Use of 11alpha-deuterium labeled cortisol as a tracer for assessing reduced 11beta-HSD2 activity in vivo following glycyrrhetinic acid ingestion in a human subject

This study describes an oral administration of 5 mg of [1,2,4,19-13C4,11alpha-2H]cortisol (cortisol-13C4,2H1) to a human subject performed on two separate occasions, one with cortisol-13C4,2H1 alone and the other with cortisol-13C4,2H1 plus 130 mg per day of glycyrrhetinic acid for 6 days. The stable isotope methodology employed allowed for the evaluation of the individual in vivo activities of the two isozymes of 11beta-hydroxysteroid dehydrogenase (11beta-HSD), 11beta-HSD1 and 11beta-HSD2, and to demonstrate the sensitivity of changes in cortisol elimination half-life for detecting inhibition of 11beta-HSD2 activity induced with glycyrrhetinic acid. The kinetic analysis associated with the loss of 11alpha-2H during the conversion of cortisol-13C4,2H1 to cortisone-13C4 by 11beta-HSD2 clearly indicated reduced 11beta-HSD2 activity with glycyrrhetinic acid ingestion, as observed by an increase in the elimination half-life of cortisol-13C4,2H1. The elimination half-life of cortisol-13C4,2H1 provided sensitive in vivo measures of 11beta-HSD2 activity and was more sensitive for detecting changes in renal 11beta-HSD2 activity than the measurement of the urinary ratio of free cortisol and free cortisone (UFF/UFE). The 2H-labeling in the 11alpha-position of cortisol served as an appropriate tracer for assessing the reduced 11beta-HSD2 activity in vivo induced by glycyrrhetinic acid.     

Exaggerated adrenarche and altered cortisol metabolism in Type 1 diabetic children

Reported literature data strongly suggest that steroid metabolism is dysregulated in Type 1 diabetes mellitus. The aim of this study was to non-invasively examine the cortisol metabolism in children with Type 1 diabetes mellitus (T1DM) in detail and to test the hypothesis that adrenarche is affected under conventional intensive insulin therapy. In 24-h urine samples of 109 patients aged 4-18 years with T1DM of more than 1 year, steroids were profiled using gas chromatography-mass spectrometry. Additionally, urinary free cortisol (UFF) and cortisone (UFE) were quantified by RIA after extraction and chromatographic purification. Data on urinary steroids from 400 healthy controls served as reference values. Enzyme activities were assessed by established steroid metabolite ratios, e.g. 5alpha-reductase and 11beta-hydroxysteroid dehydrogenase Type 2 (11beta-HSD2) by 5alpha-tetrahydrocortisol/tetrahydrocortisol and UFE/UFF, respectively. Urinary markers of adrenarche, especially dehydroepiandrosterone and its direct metabolites were elevated in patients, as were urinary 6beta-hydroxycortisol, UFE, and 11beta-HSD2 activity. However, overall cortisol secretion, as reflected by the sum of major urinary cortisol metabolites, was mostly normal and activity of 5alpha-reductase clearly reduced. Our study provides evidence for an exaggerated adrenarche in T1DM children, which may help to understand reported sequelae in female patients like hyperandrogenic symptoms. The findings also suggest a reduced cortisol inactivation via 5alpha-reductase that is not compensated by a fall in cortisol secretion. Whether the elevated urinary 6beta-hydroxycortisol and cortisone excretion, observed in the patients, are also present in other forms of hypercortisolism and may thus serve as non-invasive clinical stress markers deserves further study.     

Evaluation of 11beta-HSD activities in vivo following oral administration of cortisol-13C4,2H1 to a human subject

This study is concerned with an oral administration of 5mg of [1,2,4,19-13C(4),11alpha-2H]cortisol (cortisol-13C(4),2H(1)) to a human subject to reliably evaluate the individual activities of two isozymes of 11beta-HSD. The use of a GC-MS method allowed the simultaneous measurement of the plasma concentrations of cortisol-13C(4),2H(1), cortisone-13C(4), and cortisol-13C(4) together with endogenous cortisol and cortisone. The loss of 11alpha-2H during the conversion of cortisol-13C(4),2H(1) to cortisone-13C(4) by 11beta-HSD2 and the regenerated cortisol-13C(4) from cortisone-13C(4) by 11beta-HSD1 provided a direct and accurate means of distinguishing the activities of the two isozymes. The kinetic analysis associated with the metabolism of orally administered cortisol-13C(4),2H(1) was of great importance in assessing the 11beta-HSD activities. From a viewpoint of the chemical stability and much less pronounced kinetic isotope effect of the 13C-label and the 2H-labeling in the 11alpha-position, cortisol-13C(4),2H(1) used in this study served as an appropriate tracer for elucidating the kinetics of the interconversion of cortisol to cortisone in man.     

