Differential gene expressions in the hypertensive heart using Angiotensin II infusion model
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ABSTRACT: Differential gene expressions were constructed through expression profiling of a total of 22,556 genes in the hypertensive heart during the early and lately phase of Angiotensin II infusion, then 1019 or 647 significant differential genes were filtered based on the criteria (p<0.05 and fold change >2 or 1.5), respectively.
Project description:Renin-angiotensin system (RAS) inhibition reduces stroke and improves brain capillary integrity in stroke prone spontaneously hypertensive rats (SHRSP). We tested the hypothesis that treatment with an angiotensin II receptor subtype 1 (AT1R) antagonist has different effects, compared to an angiotensin converting enzyme (ACE) inhibitor, on gene expression in blood-brain barrier (BBB) capillaries. Six weeks old SHRSP were treated with either olmesartan (4 mg/kg, n=20), lisinopril (6 mg/kg , n=20) or remained untreated (n=20). Blood pressure was controlled by tail-cuff measurement. After 5 weeks the animals were sacrificed and cerebral capillaries were isolated. mRNA was extracted and analyzed with rat GeneChip DNA arrays. Additionally, brain histology and monocyte/macrophage infiltrates were determined. Both treatments similarly reduced neurological signs of stroke, stroke mortality, and monocyte/macrophage infiltration, compared to controls. Blood pressure was not influenced significantly by both drugs. We found 42 transcripts that were regulated by both treatments in the same manner. These genes were mostly related to inflammation. We also observed 39 differentially expressed genes between the two treatment groups that typically contribute to cell growth and differentiation. This study demonstrates that, despite similar effects on cerebral pathology and outcome, ACE inhibition and AT1R blockade have distinct molecular effects on gene expression in BBB capillaries.
Project description:Hypertension is a major risk factor for both stroke and cognitive impairment, but it is unclear whether it may specifically affect post-stroke cognitive impairment. We assessed the effect of hypertension and/or stroke on brain injury, cognitive outcome, and the brain transcriptomic profile. C57BL/6J mice (n=117; 3-5 mo.) received s.c. infusion of either saline or angiotensin II (for 14 d or 28 d) followed by sham surgery or photothrombotic stroke targeting the prefrontal cortex seven days later. Cognitive function was assessed with the Barnes maze. RNA sequencing was used to quantify transcriptomic changes in the brain. Angiotensin II treatment produced spontaneous hemorrhaging on the stroke brain. In the Barnes maze, hypertensive mice that received stroke surgery had an increased escape latency compared to other groups (day 3: hypertensive + stroke=166.6±6.0 s vs. hypertensive + sham=122.8±13.8 s vs. normotensive + stroke=139.9±10.1 s vs. normotensive + sham=101.9±16.7 s), consistent with a greater learning impairment. RNA sequencing revealed >800 differentially expressed genes related to neuroinflammation in hypertensive + stroke vs. hypertensive + sham, which included genes associated with apoptosis, microRNAs, autophagy, anti-cognitive biomarkers and Wnt signaling. The combination of hypertension and stroke resulted in greater learning impairment and brain injury.
Project description:In hypertension, abnormal regulation of microcirculation and endothelial dysfunction enhances vulnerability to hypertensive brain damage. In addition to lowering blood pressure, blockade of Angiotensin II AT1 receptors protects against stroke and stress in different animal models and this treatment may be of therapeutic advantage. We studied gene expression using Affymetrix Rat Genome U34A arrays from brain microvessels of spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto controls (WKY) rats treated with an AT1 antagonist (candesartan, 0.3 mg/kg/day) or vehicle via osmotic minipumps for 4 weeks. Keywords: other
Project description:To determine if there exists a consistent gene signature associated with vascular hypertrophy among different rat hypertensive models: treated and untreated Wistar Kyoto (WKY) rats and treated and untreated Spontaneous Hypertensive Rat (SHR) rats. Experiment Overall Design: Two strains of rat were studies: WKY which are normotensive and SHR which are hypertensive. Aortic tissue was taken from 6 untreated WKY rats and 6 WKY rats treated with angiotensin. Aortic tissue was taken from 6 untreated SHR rats, 6 treated with nifedipine for two weeks and 5 treated with nifedipine for two weeks and then washed out for three weeks. There was a total of 29 samples. A pool of RNA from 6 untreated WKY rats was used as a reference. Hybridizations were performed in duplicate with a dye-flip and always with the reference as the second color.
