The effects of green tea derived catechins upon adipocyte metabolism.
PhD thesis, University of Nottingham.
Tea, from the plant Camellia Sinensis, is after water, the most consumed drink in the world. Green tea, produced by steaming freshly harvested leaves to prevent fermentation, is high in polyphenols known as catechins or flavanols. The major flavanols found in green tea include (-) epigallocatechin-3-gallate (EGCG) and (-) epicatechin. Literature reports suggest that green tea flavanols have the potential to exert anti-obesity effects by modulating weight gain and other factors such as lipogenesis, β-oxidation and adipokine release. Key features of obesity and associated insulin resistance are adipokine dysregulation, decreased sensitivity of adipocytes to insulin and subsequently, changes in glucose uptake by cells.
The aims of this thesis were firstly to establish an efficient system of differentiated adipocytes and secondly to use this to investigate the effects of the flavanols EGCG and epicatechin on physiological outcomes such as adipokine release and glucose uptake. Thirdly, the question of whether these processes might be regulated by the ERK1/2 pathway and what may be happening upstream of this was explored. Finally, the effect of flavanol treatment on adipocyte gene expression of genes known to be modulated in obesity was investigated.
Using the well established cell culture model of 3T3-L1 adipocytes, the studies from this thesis show that EGCG and epicatechin are able to modulate the release of the adipokines adiponectin and resistin, dependent on the media glucose concentration. This modulation may be mediated by the ERK1/2 pathway, since flavanol treatment increased ERK1/2 phosphorylation. Uptake of glucose was not altered by any time or concentration of EGCG or epicatechin, and there were no significant changes in adipocyte gene expression following EGCG or epicatechin treatment.
A thorough investigation of adipokine release, ERK signalling, glucose uptake and gene expression, under the influence of flavanol treatment, showed that although molecular changes occurred in the 3T3-L1 system, these did not translate into functional readouts. Therefore, it appears unlikely that these have major direct effects on adipocyte function.
Thesis (University of Nottingham only)
||Therapeutic use of green tea, Catechin, Fat cells, Obesity prevention, Adipocytes
||W Medicine and related subjects (NLM Classification) > WB Practice of medicine
W Medicine and related subjects (NLM Classification) > WD Disorders of systemic, metabolic or environmental origin
||UK Campuses > Faculty of Medicine and Health Sciences > School of Biomedical Sciences
||25 Jul 2011 08:16
||17 Sep 2016 13:27
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