Control of Physiologic Glucose Homeostasis via the Hypothalamic Modulation of Gluconeogenic Substrate Availability.

The brain augments glucose production during fasting, but the mechanisms are poorly understood. Here, we show that Cckbr-expressing neurons in the ventromedial hypothalamic nucleus (VMNCckbr cells) prevent low blood glucose during fasting through sympathetic nervous system (SNS)-mediated augmentation of adipose tissue lipolysis and substrate release. Activating VMNCckbr neurons mobilized gluconeogenic substrates without altering glycogenolysis or gluconeogenic enzyme expression. Silencing these cells (CckbrTetTox animals) reduced fasting blood glucose, impaired lipolysis, and decreased circulating glycerol (but not other gluconeogenic substrates) despite normal insulin, counterregulatory hormones, liver glycogen, and liver gluconeogenic gene expression. Furthermore, ß3-adrenergic adipose tissue stimulation in CckbrTetTox animals restored lipolysis and blood glucose. Hence, VMNCckbr neurons impact blood glucose not by controlling islet or liver physiology, but rather by mobilizing gluconeogenic substrates. These findings establish a central role for hypothalamic and SNS signaling during normal glucose homeostasis and highlight the importance of gluconeogenic substrate mobilization during physiologic fasting.

An in Vitro triple screen model for human mineralocorticoid receptor activity.

The mineralocorticoid receptor (MR, NR3C2) mediates ion and water homeostasis in epithelial cells of the distal nephron and other tissues. Aldosterone, the prototypical mineralocorticoid, regulates electrolyte and fluid balance. Cortisol binds to MR with equal affinity to aldosterone, but many MR-expressing tissues inactivate cortisol to cortisone via 11ß-hydroxysteroid dehydrogenase type 2 (HSD11B2). Dysregulated MR activation contributes to direct cardiovascular tissue insults. Besides aldosterone and cortisol, a variety of MR agonists and/or HSD11B2 inhibitors are putative players in the pathophysiology of low-renin hypertension (LRH), and cardiovascular and metabolic pathology. We developed an in vitro human MR (hMR) model, to facilitate screening for MR agonists, antagonists, and HSD11B2 inhibitors. The CV1 monkey kidney cells were transduced with lentivirus to stably express hMR and an MR-responsive gaussia luciferase gene. Clonal populations of MR-expressing cells (CV1-MRluc) were further transduced to express HSD11B2 (CV1-MRluc-HSD11B2). CV1-MRluc and CV1-MRluc-HSD11B2 cells were treated with aldosterone, cortisol, 11-deoxycorticosterone (DOC), 18-hydroxycorticosterone (18OHB), 18-hydroxycortisol (18OHF), 18-oxocortisol (18oxoF), progesterone, or 17-hydroxyprogesterone (17OHP). In CV1-MRLuc cells, aldosterone and DOC displayed similar potency (EC50: 0.45 nM and 0.30 nM) and maximal response (31- and 23-fold increase from baseline) on hMR; 18oxoF and 18OHB displayed lower potency (19.6 nM and 56.0 nM, respectively) but similar maximal hMR activation (25- and 27-fold increase, respectively); cortisol and corticosterone exhibited higher maximal responses (73- and 52-fold, respectively); 18OHF showed no MR activation. Progesterone and 17OHP inhibited aldosterone-mediated MR activation. In the MRluc-HSD11B2 model, the EC50 of cortisol for MR activation increased from 20 nM (CV1-MRLuc) to ∼2000 nM, while the EC50 for aldosterone remained unchanged. The addition of 18ß-glycyrrhetinic acid (18ß-GA), a HSD11B2 inhibitor, restored the potency of cortisol back to ∼70 nM in CV1-hMRLuc-HSD11B2 cells. Together, these two cell models will facilitate the discovery of novel MR-modulators, informing MR-mediated pathophysiology mechanisms and drug development efforts.

Human Gonads Do Not Contribute to the Circulating Pool of 11-Oxygenated Androgens.

