Green tea polyphenols ameliorate metabolic abnormalities and insulin resistance by enhancing insulin signalling in skeletal muscle of Zucker fatty rats.

Cheng, J; Tan, Y; Zhou, J; Xiao, L; Johnson, M; Qu, X

Green tea polyphenols ameliorate metabolic abnormalities and insulin resistance by enhancing insulin signalling in skeletal muscle of Zucker fatty rats.

Cheng, J Tan, Y Zhou, J Xiao, L Johnson, M Qu, X

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Publisher:: Portland Press Ltd.
Publication Type:: Journal Article
Citation:: Clinical science (London, England : 1979), 2020, 134, (10), pp. 1167-1180
Issue Date:: 2020-05

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Field	Value	Language
dc.contributor.author	Cheng, J
dc.contributor.author	Tan, Y
dc.contributor.author	Zhou, J
dc.contributor.author	Xiao, L
dc.contributor.author	Johnson, M
dc.contributor.author	Qu, X
dc.date.accessioned	2021-03-02T00:38:02Z
dc.date.available	2020-05-18
dc.date.available	2021-03-02T00:38:02Z
dc.date.issued	2020-05
dc.identifier.citation	Clinical science (London, England : 1979), 2020, 134, (10), pp. 1167-1180
dc.identifier.issn	0143-5221
dc.identifier.issn	1470-8736
dc.identifier.uri	http://hdl.handle.net/10453/146609
dc.description.abstract	In the present study, we evaluated the metabolic effects of green tea polyphenols (GTPs) in high-fat diet (HFD) fed Zucker fatty (ZF) rats, in particular the effects of GTP on skeletal muscle insulin sensitivity. Body weight, visceral fat, glucose tolerance, lipid profiles and whole-body insulin sensitivity were measured in HFD-fed ZF rats after 8-week-treatment with GTP (200 mg/kg of body weight) or saline (5 ml/kg of body weight). Zucker lean rats were studied as controls. Ex vivo insulin-mediated muscle glucose uptake was assessed. Immunoblotting was used to evaluate the expression of key insulin signalling proteins in skeletal muscle. GTP treatment attenuated weight gain (P<0.05) and visceral fat accumulation (27.6%, P<0.05), and significantly reduced fasting serum glucose (P<0.05) and insulin (P<0.01) levels. Homoeostasis model assessment of insulin resistance (HOMA-IR), a measure of insulin resistance, was lower (P<0.01) in GTP-treated animals compared with ZF controls. Moreover, insulin-stimulated glucose uptake by isolated soleus muscle was increased (P<0.05) in GTP-ZF rats compared with ZF-controls. GTP treatment attenuated the accumulation of ectopic lipids (triacyl- and diacyl-glycerols), enhanced the expression and translocation of glucose transporter-4, and decreased pSer612IRS-1 and increased pSer473Akt2 expression in skeletal muscle. These molecular changes were also associated with significantly decreased activation of the inhibitory (muscle-specific) protein kinase (PKC) isoform, PKC-θ. Taken together, the present study has shown that regular ingestion of GTP exerts a number of favourable metabolic and molecular effects in an established animal model of obesity and insulin resistance. The benefits of GTP are mediated in part by inhibiting PKC-θ and improving muscle insulin sensitivity.
dc.format	Print
dc.language	eng
dc.publisher	Portland Press Ltd.
dc.relation	Zunyi Lusheng Health-Source Science & Technology Development Co., Ltd (China)
dc.relation.ispartof	Clinical science (London, England : 1979)
dc.relation.isbasedon	10.1042/cs20200107
dc.rights	info:eu-repo/semantics/closedAccess
dc.subject	11 Medical and Health Sciences
dc.subject.classification	Cardiovascular System & Hematology
dc.subject.mesh	Muscle, Skeletal
dc.subject.mesh	Animals
dc.subject.mesh	Rats, Zucker
dc.subject.mesh	Insulin Resistance
dc.subject.mesh	Body Weight
dc.subject.mesh	Insulin
dc.subject.mesh	Isoenzymes
dc.subject.mesh	Protein Kinase C
dc.subject.mesh	Glucose
dc.subject.mesh	Muscle Proteins
dc.subject.mesh	Glucose Tolerance Test
dc.subject.mesh	Signal Transduction
dc.subject.mesh	Protein Transport
dc.subject.mesh	Phosphorylation
dc.subject.mesh	Tea
dc.subject.mesh	Male
dc.subject.mesh	Intra-Abdominal Fat
dc.subject.mesh	Adiposity
dc.subject.mesh	Glucose Transporter Type 4
dc.subject.mesh	Polyphenols
dc.subject.mesh	Adiposity
dc.subject.mesh	Animals
dc.subject.mesh	Body Weight
dc.subject.mesh	Glucose
dc.subject.mesh	Glucose Tolerance Test
dc.subject.mesh	Glucose Transporter Type 4
dc.subject.mesh	Insulin
dc.subject.mesh	Insulin Resistance
dc.subject.mesh	Intra-Abdominal Fat
dc.subject.mesh	Isoenzymes
dc.subject.mesh	Male
dc.subject.mesh	Muscle Proteins
dc.subject.mesh	Muscle, Skeletal
dc.subject.mesh	Phosphorylation
dc.subject.mesh	Polyphenols
dc.subject.mesh	Protein Kinase C
dc.subject.mesh	Protein Transport
dc.subject.mesh	Rats, Zucker
dc.subject.mesh	Signal Transduction
dc.subject.mesh	Tea
dc.title	Green tea polyphenols ameliorate metabolic abnormalities and insulin resistance by enhancing insulin signalling in skeletal muscle of Zucker fatty rats.
dc.type	Journal Article
utslib.citation.volume	134
utslib.location.activity	England
utslib.for	11 Medical and Health Sciences
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Strength - CCET - Centre for Clean Energy Technology
pubs.organisational-group	/University of Technology Sydney/Strength - CHT - Health Technologies
utslib.copyright.status	closed_access	*
dc.date.updated	2021-03-02T00:38:00Z
pubs.issue	10
pubs.publication-status	Published
pubs.volume	134
utslib.citation.issue	10

