plasma kinetics of the tracer cortisol and the patterns of its urinary metabolites were measured. Metyrapone caused an increase in the volume of distribution of cortisol (34%) and in the MCR (75%); the half-life was decreased by 25%. There were marked changes in the urinary metabolite pattern: 3 alpha,11 beta,17,21-tetrahydroxy-5 alpha-pregnan-20-one, 3 alpha,17,21-trihydroxy-pregnane-11,20-dione(THE), pregnane-3 alpha,11 beta,17,20 alpha,21-pentol, plus pregnane-3 alpha,11 beta,17,20 beta-21-pentol (cortol), and 3 alpha,17,20 alpha,21-tetrahydroxypregnan-11-one (cortolone) all decreased by an average of 62%, 44%, 38%, 45%, and 25% respectively. In contrast, there was an increase of 296% in 3 alpha,17,20 beta,21-tetrahydroxypregnan-11-one (beta-cortolone). To account for these effects it is postulated that metyrapone has the following extraadrenal actions: 1) it inhibits the back reduction of cortisone to cortisol and 2) it stimulates the 20-ketosteroid reductase that converts THE to beta-cortolone.

Studies in the biotransformation of cortisol to the cortoic acids in man. II. The central role of tetrahydrocortisol and tetrahydrocortisone as intermediates.

The possible role of THF and THE as intermediates in the biotransformation of cortisol to the cortoic acids was studied by giving 3H-THF + 14C-cortisol tracers and 3H-THE + 14C cortisol tracers to two subjects each, measuring the 3H/14C isotope ratios of the urinary cortoic acid metabolites and relating these ratios to the dose ratio. Isotope ratios substantially higher than the dose ratio indicate that the tetrahydro compound is a better precursor than cortisol, and isotope ratios that are essentially identical to that of urinary THF or THE, respectively, indicate that the tetrahydro compound may be an obligatory intermediate in the cortisol leads to cortoic acids pathway. The isotope ratio data in these studies clearly establish that THF was a preferential precurosor of the 11 beta-hydroxy cortoic acids (cortolic and beta-cortolic) and THE was a preferential precursor of the 11-ketone cortoic acids (cortolonic and beta-cortolonic). Furthermore, the data strongly suggest that THF and THE may be obligatory intermediates in cortoic acid formation.

Metabolism of cortoic acids in man.

Administrated radioactive tracers of beta-cortolic or beta-cortolonic acids are excreted mostly unchanged, without significant alteration of the molecule at C-11 or C-20; a minor amount of cleavage to C-20 etianic acids occurs. Evidence was obtained for possible noncovalent complexing of the steroid acids to macromolecular components present in the enzyme preparation for hydrolysis of the urinary glucuronides; this complex can be dissociated by acidification to pH 2, and the acidic metabolites can then be readily extracted. The findings suggest that beta-cortoic acids are essentially terminal metabolites in man.

Studies in the biotransformation of cortisol to cortoic acids in man. III. 21-Oxidation of 4-14C,21-3H-desoxycorticosterone.

The metabolism of (4-14C, 21-3H) desoxycorticosterone (DOC) in man has been studied. DOC, like cortisol, undergoes oxidation at C-21 with the formation of acidic metabolites (2.3-8.2% of the dose). The release of 3H into the body water, either by oxidation or exchange, is approximately twice as great as the actual formation of acidic metabolites (as judged from the recovery of 14C in the urinary acidic fraction), but both parameters were considerably smaller than the corresponding values for cortisol. The principal metabolite isolated from the urine was 21-hydroxypregnanolone, which had an isotope ratio (3H/14C) greater than that of the dose; the pregnanetriols, which were formed in lesser amounts, had significantly lower isotope ratios than the dose. The absence of the 17-hydroxy group in DOC appears to modify C-21 oxidation, decreasing its magnitude and altering the character of the products.

Twenty-four-hour mean plasma testosterone concentration declines with age in normal premenopausal women.

The 24-h mean plasma concentration of total testosterone (T) was measured in 33 healthy, regularly cycling, nonobese women between 21 and 51 yr of age. Percent free T was measured in 17 of them. Plasma dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) were measured in 24 of them, and the DHEA-to-T and DHEAS-to-T ratios were calculated. It was found that the concentration of total T showed a steep decline with age; the regression equation was: T (nanomoles per L) = 37.8 x age-1.12 (r = -0.54; P < 0.003). According to this equation, the expected T concentration of a woman of 40 would be 0.61 nmol/L, about half that of a woman of 21 (1.3 nmol/L). The percent free T did not vary significantly with age, so free T concentration likewise showed a steep decline with age. The DHEA-to-T and DHEAS-to-T ratios were both age invariant, clearly because the levels of DHEA and DHEAS also decline steeply with age, as previously reported.

The relationship between serum levels of insulin and sex hormone-binding globulin in men: the effect of weight loss.

It is known that there is an inverse relationship between the serum levels of insulin and sex hormone-binding globulin (SHBG) in women, but the relationship in men has not been reported. It is not known whether changes in the one cause changes in the other, or whether they change in opposite directions in response to some third factor. Because obesity raises insulin levels and lowers SHBG levels in both sexes, we proposed to study the cause-effect question by determining whether the relationship between changes in SHBG and insulin levels during active weight loss. We studied 70 healthy weight-stable men with body mass index (BMI) from 20.7-94 (normal, 22.5 +/- 2.5) and restudied 17 of them during diet-induced weight loss. Fasting serum insulin levels in the weight-stable men showed a positive linear correlation with BMI, increasing 1 microU/mL per unit increase in BMI (P < 0.0001). SHBG levels in the weight-stable men showed a negative linear correlation with BMI, decreasing 0.2 nmol/L per unit increase in BMI (P < 0.0002). In the weight-stable men, there was an inverse hyperbolic correlation between SHBG and insulin levels; SHBG (nmol/L) = 13.1 + [30.1 divided by insulin (microU/mL)] (P < 0.002). During weight loss, insulin levels decreased at an average rate of 6.1 microU/mL per unit decrease in BMI, a much higher slope than the positive slope vs. BMI in weight stable men. During weight loss, SHBG levels increased at an average slope of 0.43 nmol/L per unit decrease in BMI, much higher than the negative slope of 0.2 nmol/L per unit increase in BMI in weight-stable men. Values for the SHBG vs. insulin coordinates in the weight-losing subjects did not differ significantly from those expected from the SHBG vs. insulin equation in weight-stable subjects. The stability of the SHBG-insulin relationship during weight loss despite the profoundly altered relationship of each separate component to BMI strongly suggests a close metabolic link between SHBG and insulin. As SHBG is not known to alter the production or metabolism of insulin, whereas insulin has been shown in vitro to decrease the synthesis of SHBG, it seems a reasonable conclusion that the predictable inverse relationship between serum insulin and SHBG indicates that insulin controls SHBG synthesis in vivo.

The mean 1300-1600 h plasma cortisol concentration as a diagnostic test for hypercortisolism.

The 24-h mean plasma cortisol concentration was compared with the mean plasma cortisol concentrations during short subperiods of the day in 88 normal subjects and 223 patients with a very wide range of mean 24-h cortisol levels. The correlation between the 1300-1600 h mean plasma cortisol concentration and the mean 24-h plasma cortisol concentration was extremely high in all groups. Mean cortisol concentrations during this short subperiod powerfully discriminate cortisol hypersecretors (patients with Cushing's syndrome, anorexia nervosa, or prostate cancer) from normal controls. Hence, it is suggested that the mean or integrated 1300-1600 h plasma cortisol concentration can be used as a reliable afternoon cortisol test for the presence of hypercortisolism.