bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucocorticoid Receptor Beta Enhances Myoblast Proliferation and Myotube Formation, and Reduces Dexamethasone‐Induced Atrogene Expression
Authors: Marino Joseph S. , Peck Bailey , Sheck Evan , Stroup Steven , Hinson Jennifer , Arthur Susan , Hinds Terry D. 
Published: November 2023

BackgroundChronic elevations in glucocorticoids from endogenous production or exogenously due to disease treatment, cause skeletal muscle proteolysis and loss of muscle mass. The alpha isoform of the glucocorticoid receptor (GRα) but not the beta isoform (GRβ), has a glucocorticoid binding domain, implicating GRα as the mediator of glucocorticoid‐induced proteolysis. Because GRβ is known to cause glucocorticoid resistance, targeting GRβ may be beneficial in impairing muscle loss as a result of GRα activity. To date, there is a significant lack of research on the role of GRβ in the regulation of glucocorticoid‐induced skeletal muscle atrophy.PurposeThe purpose of this study was to determine how the overexpression of GRβ affects myotube formation and the responsiveness of atrogenes to dexamethasone.MethodsMouse GRβ cDNA was overexpressed in C2C12 mouse myoblasts using lentivirus. Changes in cell proliferation were quantified using an MTT assay. Myosin heavy chain staining of day 4 myotubes was used to quantify the effects of GRβ overexpression on indices of myotube formation. Real‐time PCR was used to investigate changes in mRNA expression of glucocorticoid responsive genes and western blot was used to quantify changes in protein expression in response to GRβ overexpression.ResultsGRβ protein expression in C2C12 mouse myoblasts was unaffected by dexamethasone, however, increased in response to insulin. Lentiviral‐mediated GRβ overexpression increased mRNA levels of MyoD and myogenin in confluent myoblast cultures. Furthermore, GRβ overexpression led to an enhanced proliferation of myoblasts associated with reduced mRNA levels of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Following four days of differentiation, GRβ overexpressing myotubes had increased total number of nuclei within myotubes, nuclei per myotube, the number of myotubes, and a greater fusion index. Lastly, when treated with dexamethasone for 24 hours, GRβ overexpressing myotubes had a blunted MAFbx and MuRF1 atrogene response.ConclusionsOverexpression of GRβ in skeletal muscle may reduce the catabolic effects of glucocorticoids on skeletal muscle by reducing atrogene responsiveness, primarily causing a state of glucocorticoid resistance. Increasing GRβ levels may stabilize muscle mass and preserve metabolic and physical function during exposure to high doses of glucocorticoids. Future work is warranted to determine the effects of GRβ overexpression in vivo in response to physical, social, and pharmacological models of glucocorticoid excess.
Energy sensing pathways differentially regulate peroxisomes in skeletal muscle vs. liver
Authors: Fuller Scott E. , Worsham Emily A. , Simon Jacob , Gettys Thomas W. , Mynatt Randall L. , Noland Robert C. 
Published: November 2023

Peroxisomes in skeletal muscle have the potential to combat lipid‐induced insulin resistance by providing an alternate route for lipid disposal which could reduce buildup of lipotoxic species while concomitantly limiting mitochondrial lipid overload. While much is known about regulation of peroxisomes in liver, there is limited information defining regulation of peroxisomes in skeletal muscle. These studies were designed to gain an understanding of peroxisomal regulation in skeletal muscle. Results indicate peroxisomes in rodent skeletal muscle were virtually unresponsive to ‘traditional’ stimuli that induce peroxisome proliferation in liver, such as peroxisome proliferator‐activated receptor (PPAR) agonists and lipid exposure. Alternatively, peroxisomal markers increased in skeletal muscle in response to dietary methionine restriction and caloric restriction. Interestingly, this response was specific to skeletal muscle as peroxisomal markers in the liver were decreased in response to these dietary manipulations. Since many beneficial effects incurred by caloric restriction are reported to be mediated via activation of energy sensing pathways, we further examined whether AMPK or sirtuin 1 (Sirt1) mediate tissue‐specific peroxisomal regulation. In support of this concept, pharmacological activation of AMPK (AICAR) and Sirt1 (resveratrol) enhanced peroxisomal genes in C2C12 myotubes, but decreased genes in AML‐12 hepatocytes. Initial findings point toward PGC1a as a potential downstream integration point mediating these effects in skeletal muscle. Overall, these findings support a model wherein skeletal muscle peroxisomes are uniquely responsive to energy status signals and interventions that activate these pathways, such as caloric restriction, exercise, cold exposure, etc., may mediate some of their therapeutic action via upregulation of peroxisomes in skeletal muscle.Support or Funding InformationThis work utilized the Genomics Core facilities at PBRC which is supported in part by COBRE (NIH 8 P20‐GM103528) and NORC (NIH 2P30‐DK072476) center grants from the National Institutes of Health. This research was also supported by NIH grants R01DK103860 (R.C.N.), R01DK089641 (R.L.M.), and a pilot and feasibility grant from NORC 2P30‐DK072476 (R.C.N.). Also, S.E.F. is supported by T32 fellowship NIH T32 AT004094.
Increase in perceived stress distinguishes severity of menstrual disruption in young women in response to a 3 month diet and exercise intervention
Authors: Williams Nancy I. , Lieberman Jay , De Souza Mary Jane 
Published: November 2023