CONTEXT: Androstenedione (A4) and testosterone (T) are produced by both the adrenal glands and the gonads. The adrenal enzyme 11ß-hydroxylase (CYP11B1) executes the final step in cortisol synthesis; CYP11B1 also uses A4 and T as substrates, generating 11-hydroxyandrostenedione and 11-hydroxytestosterone, respectively. It has been suggested that CYP11B1 is expressed in the gonads, yet the circulating levels of all 11-oxygenated androgens (11-oxyandrogens) are similar in males and females of reproductive ages, despite enormous differences in T. OBJECTIVE: To assess the gonadal contribution to the circulating pool of 11-oxyandrogens. METHODS: We used liquid chromatography-tandem mass spectrometry to measure 13 steroids, including traditional and 11-oxyandrogens in: (I) paired gonadal and peripheral vein blood samples obtained during gonadal venograms from 11 patients (7 women), median age 37 (range 31-51 years); and (II) 17 women, median age 57 (range 41-81 years) before and after bilateral salpingo-oophorectomy (BSO). We also compared CYP11B1, 17α-hydroxylase/17,20-lyase (CYP17A1), and 3ß-hydroxysteroid dehydrogenase type 2 (HSD3B2) mRNA expression in adrenal, ovarian, and testicular tissue. RESULTS: A4, T, estradiol, estrone, progesterone, 17α- and 16α-hydroxyprogesterone were all higher in gonadal veins vs. periphery (p < 0.05 for all), while four 11-oxyandrogens were similar between matched gonadal and peripheral vein samples. Equally, in women who underwent BSO, A4 (median [interquartile range]: 59.7 [47.7-67.6] ng/dL vs. 32.7 [27.4-47.8] ng/dL, p < 0.001) and T (24.1 [16.4-32.3] vs.15.5 [13.7-19.0] ng/dL, p < 0.001) declined, while 11-oxyandrogens remained stable. Gonadal tissue displayed negligible CYP11B1 mRNA. CONCLUSION: Despite producing substantial amounts of A4 and T, human gonads are not relevant sources of 11-oxyandrogens.

Abiraterone in Classic Congenital Adrenal Hyperplasia: Results of Medical Therapy Before Adrenalectomy.

We present the case of a 20-year-old woman with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency, with uncontrolled hyperandrogenemia despite supraphysiological glucocorticoid therapy. We used abiraterone acetate, an inhibitor of the 17-hydroxylase/17,20-lyase enzyme, to suppress adrenal androgen synthesis and allow physiological glucocorticoid and mineralocorticoid therapy, as a proof-of-concept, before proceeding to bilateral adrenalectomy. We report the patient's clinical course, the changes in adrenal steroids, and the immunohistochemistry of the adrenals.

The Spectrum of Dysregulated Aldosterone Production: An International Human Physiology Study.

CONTEXT: Primary aldosteronism is a form of low-renin hypertension characterized by dysregulated aldosterone production. OBJECTIVE: To investigate the contributions of renin-independent aldosteronism and ACTH-mediated aldosteronism in individuals with a low-renin phenotype representing the entire continuum of blood pressure. DESIGN/PARTICIPANTS: Human physiology study of 348 participants with a low-renin phenotype with severe and/or resistant hypertension, hypertension with hypokalemia, elevated blood pressure and stage I/II hypertension, and normal blood pressure. SETTING: 4 international centers. INTERVENTIONS/MAIN OUTCOME MEASURES: The saline suppression test (SST) to quantify the magnitude of renin-independent aldosteronism; dexamethasone suppression and ACTH-stimulation tests to quantify the magnitude of ACTH-mediated aldosteronism; adrenal venous sampling to determine lateralization. RESULTS: There was a continuum of nonsuppressible and renin-independent aldosterone production following SST that paralleled the magnitude of the blood pressure continuum and transcended conventional diagnostic thresholds. In parallel, there was a full continuum of ACTH-mediated aldosteronism wherein post-SST aldosterone levels were strongly correlated with ACTH-stimulated aldosterone production (r = 0.75, P < .0001) and nonsuppressible aldosterone production postdexamethasone (r = 0.40, P < .0001). Beyond participants who met the criteria for primary aldosteronism (post-SST aldosterone of ≥10 ng/dL or ≥277 pmol/L), the continuum of nonsuppressible and renin-independent aldosterone production persisted below this diagnostic threshold, wherein 15% still had lateralizing aldosteronism amenable to surgical adrenalectomy and the remainder were treated with mineralocorticoid receptor antagonists. CONCLUSION: In the context of a low-renin phenotype, there is a continuum of primary aldosteronism and dysregulated aldosterone production that is prominently influenced by ACTH. A large proportion of individuals with low renin may benefit from aldosterone-directed therapy.

Multifocal, Asymmetric Bilateral Primary Aldosteronism Cannot be Excluded by Strong Adrenal Vein Sampling Lateralization: An International Retrospective Cohort Study.

