Glucocorticoid receptor antagonist alters corticosterone and receptor sensitive mRNAs in the hypoxic neonatal rat

Endocrinology ◽  
2021 ◽  
Author(s):  
Ashley L Gehrand ◽  
Jonathan Phillips ◽  
Kyle D Welhouse ◽  
Hana Siddiqui ◽  
Matthew Schulgit ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Glucocorticoid Receptor ◽  
Insulin Receptor ◽  
Plasma Corticosterone ◽  
Neonatal Rat ◽  
Target Tissue ◽  
Endogenous Hormones ◽  
Rat Pups ◽  
Pancreas Function ◽  
Neonatal Rat Model

Abstract Hypoxia, a common stressor with preterm birth, increases morbidity and mortality associated with prematurity. Glucocorticoids (GC) are administered to the preterm infant to improve oxygenation; prolonged use of GCs remains controversial. We evaluated a selective glucocorticoid receptor (GR) antagonist (CORT113176) in our neonatal rat model of human prematurity to assess how fasting and hypoxia-induced increases in neonatal corticosterone affects endogenous hormones and endocrine pancreas function. Neonatal rat pups at postnatal day (PD) 2, PD8, and PD15 were pretreated with CORT113176 and, after 60 min of separation and fasting, exposed to hypoxia (8% O2) or control (normoxia) for 30 or 60 minutes while fasting was continued. Plasma corticosterone, ACTH, glucose, and insulin were measured and fasting HOMA-IR (index of insulin resistance) calculated. Glucocorticoid and insulin receptor sensitive gene mRNAs were analyzed in liver, muscle, and adipose to evaluate target tissue biomarkers. CORT113176 pretreatment augmented baseline and hypoxia-induced increases in corticosterone and attenuated hypoxia-induced increases in insulin resistance at PD2. Normoxic and hypoxic stress increased the hepatic GR sensitive gene mRNAs, Gilz and Per1; this was eliminated by pretreatment with CORT113176. CORT113176 pretreatment decreased baseline insulin receptor sensitive gene mRNAs Akt2, Irs1, Pik3r1, and Srebp1c at PD2. We show that CORT113176 variably augments the stress-induced increases in corticosterone concentrations (attenuation of negative feedback) and that GR is critical for hepatic responses to stress in the hypoxic neonate. We also propose that measurement of Gilz and Per1 mRNA expression may be useful to evaluate the effectiveness of GR antagonism.

scholarly journals The Effect of a Novel Glucocorticoid Receptor Antagonist (CORT113176) on Glucocorticoid and Insulin Receptor Sensitive Hepatic Gene (mRNA) Expression in a Neonatal Rat Model of Human Prematurity

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A818-A818
Author(s):  
Ashley Gehrand ◽  
Jonathan Phillips ◽  
Kyle D Welhouse ◽  
Matthew Schulgit ◽  
Hana Siddiqui ◽  
...  
Keyword(s):  
Preterm Birth ◽  
Glucocorticoid Receptor ◽  
Insulin Receptor ◽  
Mrna Expression ◽  
Rat Model ◽  
Neonatal Rat ◽  
Rat Pups ◽  
Response To Stress ◽  
Neonatal Rat Model ◽  
Gene Mrna