Low energy availability and psychosocial stress can independently and in combination disrupt reproductive function in mammalian species. However, prospective studies demonstrating both of these effects in humans are rare. We previously showed a causal link between low energy availability and the total number of induced menstrual disturbances (luteal phase defects, oligomenorrhea, and anovulation) in previously sedentary women in response to a 3 month diet and exercise intervention. In the current analysis we tested whether changes in perceived stress (Cohen, 1983) also contributed to the observed menstrual disturbances. Forty previously sedentary women age 18–24 yrs, BMI 51–69 kg/m2, gynecological age 4–15 yrs completed approximately 3 months of a diet and exercise protocol where original group assignment was to either a group that maintained energy balance or one of four groups at varying combinations of diet and exercise manipulated to create low to severe energy deficiency. All subjects ovulated during the baseline cycle prior to the onset of 3 months of supervised exercise (5X per week, moderate to vigorous aerobic exercise 20–75 min) and controlled feeding. Menstrual disturbances were assessed using daily urinary measures of estrone‐1‐glucuronide, pregnanediol glucuronide, and mid‐cycle luteinizing hormone in addition to menstrual calendars. The intervention produced modest weight loss (0–4 kg) and expected increases in body composition and aerobic fitness. As previously reported, the magnitude of the energy deficit predicted the frequency but not the severity of menstrual disturbances such that the greater the energy deficit the greater the sum of all types of menstrual disturbances observed during the three month intervention. In the present analysis, subjects were divided into those who experienced a) no disturbances (NONE; n=14), b) either luteal phase defects and or oligomenorrheic cycles (36 days or greater)(LUT_OLIGO; n=13) or c) at least one anovulatory cycle (ANOV; n=10). The change from baseline to post study in perceived stress was significantly greater in ANOV vs. NONE and LUT_OLIGO: 10.1±3.6, 1.7± 1.7, −0.33± 1.9, respectively (P<0.05; ANOVA and post hoc LSD). All ANOV subjects also experienced either a luteal phase defect or an oligomenorrheic cycle during the intervention, and a higher proportion exhibited either a luteal phase defect or oligomenorrheic cycle at Baseline when compared to NONE and LUT_OLIGO (P<0.05; ANOV and post hoc LSD). These results suggest that increases in perceived stress may contribute to anovulation in the context of an exercise training program that is accompanied by weight loss.Support or Funding InformationNational Institutes of Health Grants RO1‐HD‐39245‐01 (N. I. Williams) and M01‐RR‐10732
Androgen receptor knockout in ovarian theca cells results in altered steroidogenesis in diestrous female mice
Authors: Tram Meilinn , Andrisse Stanley , Wolfe Andrew , Wu Sheng 
Published: November 2023

