bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of lisinopril on the development of renal injury associated with prepubertal obesity
Authors: Pennington Alyssa Paige , McPherson Kasi , Williams Jan
Published: November 2023

Prepubertal childhood obesity has emerged as an epidemic and major health problem in the United States. Recent studies suggest that that childhood obesity is associated with increased risk of renal injury in children. Approximately 37% of obese children develop microalbuminuria. However, an understanding of the mechanisms involved in prepubertal obesity‐mediated renal disease remains unclear due to lack of an appropriate animal model. In studies characterizing the Dahl salt‐sensitive leptin receptor mutant (SSLepRmutant) rat, we observed that this model mimics several features of prepubertal obesity (PPO strain). Recently, we reported that the PPO strain displays proteinuria and podocyte injury as early as 6 weeks of age independent of hyperglycemia and elevations in arterial pressure. The standard care of treatment for children whom suffer from PPO is an angiotensin converting enzyme inhibitor (ACEi).

Objective

Therefore, in the current study, we examined whether treatment with lisinopril, an ACEi, prevents the early development of proteinuria in the PPO model.

Methods

Experiments were performed on six week‐old Control (lean) and PPO rats that were either treated with vehicle or lisinopril and measured proteinuria at 6, 8, and 10 weeks of age.

Results

At 6 weeks of age (baseline) proteinuria was significantly higher in the PPO strain versus the control rats (130±29 vs.14±3 mg/day, respectively). Treatment with lisinopril had no effect on the progression of proteinuria in control rats. However, lisinopril decreased proteinuria in PPO by 50%.

Conclusion

These data indicate that treatment with lisinopril slowed the progression of proteinuria in PPO rats and suggest that the renin‐angiotensin plays important role in the development of progression of proteinuria in this novel model of PPO.

Support or Funding Information

This work was supported by the APS STRIDE Summer Research Fellowship (1 R25 HL115473‐01) awarded to A.P. This work was also supported by an AHA SDG 12DG9440034 and by the National Institute of General Medical Sciences of the National Institutes of Health under Award number P20GM104357 awarded to J.M.W.
Impact of treadmill exercise on endothelial function during estrogen deficiency in ovariectomized db/db female mice
Authors: Song Wencong , Huang Yu
Published: November 2023

Purpose

Cardiovascular disease (CVD), obesity and diabetes are major health problem worldwide. The majority of diabetics died of cardiovascular and renal events, largely as the consequence of initial endothelial dysfunction.

Postmenopausal women with type 2 diabetes experience higher risks for cardiovascular diseases than age‐matched men and pre‐menopausal women. Current drug therapies have limited effect on the CVD prevention and they also produce side effects and drug resistance. Physical exercise is gaining a growing attention in terms of preventive measure against vasculopathy in obesity and diabetes. This study aims to investigate the possible protective effects of regular physical exercise on vascular endothelial function in ovariectomized diabetic db/db mice.

Methods and results

We created the ovariectomized (OVX) db/db mice to mimics the postmenopausal state in women with type 2 diabetes, and studied the effects of exercise on restoring of endothelial function and metabolic profile in the OVX db/db mice. Running exercise (10 m/min, 30 min/time, 3 times a week for 4 weeks) resulted in slight improvement of acetylcholine‐induced endothelium‐dependent relaxations without affecting endothelium‐independent relaxations induced by sodium nitroprusside in OVX db/db mouse aortas. Exercise also improved glucose metabolism and insulin sensitivity. qPCR analysis of mouse aortas shows that exercise increased the mRNA expression of SOD2 while it slightly reduced the mRNA of NOX4.

Conclusions

The preliminary results indicate that regular physical exercise is beneficial to increase anti‐oxidant defense, to improve endothelial function and to enhance insulin sensitivity during estrogen deficiency in OVX diabetic mice. Ongoing experiments will examine the impact of longer period of exercise and different exercise intensity on vascular function, oxidative stress and inflammation, and metabolic function in other metabolic organs such as liver and skeletal muscle.

Support or Funding Information

Research Grants Council of Hong Kong (CUHK2/CRF/12G, T12‐402/13N), National Natural Science Foundation of China (91339117)
A role for REDD1 on insulin‐stimulated signaling activation following acute treadmill exercise
Authors: Dungan Cory M , Williamson David L
Published: November 2023

The protein, regulated in development and DNA damage 1 (REDD1), has been suggested to be a required molecule for normal insulin‐stimulated signaling, as a loss of REDD1 reduces insulin signaling, potentially through hyperactive mechanistic target of rapamycin (mTOR) signaling. Aerobic exercise inhibits mTORC1 activation and improves insulin signaling protein responses to insulin. Thus, the goal of this study was to determine if an acute bout of aerobic exercise was sufficient to improve insulin signaling in mice lacking REDD1. REDD1 wildtype (WT) and REDD1 knockout (KO) mice underwent an acute bout of treadmill exercise for 30 minutes at 20m/min on a 5% grade or remained sedentary. The plantar flexor complex group was then removed from the lower limbs before or after receiving acute insulin treatment (0.5 IU/kg BW) Changes to skeletal muscle insulin (IRS‐1 Y1222, Akt S473) and mTOR (4E‐BP1 S37/46, S6K1 T389) signaling intermediates, along with markers of acute aerobic exercise (REDD1, AMPK T172, ERK1/2 T202/Y204), were determined immediately after the exercise bout, before and after IP insulin treatment (10 min). Despite no effect of insulin, aerobic exercise significantly increased (p<0.05) REDD1 expression in the WT mice versus sedentary mice. As expected, there was no observable REDD1 protein expression in the KO mice. AMPK activation was significantly elevated (p<0.05) following the acute bout of exercise in both WT and KO versus sedentary mice, though no effect of insulin was observed. Conversely, a significantly greater reduction (p<0.05) in 4E‐BP1 and S6K1 activation was observed in the exercised KO mice versus the exercised WT mice, which then contributed to significantly greater responses (p<0.05 versus exercise+insulin WT mice) to insulin by the exercised KO mice. Lastly, a significantly greater activation (p<0.05) of IRS‐1 and ERK1/2 was observed in response to insulin in the exercise+insulin KO mice versus exercise+insulin WT mice. Our data show that an acute bout of aerobic exercise is sufficient to improve insulin‐stimulated signaling in the absence of REDD1, but REDD1 is still required for a normal insulin signaling response independent of exercise.