Abstract Preterm birth is a global health problem the sequelae of which are not well understood. Hypoxia, a common stressor with prematurity, can affect blood glucose via stress-induced increases in glucocorticoids (GC). GCs are also administered to preterm infants to improve oxygenation; however, this is controversial. CORT113176 (Corcept Therapeutics) is a novel, selective glucocorticoid receptor (GR) antagonist that does not bind to the progesterone receptor. We have demonstrated that CORT113176 (in our rat model of preterm birth) increases baseline corticosterone (due to loss of GC negative feedback) and attenuates hypoxia-induced increases in insulin resistance implicating endogenous corticosterone in post-natal metabolic adaptations to stress. We now propose that CORT113176 is useful to evaluate the hepatic effects of endogenous GCs in our rat model of preterm birth by measuring critical GC and insulin receptor sensitive gene mRNAs. Postnatal day (PD) 2 rat pups of both sexes (N=5 per treatment/sex) were pretreated with CORT113176 (600 mg/kg IP) or vehicle. After 60 minutes, a group of pups were euthanized with livers collected and preserved in RNAlater (baseline). The remaining pups were separated from their dams, exposed to normoxia (control) or hypoxia (8% O2) for 60 minutes, and livers obtained. Total hepatic RNA was extracted, and mRNA expression was analyzed (RT-qPCR) for GC and insulin receptor sensitive genes: GC: Fkbp5, Gilz, Nr3c1 (Gr), Nr3c2 (Mr), Per1, Ttpa. INSULIN: Akt2, G6Pase, Igf1r, Insr, Irs1, Irs2, Pik3cb, Pik3r1, Srebp1c. CORT113176 decreased the expression of all baseline hepatic insulin receptor mRNAs in both sexes, except for G6Pase. Pik3r1 mRNA expression significantly decreased with 60 minutes of normoxic separation (fasting) in males and females compared to baseline and hypoxic separation; this was blocked by CORT113176. In the GC receptor sensitive panel, CORT113176 decreased basal Nr3c1 (Gr) mRNA. Normoxic and hypoxic separation increased Per1 and Gilz mRNA expression; this effect was blocked by CORT113176. Interestingly, Fkbp5 expression, a proposed clinical marker for GR antagonism, was not altered by CORT113176. The hepatic GC and insulin receptor sensitive gene mRNA panels we developed are sensitive to GR antagonism suggesting they may be a useful addition to Fkbp5. The increase in endogenous corticosterone, acting via GR, is critical in the hepatic response to stress in our neonatal rat model of hypoxia and prematurity.

scholarly journals SUN-214 A Novel Glucocorticoid Receptor Antagonist (CORT113176) Reveals Unique Developmental and Tissue-Specific Effects in a Neonatal Rat Model of Human Prematurity

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Kyle D Welhouse ◽  
Ashley Gehrand ◽  
Jonathan Phillips ◽  
Hana Siddiqui ◽  
Matthew Schulgit ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Rat Model ◽  
Premature Birth ◽  
Neonatal Rat ◽  
Whole Body ◽  
Target Tissue ◽  
Plasma Acth ◽  
Corticosteroid Administration ◽  
Tissue Specific ◽  
Neonatal Rat Model

Abstract Premature birth is a major public health problem worldwide and can lead to transient adrenal insufficiency1,2. The stress of premature birth includes the inability to control blood glucose and maintain normal oxygenation leading to hypoxia3. Corticosteroid administration enhances surfactant production and improves oxygenation in preterm humans. However, corticosteroids can also have negative consequences4,5. We have validated a rat model of separation and hypoxia on post-natal day (PD) 2 that emulates the stress and treatment of hypoxia in the preterm human infant6,7. We hypothesized that the role of endogenous glucocorticoids in our neonatal rat model of preterm birth can be evaluated using the novel selective glucocorticoid receptor (GR) antagonist CORT113176 (Corcept) which is devoid of progesterone receptor effects8. Pups (PD 2, 8, or 15; N=6–8 per treatment/timepoint) were given CORT113176 (60 mg/kg IP) or vehicle, then placed into chambers in room air with mild warming to prevent hypothermia due to maternal separation. 60 min later, one group of pups was euthanized and trunk blood collected (baseline). The remaining pups were exposed to hypoxia (8% O2) or normoxia (time control) for 30 or 60 min at which times trunk blood was collected for the measurement of plasma glucose, insulin, ACTH, and corticosterone. Plasma ACTH, corticosterone, and insulin were measured by immunoassay. Glucose was measured by glucose oxidase method and insulin sensitivity calculated (HOMA-IR). Organs were frozen (brain, pituitary, adrenal glands, kidney, liver, muscle, fat) for future assessment of tissue-specific glucocorticoid-sensitive gene expression. In PD2 rats, basal and hypoxia-stimulated plasma ACTH and corticosterone were lower and basal HOMA-IR greater with CORT113176 pretreatment suggesting (unexpectedly) glucocorticoid agonist activity. In PD8 and PD15 rats, basal and hypoxia-stimulated plasma ACTH and corticosterone were augmented after CORT113176 pretreatment demonstrating classic antagonist activity. However, in PD8 rats, CORT113176 effects were tissue-specific acting as a classic antagonist on the HPA-axis, but as an agonist on whole-body insulin resistance. The differential effects of CORT113176 based on age and target tissue indicate that GR regulation changes in early development in our animal model of human prematurity. These findings may have significant implications in the treatment of hypoxia and transient adrenal insufficiency in the preterm infant1,2 as well as give insight into the nuances of the control of glucocorticoid receptor function. 1Lancet 392:1923–1994, 2018 2Curr Opin Endocrinol Diabetes Obes 17:8–12, 2010 3Compr Ther 13:14–19, 1987 4Int Immunopharmacol 66:242–250, 2019 5J Neuroendocrinol 27:468–480, 2015 6Am J Physiol 300:R708-715, 2011 7Am J Physiol 302:R627-R633, 2012 8Med Chem Lett 25:5720−5725, 2015

