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Green Tea Extract Supplementation

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Green Tea Extract Supplementation Induces the Lipolytic Pathway, Attenuates Obesity, and Reduces Low-Grade Inflammation in Mice Fed a High-Fat Diet.

Cláudio A. Cunha,1 Fábio S. Lira,2 José C. Rosa Neto,1
Gustavo D. Pimentel,3 Gabriel I. H. Souza,1 Camila Morais Gonçalves da Silva,4
Cláudio T. de Souza,2 Eliane B. Ribeiro,1 Alexandra Christine Helena Frankland Sawaya,5
Cláudia M. Oller do Nascimento,1 Bruno Rodrigues,6
Patrícia de Oliveira Carvalho,4 and Lila M. Oyama1

Te aim of this study was to evaluate the effects of green tea Camellia sinensis extract on proinflammatory molecules and lipolytic protein levels in adipose tissue of diet-induced obese mice.

Our results show that green tea increases the lipolytic pathway and reduces adipose tissue, and this may explain the attenuation of low-grade inflammation in obese mice.

Introduction

Obesity is a serious health problem in developed countries,and the prevalence of obesity has increased dramatically for several decades. Both genetic and  environmental factors are implicated in the development of obesity, in particular food overconsumption.

Being severely overweight or obese is associated with major health risks such as cardiovascular disease, diabetes, nonalcoholic fatty liver disease, and cancer. An important feature of obesity is its association with chronic low-grade inflammation. Adipose tissue is the largest endocrine organ in the body and is characterised by cytokine and chemokine production and acute-phase inflammatory signalling .

As an established in 3T3-L1 adipocyte cells comprise main features relating to innate immunity ;this stage also is known to involve the toll-like receptors (TLRs) .

Stimulation of TLRs causes an immediate defensive response, including the production of an array of antimicrobial peptides and cytokines ;this response includes adaptor molecules, such as myeloid differentiation primary response gene 88 (MyD88) and the tumour necrosis factor receptor-associated factor 6 (TRAF6) .

Te adipose tissue is involved in metabolic, physiological,and immunological regulation including the cytokines.

Adipose tissue fat stores are mainly dependent upon fatty acid (FA) supply, FA esterifcation to triglycerides (TG), and TG breakdown, or lipolysis. Adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) both have the capacity to degrade TG by cleaving the ester bond, thus governing the lipolysis pathway in adipose tissue .

Adipose tissue lipolysis has received much attention over the past 10 years because of its altered regulation in obesity. Terefore, prevention and treatment of obesity should focus on antiinflammatory effects, and various treatments have emerged, including phytoterapic therapy.

Green tea contains high levels of polyphenols, which may have a number of positive health effects in the prevention of lifestyle-related diseases . Tea is one of the most popular beverages worldwide.

Habitual consumption of green tea (Camellia sinensis), a popular beverage used in traditional Chinese medicine, has been associated with decreased risks for obesity , diabetes , hypertension , dyslipidemia , and CVD mortality  in several epidemiological studies. In selected clinical trials, green tea supplementation has been shown to  signifcantly improve features of metabolic syndrome, such as decreased abdominal adiposity indicated by waist circumference in obese subjects .

Tea and tea components have been reported to possess various biological and pharmacological effects, such as antibacterial actions  and lowering plasma lipids and glucose levels . Green tea catechins are efcacious in cell and animal models of obesity, and the proposed modes of action include: decreased adipocyte differentiation and lipogenesis; increased beta-oxidation; and decreased lipid absorption .

However, relatively little is known about the underlying mechanism of action, in the regulation of body weight, lipolytic action and its relationship with inflammatory status. Te aim of this study was to examine the effects of green tea extract on the body fat mass and lipolytic enzymes in adipose tissue of mice fed a high-fat diet and to observe whether reduction of fat mass is associated with diminished low-grade inflammation.

Discussion

Numerous studies have been conducted to increase our understanding of the cause and treatment of obesity.

In this sense, an alternative strategy is necessary such as phytotherapy treatment. Chronic systemic inflammation directly contributes to the development of obesity.For instance, overweight and obese women generally have elevated serum levels of inflammatory cytokines, such as TNF-α.Terefore, suppressing chronic inflammation may be a good strategy to prevent and/or treat obesity.

Interestingly, previous studies suggest the positive impacts of green tea polyphenols could be via its ability to suppress chronic inflammation .

In addition, the impacts of green tea consumption on weight loss have been reported in clinical  and laboratory studies .

Antiobesity effects of green tea are probably due to its capacity to elevate thermogenesis and fat oxidation. Thus, we hypothesise that green tea supplementation reduces body-fat mass by regulating lipolytic pathway-related genes; such changes will result in downregulation of cytokine production and proinflammatory molecule protein levels.

In the study, we measured body weight of the animals at the beginning and end of the study. Our results demonstrate that a high-fat diet induced body-weight gain (as observed by delta weight) and epididymal and mesenteric adipose tissue pads. However, green tea promoted a reduced delta weight and adipose tissue pads.

Further, green tea extract led to increased lipolytic pathway protein levels, adiponectin, and anti-inflammatory cytokine IL-10 and reduced proinflammatory cytokine TNF-α.The therapeutic uses of tea are confned to alternative medicine.

Although the anticarcinogenic, anti-inflammatory,and antimicrobial properties of tea have been known for many years, clinical medicine has not included its use in treatments, almost certainly due to the lack of knowledge about its exact mechanisms of action .

In human experiments, acute ingestion of green tea extract, which is mainly composed of catechins, has been reported to increase the proportion of whole-body fat utilisation by

augmenting oxidation and lipolysis . Lee et al demonstrated in an in vitro study that EGCG modulates the increase in lipolysis by directly increasing the gene expression of HSL, demonstrating its important role in lipid metabolism.

Habitual consumption green tea extract has been reported to reduce body weight and body fat ; this may occur via increased lipolysis in adipose tissue, and our data support this.

The anti-inflammatory effect of green tea has been attributed to the polyphenol content . In Asian countries, green tea, which contains a class of polyphenolsknown as tea catechins, has been habitually consumed as one of the most popular beverages. Tea polyphenols have been shown to inhibit proteasome function, thereby terminating inflammation. Although tea polyphenols have been claimed to be the most potent constituents of tea, there is increasing evidence that these compounds are not the only constituents responsible for the benefcial effects on health from tea .

Our results demonstrate that green tea is able to decrease the protein content of TNF-α in adipose tissues and stimulate lipolytic enzymes. These conditions may favour reduced body weight and adipose tissues.

In addition, we found that green tea reduced TLR4 expression, blocking roinflammatory effects. Youn et al. showed that EGCG in cultured cells of the immune system had an anti-inflammatory effect, which was partly explained by the inhibition of the TLR.

In summary, our results show that green tea extract intake increases expression of lipases, reduces adipose fat mass, and in parallel reduces inflammatory molecules and cytokines.

Futures studies are needed to better understand the mechanism involved in the enefcial effects promoted by green tea extract intake, especially in mice fed a high-fat diet.

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