Support or Funding Information

Mark Diamond Foundation
Cardiac chronotropic competence to beta‐adrenergic stimulation in insulin resistance
Authors: Barreto Andre Sales , Macedo Fabricio Nunes , Araujo Joao Eliakim S. , Melo Vitor Ulisses , Dantas Cacia Oliveira , de Souza Siqueira Barreto Rosana , Guimaraes Adriana Gibara , de Souza Siqueira Quintans Jullyana , Quintans‐Junior Lucindo Jose , Santos Marcio Roberto Viana , Santana‐Filho Valter Joviniano
Published: November 2023

Insulin resistance (IR) precedes clinical manifestation of diseases such as diabetes mellitus and hypertension and is associated with increased sympathetic modulation. However, in the dexamethasone‐induced IR no changes have been noted in heart rate (HR). Therefore, we evaluated the heart chronotropic competence through beta‐adrenergic agonist stimulation in dexamethasone‐induced IR. Young male rats were divided into two groups: Control (CT)(n=6) and IR (n=6). CT and IR groups received vehicle or dexamethasone (DEX) (2mg/kg/day) i.p during seven days, respectively. To confirm Insulin resistance, insulin tolerance test (ITT) was performed after 6h fasted. Left femoral artery and vein were cannulated to measure blood pressure (2 kHz sampling rate) and isoproterenol (4μg/kg) administration respectively, 24h before evaluation. IR group presented attenuated decrease in glycaemia during ITT (CT: 42.5 ± 5 vs IR: 110.7 ± 14), hypertension (CT: 100 ± 2 vs IR: 135 ± 9 mmHg) without heart rate changes. In addition, increased cardiac sympathetic modulation by spectral analysis (LF/HF ratio CT: 0.52 ± 0.03 vs IR: 0.69 ± 0.04 un). After beta‐adrenergic stimulation IR group showed lower variation from basal level (ΔHR CT: 179 ± 4 vs IR: 78 ± 5 bpm). The reduction in heart chronotropic competence observed in this IR model could be a defense mechanism due cardiac sympathetic over activity.

Support or Funding Information

Fapitec‐SE; CAPES; CNPq.
Endoplasmic reticulum stress associated with purinergic stimulation
Authors: Reyes Juan Pablo , Castillo‐Hernández Jesús Ramón , Maldonado‐Cervantes Martha Imelda , Maldonado‐Cervantes Enrique
Published: November 2023

A number of evidences suggest that P2X7 receptors (P2X7R) stimulation is related to cytotoxic events and cell death, yet not so deleterious effects may also result in cellular stress, including endoplasmic reticulum stress. Here, we describe our approach into the study of P2X7R‐induced endoplasmic reticulum stress, using P2X7R‐expressing HEK‐293 cells and Thioflavin‐T as stress indicator. We present the results in our hands so far. We are just beginning in this approach and we estimate that feedback from other researchers in the hallmark of this Meeting could be much beneficial for our purposes.

Support or Funding Information

The present work was supported by Programa para el Desarrollo Profesional Docente (PRODEP)‐Apoyo a la Incorporacion de Nuevos PTC of Secretaria de Educacion Publica (SEP) from the Mexican Government under grant DSA/103.5/16/10419 and by Fondo de Apoyo a la Investigación (FAI) under grant C16‐FAI‐09‐20.20 from Universidad Autónoma de San Luis Potosí (UASLP), Mexico
Beta‐hydroxybutyrate favorably alters muscle cell survival and mitochondrial bioenergetics
Authors: Parker Brian , Dallon Blake , Draney Carrie , Sampson MaryJane , Witt Jeffrey , Gibbs Jonathan , Tessem Jeffery S. , Bikman Benjamin T.
Published: November 2023

Research has recently revealed that endurance athletes successfully compete while in states of ketosis, where the muscle is predominantly fueled by fatty acids and ketones. With these data in mind, we sought to determine the effect of ketones on muscle cell mitochondrial physiology. Murine myotubes were incubated with b‐hydroxybutyrate (bHB), then used for analysis. bHB treatment increased muscle cell survival and proliferation, while also increasing mitochondrial mass. Importantly, and perhaps reflective of its benefit to muscle tissue performance, bHB increased ATP production over control conditions. Collectively, these findings have to two implications. First, they indicate that muscle cells thrive in the midst of bHB, the circulating form of ketones. Second, improved mitochondrial function and proliferation may be insufficient to increase muscle and whole‐body endurance performance.
Knockdown of angiopoietin‐like 2 mimics the benefits of intermittent fasting on weight loss and insulin sensitivity in mice
Authors: Pinçon Anthony , Martel Cécile , Bélanger Alexandre , Gillis Marc‐Antoine , Thorin‐Trescases Nathalie , Thorin Éric
Published: November 2023