Apparent cortisone reductase deficiency: a rare cause of hyperandrogenemia and hypercortisolism

A 55-year-old woman presented with androgenetic alopecia which had started at age 40. Her clinical history revealed that, unlike her younger sister, she was unable to conceive and was diagnosed as being sterile at age 30. At age 45, 21-hydroxylase deficiency (late-onset CAH) was assumed and glucocorticoid treatment suggested, but not initiated. There was slight hirsutism, but no other sign of virilization. Retesting of plasma steroids revealed elevated 17-OH-progesterone and free testosterone. Treatment with prednisone, cyproterone acetate, and spironolactone was started with significant clinical success. Surprisingly, the analyses of urinary steroid metabolites revealed a pattern that did not support the diagnosis of 21-hydroxylase deficiency (pregnanetriolone absent, pregnanediol, 17-OH-pregnanolone and pregnanetriol not increased). Abdominal CT showed bilateral adrenal hyperplasia and masses in both ovaries. Bilateral adnexectomy was performed, and cystic teratomas were diagnosed. Postoperative urinary steroid analyses showed a decreased tetrahydrocortisol/tetrahydrocortisone ratio (values around 0.08 as compared to age- and sex-matched controls with a ratio of about 0.5-0.8). Plasma cortisol appeared to be repeatedly elevated with exogenous sources excluded. Mass spectrometry showed that, while the tetrahydro metabolites were mainly cortisone-derived, the metabolites not reduced in A ring were mostly cortisol derivatives. This constellation clearly indicates cortisone reductase deficiency, a defect of hepatic 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD1). This enzyme catalyzes the oxidation of cortisol to cortisone and the reduction of cortisone to cortisol. In contrast to the corresponding kidney enzyme (11 beta-HSD2), its primary activity is, however, reductive. Although this is only the fifth reported case of that defect, more attention should be paid to this condition in hyperandrogenic women, even if elevated 17-OH-progesterone and testosterone suggest a more frequent cause.     

Increased ratio of serum cortisol to cortisone in acute-phase response

BACKGROUND/OBJECTIVES: 11beta-Hydroxysteroid dehydrogenase (11beta-HSD) enzymes convert cortisol into inactive cortisone and vice versa. While 11beta-HSD type 2 (mainly localized in the kidney) unidirectionally inactivates cortisol to cortisone, type I isoform (mainly localized in the liver) acts bidirectionally and can thus potentially restore cortisone to active cortisol. The aim of this pilot study was to investigate whether the serum cortisol:cortisone ratio is altered during the acute-phase response, possibly due to altered modulation of 11beta-hydroxysteroid dehydrogenase isoforms. METHODS: Using liquid chromatography electrospray tandem mass spectrometry, cortisol and cortisone were measured in the serum of hospitalized patients with normal and abnormal CRP concentrations, the latter indicating acute-phase response. Fifteen unselected samples were analyzed, all with a CRP concentration within one of the following ranges to cover a wide range of CRP concentrations evenly: <5, 5-20, 21-50, 51-100, 101-200, and >200 mg/l. RESULTS: In the heterogeneous study population, increased CRP concentrations significantly correlated with an increased cortisol:cortisone ratio (p < 0.001; r = 0.65, Spearman correlation coefficient). This correlation was independent of increased serum cortisol concentrations found by multivariate regression analysis. The median ratio was 6.4 (interquartile range 5.5-7.4; n = 30) in patients with a CRP concentration < or =20 mg/l, and 11.2 (interquartile range 8.8-13.9; n = 60) in patients with CRP >20 mg/l (p < 0.01). CONCLUSION: The balance between serum cortisol and cortisone is altered during acute-phase response with a shift towards active cortisol, suggesting that 11beta-HSD isoenzymes play a role in the modulation of systemically available cortisol during acute illness.     