Approximately one out of ten women experience polycystic ovarian syndrome (PCOS). PCOS women exhibit hyperandrogenemia, oligo‐ or anovulation, and polycystic ovarian follicles. Females who exhibit elevated androgen levels have been shown to have reproductive abnormalities. However, it is unknown which target organs are impacted by elevated androgen levels. This study aims to determine the role of androgen receptors (AR) on steroidogenesis and the reproduction of female mice in ovarian theca cells. We utilized a cre‐lox model system to produce ovarian theca cell‐specific androgen receptor knockout (ThARKO) mice. ThARKO mice have dramatically reduced AR expression levels as assessed by both immunocytochemistry and real‐time qPCR. We also investigated age at puberty by assessing the age at vaginal opening and first estrus. There was no difference in the age at vaginal opening between control and ThARKO mice. There was also no significant difference in estrous cyclicity assessed by vaginal cytology. Ovaries of control and ThARKO mice were collected at diestrus and ovarian gene expression was compared in 2 month old mice. During diestrus, we observed an increased mRNA expression of cyp17 compared to control littermates. Cyp17 is the rate limiting step of androgen synthesis. Although fertility was not altered, the AR in theca cells may play a role in steroidogenesis.Support or Funding InformationR00 DH056139, P60 DK079637, R01 HD068777
Differential Effects of Menopausal Hormone Formulations on Plasma Orexin A levels in Women of the Kronos Early Estrogen Prevention Study
Authors: Cintron Dahima , Beckman John , Muthuvel Jayandran , Miller Virginia 
Published: November 2023

Orexin A (OxA) is a hypothalamic neuropeptide involved in regulation of feeding behavior, metabolism, sleep‐wakefulness and emotion. Plasma levels of this peptide increase with age in both men and women. However, little is known about changes in circulating OxA levels during age‐associated, sex‐ specific hormonal changes, such as menopause, or the effect of menopausal hormone therapy (MHT) on OxA levels. No studies have assessed changes of OxA levels after discontinuation of MHT. The objective of this study was to assess plasma OxA during and three years after cessation of either oral conjugated equine estrogen (o‐CEE, n = 17), transdermal 17β‐estradiol (t‐E2; n= 20), or placebo pills and patches (n = 22) in healthy recently menopausal women (> 6 months < 3 years from their menses) who participated in the Kronos Early Estrogen Prevention Study. The plasma OxA was measured by enzyme‐linked immune absorbent assay prior to randomization to treatment (Baseline) and at 12 months, 24 months, 36 months, 48 months after randomization and at 36 months after cessation of study MHT. Data are presented as median with 25th and 75th percentile. Baseline plasma levels of OxA did not differ among groups (o‐CEE: 3.02 (2.2–4.4) ng/mL, t‐E2=4.09 (3.6–4.5) ng/mL, Placebo= 3.15 (2.5–6.2) ng/mL. During MHT treatment, women randomized to o‐CEE had higher OxA levels when compared to their baseline values at 24, 36 and 48 months of exposure (4.4 ng/mL (2.5–6.3), 4.1 ng/mL(2.5–7.3), 4.2 ng/mL(3.1–6.5), respectively). Changes of OxA levels in the t‐E2 and placebo groups were variable and did not show a consistent trend over the MHT treatment period. Three years after cessation of MHT, only the o‐CEE group showed significantly higher Ox A levels than during the treatment phase of the trial (treatment 3 year discontinuation median – 48 month treatment median =1.369 ng/mL). Our study suggests that the formulation of MHT, in particular o‐CEE (contain metabolites of estrogen) increases plasma OxA. This is the first study to assess Ox A levels for a period of more than 6 months under MHT and after years of discontinuation. If plasma levels of OxA reflect those in the brain, these results may explain in part the beneficial effects of o‐CEE on mood and other menopausal symptoms in women of KEEPS. An increase in OxA driven by o‐CEE could be a mechanism by which MHT helps women regulate energy metabolism and emotional behavior responses.Support or Funding InformationThis project was supported by the Mayo Clinic Office of Health Disparities Research and NIH AG 44170. In addition DC was supported by the CTSA Grant Number TL1 TR000137 from the National Center for Advancing Translational Science, a component of the National Institutes of Health.
Electrophysiological Properties of TRPV1‐Expressing Neurons in the Paraventricular Nucleus of the Hypothalamus
Authors: Butcher Sierra Morgan , Miyata Kayoko , Anwar Imran John , Zsombok Andrea 
Published: November 2023