Obesity and elevated body fat are generally associated with a higher risk of metabolic diseases such as type 2 diabetes, but the mechanisms involved are not clear. Angiopoietin‐like 2 (ANGPTL2), a circulating pro‐inflammatory glycoprotein mainly secreted by adipose tissues, is now considered as a key mediator linking obesity to insulin resistance. Accordingly, high levels of ANGPTL2 in humans are associated with obesity and the development of diabetes, and in Angptl2−/− mice exposed to a high fat diet, body fat is lower and insulin sensitivity better than in wild‐type (WT) mice. Various approaches have been developed to promote weight loss and increase insulin sensitivity such as intermittent fasting, an efficient but strenuous lifestyle intervention that involves alternating cycles of fasting and eating. Our objective was to investigate whether the knockdown of ANGPTL2 in mice reproduces or improves the benefits of intermittent fasting in WT mice on weight and insulin sensitivity. Intermittent fasting (one day of fasting/one day of free access to food) for 4 months reduced (p<0.05) Angptl2 mRNA expression by 53% in adipose tissue from WT mice. Both intermittent fasting for 4 months and knockdown of ANGPTL2 similarly decreased (p<0.05) feeding efficiency by 55%, weight gain by 55%, liver (38%) and adipose (around 55%) tissue weights and similarly increased (p<0.05) insulin sensitivity (measured by the insulin tolerance test). All measured parameters were similar between WT mice fed with an intermittent fasting regimen and ANGPTL2 knockdown mice fed ad libitum, suggesting that knockdown of ANGPTL2 reproduces the benefits of intermittent fasting on weight loss and insulin sensitivity. Finally, intermittent fasting in ANGPTL2 knockdown mice did not further reduce weight gain, adipose tissue and liver weight, and did not further improve insulin sensitivity. We therefore propose that lowering ANGPTL2 could be a useful and promising strategy to limit obesity and prevent insulin resistance. The development of pharmacological inhibitors of ANGTPL2 is needed.

Support or Funding Information

Canadian Institutes of Health Research
Identification of Novel Circadian Clock Target Genes Associated With Renal Pathophysiology
Authors: Gumz Michelle L , Solocinski Kristen , Cheng Kit‐Yan , Wu Gang , Hogenesch John , Montgomery Darrice , Alli Abdel A.
Published: November 2023

Most aspects of physiological function exhibit circadian variation. Increasing evidence supports the importance of maintaining circadian rhythms for overall health. Disrupted circadian rhythms in sleep/wake patterns and blood pressure are strongly associated with negative cardiovascular outcomes. Less is known about the consequences of circadian disruption in other tissues, such as the kidney. It is well established that renal function exhibits a circadian pattern of oscillation. Large scale transcriptomic studies have demonstrated that the molecular circadian clock acts as a master regulator of gene expression in most tissues, including the kidney. In order to better understand the importance of this regulatory mechanism for renal function, we interrogated publically available databases. The goal of this study was to identify novel circadian clock target genes known to be associated with disease processes related to the kidney. Genes identified included Heat shock protein a5 (Hspa5), associated with diabetic kidney disease, salt‐inducible kinase 1 (Sik1), associated with hypertension and diabetic kidney disease, and Endothelin‐1 (Edn1), also associated with hypertension and diabetic kidney disease. In independent kidney tissue samples collected at two distinct time points over the circadian cycle from wild type male C57BL/6 mice, we confirmed time‐dependent regulation of these genes. Hspa5 mRNA exhibited a 2.5× difference in expression between noon and midnight in the renal cortex (P<0.05). Sik1 expression varied by 25% (P<0.05) in these samples. Edn1 mRNA expression varied by ~33% (P<0.05). Because altered expression of these genes is associated with diabetic kidney disease, we also tested whether timed regulation of renal function was disrupted in diabetic mice. Split urine collections were made in order to compare urinary sodium and potassium excretion during the night (mouse active phase) versus the day (mouse inactive phase). Consistent with previous reports, control mice exhibited significant day/night differences in urinary [Na] and [K] of 1.5 to 2 fold (P<0.05). In contrast, diabetic mice did not exhibit a day/night difference in urinary [Na] and [K]. Together these data suggest that the circadian clock mechanism is critical for regulation of normal gene expression in the kidney with consequences for normal circadian renal function.

Support or Funding Information

NIH NIDDK

UF Department of Medicine, Division of Nephrology

American Society of Nephrology

UF Hypertension Center

T32 Grant # 2T32HL083810 AHA
Impaired blood pressure response in Btg2 mutant female rats
Authors: Hoffman Matthew J , Imam Sara , Schilling Rebecca , Takizawa Akiko , Grzybowski Michael , Geurts Aron , Dwinell Melinda R.
Published: November 2023

