Androgen excess predisposes women to type 2 diabetes (T2D), but the mechanism of this is poorly understood. We report that female mice fed a Western diet and exposed to chronic androgen excess using dihydrotestosterone (DHT) exhibit hyperinsulinemia and insulin resistance associated with secondary pancreatic β cell failure, leading to hyperglycemia. These abnormalities are not observed in mice lacking the androgen receptor (AR) in β cells and partially in neurons of the mediobasal hypothalamus (MBH) as well as in mice lacking AR selectively in neurons. Accordingly, i.c.v. infusion of DHT produces hyperinsulinemia and insulin resistance in female WT mice. We observe that acute DHT produces insulin hypersecretion in response to glucose in cultured female mouse and human pancreatic islets in an AR-dependent manner via a cAMP- and mTOR-dependent pathway. Acute DHT exposure increases mitochondrial respiration and oxygen consumption in female cultured islets. As a result, chronic DHT exposure in vivo promotes islet oxidative damage and susceptibility to additional stress induced by streptozotocin via AR in β cells. This study suggests that excess androgen predisposes female mice to T2D following AR activation in neurons, producing peripheral insulin resistance, and in pancreatic β cells, promoting insulin hypersecretion, oxidative injury, and secondary β cell failure.

High-fat diet (HFD) for 28 wk leads to type 2 diabetes mellitus (T2DM) phenotype, concomitant with increased plasma soluble prorenin receptor (sPRR), nondipping blood pressure, and vascular stiffness in male mice. HFD-fed female mice exhibiting a preserved cardiometabolic phenotype until ovariectomy revealed increased plasma sPRR and blood pressure. Plasma sPRR may indicate the status of systemic renin-angiotensin-aldosterone system (RAAS) activation and the onset of vascular complications during T2DM in a sex-dependent manner.

(1) Background: Apolipoprotein E (ApoE) is a critical plasma apolipoprotein for lipid transport and nonlipid-related functions. Humans possess three isoforms of ApoE (2, 3, and 4). ApoE2, which exhibits beneficial effects on cardiac health, has not been adequately studied. (2) Methods: We investigated the cardiac phenotypes of the humanized ApoE knock-in (hApoE KI) rats and compared to wild-type (WT) and ApoE knock-out (ApoE KO) rats using echocardiography, ultrasound, blood pressure measurements, histology strategies, cell culture, Seahorse XF, cardiomyocyte contractility and intracellular Ca²⁺ tests, and Western blotting; (3) Results: hApoE2 rats exhibited enhanced heart contractile function without signs of detrimental remodeling. Isolated adult hApoE2 cardiomyocytes had faster and stronger sarcomere contractility because of more mitochondrial energy generation and stimulation-induced fast and elevated intracellular Ca²⁺ transient. The abundant energy is a result of elevated mitochondrial function via fatty acid β-oxidation. The fast and elevated Ca²⁺ transient is associated with decreased sarcoplasmic reticulum (SR) Ca²⁺ ATPase (SERCA2) and increased expression of cardiac ryanodine receptor 2 (RyR2) conducting a potent Ca²⁺ release from SR.; (4) Conclusions: Our studies validated the association of polymorphic ApoEs with cardiac health in the rat model, and revealed the possible mechanisms of the protective effect of ApoE2 against heart diseases.