Whole body glucose homeostasis is regulated throughperipheral and central mechanisms, and transient receptor potential vanilloidtype 1 (TRPV1) has been shown to play a role in modulation of glucosehomeostasis. Previously, our datarevealed that liver‐related neurons in the paraventricular nucleus (PVN) of thehypothalamus are regulated by TRPV1‐dependent excitatory neurotransmission, which was diminished in diabetic condition. In this study, a reporter mousemodel was established (TRPV1TdTomato) to identify the location, determinethe cellular properties, and phenotype of TRPV1‐expressing cells. Within the hypothalamus, TRPV1TdTomato cellswere observed in the PVN, dorsomedial, and lateral hypothalamus. Whole‐cell patch‐clamp electrophysiology wasused to establish the cellular properties of TRPV1TdTomato neuronsin the PVN. The average frequency of spontaneousexcitatory postsynaptic currents (sEPSCs) was 2.38 ± 0.6 Hz, with an averageamplitude of 15.83 ± 1.8 pA (n=15). Frequency of miniature EPSCs (mEPSCs) averaged 1.79 ± 0.4 Hz, with an amplitude of 15.66 ± 2.7 pA (n=12). The frequency of spontaneous inhibitory postsynaptic currents (sIPSCs)was 2.37 ± 0.6 Hz, while the average amplitude was 37.61 ± 5.2 pA (n=12). The average frequency of miniature IPSCs (mIPSCs)was 1.44 ± 0.4 Hz, with an amplitude of 31.92 ± 4.6 pA (n=9). The frequency and amplitude of EPSCs andIPSCs recorded from TRPV1TdTomato PVN neurons were similar to thosepreviously recorded from liver‐related and kidney‐related PVN neurons. TRPV1TdTomato neurons fired actionpotentials spontaneously, the firing rate was 1.50 ± 0.44 Hz (n=6) and theinput resistance was 2.06 ± 0.66 GΩ. To determine the phenotype of TRPV1TdTomatoneurons, immunostaining for neuronal cell type markers and an astrocyte marker wasperformed. Our data did not reveal co‐localization with vasopressin, oxytocin, orthe astrocyte marker, suggesting that TRPV1TdTomato cells are notmagnocellular neurons or astrocytes. Insummary, the TRPV1TdTomato mouse model is a useful tool to study therole of TRPV1 in autonomic control; however, further studies are necessary todetermine their phenotype and cellular properties in control and diabeticconditions.Support or Funding InformationNational Institutes of Health (R01 DK099598 for AZ)
Effects of the Neurointermediate Pituitary Lobectomy (NIL) on Pituitary Hormones Blood Level in the Rat
Authors: Organista‐Esparza Alejandro , Viñuela‐Berni Verónica , Tinajero‐Ruelas Manuel , Valdez‐Urias Fernando , Kovacs Kalman , Berczi Istvan , Quintanar‐Stephano Andrés 
Published: November 2023

The characterization of the functional state of the NIL animals is important to know all the possible physiological implications of the permanent deficiency of the hormones arginine vasopressin (AVP) and oxytocin (OT). In order to obtain knowledge of the unknown relationships of the effects of NIL on pituitary hormones blood level (GH, PRL, ACTH, TSH, LH, AVP and OT), as well as on urine production, water intake and body weight, groups of Intact Control (IC) and NIL male Wistar rats were compared at 3 and 8 weeks post‐surgery. Hormone levels were assessed by ELISA kits.ResultsNIL caused a transient diabetes insipidus; urine production and water intake returned to normal values between 2 to 4 weeks post‐NIL. AVP and OT serum levels in NIL rats were significantly decreased in 80% and 90% at 3 and 8 weeks post‐surgery. GH and TSH, were significantly decreased at 3 but not at 8 weeks post‐NIL. PRL and ACTH serum levels remained unchanged in both times. Final body weights of NIL animals were 20% less than the IC.ConclusionsNIL animals are a good experimental paradigm to study the protracted effects of AVP and OT deficiency. It is possible that the decreased GH serum levels NIL‐induced, caused the less gain of body weight of these animals.Support or Funding InformationSupported by CONACYT‐221262. México (AQS)
A Novel Hypothalamic Action of Adropin: Regulation of Fluid Homeostasis
Authors: Stein Lauren Michelle , Yosten Gina , Samson Willis 
Published: November 2023

