Browsing by Author "Kroukamp, Marlouw"

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    The effect of chronic ingestion of afriplex grt™ on myocardial insulin resistance and mitochondrial function – a preclinical study.
    (Stellenbosch : Stellenbosch University, 2018-03) Kroukamp, Marlouw; Huisamen, Barbara; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Medical Physiology.
    Introduction: Obesity is an excessive fat accumulation in the body, known to be a significant precursor to insulin resistance and type 2 diabetes. Complications associated with obesity can contribute to the development of cardiovascular disease which, in turn, is associated with abnormal mitochondrial energetics. Rooibos (Aspalathus linearis) has known antidiabetic, anti-obesity and cardiovascular benefits. We investigated these properties with a focus on mitochondrial function, using an aspalathin-rich green rooibos extract, Afriplex GRT Extract. Aims: (i) To determine whether Afriplex GRT Extract ingestion can improve the insulin resistance state elicited by a high fat diet using a rat model. (ii) To determine whether Afriplex GRT Extract ingestion has any effects on myocardial mitochondrial oxidative phosphorylation potential and the process of mitophagy Methods: Male Wistar rats were fed either a control or a high fat diet (HFD) for 16 weeks. Half of each group was treated with Afriplex GRT Extract (60mg/kg/day) from weeks 11 to 16. Body weight, food and water intake were monitored, and liver- and intraperitoneal fat (IP) weighed at sacrifice. After sacrifice, myocardial mitochondria were isolated. Half of these were used to measure respiration on an oxygraph and the other half for Western Blot analysis of proteins involved in mitophagy. In addition, hearts were freeze clamped immediately after sacrifice and used to determine levels of insulin signalling proteins. Results: The HFD caused increased body weight-, liver- and IP fat gain, and elevated leptin levels while it decreased insulin signalling protein expression (GLUT4, tAkt/PKB and tAMPK). Ingestion of Afriplex GRT Extract diminished the weight gain, liver weight gain, IP fat weight gain and leptin in HFD animals. Moreover, it improved oral glucose tolerance in control animals and, according to a borderline significance in a HOMA-IR calculation, insulin resistance in the control animals. However, an increased basal glucose level was seen in HFD animals treated with Afriplex GRT Extract. Afriplex GRT Extract improved mitochondrial coupling efficiency in HFD animals and oxidative phosphorylation in control animals. Afriplex GRT Extract decreased mitochondrial p62 and cytosolic Beclin-1 levels and BNIP3 dimerization in the mitochondria of the control animals, while increasing autophagic flux (LC3-II expression) in hearts from HFD animals. A decrease in Sesn2 levels indicated possible anti-oxidant effects. Conclusion: We conclude that Afriplex GRT Extract resulted in less weight gain in HFD animals, improved whole-body insulin sensitivity and enhanced mitochondrial function. At the dose used, no detrimental effects were observed.