Sex‐specific blood pressure loci were previously identified on chromosome 13 using SS‐BN13 congenic rat strains. Previous work identified Btg2 as a candidate gene for salt‐sensitive hypertension in female rats. Two small congenic SS‐BN13 lines were developed that differed by 23 Kb with only Btg2 residing within this region. The strain containing BN Btg2 allele had significantly higher mean arterial pressure (MAP) (186±3.1 mmHg) than SS Btg2allele in females (151±5.8mmHg). Subsequent qRT‐PCR analysis demonstrated significant difference in Btg2 expression between these strains in kidney cortex (Btg2BN: 1.8±0.2 fold change, Btg2SS: 0.4±.01). Based on this previous data we hypothesized that mutating Btg2BN would mitigate the elevated blood pressure response we had seen in rats with the Btg2BN allele. TALEN and CRISPR/Cas9 reagents were used to target exon 1 of Btg2 and generate three mutant lines on the SS‐BN13 congenic with Btg2BN allele: m7 (TALEN) with 44bp deletion, m11 (CRISPR/Cas9) with 3bp deletion and 1bp insertion, and m13 (CRISPR/Cas9) with 16 bp deletion. Following telemetry transmitter implantation, blood pressure was measured in male and female rats on low salt and during 21 days of 8% NaCl diet. On day 17 of high salt, urine was collected for determination of protein and microalbumin. After 21 days on high salt, female homozygous m7 mutant rats MAP was 8 mmHg higher compared to female wild type littermates (167±8mmHg vs. 175±7mmHg). Urinary microalbumin and protein measurement in these female rats demonstrated a similar trend both showing a 1.4 fold increase in homozygous compared to wild type (93±18mg/day vs.131±41mg/day, 135±21mg/day vs.186±54mg/day respectively). Normalized kidney weight showed a 6% increase in female homozygous versus wildtype animals (0.0118±0.0002g/g vs.0.0125±0.0004g/g). Male homozygous and wild type m7 rats were not different after 21 days of high salt for these phenotypes. Preliminary results in the m13 mutant Btg2 rats suggest similar trends in the female vs. male rats. Taken together, our hemodynamic, urinary and morphometric data suggest the m7 mutant Btg2 allele produces an impaired blood pressure and renal response in female rats.

Support or Funding Information

Funding: The National Heart, Lung, and Blood Institute of the National Institutes of Health, R24HL114474
The RGD PhenoMiner Database and Query Tool: A Resource for Quantitative Phenotypes in the Rat
Authors: Smith Jennifer R , De Pons Jeffrey L , Laulederkind Stanley J , Hayman G Thomas , Wang Shur‐Jen , Hoffman Matthew J , Zhao Yiqing , Tutaj Marek , Ghiasvand Omid , Dwinell Melinda R , Shimoyama Mary E
Published: November 2023

Phenotype is defined as any one trait, or any group of traits, which contribute to the physical, biochemical, and physiological makeup of an individual as determined by both genetic composition and environmental influences. As such, the information needed to fully describe a measurement of a phenotype or trait should include both an indication of the genetics of the organism being assessed and information about environmental influences that might affect the measurement. The Rat Genome Database (http://rgd.mcw.edu) has developed a system to standardize and fully describe quantitative phenotype measurements using a suite of controlled vocabularies. These quantitative phenotype records, available through the PhenoMiner tool (http://rgd.mcw.edu/phenotypes/), include information on the trait being assessed (Vertebrate Trait Ontology), the exact measurement that was made (Clinical Measurement Ontology), the method used to make that measurement (Measurement Method Ontology), the condition(s) under which the measurement was made (Experimental Condition Ontology), and the sample measured—and by extension, its associated genetics—including information on rat strain (Rat Strain Ontology), number of individuals, sex and age. This structure has provided the framework to integrate more than 60,000 phenotype records, including over 17,000 cardiovascular measurements from approximately 140 different studies. PhenoMiner's flexible query wizard allows researchers to retrieve, view and download data from multiple studies, and to compare experimental values across multiple strains, methods and/or conditions, allowing investigators to choose appropriate disease models and controls among the vast number of rat strains available. Work is currently underway to utilize these data to statistically determine expected ranges for standard measurements in commonly used rat strains and to provide methods by which users can compare their own data to the expected ranges.

Support or Funding Information

The National Heart, Lung, and Blood Institute of the National Institutes of Health, Grant #R01HL064541
Loss of Arhgef11 on the Genetic Background of the Dahl Salt‐Sensitive (SS) Rat Significantly Attenuates Blood Pressure and Renal Injury
Authors: Johnson Ashley C. , Garrett Michael R
Published: November 2023

We have previously implicated genetic variants in Arhgef11, a Rho guanine nucleotide exchange factor, in kidney injury exhibited in the Dahl salt‐sensitive (SS) rat, a widely studied model of hypertension and chronic kidney disease. ARHGEF11, through the exchange of GDP for GTP, plays a central role in the activation of RhoA signaling cascades via a number of cell stimuli that can impact cytoskeletal structure and influence cell‐cell contacts and promote cell transformation. The SS form of Arhgef11 is associated with increased expression (before onset of detectable injury) as well as several SNPs are predicted to have impact on protein function (compared to kidney injury resistant SHR). The study of an SS‐Arhgef11‐minimal congenic model, which substituted the SS allele with that of the SHR, demonstrated significantly decreased proteinuria, tubulointerstitial injury/fibrosis, and improved renal hemodynamics compared to the SS. Primary proximal tubule cells cultured from the SS exhibited increased expression of Arhgef11, activation of Rho‐ROCK, and were more prone (vs. control) to epithelial‐mesenchymal transition (EMT), a driver of fibrosis. In the current study, we sought to investigate the loss of Arhgef11 on renal injury and renal function. A study comparing the SS‐WT and SS‐Arhgef11−/− animals for measures of renal injury (proteinuria) and blood pressure on low‐salt (0.3% NaCl) found that knockout animals exhibited a significant reduction in proteinuria, but no significant difference in blood pressure. On an elevated‐salt diet (2% NaCl), SS‐Arhgef11−/− animals demonstrated a significant (p<0.001) attenuation of proteinuria/renal injury (41±7.9 mg/24 hrs) and reduction in blood pressure (124±2.6 mm Hg) compared to SS‐WT (149±15.3 mg/24 hrs and 151±5.9 mm Hg). A more extensive characterization of renal injury (e.g. histological, transcriptome, etc.) and renal hemodynamics (RBF, GFR, and RVR) is being currently planned. In summary, genetic studies using several animal models, genetically modified cells, and primary cells identified a gene/pathway involved in kidney injury, which could ultimately lead to new insight into the pathophysiology CKD.