Adropin, a recently described endogenous peptide encoded by the Energy Homeostasis Associated (Enho) gene, has been reported to be abundantly produced in the liver, smooth muscle and brain. While clinical and transgenic studies have identified adropin as a potent peripheral regulator of energy homeostasis, little is known about its action within the CNS. Therefore, the purpose of our study was to investigate a potential hypothalamic site of action to regulate ingestive behaviors. Male Sprague‐Dawley rats (200–250g) bearing an indwelling cannula in the right lateral ventricle were placed in metabolic cages with free access to lab chow and water (lights out 1800–0600h). During a two‐day habituation period, body weight and ad libitum water and food intakes were recorded. On the day of the experiment, rats were given a 2μl i.c.v. injection of vehicle or vehicle containing 0.3nmol, 1nmol, or 3nmol adropin at 1730h. Cumulative water and food intake was recorded in 30‐minute intervals until 1930h and again the next day at 0800h. While exogenous adropin had only a modest effect on food intake, we observed a profound inhibitory action on anticipatory water intake. Furthermore, after overnight water deprivation male rats administered 3nmol adropin i.c.v. exhibited significantly reduced water intake compared to vehicle treated controls. Importantly, using a deductive ligand receptor matching strategy (AJP 303:R941, 2012) we have identified a putative receptor for adropin. To demonstrate a functional relationship between our candidate receptor and adropin, rats were pretreated with i.c.v. injections of siRNA targeted against either eGFP as a control or our candidate receptor, followed by overnight dehydration and treatment with 3nmol adropin i.c.v. Cumulative water intake was recorded over the next four hours. Compromise of the endogenous candidate receptor significantly abrogated the adropin‐induced inhibition in dehydration‐stimulated water intake. Not only are these studies the first to demonstrate physiologic relevance of adropin as a central regulator of fluid homeostasis, but they provide compelling evidence that the adropin receptor is a formerly orphaned, G protein‐coupled receptor.Support or Funding InformationNIH RO1 HL121456
Identification of cell surface receptors for the novel adipokine CTRP3
Authors: Peterson Jonathan M 
Published: November 2023

C1q TNF Related Protein 3 (CTRP3) is a member of a family of secreted proteins that exert a multitude of biological effects throughout the body. Our initial work shows promise in the development of CTRP3‐induced cellular processes as a means to combat nonalcoholic fatty liver disease (NAFLD). Clinically, NAFLD is defined as the excessive accumulation of fat in the liver, usually due to obesity, and NAFLD effects 1 in 10 Americans. Our previous data show that when high fat fed mice are treated with CTRP3 they are protected from developing NAFLD. However, the mechanism for this effect remains unclear. The purpose of this project was to identify the unknown receptor that mediates the hepatic actions of CTRP3.METHODSWe used Ligand‐receptor glycocapture technology with TriCEPS™‐based ligand‐receptor capture (LRC‐TriCEPS; Dualsystems Biotech AG). The LRC‐TriCEPS experiment with CTRP3‐FLAG protein as ligand and Insulin as the control ligand was performed on H4IIE rat hepatoma cell line. Additional analysis using siRNA induced knockdown of the identified receptors was used to validate the findings.RESULTSInitial analysis demonstrated efficient coupling of TriCEPS to CTRP3. Further, flow cytometry analysis demonstrated successful oxidation and crosslinking of CTRP3‐TriCEPS and Insulin‐TriCEPS to the cell surface glycans. In total, an enrichment of glycopeptides of 11% (261 peptides) was observed. Under these conditions, INSR (Insulin receptor) could be identified and quantified in the control dataset. For the ligand sample two unique receptors were identified. Flow cytometry analysis with siRNA induced knockdown of these proteins confirmed that the presence of the protein is needed for CTRP3 binding to occur.CONCLUSIONThe LRC‐TriCEPS methodology was successful in identifying the receptor for CTRP3.RELEVANCEThe identification of the receptors for CTRP3 and CTRP3‐induced cellular signaling pathways are important prerequisites for the development of small molecule drug candidates that exert effects beneficial to human health.Support or Funding InformationEast Tennessee State University Research Development CommitteeNational Institute On Alcohol Abuse And Alcoholism of the National Institutes of Health under Award Number R03AA023612