Abstract:

In the present study, we evaluated the metabolic effects of green tea polyphenols (GTPs) in high-fat diet (HFD) fed Zucker fatty (ZF) rats, in particular the effects of GTP on skeletal muscle insulin sensitivity. Body weight, visceral fat, glucose tolerance, lipid profiles and whole-body insulin sensitivity were measured in HFD-fed ZF rats after 8-week-treatment with GTP (200 mg/kg of body weight) or saline (5 ml/kg of body weight). Zucker lean rats were studied as controls. Ex vivo insulin-mediated muscle glucose uptake was assessed. Immunoblotting was used to evaluate the expression of key insulin signalling proteins in skeletal muscle. GTP treatment attenuated weight gain (P<0.05) and visceral fat accumulation (27.6%, P<0.05), and significantly reduced fasting serum glucose (P<0.05) and insulin (P<0.01) levels. Homoeostasis model assessment of insulin resistance (HOMA-IR), a measure of insulin resistance, was lower (P<0.01) in GTP-treated animals compared with ZF controls. Moreover, insulin-stimulated glucose uptake by isolated soleus muscle was increased (P<0.05) in GTP-ZF rats compared with ZF-controls. GTP treatment attenuated the accumulation of ectopic lipids (triacyl- and diacyl-glycerols), enhanced the expression and translocation of glucose transporter-4, and decreased pSer612IRS-1 and increased pSer473Akt2 expression in skeletal muscle. These molecular changes were also associated with significantly decreased activation of the inhibitory (muscle-specific) protein kinase (PKC) isoform, PKC-θ. Taken together, the present study has shown that regular ingestion of GTP exerts a number of favourable metabolic and molecular effects in an established animal model of obesity and insulin resistance. The benefits of GTP are mediated in part by inhibiting PKC-θ and improving muscle insulin sensitivity.

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