Validation of the plasma half-life of 11alpha-deuterium cortisol as a sensitive index for the analysis of human 11beta-HSD2 activity in vivo

This study is concerned with validating the measurement of the plasma half-life of 11alpha-(2)H cortisol in an attempt to accurately assess the in vivo activity of 11beta-HSD2 in man. Oral administration of 5mg of cortisol-(13)C(4),(2)H(1) to a human subject after repeated ingestions of 130mg/day of glycyrrhetinic acid for 5 days resulted in a decrease in the rate constant of the cortisol-(13)C(4),(2)H(1) to cortisone-(13)C(4) conversion, a direct index reflecting 11beta-HSD2 activity. The reduced 11beta-HSD2 activity led to an increase in the elimination half-life of cortisol-(13)C(4),(2)H(1), indicating that the loss of 11alpha-(2)H is a sensitive in vivo means of assessing 11beta-HSD2 activity. A simultaneous oral administration of 3mg each of [1,2,4,19-(13)C(4),11alpha-(2)H]cortisol (cortisol-(13)C(4),(2)H(1)) and 11alpha-(2)H cortisol to another human subject confirmed the bioequivalency of the two labeled cortisols. The information obtained from the kinetic analysis of the 11beta-HSD2-catalyzed conversion of cortisol-(13)C(4),(2)H(1) to cortisone-(13)C(4) indicated that the elimination half-life of 11alpha-(2)H cortisol was a sensitive index of renal 11beta-HSD2 activity. The use of 11alpha-(2)H cortisol as a tracer appears to offer a significant advance in evaluating human 11beta-HSD2 activity in vivo.     

Effect of glucocorticoid excess on the cortisol/cortisone ratio

OBJECTIVE: The conversion of cortisol, which binds avidly to the mineralocorticoid receptor, to cortisone, which no longer has mineralocorticoid function, is predominantly catalyzed by the 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD 2). It was the objective of the present study to examine the impact of different forms of glucocorticoid excess on the cortisol/cortisone ratio and to differentiate their role in the genesis of hypertension. DESIGN AND METHODS: Plasma cortisol and cortisone levels were determined in 12 adults with Cushing's disease, 12 adults with hypercortisolism due to an adrenal tumor, and 20 healthy volunteers before and after an intravenous ACTH test, using specific radioimmunoassays after automated Sephadex LH 20 chromatography. RESULTS: The cortisol/cortisone ratios were significantly higher in patients with Cushing's disease (13.9 +/- 1.1), adrenal tumors (11.5 +/- 2.3), and in healthy volunteers after ACTH stimulation (14.1 +/- 2.0) than in untreated controls (6.0 +/- 0.5) (P < 0.001, P < 0.05, and P < 0.001, respectively). Similar differences were seen for cortisol plasma concentrations, whereas cortisone concentrations did not differ among the groups. CONCLUSIONS: Our data suggest that the excessive mineralocorticoid effects in patients with hypercortisolism are inflicted by elevated cortisol/cortisone ratios possibly due to an insufficient conversion of cortisol to cortisone by 11beta-HSD 2. This may provide a possible explanation for the occurrence of hypertension. This effect seems to be independent of the role of ACTH in the mechanism of hypercortisolism.     

The 11 beta-hydroxysteroid dehydrogenase type 2 activity in human placental microsomes is inactivated by zinc and the sulfhydryl modifying reagent N-ethylmaleimide