Project description:In hypertension, abnormal regulation of microcirculation and endothelial dysfunction enhances vulnerability to hypertensive brain damage. In addition to lowering blood pressure, blockade of Angiotensin II AT1 receptors protects against stroke and stress in different animal models and this treatment may be of therapeutic advantage. We studied gene expression using Affymetrix Rat Genome U34A arrays from brain microvessels of spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto controls (WKY) rats treated with an AT1 antagonist (candesartan, 0.3 mg/kg/day) or vehicle via osmotic minipumps for 4 weeks. Experiment Overall Design: brain microvessels from hypertensive and normotensive rats treated with candesartan and vehicle were analyzed
Project description:Over-expression of human angiotensin-II receptor type1 (hAT1R) may cause pathological outcomes due to overactivation of renin-angiotensin system. Transgenic (TG) mice containing Hap-I (hypertensive genotype) of human hAT1R gene are more prone to develop metabolic syndrome disorders as compared to TG mice with Hap-II (normotensive genotype). This gene variant associated risk of hypertension together with Western diet and aging may lead to renal disorders. However, mechanisms underlying this process are not well examined. For this purpose, we studied the renal gene expression alterations in aged TG mice containing either Hap-I or Hap-II of hAT1R gene. Aged mice (20-24 months of age) were maintained on a regular diet or high fat diet with 2% NaCl (Western diet, WD) for 16 weeks. On a regular diet, aged Hap-I mice presented higher (~9 mmHg) systolic blood pressure with respect to age-matched Hap-II animals. Following administration of Western diet, blood pressure increased in both groups of mice, but to a larger extent in Hap-I animals (~15 mmHg in comparison to ~7 mmHg in Hap-II). Aged Hap-I mice on Western diet showed increased renal fibrosis. RNA-seq data from renal tissue of Hap-I aged mice revealed that WD significantly altered the expression of >400 genes (p-adj. <0.05). Bioinformatics analysis (Qiagen IPA software) identified major alterations in main canonical pathways involved in renal function and oxidative damage. These changes in turn resulted in kidney failure, renal tubular injury, and renal proliferation. In addition, post WD treatment, RNA seq. analysis from Hap-I and Hap-II kidneys also reveals haplotype specific regulation of genes associated with blood pressure regulation and kidney disorders. Overall, these results indicate that Western diet promotes hypertension and fibrosis in the kidneys of aged mice. These alterations are paralleled by perturbation of renal transcriptional profile. Overall, these studies will assist in the identification of novel mechanisms and molecules involved in hypertension and associated kidney pathophysiology.
Project description:Over-expression of human angiotensin-II receptor type1 (hAT1R) may cause pathological outcomes due to overactivation of renin-angiotensin system. Transgenic (TG) mice containing Hap-I (hypertensive genotype) of human hAT1R gene are more prone to develop metabolic syndrome disorders as compared to TG mice with Hap-II (normotensive genotype). This gene variant associated risk of hypertension together with Western diet and aging may lead to renal disorders. However, mechanisms underlying this process are not well examined. For this purpose, we studied the renal gene expression alterations in aged TG mice containing either Hap-I or Hap-II of hAT1R gene. Aged mice (20-24 months of age) were maintained on a regular diet or high fat diet with 2% NaCl (Western diet, WD) for 16 weeks. On a regular diet, aged Hap-I mice presented higher (~9 mmHg) systolic blood pressure with respect to age-matched Hap-II animals. Following administration of Western diet, blood pressure increased in both groups of mice, but to a larger extent in Hap-I animals (~15 mmHg in comparison to ~7 mmHg in Hap-II). Aged Hap-I mice on Western diet showed increased renal fibrosis. RNA-seq data from renal tissue of Hap-I aged mice revealed that WD significantly altered the expression of >400 genes (p-adj. <0.05). Bioinformatics analysis (Qiagen IPA software) identified major alterations in main canonical pathways involved in renal function and oxidative damage. These changes in turn resulted in kidney failure, renal tubular injury, and renal proliferation. In addition, post WD treatment, RNA seq. analysis from Hap-I and Hap-II kidneys also reveals haplotype specific regulation of genes associated with blood pressure regulation and kidney disorders. Overall, these results indicate that Western diet promotes hypertension and fibrosis in the kidneys of aged mice. These alterations are paralleled by perturbation of renal transcriptional profile. Overall, these studies will assist in the identification of novel mechanisms and molecules involved in hypertension and associated kidney pathophysiology.