Insulin action and resistance in obesity and noninsulin-dependent type II diabetes mellitus

1982 ◽  
Vol 243 (1) ◽  
pp. E15-E30 ◽  
Author(s):  
J. M. Olefsky ◽  
O. G. Kolterman ◽  
J. A. Scarlett
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Insulin Receptor ◽  
Insulin Action ◽  
Insulin Receptors ◽  
Tissue Level ◽  
Dependent Diabetes Mellitus ◽  
Target Tissue ◽  
Severe Insulin Resistance ◽  
Glucose Clamp Technique

Resistance to the action of insulin can result from a variety of causes, including the formation of abnormal insulin or proinsulin molecules, the presence of circulating antagonists to insulin or the insulin receptor, or defects in insulin action at the target tissue level. Defects of the latter type are characteristic of obesity and of noninsulin-dependent diabetes mellitus. Analysis of the nature of the insulin resistance in those disorders has been investigated in intact subjects with the use of the euglycemic glucose clamp technique, and both insulin receptors and insulin-mediated glucose metabolism have been studied in adipocytes and monocytes from affected individuals. In both conditions, the cause of insulin resistance is heterogeneous. In some, insulin resistance appears to be due to a defect in the insulin receptor, whereas others have a defect both in the receptor and at the postreceptor level. In both groups, more severe insulin resistance is due to the postreceptor lesion and is correctable with appropriate therapy.

scholarly journals A high-carbohydrate diet in the immediate postnatal life of rats induces adaptations predisposing to adult-onset obesity

2008 ◽  
Vol 197 (3) ◽  
pp. 565-574 ◽  
Author(s):  
Malathi Srinivasan ◽  
Paul Mitrani ◽  
Gigani Sadhanandan ◽  
Catherine Dodds ◽  
Suhad Shbeir-ElDika ◽  
...  
Keyword(s):  
Body Weight ◽  
Insulin Receptor ◽  
Neonatal Rat ◽  
Melanocortin Receptor ◽  
Milk Formula ◽  
Postnatal Life ◽  
Mrna Levels ◽  
Adult Onset ◽  
High Carbohydrate ◽  
Rat Pups