BACKGROUND: Primary aldosteronism (PA) has been broadly dichotomized into unilateral and bilateral forms. Adrenal vein sampling (AVS) lateralization indices (LI) ≥2 to 4 are the standard-of-care to recommend unilateral adrenalectomy for presumed unilateral PA. We aimed to assess the rates and characteristics of residual PA after AVS-guided adrenalectomy. METHODS: We conducted an international, retrospective, cohort study of patients with PA from 7 referral centers who underwent unilateral adrenalectomy based on LI≥4 on baseline and/or cosyntropin-stimulated AVS. Aldosterone synthase (CYP11B2) immunohistochemistry and next generation sequencing were performed on available formalin-fixed paraffin-embedded adrenal tissue. RESULTS: The cohort included 283 patients who underwent AVS-guided adrenalectomy, followed for a median of 326 days postoperatively. Lack of PA cure was observed in 16% of consecutive patients, and in 22 patients with lateralized PA on both baseline and cosyntropin-stimulated AVS. Among patients with residual PA postoperatively, 73% had multiple CYP11B2 positive areas within the resected adrenal tissue (versus 23% in those cured), wherein CACNA1D mutations were most prevalent (63% versus 33% in those cured). In adjusted regression models, independent predictors of postoperative residual PA included Black versus White race (odds ratio, 5.10 [95% CI, 1.45-17.86]), AVS lateralization only at baseline (odds ratio, 8.93 [95% CI 3.00-26.32] versus both at baseline and after cosyntropin stimulation), and CT-AVS disagreement (odds ratio, 2.75 [95% CI, 1.20-6.31]). CONCLUSIONS: Multifocal, asymmetrical bilateral PA is relatively common, and it cannot be excluded by robust AVS lateralization. Long-term postoperative monitoring should be routinely pursued, to identify residual PA and afford timely initiation of targeted medical therapy.

Evaluation of a Best-Practice Advisory for Primary Aldosteronism Screening.

Importance: Primary aldosteronism (PA) is a common cause of secondary hypertension and an independent risk factor for cardiovascular morbidity and mortality. Fewer than 2% to 4% of patients at risk are evaluated for PA. Objective: To develop and evaluate an electronic health record best-practice advisory (BPA) that assists with PA screening. Design, Setting, and Participants: This prospective quality improvement study was conducted at academic center outpatient clinics. Data analysis was performed between February and June 2023 and included adults with hypertension and at least 1 of the following: 4 or more current antihypertensive medications; hypokalemia; age younger than 35 years; or adrenal nodule(s). Patients previously tested for PA were excluded. Exposure: A noninterruptive BPA was developed to trigger for PA screening candidates seen in outpatient setting by clinicians who treat hypertension. The BPA included an order set for PA screening and a link to results interpretation guidance. Main Outcomes and Measures: (1) The number of PA screening candidates identified by the BPA between October 1, 2021, and December 31, 2022; (2) the rates of PA screening; and (3) the BPA use patterns, stratified by physician specialty were assessed. Results: Over 15 months, the BPA identified 14 603 unique candidates (mean [SD] age, 65.5 [16.9] years; 7300 women [49.9%]; 371 [2.5%] Asian, 2383 [16.3%] Black, and 11 225 [76.9%] White individuals) for PA screening, including 7028 (48.1%) with treatment-resistant hypertension, 6351 (43.5%) with hypokalemia, 1537 (10.5%) younger than 35 years, and 445 (3.1%) with adrenal nodule(s). In total, 2040 patients (14.0%) received orders for PA screening. Of these, 1439 patients (70.5%) completed the recommended screening within the system, and 250 (17.4%) had positive screening results. Most screening orders were placed by internists (40.0%) and family medicine physicians (28.1%). Family practitioners (80.3%) and internists (68.9%) placed most orders via the embedded order set, while specialists placed most orders (83.0%-95.4%) outside the BPA. Patients who received screening were younger and included more women and Black patients than those not screened. The likelihood of screening was higher among patients with obesity and dyslipidemia and lower in those with chronic kidney disease and established cardiovascular complications. Conclusions and Relevance: The study results suggest that noninterruptive BPAs are potentially promising PA screening-assistance tools, particularly among primary care physicians. Combined with artificial intelligence algorithms that optimize the detection yield, refined BPAs may contribute to personalized hypertension care.