Expression of Peroxisome Proliferator-Activated Receptors Is Affected by Metabolic State and Bitter Melon (Momordica Charantia) Supplementation

This dissertation, "Expression of Peroxisome Proliferator-activated Receptors is Affected by Metabolic State and Bitter Melon (Momordica Charantia) Supplementation" by Hoi-man, Po, 浦愷文, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled EXPRESSION OF PEROXISOME PROLIFERATOR-ACTIVATED RECEPTORS IS AFFECTED BY METABOLIC STATE AND BITTER MELON (MOMORDICA CHARANTIA) SUPPLEMENTATION Submitted by PO HOI MAN For the degree of Master of Philosophy at The University of Hong Kong in August 2006 Compared to rats given a high fat (HF) diet, rats given HF and bitter melon (BM) had slower weight gain. The triglyceride content of the BM rats was also lower but their serum free fatty acid level was higher. This suggests that BM may alter energy metabolism. Peroxisome proliferator-activated receptors (PPARs) are transcription factors that affect an array of genes involved in energy homeostasis. Hence, we examined the hypothesis that PPARs mRNA expression is altered by BM supplementation. Since PPARs are sensitive to fasting, the effect of metabolic state on PPARs under HF diet and BM supplementation was also studied. Sprague-Dawley rats were given free access to basal (7% fat) diet, HF (30%) diet or HF diet with BM (1% w/w, HFBM). The HFBM group gained less weight than the HF one. Their energy efficiency, blood glucose level and hepatic triglyceride concentration were also found to be lower. In another experiment, rats were divided into two metabolic states, fasted and fed. This experiment confirmed that fasting increased hepatic PPAR-α expression and suppressed PPAR-γ expression in adipose tissue. The extent of reduction in PPAR-γ expression was larger under the supplementation of bitter melon (P The present results suggested that in the fasted state, bitter melon supplementation reduced adipogenesis and increased lipolysis by lowering PPAR-γ2 and perilipin expression; while in the fed state, it stimulated glucose uptake in muscle by increasing PPAR-α and β expression. DOI: 10.5353/th_b3705339 Subjects: Nuclear receptors (Biochemistry) Momordica charantia Transcription factors Peroxisomes - Receptors Gene expression Rats - Physiology