Newborn rat pups artificially raised on a high-carbohydrate (HC) milk formula are chronically hyperinsulinemic and develop adult-onset obesity. As HC rats display aberrations in body weight regulation, hypothalamic adaptations predisposing to obesity have been investigated in this study. The artificial rearing of neonatal rat pups on the HC milk formula resulted in significant increases in the mRNA levels of neuropeptide Y, agouti-related polypeptide, and galanin in the hypothalamus of 12-day-old HC rats. Simultaneously, decreases in the mRNA levels of POMC, melanocortin receptor-4, cocaine- and amphetamine-regulated transcript, and corticotrophin-releasing factor were observed in the hypothalamus of these rats. These changes persisted in 100-day-old HC rats despite weaning onto a rodent diet on postnatal day 24. Marked hyperphagia and increased body weight gain were observed in the post-weaning period. The mRNA levels and protein content of insulin receptor β (IR-β) and leptin receptor (long form) showed significant decreases in the hypothalamus of both 12- and 100-day-old HC rats. Further investigation of insulin signaling in the hypothalamus of HC rats indicated significant decreases in the proximal signaling components (insulin receptor substrate proteins 1 and 2 and phosphotidylinositol 3-kinase) in 100-day-old HC rats. These results suggest that hypothalamic neuropeptides respond to the increased carbohydrate availability with associated hormonal alterations during the period of dietary modulation and that these adaptations by persisting in the post-weaning period predispose the HC rats for adult-onset obesity.

scholarly journals Aldosterone Inhibits Insulin-Induced Glucose Uptake by Degradation of Insulin Receptor Substrate (IRS) 1 and IRS2 via a Reactive Oxygen Species-Mediated Pathway in 3T3-L1 Adipocytes

Endocrinology ◽  
2008 ◽  
Vol 150 (4) ◽  
pp. 1662-1669 ◽  
Author(s):  
Tsutomu Wada ◽  
Satoshi Ohshima ◽  
Eriko Fujisawa ◽  
Daisuke Koya ◽  
Hiroshi Tsuneki ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Reactive Oxygen Species ◽  
Glucocorticoid Receptor ◽  
Insulin Receptor ◽  
Receptor Antagonist ◽  
Glucose Uptake ◽  
Reactive Oxygen ◽  
Insulin Receptor Substrate ◽  
Oxygen Species ◽  
Metabolic Signaling

Serum aldosterone level is clinically known to correlate with body weight and insulin resistance. Because the underlying molecular mechanism is largely unknown, we examined the effect of aldosterone on insulin-induced metabolic signaling leading to glucose uptake in 3T3-L1 adipocytes. Aldosterone reduced the amounts of insulin receptor substrate (IRS) 1 and IRS2 in a time- and dose-dependent manner. As a result, insulin-induced phosphorylation of Akt-1 and -2, and subsequent uptake of 2-deoxyglucose were decreased. Degradation of IRSs was effectively prevented by a glucocorticoid receptor antagonist and antioxidant N-acetylcysteine, but not by a mineralocorticoid receptor antagonist. Because aldosterone induced phosphorylation of IRS1 at Ser307, responsible kinases were investigated, and we revealed that rapamycin and BMS345541, but neither SP600125 nor calphostin C, conferred for degradation of IRSs. Although lactacystin prevented the degradation of IRSs, glucose uptake was not preserved. Importantly, sucrose-gradient-sediment intracellular fraction analysis revealed that lactacystin did not effectively restore the reduction of IRS1 in the low-density microsome fraction, important for the transduction of insulin’s metabolic signaling. These results indicate that aldosterone deteriorates metabolic action of insulin by facilitating the degradation of IRS1 and IRS2 via glucocorticoid receptor-mediated production of reactive oxygen species, and activation of IκB Kinase β and target of rapamycin complex 1. Thus, aldosterone appears to be a novel key factor in the development of insulin resistance in visceral obesity.

Adrenocorticotropic hormone and corticosterone responses to acute hypoxia in the neonatal rat: effects of body temperature maintenance

2011 ◽  
Vol 300 (3) ◽  
pp. R708-R715 ◽  
Author(s):  
Eric D. Bruder ◽  
Kimberli J. Kamer ◽  
Mitchell A. Guenther ◽  
Hershel Raff
Keyword(s):  
Stress Response ◽  
Body Temperature ◽  
Acute Hypoxia ◽  
Plasma Corticosterone ◽  
Neonatal Rat ◽  
Plasma Acth ◽  
Neonatal Hypoxia ◽  
Rat Pups ◽  
Expression Of Genes ◽  
Corticosterone Response