Support or Funding Information

Supported by NIH/NHLBI HL094446 and funds from University of Mississippi Medical Center
Effects of DHA on Orchidectomy‐Associated Alterations in Vascular Responses
Authors: Villalpando Diva M. , del Campo Lara , Navarro Rocío , Largó Carlota , Muñoz David , Tabernero María , Otero Cristina , García Hugo S. , Ferrer Mercedes
Published: November 2023

The loss of gonadal function induces vascular dysfunction by altering the release and action of NO, prostanoids and reactive oxygen species. Although, the cardioprotective effect of n‐3 polyunsaturated fatty acids has been documented, the specific effect of docosahexaenoic acid (DHA) in vascular function of orchidectomized rats has been scantly investigated. Therefore, the objective of this study was to analyze whether a DHA‐supplemented diet prevents vasodilator and vasoconstrictor alterations induced by impaired gonadal function. For this purpose, mesenteric arteries from control (C) and orchidectomized (CX) 6 months‐old Sprague‐Dawley rats were used. Control rats were fed with a control diet (V‐C), while CX rats were fed with a control diet (V‐CX) or one containing 2% (w/w) DHA (DHA‐CX). Hydrogen peroxide and antioxidant activity were analyzed in serum samples. Mesenteric artery segments were used to analyze: (i) the levels of NO and thromboxane A2 (TXA2); (ii) the vasodilator response induced by acetylcholine (Ach) in the absence and presence of L‐NAME and indomethacin, the respective inhibitors of NO synthase and cyclooxygenases; (iii) the vasodilator response to the NO donor, sodium nitroprusside (SNP); and (iv) the effect of L‐NAME on the contractile response induced by noradrenaline (NA). The results showed that orchidectomy increased the production of hydrogen peroxide while decreased the antioxidant activity and the DHA‐diet prevented these alterations. The release of NO was decreased in arteries from CX rats and it was restored by the DHA‐diet. The Ach‐induced response was decreased by L‐NAME plus indometacin in arteries from all groups, being the smallest decrease that of arteries from the V‐CX group. In KCl‐precontracted arteries, the SNP‐induced relaxation was greater in arteries from V‐CX group than those of C or CX‐DHA groups. Regarding NA‐induced response, L‐NAME failed to modify that response in V‐CX group, while in arteries from C and CX‐DHA L‐NAME increased the NA‐induced response. These results show that orchidectomy promotes oxidative stress that accounts for a decreased NO and an increased TXA2 release. The DHA‐supplemented diet in CX rats restored the redox status by decreasing hydrogen peroxide production and by increasing the antioxidant activity; in turn, the production of NO was recovered. Dietary DHA supplementation in CX rats increased the participation of NO in the Ach‐induced vasodilation and in the NA‐induced vasoconstriction.

Support or Funding Information

Supported by grants (to M. F.) from the Fondo de Investigaciones Sanitarias (PI1100416), Comunidad de Madrid (S2013/ABI‐2783, “INSPIRA1‐CM”) and Fondo Europeo de Desarrollo Regional.
Effects of Androgens on the Function of Mesenteric Arteries from Normotensive and Hypertensive Rats
Authors: Isidoro Lucía , Villalpando Diva M. , Perusquía Mercedes , Ferrer Mercedes
Published: November 2023

It has been suggested that androgens may exert cardiovascular protective actions by regulating the release and function of different vascular factors. In addition, increasing attention is paying to testosterone (TES) and its 5‐reduced metabolites, 5α‐ and 5β‐dihydrotestosterone (5α‐ and 5β‐DHT) to induce vasorelaxation in several vascular beds and hypotensive effects in normotensive conscious rats. Interestingly, 5β‐DHT is the most potent vasorelaxant androgen which is genomically inactive. In view of these data, and the lack of studies analyzing the effects of TES, 5α‐ and 5β‐DHT on the function of mesenteric artery from hypertensive rats, the objective of this study was to investigate whether hypertension alters the androgens‐mediated vasorelaxation, as well as their effects on the contractile response induced by electrical field stimulation (EFS); the vasomotor responses induced by the three major released neurotransmitters: noradrenaline (NA), calcitonine gene‐related peptide (CGRP) and nitric oxide were also analyzed. For this purpose, mesenteric artery segments from male Spontaneously Hypertensive rats (SHR) and its normotensive counterparts, Wistar‐Kyoto (WKY) rats, were used to analyze: (i) the concentration‐vasodilator response curve (0.1 μM – 0.1 mM) to TES, 5α‐ and 5β‐DHT; (ii) the effect of androgens (10 nM, incubated for 30 min) on the contractile response induced by EFS (200 mA; 0.3 ms; 1, 2, 4, 8, 16 Hz), and (iii) the vasoconstrictor‐response curve to NA (1 nM–10 μM), and the vasodilator‐response curve to CGRP (1 pM – 0.1 μM) and to the nitric oxide donor, sodium nitroprusside (SNP, 1 pM – 10 μM). The results showed that TES induced a similar relaxation in arteries from SHR or WKY rats, while 5β‐DHT‐induced a greater relaxation in arteries from SHR than those of WKY rats. In arteries from WKY rats, androgens did not modify the EFS‐ or NA‐induced contraction nor the CGRP‐induced relaxation, and only 5β‐DHT increased the SNP‐induced relaxation. In arteries from SHR, androgens unaltered the NA‐induced response, while TES and 5β‐DHT increased the SNP‐induced vasodilation in similar extent. The fact that 5β‐DHT increased the CGRP‐induced vasodilation in a greater extent than TES did, might account for the increased EFS‐induced contraction observed in the presence of TES. These results suggest that 5β‐DHT could be a drug with potential therapeutic benefits for the treatment of hypertension.

Support or Funding Information

Supported by grants (to M.F.) from the Fondo de Investigaciones Sanitarias (PI1100406), Comunidad de Madrid (S2013/ABI‐2783, “INSPIRA1‐CM”) and Fondo Europeo de Desarrollo Regional.
Cold‐Induced Metabolic Adjustments in Brown Adipose Tissue and Skeletal Muscle Gene Expression are Influenced by Time‐of‐Day
Authors: Machado Frederico Sander Mansur , Zhang Zhi , Su Yan , Jansen Remi , Foppen Ewout , Coimbra Cândido Celso , Kalsbeek Andries
Published: November 2023

Background

Cyclic daily changes in environmental conditions are key signals for anticipatory and adaptive adjustments of most living species, including mammals. Exposure to a lower ambient temperature increases thermogenic activity of brown adipose tissue and skeletal muscle. Given that the components of the molecular clock interact with the thermal and metabolic mechanisms directly involved with the defense of body temperature, the present study evaluated the interdependence of homeostatic and circadian‐related mechanisms in response to a cold stimulus at distinctive moments of the day.

Methods

Male Wistar rats were subjected to a single 3‐h episode of cold ambient temperature (4°C) at one of 6 time‐points along the light/dark cycle starting at: ZT2, ZT6, ZT10, ZT14, ZT18 and ZT22 (ZT0 being the time of light onset and ZT12 time of dark onset). Metabolic rate, body temperature, locomotor activity, feeding and drinking behavior were recorded during both control (room temperature) and cold conditions at each time‐point. Immediately after the 3‐h cold stimulus, rats were euthanized and both the soleus and brown adipose tissue were collected for rtPCR analysis of genes of interest.

Results

Exposure to a lower environmental temperature during the light (i.e., sleep) phase resulted in a slight hyperthermia associated with an increased metabolic rate. This association occurred regardless of time‐of‐day differences in increased locomotor activity. Additionally, the well‐known shift in substrate oxidation towards fat metabolism was attenuated during the inactive phase. These metabolic changes were accompanied by tissue‐specific adjustments to both cold and time‐of‐day in core‐clock genes expression, such as DBP and Rev‐erbα in the brown adipose tissue and CLOCK, PER1, CRY1, CRY2 and also Rev‐erbα in the soleus skeletal muscle. Simultaneously, different pathways in substrate oxidation and thermogenesis were also tissue‐specifically affected by time‐of‐day and cold.

Conclusion

In summary, the present results show a strong interdependence between homeostatic adjustments to environmental challenges, the daily rhythms in thermal balance and behavior and the core components of the molecular clock.

Support or Funding Information

CAPES and ZonMw
Cross talk between Skeletal muscle and Brown adipose tissue during cold and diet induced thermogeneis
Authors: Periasamy Muthu
Published: November 2023

The importance of brown adipose tissue as a site of nonshivering thermogenesis has been well documented. Emerging studies suggest that skeletal muscle is also an important site of thermogenesis especially when brown adipose tissue function is lacking. We recently showed that sarcolipin (SLN), an uncoupler of the sarco(endo) plasmic reticulum Ca2+ ATPase (SERCA) pump, could contribute to heat production in skeletal muscle. In this study, we sought to understand how loss of UCP1 or SLN is compensated during cold exposure and whether they are both necessary for thermogenesis. Toward this goal, we generated a UCP1; SLN double knock‐out (DKO) mouse model and challenged the single and DKO mice to acute and long‐term cold exposures. Results from this study show that there is up‐regulation of SLN expression in UCP1‐KO mice, and loss of SLN is compensated by increased expression of UCP1 and browning of white adipose tissue. We found that the DKO mice were viable when reared at thermoneutrality. When challenged to acute cold, the DKO were extremely cold‐sensitive and became hypothermic Paradoxically, the DKO mice were able to survive gradual cold challenge, but these mice lost significant weight and depleted their fat stores, despite having higher caloric intake. Interestingly loss of either SLN or UCP1 alone was sufficient to cause high fat diet‐induced obesity. No compensatory upregulation of UCP1 in SLN−/− mice or vice versa was found. However loss of both mechanisms failed to exacerbate the obesity phenotype. These studies imply that brown adipose tissue and skeletal muscle are recruited differently during cold vs diet induced thermogenesis.

Support or Funding Information

NIH R01‐HL‐088555 and R01‐DK098240‐01American Diabetes Association Basic Science Research Award (7‐13‐BS‐131) (to MP) and by the NIDDK‐NIH Award (K01‐DK102772) (to NCB).
Effect of Gut Microbiota Eradication on Adaptive Thermogenesis in Mice
Authors: Beserra Bruna Teles Soares , da Costa Silva Janice , Oliveira Fernanda Cerqueira Barroso , Ribeiro Carolina Martins , Perreira Sidney Alcântara , de Assis Rocha Neves Francisco , Coelho Michella Soares , Amato Angélica Amorim
Published: November 2023

The gut microbiota is identified as an important regulator of metabolism and plays a relevant role in the development and progression of obesity. Among the mechanisms proposed to explain the regulation of energy metabolism by the gut microbiota, is its influence on host's energy expenditure. One of the components of energy expenditure is the adaptive thermogenesis, resulting from the activity of thermogenic adipose tissue, consisting of the beige or brown adipocyte. This type of thermogenesis seems to be important for the metabolic health of rodents and humans.

Objective

To investigate the effect of gut microbiota eradication on the thermongenic phenotype of adipose tissue in lean and obese mice.

Methods

Five week old C57BL/6 male mice fed a control or high‐fat diet (HFD) for 10 weeks were randomly assigned to receive vehicle, antibiotics (ciprofloxacin 0.2g l−1 and vancomycin 0.5 g l−1 from the 10th to the 15th week, in drinking water), the b3‐adrenergic agonist CL 316,243 (1mg/kg/d for 5 days, intraperitoneally) or the combination of antibiotics and CL 316,243. Weight gain, energy intake and water intake were measured. Visceral adipose tissue white (vWAT), subcutaneous adipose tissue white (sWAT) and interescapular adipose brown (iBAT) were excised for determination of adiposity and expression of thermogenesis‐related gene.

Results

(p<0.05 compared with vehicle, 5 mice/group): There was no difference in weight gain, energy intake and water intake among the study groups, both in control and HFD‐fed mice. Control diet‐fed mice treated with the combination of antibiotics and CL 316,243 exhibited decreased vWAT and sWAT mass, whereas mice fed a HFD had a slight but nonsignificant trend towards decreased vWAT and sWAT mass. There was no difference in iBAT mass in mice fed a control and HFD and treated with antibiotics and/or CL 316,243 for both diets. There was a trend towards increased expression of the thermogenesis‐related gene Ucp‐1 in vWAT and sWAT of mice fed control or HFD and treated with antibiotics. In mice treated with both antibiotics and CL 316,243 there was a significant increase in Ucp1 expression in these WAT depots. Ucp1 expression in iBAT was unchanged by either treatment.

Conclusion

Our findings indicate that gut microbiota eradication by antibiotics increases the thermogenic phenotype in WAT and therefore suggest that some components of microbiota may have a negative impact in adaptive thermogenesis.

Support or Funding Information

CNPq/CAPES/FAPDF
Fish‐oils Increase BAMBI Expression to Protect Against Fibrotic Activity in LPS Stimulated Hepatic Tissue
Authors: Schaller Megan L. , Harris Matthew P. , Kamm Dakota , Witt Kenneth A. , Sandoval Karin E. , Wooten Joshua S.
Published: November 2023

Non‐alcoholic steatohepatitis (NASH), defined as excess hepatic lipid and chronic inflammation, provides an environment prone for the development of hepatic fibrosis. Recent evidence suggests that the antifibrotic protein BAMBI (BMP‐Activin membrane bound inhibitor) is downregulated in the presence of inflammation, and may be central to the development of fibrosis. Diets rich in omega‐3 (ω‐3) fatty acids are known to provide anti‐inflammatory effects; however, the effects of ω‐3 fatty acids on hepatic fibrosis are not well‐established.

PURPOSE

To determine the effects of fish‐oils on the hepatic fibrosis signaling cascade, following 32‐weeks of high‐fat feeding in a LPS‐induced model of NASH.

METHODS

Male C57BL/6 mice were randomly assigned to one of four diets for 32 weeks (n=9/group): low‐fat lard based (LFL, 10% kcal fat), low‐fat fish‐oil based (LFFO, 10% kcal fat), high‐fat lard based (HFL, 41% kcal fat), or high‐fat fish‐oil based (HFFO, 41% kcal fat). Following in situ LPS stimulation, liver mRNA expression of CD14, TLR4, MyD88, BAMBI, and TGF‐β1 was quantified using quantitative RT‐PCR. Differences between diets were identified using a one‐way ANOVA with statistical significance set at p<0.05.

RESULTS

Following LPS stimulation, CD14 was increased 2.5 fold (p=0.020) in HFFO when compared to HFL. Despite the increase in CD14, TLR4 showed no difference between groups. In contrast, MyD88 was 2.8 fold greater (p<0.001) in HFL compared to HFFO. In comparison to untreated tissue, BAMBI was 1.7 fold (p=0.017) higher in the HFFO LPS‐stimulated tissue, which best explained the 1‐fold (p=0.004) lower expression of TGF‐β1 in HFFO when compared to HFL post‐LPS stimulation.

CONCLUSION

Despite the increase in extracellular LPS signaling receptor CD14, the consumption of fish‐oils produced a protective intracellular response as observed by an increase in BAMBI and decrease in TGF‐β1. These results suggest that a diet high in ω‐3 fatty acids may protect against the development of hepatic fibrosis.

