Modulation of myocardial injury by dietary flaxseed

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dc.contributor.authorParikh, Mihir
dc.contributor.examiningcommitteeJassal, Davinder (Physiology and Pathophysiology) Anderson, Hope (Pharmacy) Maurice, Donald (Queen's University)en_US
dc.contributor.supervisorPierce, Grant (Physiology and Pathophysiology) Netticadan, Thomas (Physiology and Pathophysiology)en_US
dc.date.accessioned2020-07-15T14:46:09Z
dc.date.available2020-07-15T14:46:09Z
dc.date.copyright2020-07-09
dc.date.issued2020en_US
dc.date.submitted2020-07-09T23:21:03Zen_US
dc.degree.disciplinePhysiology and Pathophysiologyen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractFlaxseed is one of the richest plant sources of omega-3 polyunsaturated fatty acid alpha-linolenic acid (ALA), lignan secoisolariciresinol (SDG), and dietary fiber. Dietary intake of flaxseed has been shown to suppress the progression and accelerate the regression of atherosclerotic plaques. However, the effect of flaxseed supplementation on cardiac damage induced by ischemic heart disease is not known. In the first study, myocardial infarction (MI) was induced by the surgical ligation of the left anterior descending coronary artery in rats. The addition of ground flaxseed, flax oil rich in ALA, and flax lignan rich in SDG to the diet before and after the induction of the MI decreased the incidence of arrhythmias, reduced myocardial infarct size, prevented excessive left ventricular dilatation, decreased myocardial fibrosis, and lowered the levels of inflammatory proteins and collagen compared to the untreated MI control. Dietary flax oil supplementation upregulated the expression of microRNAs 133a, 135a, and 29b which exert an antiarrhythmic, antiapoptotic and antifibrotic effect in myocardial tissue. Based on these positive results, the effect of flaxseed was further investigated in the JCR:LA-cp rat model of metabolic syndrome that naturally develops spontaneous myocardial ischemic lesions. A high-fat high sucrose diet was employed to exacerbate metabolic and cardiac dysfunction and any potential sex differences were also investigated. The lean genotype of JCR:LA-cp rats served as control animals. Dietary flaxseed supplementation reduced total cholesterol and low-density lipoprotein-cholesterol levels in obese male JCR rats. A high-fat high-sucrose diet compounded the metabolic dysfunction evident from liver injury in obese male animals. The addition of flaxseed to the diet improved liver weight and markers of hepatic injury. A high-fat high-sucrose diet increased the frequency of myocardial ischemic lesions in male and female obese JCR rats and abolished the protective effect of female sex on cardiac structure and function. Dietary flaxseed supplementation reduced myocardial ischemic lesions and improved cardiac systolic and diastolic function in JCR:LA-cp rats. Collectively, these findings in myocardial ischemia and in MIs further extend the beneficial cardiovascular effects of flaxseed. It can also be concluded that dietary flaxseed has cardioprotective potential as a therapeutic option in conditions of ischemic heart disease or cardiac complications associated with metabolic syndrome.en_US
dc.description.noteOctober 2020en_US
dc.identifier.urihttp://hdl.handle.net/1993/34781
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectIschemic heart diseaseen_US
dc.subjectFlaxseeden_US
dc.subjectOmega-3 fatty acidsen_US
dc.subjectMyocardial infarctionen_US
dc.subjectObesityen_US
dc.subjectMetabolic syndromeen_US
dc.subjectJCR:LA-cp ratsen_US
dc.titleModulation of myocardial injury by dietary flaxseeden_US
dc.typedoctoral thesisen_US
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