Proper glucocorticoid exposure in utero is vital to normal fetal organ growth and maturation. The human placental 11 beta-hydroxysteroid dehydrogenase type 2 enzyme (11 beta-HSD2) catalyzes the unidirectional conversion of cortisol to its inert metabolite cortisone, thereby controlling fetal exposure to maternal cortisol. The present study examined the effect of zinc and the relatively specific sulfhydryl modifying reagent N-ethylmaleimide (NEM) on the activity of 11 beta-HSD2 in human placental microsomes. Enzyme activity, reflected by the rate of conversion of cortisol to cortisone, was inactivated by NEM (IC(50)=10 microM), while the activity was markedly increased by the sulfhydryl protecting reagent dithiothreitol (DTT; EC(50)=1 mM). Furthermore, DTT blocked the NEM-induced inhibition of 11 beta-HSD2 activity. Taken together, these results suggested that the sulfhydryl (SH) group(s) of the microsomal 11 beta-HSD2 may be critical for enzyme activity. Zn(2+) also inactivated enzyme activity (IC(50)=2.5 microM), but through a novel mechanism not involving the SH groups. In addition, prior incubation of human placental microsomes with NAD(+) (cofactor) but not cortisol (substrate) resulted in a concentration-dependent increase (EC(50)=8 microM) in 11 beta-HSD2 activity, indicating that binding of NAD(+) to the microsomal 11 beta-HSD2 facilitated the conversion of cortisol to cortisone. Thus, this finding substantiates the previously proposed concept that a compulsorily ordered ternary complex mechanism may operate for 11 beta-HSD2, with NAD(+) binding first, followed by a conformational change allowing cortisol binding with high affinity. Collectively, the present results suggest that cellular mechanisms of SH group modification and intracellular levels of Zn(2+) may play an important role in regulation of placental 11 beta-HSD2 activity.     

ATP stimulates human placental 11beta-hydroxysteroid dehydrogenase type 2 activity by a novel mechanism independent of phosphorylation.

The human placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) is believed to play a key role in fetal development since this enzyme protects the fetus from exposure to high levels of maternal cortisol by virtue of converting maternal cortisol to its inert metabolite cortisone. The present study was undertaken to examine the effect of ATP on 11beta-HSD2 activity in human placental microsomes. Enzyme activity, reflected by the rate of conversion of cortisol to cortisone, was stimulated more than six-fold by 0.5 mM ATP (EC(50) = 0.2 mM). Such stimulation appears to be mediated through a novel mechanism independent of ATP-induced phosphorylation of the reaction components since AMP-PNP, a non-hydrolyzable analogue of ATP, was equally effective. The ATP-induced stimulation of 11beta-HSD2 activity is adenine nucleotide specific in that a similar stimulation was observed with ADP and AMP but not with CTP, GTP, or UTP. Furthermore, ATP increased the maximal velocity (V(max)) of the 11beta-HSD2 catalyzed conversion of cortisol to cortisone without altering the apparent K(m) of 11beta-HSD2 for cortisol, suggesting that ATP may stimulate enzyme activity by interacting with the enzyme at a site other than that involved in substrate binding. In conclusion, the present study has identified ATP as a novel regulator of human placental 11beta-HSD2 in vitro. It is conceivable that intracellular ATP may have a profound effect on 11beta-HSD2 function in vivo.     

Guinea pig 11beta-hydroxysteroid dehydrogenase type 1: primary structure and catalytic properties

The 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) enzyme is responsible for the interconversion of glucocorticoids and their inactive metabolites, and thus modulates the intracellular level of bioactive glucocorticoids. The present study was designed to clone and characterize 11beta-HSD1 in the guinea pig, a laboratory animal known for resistance to glucocorticoids. The cDNA encoding guinea pig 11beta-HSD1 was cloned by a modified 3'-RACE (rapid amplification of cDNA ends) protocol using the hepatic RNA as template. The cloned cDNA encodes a protein of 300 amino acids that shares 71 to 74% sequence identity with other known mammalian 11beta-HSD1 proteins. Sequence comparison analysis revealed that the deduced guinea pig 11beta-HSD1 was longer, by eight amino acids at the C terminus, than those of other mammals. Moreover, one of the two absolutely conserved consensus sites for N-glycosylation was absent. To examine the functional significance of these structural changes, we also characterized 11beta-HSD1 activity in the hepatic microsomes. Although the guinea pig hepatic enzyme was NADP(H)-dependent and reversible, it displayed equal affinity for cortisol and cortisone (apparent K(m) for both substrates was 3 microM). This is in marked contrast to 11beta-HSD1 in other mammals whose affinity for cortisone is approximately 10 times higher than that for cortisol (apparent K(m) of 0.3 vs. 3.0 microM). The apparent lower affinity of the guinea pig enzyme for cortisone would suggest that the intracellular bioformation of cortisol from circulating cortisone may be less efficient in this species. Northern blot analysis and RT-PCR revealed that the mRNA for 11beta-HSD1 was widely expressed in the adult guinea pig but at low amounts. In conclusion, the present study has identified distinct features in the deduced primary structure and catalytic function of 11beta-HSD1 in the guinea pig. Thus, the guinea pig provides a useful model in which the structural determinants of catalytic function of 11beta-HSD1 may be studied.     