Increased body weight (BW) induces inappropriate renin–angiotensin system (RAS) activation. The activation of the intrarenal RAS is associated with increased urinary angiotensinogen (uAGT), blood pressure (BP), and kidney damage. Here, we examined uAGT excretion levels in young non-diabetic human subjects with overweight (OW) and non-diabetic mice with high-fat diet (HFD)-induced OW. Human subjects (women and men; 20–28 years old) included two groups: (a) overweight (OW, n = 17, BMI ≥ 25); and (b) controls (normal weight (NW; n = 26, BMI ≤ 25). In these subjects, we measured BP, albuminuria, and protein levels of uAGT by ELISA adjusted by urinary creatinine (expressed by uAGT/uCrea). Mice (female and male C57BL/6J mice, 8 ± 2 weeks of age) also included two groups: HFD or normal fat diet (NFD) fed for 8 weeks. We measured BW, fasting blood glucose (FBG), BP by telemetry, albuminuria, and uAGT by ELISA. In humans: (i) no significant changes were observed in BP, albuminuria, and FBG when comparing NW and OW subjects; (ii) multivariate logistic regression analysis of independent predictors related to uAGT/uCrea levels demonstrated a strong association between uAGT and overweight; (iii) urinary reactive oxygen species (ROS) were augmented in men and women with OW; (iv) the uAGT/uCrea ratio was higher in men with OW. However, the uAGT/uCrea values were lower in women even with OW. In mice: (i) males fed an HFD for 8 weeks became OW while females did not; (ii) no changes were observed either in FBG, BP, or albuminuria; (iii) kidney ROS were augmented in OW male mice after 28 weeks but not in females; (iv) OW male mice showed augmented excretion of uAGT but this was undetectable in females fed either NFD or HFD. In humans and mice who are OW, the urinary excretion of AGT differs between males and females and overcomes overt albuminuria.

Objective: Brain Microvascular endothelial cells (BMECs) form the blood‐brain barrier (BBB) with other cell types such as microglia, astrocytes end feet, pericytes, and a basement membrane. Ischemic stroke damages BBB causing brain injury during reperfusion. Ischemic stroke in endothelial nitric oxide synthase (eNOS) knockout mice showed increased infarct size compared to wild‐type and the underlying mechanisms are not clear. eNOS produces nitric oxide which plays an important role in maintaining vascular homeostasis. Mitochondria play a key role in pathophysiological conditions such as ischemic stroke and diabetes. In addition, NOS has been showed to uncouple and produce superoxide during pathological conditions. Our objective is to study the effect of NOS inhibition on mitochondrial function in BMECs under normoxic and OGD‐R conditions. Methods: BMECs isolated from 2 weeks old Sprague Dawley rat pups were exposed to normoxic and OGD‐R conditions with and without NOS inhibitor N‐ω‐propyl‐L‐arginine (L‐NAME). We used Seahorse XFe 24 bioanalyzer (Agilent technologies) to measure mitochondrial oxygen consumption rates (OCR) using mito‐stress assay. Reactive oxygen species (ROS) levels were measured using Electron spin resonance (ESR) spectrometry (Bruker Bio‐Spin spectrometer, Germany). In addition, mitochondrial membrane potential was measured using Rhodamine 123 fluorescence and CCK‐8 kit was used to measure cell viability. Results: NOS inhibition using L‐NAME in BMECs under normoxic conditions reduced basal and maximal respiration. However, there is no significant difference in spare respiratory capacity, proton leak and non‐mitochondrial respiration in L‐NAME treated cells compared to the control group under normoxic conditions. Interestingly, NOS inhibition in BMECs exposed to OGD‐R decreased all the parameters of mitochondrial respiration such as basal respiration, maximal respiration, proton leak, and spare respiratory capacity compared to control group. ESR measurements using ROS specific spin probe CMH showed that NOS inhibition reduced ROS production compared to untreated cells in BMECs exposed to both normoxic and OGD‐R conditions. Fluorescence measurements using Rhodamine 123 have shown that cells exposed to OGD‐R reduced mitochondrial membrane potential and L‐NAME treatment improved mitochondrial membrane potential whereas, in cells grown under normoxic conditions, NOS inhibition has no significant effect on mitochondrial membrane potential. Finally, viability studies have shown that OGD‐R decreases cell viability and NOS inhibition in BMECS exposed to OGD‐R improves cell survival whereas, in normoxic conditions, L‐NAME treatment reduced cell viability after 24 hours. Conclusion: NOS inhibition using L‐NAME in BMECs exposed to OGD‐R improves cell survival rate by decreasing ROS production and by reducing mitochondrial respiration. Support or Funding Information National Institute of Health: National Institute of General Medical Sciences and National Institute of Neurological Disorders and Stroke (Katakam: R01NS094834) This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .