BackgroundLong ncRNAs (lncRNAs) are known to influence numerous biological processes including ce... more BackgroundLong ncRNAs (lncRNAs) are known to influence numerous biological processes including cellular differentiation and tissue development. They are also implicated in the maintenance, health and physiological function of many tissues including the heart. Indeed, manipulating the expression of specific lncRNAs has been shown to improve pathological cardiac phenotypes such as heart failure. One lncRNA studied in various settings is OIP5-AS1 (also known as 1700020I14Rik and Cyrano), however its role in cardiac pathologies remains mostly uncharacterised.MethodsWe used data generated from FACS sorted murine cardiomyocytes, human iPSC derived cardiomyocytes, as well as heart tissue from various animal models to investigate OIP5-AS1 expression in health and disease. Using CRISPR we engineered a global OIP5-AS1 knock out (KO) mouse model and performed cardiac pressure overload experiments to study heart failure in these animals. RNA-sequencing of left ventricles provided mechanistic in...
Background: High blood pressure (BP) continues to be a major, poorly controlled but modifiable ri... more Background: High blood pressure (BP) continues to be a major, poorly controlled but modifiable risk factor for cardiovascular death. Amongst key Western lifestyle factors, a diet poor in fibre is associated with prevalence of high BP. The impact of lack of prebiotic fibre and the associated mechanisms that lead to higher BP are unknown. Here we show that lack of prebiotic dietary fibre leads to the development of a hypertensinogenic gut microbiome, hypertension and its complications, and demonstrate a role for G-protein coupled-receptors (GPCRs) that sense gut metabolites. Methods: 179 mice including C57BL/6J, gnotobiotic C57BL/6J, and knockout strains for GPR41, GPR43, GPR109A and GPR43/109A were included. C57BL/6J mice were implanted with minipumps containing saline or a slow-pressor dose of angiotensin II (0.25 mg/kg/d). Mice were fed diets lacking prebiotic fibre with or without addition of gut metabolites called short-chain fatty acids (SCFAs; produced during fermentation of pr...
American Journal of Physiology-Heart and Circulatory Physiology
Informal training in preclinical research may be a contributor to the poor reproducibility of pre... more Informal training in preclinical research may be a contributor to the poor reproducibility of preclinical cardiology research and low rates of translation into clinical research and practice. Mouse echocardiography is a widely used technique to assess cardiac structure and function in drug intervention studies using disease models. The interobserver variability of clinical echocardiographic measurements has been shown to improve with formalized training, but preclinical echocardiography lacks similarly critical standardization of training. The aims of this investigation were to assess the interobserver variability of echocardiographic measurements from studies in mice and address any technical impediments to reproducibility by implementing standardized guidelines through formalized training. In this prospective, single-site, observational cohort study, 13 scientists performing preclinical echocardiographic image analysis were assessed for measurement of short-axis M-mode-derived dim...
American Journal of Physiology-Heart and Circulatory Physiology
Dilated cardiomyopathy (DCM) is a major cause of heart failure without effective therapy. Fibroge... more Dilated cardiomyopathy (DCM) is a major cause of heart failure without effective therapy. Fibrogenesis plays a key role in the development of DCM, but little is known of the expression of the profibrotic factor galectin-3 (Gal-3) and its role in DCM pathophysiology. In a mouse DCM model with transgenic (TG) overexpression of mammalian sterile 20-like kinase 1 (Mst1), we studied Gal-3 expression and effects of the Gal-3 inhibitor modified citrus pectin (MCP) or Gal-3 gene knockout (KO). Gal-3 deletion in TG mice (TG/KO) was achieved by crossbreeding Mst1-TG mice with Gal-3 KO mice. The DCM phenotype was assessed by echocardiography and micromanometry. Cardiac expression of Gal-3 and fibrosis were determined. The cardiac transcriptome was profiled by RNA sequencing. Mst1-TG mice at 3−8 mo of age exhibited upregulated expression of Gal-3 by ~40-fold. TG mice had dilatation of cardiac chambers, suppressed left ventricular (LV) ejection fraction, poor LV contractility and relaxation, a t...
Statins are effective in management of dyslipidaemia, and a cornerstone of CVD prevention strateg... more Statins are effective in management of dyslipidaemia, and a cornerstone of CVD prevention strategies. However, the impacts of their pleiotropic effects on other cardiovascular risk factors and myocardial responses to infarction are not well characterised. We hypothesised that pravastatin treatment in obesity improves lipid profiles, insulin-resistance and myocardial resistance to ischaemia/reperfusion (I/R) injury. Wistar rats were fed a control (C) chow or high carbohydrate and fat diet (HCFD) for 16 weeks with vehicle or pravastatin (prava 7.5 mg/kg/day) treatment for 8 weeks. At 16 weeks HOMAs were performed, blood samples collected and hearts excised for Langendorff perfusions/biochemical analyses. Anti-oxidant activity and proteins regulating mitochondrial fission/fusion and apoptosis were assessed. The HCFD increased body weight (736±15 vs. 655±12 g for C; P<0.001), serum triglycerides (2.91±0.52 vs. 1.64±0.26 mmol/L for C; P<0.001) and insulin-resistance (HOMA- 6.9±0.8 ...
SummaryConsumption of palatable foods high in refined carbohydrate has been implicated as a contr... more SummaryConsumption of palatable foods high in refined carbohydrate has been implicated as a contributing factor to the epidemic levels of obesity. Such foods may disrupt appetite regulation in the hypothalamus through alterations in hunger and satiety signalling. This investigation examined whether a palatable high refined carbohydrate (HRC) diet with the potential to induce obesity was linked to modulation of serotonin and dopamine signalling within the hypothalamus of rats. Male Wistar rats were allowedad libitumaccess to either a palatable refined carbohydrate enriched (HRC) diet or standard chow (SC). Visceral fat percentage was used as a measure of the animals' weight gain during the trial. Real-time PCR was applied to determine any variation in levels of expression of the serotonin (Slc6A4orSert) and dopamine transporter (Slc6A3orDat) genes. After 29 weeks, the HRC group showed a significant increase in visceral fat percentage accompanied by increased expression ofSert. Hi...
ABSTRACT Introduction/Aim: Correcting the hypogonadic phenotype with exogenous androgen treatment... more ABSTRACT Introduction/Aim: Correcting the hypogonadic phenotype with exogenous androgen treatment may prove to be preventative against obesity-related pathologies. However, testosterone replacement therapy is associated with additional metabolic perturbances due, in part, to its susceptibility to aromatization in the highly prevalent adipocytes of obese individuals. This study evaluated the effects of a novel selective androgen against classical testosterone replacement therapy in obese, hypogonadic rats. Methods: At 8 weeks of age, fifty male Wistar rats (300±30g) were fed either a standard rat chow (CTRL) or obesogenic diet (OGD). At 28 weeks of age, rats were randomly assorted into groups receiving either sham (OGD) or orchiectomy procedures. At 32 weeks, orchiectomised rats were implanted with an osmotic infusion pump delivering either vehicle (45% w/v 2β-hydroxypropyl cyclodextrin in water, ORX), or either 1mg/day testosterone (TEST) or trenbolone (TREN). Comprehensive physiological assessments were carried out to evaluate body composition, insulin sensitivity and cardiac tolerance to an ischemia-reperfusion event (45 min LAD coronary ligature, 120 min reperfusion). Results: The obesogenic diet increased visceral and subcutaneous adiposity and, absent of insulin resistance, reduced cardiac infarct size in OGD animals (19.64±1.16 vs. 25.91±1.65 % AAR in CTRL, p&lt;0.05). Cardiac infarct size increased in response to orchiectomy (ORX: 41.23±1.38%, p&lt;0.001). Both treatments effectively reduced infarct size (p&lt;0.001) however TREN’s effect was greater (17.49±1.45 vs. 23.27±0.89 % in TEST, p&lt;0.05). Although no differences in body weights were observed, fat mass percentage was greater in ORX animals (45.9±1.6, p&lt;0.05) but was not associated with insulin insensitivity (p&gt;0.05). Although both treatments improved body composition, TREN was more effective at: 1) reducing adiposity; and 2) improving lean mass, compared to TEST. Conclusion: Trenbolone treatment improved body composition and cardiac tolerance to ischemia-reperfusion more significantly than testosterone treatment in obese, hypogonadic rats.
The increasing prevalence of obesity adds another dimension to the pathophysiology of testosteron... more The increasing prevalence of obesity adds another dimension to the pathophysiology of testosterone deficiency (TD) and potentially impairs the therapeutic efficacy of classical testosterone replacement therapy (TRT). We investigated the therapeutic effects of selective androgen receptor modulation with trenbolone in a model of TD with the metabolic syndrome (MetS). Male Wistar rats (n=50) were fed either a control standard rat chow (CTRL) or a high-fat/high-sucrose diet (HF/HS). Following 8 weeks of feeding, rats underwent sham surgery or an orchiectomy (ORX). Alzet mini-osmotic pumps containing either vehicle, 2 mg/kg/day testosterone (TEST) or 2 mg/kg/day trenbolone (TREN) were implanted in HF/HS+ORX rats. Body composition, fat distribution, lipid profile and insulin sensitivity were assessed. Infarct size was quantified to assess myocardial damage following in vivo ischaemia-reperfusion, before cardiac and prostate histology was performed. The HF/HS+ORX animals had increased subc...
Introduction: Obesity and the metabolic syndrome (MS) decreases myocardial tolerance to ischaemia... more Introduction: Obesity and the metabolic syndrome (MS) decreases myocardial tolerance to ischaemia and reperfusion. Although our recent data suggests that this decreased tolerance to ischaemia may be related to myocardial metabolic perturbations associated with MS, there is some evidence to suggest that myocardial RISK pathway function may also be compromised by MS. We hypothesise that myocardial tolerance to ischaemia is reduced by compromised RISK pathway functionality in obesity with insulin resistance (MS). Aims: We set out to determine how visceral obesity, dyslipidaemia and insulin resistance (MS) affects, 1) myocardial infarct size and reperfusion function, and 2) myocardial RISK pathway protein expression and activity. Methods: 2 month old Wistar-Kyoto rats were fed a high fat diet (HFD) (74%carbohydrates, 10%protein, 16%fat) or a standard rat chow diet (SRC)(73%carbohydrates, 18%protein, 9%fat) for 30 weeks. Rats were anaesthetised and hearts perfused on a Langendorff rat he...
Trenbolone (TREN) is used for anabolic growth-promotion in over 20 million cattle annually and co... more Trenbolone (TREN) is used for anabolic growth-promotion in over 20 million cattle annually and continues to be misused for aesthetic purposes in humans. The current study investigated TREN's effects on body composition and cardiometabolic risk factors; and its tissue-selective effects on the cardiovascular system, liver and prostate. Male rats (n=12) were implanted with osmotic infusion pumps delivering either cyclodextrin vehicle (CTRL) or 2mg/kg/day TREN for 6weeks. Dual-energy X-ray Absorptiometry assessment of body composition; organ wet weights and serum lipid profiles; and insulin sensitivity were assessed. Cardiac ultrasound examinations were performed before in vivo studies assessed myocardial susceptibility to ischemia-reperfusion (I/R) injury. Circulating sex hormones and liver enzyme activities; and prostate and liver histology were examined. In 6weeks, fat mass increased by 34±7% in CTRLs (p<0.01). Fat mass decreased by 37±6% and lean mass increased by 11±4% with ...
BackgroundLong ncRNAs (lncRNAs) are known to influence numerous biological processes including ce... more BackgroundLong ncRNAs (lncRNAs) are known to influence numerous biological processes including cellular differentiation and tissue development. They are also implicated in the maintenance, health and physiological function of many tissues including the heart. Indeed, manipulating the expression of specific lncRNAs has been shown to improve pathological cardiac phenotypes such as heart failure. One lncRNA studied in various settings is OIP5-AS1 (also known as 1700020I14Rik and Cyrano), however its role in cardiac pathologies remains mostly uncharacterised.MethodsWe used data generated from FACS sorted murine cardiomyocytes, human iPSC derived cardiomyocytes, as well as heart tissue from various animal models to investigate OIP5-AS1 expression in health and disease. Using CRISPR we engineered a global OIP5-AS1 knock out (KO) mouse model and performed cardiac pressure overload experiments to study heart failure in these animals. RNA-sequencing of left ventricles provided mechanistic in...
Background: High blood pressure (BP) continues to be a major, poorly controlled but modifiable ri... more Background: High blood pressure (BP) continues to be a major, poorly controlled but modifiable risk factor for cardiovascular death. Amongst key Western lifestyle factors, a diet poor in fibre is associated with prevalence of high BP. The impact of lack of prebiotic fibre and the associated mechanisms that lead to higher BP are unknown. Here we show that lack of prebiotic dietary fibre leads to the development of a hypertensinogenic gut microbiome, hypertension and its complications, and demonstrate a role for G-protein coupled-receptors (GPCRs) that sense gut metabolites. Methods: 179 mice including C57BL/6J, gnotobiotic C57BL/6J, and knockout strains for GPR41, GPR43, GPR109A and GPR43/109A were included. C57BL/6J mice were implanted with minipumps containing saline or a slow-pressor dose of angiotensin II (0.25 mg/kg/d). Mice were fed diets lacking prebiotic fibre with or without addition of gut metabolites called short-chain fatty acids (SCFAs; produced during fermentation of pr...
American Journal of Physiology-Heart and Circulatory Physiology
Informal training in preclinical research may be a contributor to the poor reproducibility of pre... more Informal training in preclinical research may be a contributor to the poor reproducibility of preclinical cardiology research and low rates of translation into clinical research and practice. Mouse echocardiography is a widely used technique to assess cardiac structure and function in drug intervention studies using disease models. The interobserver variability of clinical echocardiographic measurements has been shown to improve with formalized training, but preclinical echocardiography lacks similarly critical standardization of training. The aims of this investigation were to assess the interobserver variability of echocardiographic measurements from studies in mice and address any technical impediments to reproducibility by implementing standardized guidelines through formalized training. In this prospective, single-site, observational cohort study, 13 scientists performing preclinical echocardiographic image analysis were assessed for measurement of short-axis M-mode-derived dim...
American Journal of Physiology-Heart and Circulatory Physiology
Dilated cardiomyopathy (DCM) is a major cause of heart failure without effective therapy. Fibroge... more Dilated cardiomyopathy (DCM) is a major cause of heart failure without effective therapy. Fibrogenesis plays a key role in the development of DCM, but little is known of the expression of the profibrotic factor galectin-3 (Gal-3) and its role in DCM pathophysiology. In a mouse DCM model with transgenic (TG) overexpression of mammalian sterile 20-like kinase 1 (Mst1), we studied Gal-3 expression and effects of the Gal-3 inhibitor modified citrus pectin (MCP) or Gal-3 gene knockout (KO). Gal-3 deletion in TG mice (TG/KO) was achieved by crossbreeding Mst1-TG mice with Gal-3 KO mice. The DCM phenotype was assessed by echocardiography and micromanometry. Cardiac expression of Gal-3 and fibrosis were determined. The cardiac transcriptome was profiled by RNA sequencing. Mst1-TG mice at 3−8 mo of age exhibited upregulated expression of Gal-3 by ~40-fold. TG mice had dilatation of cardiac chambers, suppressed left ventricular (LV) ejection fraction, poor LV contractility and relaxation, a t...
Statins are effective in management of dyslipidaemia, and a cornerstone of CVD prevention strateg... more Statins are effective in management of dyslipidaemia, and a cornerstone of CVD prevention strategies. However, the impacts of their pleiotropic effects on other cardiovascular risk factors and myocardial responses to infarction are not well characterised. We hypothesised that pravastatin treatment in obesity improves lipid profiles, insulin-resistance and myocardial resistance to ischaemia/reperfusion (I/R) injury. Wistar rats were fed a control (C) chow or high carbohydrate and fat diet (HCFD) for 16 weeks with vehicle or pravastatin (prava 7.5 mg/kg/day) treatment for 8 weeks. At 16 weeks HOMAs were performed, blood samples collected and hearts excised for Langendorff perfusions/biochemical analyses. Anti-oxidant activity and proteins regulating mitochondrial fission/fusion and apoptosis were assessed. The HCFD increased body weight (736±15 vs. 655±12 g for C; P<0.001), serum triglycerides (2.91±0.52 vs. 1.64±0.26 mmol/L for C; P<0.001) and insulin-resistance (HOMA- 6.9±0.8 ...
SummaryConsumption of palatable foods high in refined carbohydrate has been implicated as a contr... more SummaryConsumption of palatable foods high in refined carbohydrate has been implicated as a contributing factor to the epidemic levels of obesity. Such foods may disrupt appetite regulation in the hypothalamus through alterations in hunger and satiety signalling. This investigation examined whether a palatable high refined carbohydrate (HRC) diet with the potential to induce obesity was linked to modulation of serotonin and dopamine signalling within the hypothalamus of rats. Male Wistar rats were allowedad libitumaccess to either a palatable refined carbohydrate enriched (HRC) diet or standard chow (SC). Visceral fat percentage was used as a measure of the animals' weight gain during the trial. Real-time PCR was applied to determine any variation in levels of expression of the serotonin (Slc6A4orSert) and dopamine transporter (Slc6A3orDat) genes. After 29 weeks, the HRC group showed a significant increase in visceral fat percentage accompanied by increased expression ofSert. Hi...
ABSTRACT Introduction/Aim: Correcting the hypogonadic phenotype with exogenous androgen treatment... more ABSTRACT Introduction/Aim: Correcting the hypogonadic phenotype with exogenous androgen treatment may prove to be preventative against obesity-related pathologies. However, testosterone replacement therapy is associated with additional metabolic perturbances due, in part, to its susceptibility to aromatization in the highly prevalent adipocytes of obese individuals. This study evaluated the effects of a novel selective androgen against classical testosterone replacement therapy in obese, hypogonadic rats. Methods: At 8 weeks of age, fifty male Wistar rats (300±30g) were fed either a standard rat chow (CTRL) or obesogenic diet (OGD). At 28 weeks of age, rats were randomly assorted into groups receiving either sham (OGD) or orchiectomy procedures. At 32 weeks, orchiectomised rats were implanted with an osmotic infusion pump delivering either vehicle (45% w/v 2β-hydroxypropyl cyclodextrin in water, ORX), or either 1mg/day testosterone (TEST) or trenbolone (TREN). Comprehensive physiological assessments were carried out to evaluate body composition, insulin sensitivity and cardiac tolerance to an ischemia-reperfusion event (45 min LAD coronary ligature, 120 min reperfusion). Results: The obesogenic diet increased visceral and subcutaneous adiposity and, absent of insulin resistance, reduced cardiac infarct size in OGD animals (19.64±1.16 vs. 25.91±1.65 % AAR in CTRL, p&lt;0.05). Cardiac infarct size increased in response to orchiectomy (ORX: 41.23±1.38%, p&lt;0.001). Both treatments effectively reduced infarct size (p&lt;0.001) however TREN’s effect was greater (17.49±1.45 vs. 23.27±0.89 % in TEST, p&lt;0.05). Although no differences in body weights were observed, fat mass percentage was greater in ORX animals (45.9±1.6, p&lt;0.05) but was not associated with insulin insensitivity (p&gt;0.05). Although both treatments improved body composition, TREN was more effective at: 1) reducing adiposity; and 2) improving lean mass, compared to TEST. Conclusion: Trenbolone treatment improved body composition and cardiac tolerance to ischemia-reperfusion more significantly than testosterone treatment in obese, hypogonadic rats.