Measurement of cortisol secretion rate by stable isotope methodology following oral administration of 13C-labeled cortisol to a human subject

Plasma concentration measurements of 13C-labeled cortisol ([1,2,4,19-13C(4)]cortisol, cortisol-13C(4)) and its metabolite cortisone-13C(4) were made simultaneously with measurements of endogenous cortisol and cortisone by gas chromatography-mass spectrometry (GC-MS). After administering a small amount (3mg) of cortisol-13C(4) to a human subject, changes in cortisol secretion rates were estimated by deconvolution techniques from the measured plasma cortisol and cortisone levels and the rates of elimination and interconversion of cortisol and cortisone were obtained from the plasma concentration-time data of cortisol-13C(4) and cortisone-13C(4). The objective of this study was to look for a novel approach to quantitate rates of minute-to-minute cortisol secretion in man by taking into account the interconversion of cortisol and cortisone by 11beta-hydroxysteroid dehydrogenase (11beta-HSD).     

Increased production of 11beta-hydroxysteroid dehydrogenase type 2 in the kidney microsomes of squirrel monkeys (Saimiri spp.)

In squirrel monkeys (Saimiri spp.), cortisol circulates at levels much higher than those seen in man and other Old World primates, but squirrel monkeys exhibit no physiologic signs of the mineralocorticoid effects of cortisol. These observations suggest that squirrel monkeys have mechanisms for protection of the mineralocorticoid receptor (MR) from these high levels of cortisol. We previously showed that the serum cortisol to cortisone ratio in these animals is low relative to that in human serum, suggesting that production of the MR protective enzyme, 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), is increased in squirrel monkeys. Here, we directly evaluate whether increased production of 11beta-HSD2, which inactivates cortisol to cortisone, is a mechanism for protection of MR. In vitro assays showed that 11beta-HSD2 activity in squirrel monkey kidney microsomes was 3 to 7 times higher than that seen in kidney microsomes from pig or rabbit. 11beta-HSD2 protein detected by Western blot analysis was 4 to 9 times greater in squirrel monkey microsomes than in pig or rabbit microsomes. Comparison of the effect of expression of either human or squirrel monkey 11beta-HSD2 on MR transactivation activity showed similar inhibition of MR response to cortisol by both enzymes, indicating that the intrinsic activities of the human and squirrel monkey enzymes are similar. These findings suggest that one mechanism by which squirrel monkeys protect the MR from activation by high cortisol levels in the kidney is by upregulation of 11beta-HSD2 activity through increased production of the enzyme.     

11 Beta-hydroxysteroid dehydrogenase type 1 is induced in human monocytes upon differentiation to macrophages.

11beta-hydroxysteroid dehydrogenases (11beta-HSD) perform prereceptor metabolism of glucocorticoids through interconversion of the active glucocorticoid, cortisol, with inactive cortisone. Although the immunosuppressive and anti-inflammatory activities of glucocorticoids are well documented, the expression of 11beta-HSD enzymes in immune cells is not well understood. Here we demonstrate that 11beta-HSD1, which converts cortisone to cortisol, is expressed only upon differentiation of human monocytes to macrophages. 11beta-HSD1 expression is concomitant with the emergence of peroxisome proliferator activating receptor gamma, which was used as a surrogate marker of monocyte differentiation. The type 2 enzyme, 11beta-HSD2, which converts cortisol to cortisone, was not detectable in either monocytes or cultured macrophages. Incubation of monocytes with IL-4 or IL-13 induced 11beta-HSD1 activity by up to 10-fold. IFN-gamma, a known functional antagonist of IL-4 and IL-13, suppressed the induction of 11beta-HSD1 by these cytokines. THP-1 cells, a human macrophage-like cell line, expressed 11beta-HSD1 and low levels of 11beta-HSD2. The expression of 11beta-HSD1 in these cells is up-regulated 4-fold by LPS. In summary, we have shown strong expression of 11beta-HSD1 in cultured human macrophages and THP-1 cells. The presence of the enzyme in these cells suggests that it may play a role in regulating the immune function of these cells.     