The corticosterone response to acute hypoxia in neonatal rats develops in the 1st wk of life, with a shift from ACTH independence to ACTH dependence. Acute hypoxia also leads to hypothermia, which may be protective. There is little information about the endocrine effects of body temperature maintenance during periods of neonatal hypoxia. We hypothesized that prevention of hypothermia during neonatal hypoxia would augment the adrenocortical stress response. Rat pups separated from their dams were studied at postnatal days 2 and 8 ( PD2 and PD8). In one group of pups, body temperature was allowed to spontaneously decrease during a 30-min prehypoxia period. Pups were then exposed to 8% O2 for 3 h and allowed to become spontaneously hypothermic or externally warmed (via servo-controlled heat) to maintain isothermia. In another group, external warming was used to maintain isothermia during the prehypoxia period, and then hypoxia with or without isothermia was applied. Plasma ACTH and corticosterone and mRNA expression of genes for upstream proteins involved in the steroidogenic pathway were measured. Maintenance of isothermia during the prehypoxia period increased baseline plasma ACTH at both ages. Hypothermic hypoxia caused an increase in plasma corticosterone; this response was augmented by isothermia at PD2, when the response was ACTH-independent, and at PD8, when the response was ACTH-dependent. In PD8 rats, isothermia also augmented the plasma ACTH response to hypoxia. We conclude that maintenance of isothermia augments the adrenocortical response to acute hypoxia in the neonate. Prevention of hypothermia may increase the stress response during neonatal hypoxia, becoming more pronounced with increased age.

scholarly journals Differential gene expression of insulin receptor isoforms A and B and insulin receptor substrates 1, 2 and 3 in rat tissues: modulation by aging and differentiation in rat adipose tissue

2005 ◽  
Vol 34 (1) ◽  
pp. 153-161 ◽  
Author(s):  
R Serrano ◽  
M Villar ◽  
C Martínez ◽  
J M Carrascosa ◽  
N Gallardo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Insulin Resistance ◽  
Adipose Tissue ◽  
Insulin Receptor ◽  
Differential Gene Expression ◽  
Target Tissue ◽  
Insulin Receptor Isoforms ◽  
Alternatively Spliced ◽  
Differential Gene ◽  
Exon 11

The insulin receptor (IR) occurs as two alternatively spliced isoforms, IR-A (exon 11−) and IR-B (exon 11+), which exhibit functional differences and are expressed in a tissue-specific manner. The IR substrate (IRS) proteins 1, 2 and 3 also differ in function and tissue distribution. Here we show the differential gene expression of IRs and IRSs in several rat target tissues of insulin action. IR-B is significantly higher than IR-A in epididymal white adipose tissue and adipogenesis induces a shift in the alternatively spliced species of IR from the A to the B isoform. Moreover, since aging in the rat is associated with the development of insulin resistance we looked for alterations of expression of these proteins in adipocytes from old rats. Our results reveal that there is a specific decrease in the expression of the IR-B isoform, as well as both mRNA and protein levels of IR, IRS-1 and IRS-3 being significantly decreased, in epididymal adipose tissue from old compared with adult rats. It is concluded that the down-regulation of early components of the insulin transduction pathway in a primary insulin target tissue could be related to the insulin resistance of aging.

scholarly journals Rotavirus Viremia and Extraintestinal Viral Infection in the Neonatal Rat Model

2006 ◽  
Vol 80 (10) ◽  
pp. 4820-4832 ◽  
Author(s):  
Sue E. Crawford ◽  
Dinesh G. Patel ◽  
Elly Cheng ◽  
Zuzana Berkova ◽  
Joseph M. Hyser ◽  
...  
Keyword(s):  
Rat Model ◽  
Specific Antigen ◽  
Portal Tract ◽  
Neonatal Rat ◽  
Enzyme Linked Immunosorbent Assay ◽  
Rotavirus Infection ◽  
Multiple Organs ◽  
Rat Pups ◽  
Residual Blood ◽  
Neonatal Rat Model