Support or Funding Information

Supported by NIH R21NS090282‐01
Use of Low‐Density Lipoprotein receptor and Very Low‐Density Lipoprotein Receptor as potential genetic markers to investigate the development of obesity in a non‐model fish species, Ictalurus punctarus
Authors: Ordonez‐Castillo Norelia , Abernathy Oaklee , Spainhour Rebekah , Kobayashi Yass
Published: November 2023

Dyslipidemia is a metabolic disorder that often develops in association with obesity. Most research regarding human metabolic disorders, including dyslipidemia, has been conducted using rodents. However, channel catfish selected for increased growth often develop obese‐like phenotype with increased fat accumulation in the abdomen, suggesting channel catfish can be useful in investigating the mechanism(s) associated with development of obesity in humans. Objectives of this experiment were to identify the genes encoding mRNA for two low density lipoprotein receptors (LDLrA and LDLrB) and examine their tissue distributions in channel catfish (Ictalurus punctarus). In addition, mRNA encoding very low density lipoprotein receptor (VLDLr) was identified and characterized. Channel catfish LDLrA, LDLrB, and VLDLr mRNA sequences were identified by screening the channel catfish genome database and their expression was examined in the brain, spleen, trunk kidney, liver, Bockmann body, and muscle. The PCR amplicon for respective mRNA was highly similar (>70%) with other species of fish. The sequences of LDLrA and LDLrB mRNA also shared a high degree of similarities (>65%) with rodents and humans. Expression of LDLrA and VLDLr mRNA sequences were detected at various levels in all tissues examined. LDLrB mRNA sequences were also detected at various levels in all tissues except in the brain. Currently, the changes in expression of the three mRNA expressions in relation to changes in food intake and development of obese‐like phenotype are being investigated.

Support or Funding Information

This research is supported by the Kansas Idea Network of Biomedical Research Excellence (P20GM103418).
Characterization of Aquaporin Expression and Function in the Malpighian Tubules of the Larval Mosquito, Aedes aegypti
Authors: Misyura Lidiya , Donini Andrew
Published: November 2023

The mosquito, Aedes aegypti, is the primary vector for the arboviral diseases Zika, dengue fever, chikungunya, and yellow fever that affect millions of people worldwide. The larvae of A. aegypti reside in hypo‐osmotic freshwater habitats, where they face dilution of bodily fluids due to the influx of water. The Malpighian tubules (MTs) are one of the major contributors to osmoregulation, whereby, they function in concert with the rectum, to remove excess water from the hemolymph, thus maintaining ionic homeostasis. The epithelium of the Malpighian tubules actively transports ions from the hemolymph into the lumen which creates an osmotic gradient that drives paracellular and transcellular water movement in the same direction. Our previous study has shown that this transcellular water transport occurs through at least one of the six aquaporins (AQP) that A. aegypti possesses, AQP5. In the present study, the function of other AQPs with high relative mRNA abundance in the MTs were studied with the aid of double stranded RNA knockdown. The MT fluid secretion rate and ionic composition of secreted fluid were assessed using Ramsay assay and ion selective microelectrode (ISME), respectively. Hemolymph ion concentrations and larval survival were measured to gauge effects of AQP knockdown on osmoregulation in the larvae. Water transport across the Malpighian tubules of the larval mosquito is a critical physiological process because it is the first essential step in eliminating the excess water, a consequence of living in hypo‐osmotic habitats. Our study sheds light on the relative contribution of AQPs in this vital process.

Support or Funding Information

Natural Sciences and Engineering Research Council of Canada (NSERC) discovery grant awarded to Andrew Donini
Using Virtual Microscopy – Advancing Anatomical Education Worldwide
Authors: Hortsch Michael
Published: November 2023

Since optical instruments were first used in the early 17th century to visualize biological material at the microscopic scale, the morphological study of cells and tissues has largely been driven by technological advances, such as the development of high quality light microscopes, new procedures for preparing biological specimens for visual analysis, and novel microscope equipment and approaches (Hortsch, FASEB J. 27: 411–3, 2013). Over the last 25 years, virtual microscopy has gradually replaced light microscopes and glass slides for the teaching of cell, tissue, and organ structure (histology or microanatomy). Teachers and learners use high‐resolution, digitized histological images that are accessed by computers from a central server to dynamically view and explore normal and pathological cells and tissues. In 2005, the University of Michigan Medical School introduced virtual microscopy as the main histology teaching modality. Hundreds of existing glass histology slides were digitized to create a large library of virtual histology files that now forms the basis of the Michigan Histology website (http://histology.sites.uofmhosting.net). Each month, this freely accessible website, containing virtual light microcopy and EM images of all major human tissues and organs, is visited 30,000 to 80,000 times from over 160 different countries. This and other similar websites that offer virtual histology images specifically benefit students and teachers at new educational institutions, especially those located in developing countries, which frequently lack the funds to purchase expensive microscope equipment for all students. In addition, high quality histology glass slides are often difficult to obtain or prohibitively expensive. As limitations, access to a single virtual microcopy website relies on a fast, stable Internet connection and its content may not align with different curricular and course structures. Therefore, we shared the Michigan virtual microscopy file collection, which is over 200 Gb in size, with about 30 national and international institutions of higher learning. These schools have adopted the Michigan image material to their own style of teaching and educational needs, sometimes using them to complement their own virtual slide collections. Several examples of how virtual microscopy is integrated into the teaching of histology at educational institutions located on five different continents will be discussed in the presentation. These samples indicate that an Internet‐based large repository of virtual microscopy files will allow histology teachers worldwide, especially those who might not have the equipment to digitize their own histology glass slides, to select appropriate image material and to use it in customized ways that are best suited to their individual didactic requirements.