The intracellular localization of the mineralocorticoid receptor is regulated by 11beta-hydroxysteroid dehydrogenase type 2

11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2 has been considered to protect the mineralocorticoid receptor (MR) by converting 11beta-hydroxyglucocorticoids into their inactive 11-keto forms, thereby providing specificity to the MR for aldosterone. To investigate the functional protection of the MR by 11beta-HSD2, we coexpressed epitope-tagged MR and 11beta-HSD2 in HEK-293 cells lacking 11beta-HSD2 activity and analyzed their subcellular localization by fluorescence microscopy. When expressed alone in the absence of hormones, the MR was both cytoplasmic and nuclear. However, when coexpressed with 11beta-HSD2, the MR displayed a reticular distribution pattern, suggesting association with 11beta-HSD2 at the endoplasmic reticulum membrane. The endoplasmic reticulum membrane localization of the MR was observed upon coexpression only with 11beta-HSD2, but not with 11beta-HSD1 or other steroid-metabolizing enzymes. Aldosterone induced rapid nuclear translocation of the MR, whereas moderate cortisol concentrations (10-200 nm) did not activate the receptor, due to 11beta-HSD2-dependent oxidation to cortisone. Compromised 11beta-HSD2 activity (due to genetic mutations, the presence of inhibitors, or saturating cortisol concentrations) led to cortisol-induced nuclear accumulation of the MR. Surprisingly, the 11beta-HSD2 product cortisone blocked the aldosterone-induced MR activation by a strictly 11beta-HSD2-dependent mechanism. Our results provide evidence that 11beta-HSD2, besides inactivating 11beta-hydroxyglucocorticoids, functionally interacts with the MR and directly regulates the magnitude of aldosterone-induced MR activation.     

11 Beta-hydroxysteroid dehydrogenase type 1 from human liver: dimerization and enzyme cooperativity support its postulated role as glucocorticoid reductase

11Beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD 1) is a microsomal enzyme that catalyzes the reversible interconversion of receptor-active 11-hydroxy glucocorticoids (cortisol) to their receptor-inactive 11-oxo metabolites (cortisone). However, the physiological role of 11beta-HSD 1 as prereceptor control device in regulating access of glucocorticoid hormones to the glucocorticoid receptor remains obscure in light of its low substrate affinities, which is in contrast to low glucocorticoid plasma levels and low Kd values of the receptors to cortisol. To solve this enigma, we performed detailed kinetic analyses with a homogeneously purified 11beta-HSD 1 from human liver. The membrane-bound enzyme was successfully obtained in an active state by a purification procedure that took advantage of a gentle solubilization method as well as providing a favorable detergent surrounding during the various chromatographic steps. The identity of purified 11beta-HSD 1 was proven by determination of enzymatic activity, N-terminal amino acid sequencing, and immunoblot analysis. By gel-permeation chromatography we could demonstrate that 11beta-HSD 1 is active as a dimeric enzyme. The cDNA for the enzyme was cloned from a human liver cDNA library and shown to be homologous to that previously characterized in human testis. Interestingly, 11beta-HSD 1 exhibits Michaelis-Menten kinetics with cortisol and corticosterone (11beta-dehydrogenation activity) but cooperative kinetics with cortisone and dehydrocorticosterone (11-oxoreducing activity). Accordingly, this enzyme dynamically adapts to low (nanomolar) as well as to high (micromolar) substrate concentrations, thereby providing the fine-tuning required as a consequence of great variations in circadian plasma glucocorticoid levels.     