The increasing prevalence of obesity adds another dimension to the pathophysiology of testosteron... more The increasing prevalence of obesity adds another dimension to the pathophysiology of testosterone deficiency (TD) and potentially impairs the therapeutic efficacy of classical testosterone replacement therapy (TRT). We investigated the therapeutic effects of selective androgen receptor modulation with trenbolone in a model of TD with the metabolic syndrome (MetS). Male Wistar rats (n=50) were fed either a control standard rat chow (CTRL) or a high-fat/high-sucrose diet (HF/HS). Following 8 weeks of feeding, rats underwent sham surgery or an orchiectomy (ORX). Alzet mini-osmotic pumps containing either vehicle, 2 mg/kg/day testosterone (TEST) or 2 mg/kg/day trenbolone (TREN) were implanted in HF/HS+ORX rats. Body composition, fat distribution, lipid profile and insulin sensitivity were assessed. Infarct size was quantified to assess myocardial damage following in vivo ischaemia-reperfusion, before cardiac and prostate histology was performed. The HF/HS+ORX animals had increased subc...
Introduction: Obesity and the metabolic syndrome (MS) decreases myocardial tolerance to ischaemia... more Introduction: Obesity and the metabolic syndrome (MS) decreases myocardial tolerance to ischaemia and reperfusion. Although our recent data suggests that this decreased tolerance to ischaemia may be related to myocardial metabolic perturbations associated with MS, there is some evidence to suggest that myocardial RISK pathway function may also be compromised by MS. We hypothesise that myocardial tolerance to ischaemia is reduced by compromised RISK pathway functionality in obesity with insulin resistance (MS). Aims: We set out to determine how visceral obesity, dyslipidaemia and insulin resistance (MS) affects, 1) myocardial infarct size and reperfusion function, and 2) myocardial RISK pathway protein expression and activity. Methods: 2 month old Wistar-Kyoto rats were fed a high fat diet (HFD) (74%carbohydrates, 10%protein, 16%fat) or a standard rat chow diet (SRC)(73%carbohydrates, 18%protein, 9%fat) for 30 weeks. Rats were anaesthetised and hearts perfused on a Langendorff rat he...
Trenbolone (TREN) is used for anabolic growth-promotion in over 20 million cattle annually and co... more Trenbolone (TREN) is used for anabolic growth-promotion in over 20 million cattle annually and continues to be misused for aesthetic purposes in humans. The current study investigated TREN's effects on body composition and cardiometabolic risk factors; and its tissue-selective effects on the cardiovascular system, liver and prostate. Male rats (n=12) were implanted with osmotic infusion pumps delivering either cyclodextrin vehicle (CTRL) or 2mg/kg/day TREN for 6weeks. Dual-energy X-ray Absorptiometry assessment of body composition; organ wet weights and serum lipid profiles; and insulin sensitivity were assessed. Cardiac ultrasound examinations were performed before in vivo studies assessed myocardial susceptibility to ischemia-reperfusion (I/R) injury. Circulating sex hormones and liver enzyme activities; and prostate and liver histology were examined. In 6weeks, fat mass increased by 34±7% in CTRLs (p<0.01). Fat mass decreased by 37±6% and lean mass increased by 11±4% with ...
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