ABSTRACT Rotaviruses infect mature, differentiated enterocytes of the small intestine and, by an unknown mechanism, escape the gastrointestinal tract and cause viremia. The neonatal rat model of rotavirus infection was used to determine the kinetics of viremia, spread, and pathology of rotavirus in extraintestinal organs. Five-day-old rat pups were inoculated intragastrically with an animal (RRV) or human (HAL1166) rotavirus or phosphate-buffered saline. Blood was collected from a subset of rat pups, and following perfusion to remove residual blood, organs were removed and homogenized to analyze rotavirus-specific antigen by enzyme-linked immunosorbent assay and infectious rotavirus by fluorescent focus assay or fixed in formalin for histology and immunohistochemistry. Viremia was detected following rotavirus infection with RRV and HAL1166. The RRV 50% antigenemia dose was 1.8 × 103 PFU, and the 50% diarrhea dose was 7.7 × 105 PFU, indicating that infection and viremia occurred in the absence of diarrhea and that detecting rotavirus antigen in the blood was a more sensitive measure of infection than diarrhea. Rotavirus antigens and infectious virus were detected in multiple organs (stomach, intestines, liver, lungs, spleen, kidneys, pancreas, thymus, and bladder). Histopathological changes due to rotavirus infection included acute inflammation of the portal tract and bile duct, microsteatosis, necrosis, and inflammatory cell infiltrates in the parenchymas of the liver and lungs. Colocalization of structural and nonstructural proteins with histopathology in the liver and lungs indicated that the histological changes observed were due to rotavirus infection and replication. Replicating rotavirus was also detected in macrophages in the lungs and blood vessels, indicating a possible mechanism of rotavirus dissemination. Extraintestinal infectious rotavirus, but not diarrhea, was observed in the presence of passively or actively acquired rotavirus-specific antibody. These findings alter the previously accepted concept of rotavirus pathogenesis to include not only gastroenteritis but also viremia, and they indicate that rotavirus could cause a broad array of systemic diseases in a number of different organs.

Adrenocortical sensitivity to ACTH in neonatal rats: correlation of corticosterone responses and adrenal cAMP content

2014 ◽  
Vol 307 (3) ◽  
pp. R347-R353 ◽  
Author(s):  
Jonathan Bodager ◽  
Thomas Gessert ◽  
Eric D. Bruder ◽  
Ashley Gehrand ◽  
Hershel Raff
Keyword(s):  
Plasma Corticosterone ◽  
Neonatal Rat ◽  
Neonatal Rats ◽  
Plasma Acth ◽  
Camp Content ◽  
Rat Pups ◽  
Adrenal Steroidogenesis ◽  
Corticosterone Response ◽  
High Doses ◽  
Corticosterone Release

A coordinated hypothalamic-pituitary-adrenal axis response is important for the survival of newborns during stress. We have previously shown that prior to postnatal day (PD) 5, neonatal rats exposed to hypoxia (one of the most common stressors effecting premature neonates) exhibit a large corticosterone response with a minimal increase in immunoassayable plasma ACTH and without a detectable increase in adrenal cAMP content (the critical second messenger). To explore the phenomenon of ACTH-stimulated steroidogenesis in the neonate, we investigated the adrenal response to exogenous ACTH in the normoxic neonatal rat. Rat pups at PD2 and PD8 were injected intraperitoneally with porcine ACTH at low, moderate, or high doses (1, 4, or 20 μg/kg body wt). Trunk blood and whole adrenal glands were collected at baseline (before injection) and 15, 30, or 60 min after the injection. ACTH stimulated corticosterone release in PD2 and PD8 pups. In PD2 pups, plasma corticosterone at baseline and during the response to ACTH injection was greater than values measured in PD8 pups, despite lower adrenal cAMP content in PD2 pups. Specifically, the low and moderate physiological ACTH doses produced a large corticosterone response in PD2 pups without a change in adrenal cAMP content. At extremely high, pharmacological levels of plasma ACTH in PD2 pups (exceeding 3,000 pg/ml), an increase in adrenal cAMP was measured. We conclude that physiological increases in plasma ACTH may stimulate adrenal steroidogenesis in PD2 pups through a non-cAMP-mediated pathway.

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