Modulation of cortisol metabolism during treatment of acromegaly is independent of body composition and insulin sensitivity

OBJECTIVES: The set point of cortisol-cortisone conversion is shifted in the direction of cortisone by the inhibition of the activity of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) during adult GH replacement and in active acromegaly. Additionally, both fat mass and insulin may modulate 11beta-HSD1 and are both influenced by changes in GH status. This study examined the relative direct contribution of GH/IGF1 in modulating cortisol metabolism. METHODS: Overall cortisol/cortisone conversion (ratio of urine 11-hydroxy-/11-oxo-cortisol metabolites; Fm/Em), insulin sensitivity (homeostatic model assessment; HOMA %S) and fat mass (DXA) were examined in parallel in 6 patients (mean age 53 years, range 42-76; 4 males, 2 females) with previously untreated active acromegaly during 6 months of therapy with Sandostatin LAR (20-30 mg i.m. 4 weekly). All but 1 patient had normal ACTH reserve. RESULTS: At baseline, Pearson correlation demonstrated an inverse relationship between serum GH (mean of a 5-point day curve) and Fm/Em (r = -0.83, p = 0.04) and a trend towards an inverse relationship between HOMA %S and Fm/Em (r = -0.79, p = 0.06) but no other patterns were evident. During the course of treatment, serum GH decreased from 9.9 +/- 6.4 (mean +/- SD) to 3.5 +/- 3.1 ng/ml (p < 0.01) and serum IGF-1 from 785 +/- 268 to 431 +/- 156 ng/ml (p < 0.005). Fm/Em increased from 0.52 +/- 0.1 to 0.75 +/- 0.08 (p < 0.03) consistent with increased 11beta-HSD1 activity. There were no significant changes in truncal fat percentage (33.0 +/- 9.0 vs. 33.0 +/- 8.2) or insulin sensitivity (HOMA %S: 37.1 +/- 8.6 vs. 52.8 +/- 33.7). CONCLUSIONS: Modulation of cortisol metabolism during treatment of active acromegaly is dependent on changes in GH/IGF-1 status and is not influenced by any individual change in body composition or insulin sensitivity.     

Dehydrogenase and oxoreductase activities of porcine placental 11beta-hydroxysteroid dehydrogenase

Dehydrogenase (cortisol to cortisone) and oxoreductase (cortisone to cortisol) activities of porcine placental 11beta-hydroxysteroid dehydrogenase (11beta-HSD) were measured in tissue fragment cultures on day 75 of gestation. Dehydrogenase activity was over fivefold greater than oxoreductase activity (p < .001). There were positive linear associations (p < .01) between net dehydrogenase activity (dehydrogenase minus oxoreductase) and fetal weight, fetal length, and placental weight. These data indicate a predominance of placental 11beta-HSD dehydrogenase activity at this gestational stage that would insure a net conversion of cortisol to cortisone as it traverses the placenta. The data further suggest that 11beta-HSD activities may provide an optimal glucocorticoid environment that is supportive of enhanced fetal and placental growth.     

Cortisol production rate in children by gas chromatography/mass spectrometry using [1,2,3,4-13C]cortisol

A urinary method of determining the cortisol production rate (CPR) in children was studied under physiologic conditions by administration of low amounts of [1,2,3,4-13C]cortisol. The CPR in three patients with multiple pituitary deficiency ranged from 7 to 16 mumoles d-1 m-2, and the CPR in three patients with congenital adrenal hyperplasia (CAH) due to 11 beta-hydroxylase deficiency (11 beta OHD) and 17 alpha-hydroxylase deficiency (17 alpha OHD) from 0.1 to 2.11 mumoles d-1 m-2. Results showed that with this method, very low CPRs can be reliably measured. The metabolism of [13C4]cortisol or [9,12,12-2H]cortisol was compared with that of native cortisol in adrenalectomized piglets. For the urinary cortisol metabolites, small to substantial differences in isotope dilution were noted relative to that in the original cortisol mixture. With [13C4]cortisol, the so-called secondary isotope effects were approximately 2% to 3% for tetrahydrocortisone (THE) and tetrahydrocortisol (THF), and about 10% for the cortolones, relative to the cortisol mixture. When [2H3]cortisol was used, the cortisol metabolites THE and THF contained only two deuterium atoms. Together with this apparent loss of one deuterium atom, the secondary isotope effects in these steroids amounted to 5% to 10%. It was concluded that [13C4]cortisol was the better tracer to use for the measurement of urinary CPR.