Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Pathophysiol. Nov 15, 2015; 6(4): 110-119
Published online Nov 15, 2015. doi: 10.4291/wjgp.v6.i4.110
New-found link between microbiota and obesity
Chandra Kanti Chakraborti
Chandra Kanti Chakraborti, Department of Pharmacology, Kanak Manjari Institute of Pharmaceutical Sciences, Rourkela 769015, Orissa, India
Author contributions: Chakraborti CK designed research, performed research, contributed new reagents or analytic tools, analyzed data and wrote the paper.
Conflict-of-interest statement: The author has no conflict of interests.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Chandra Kanti Chakraborti, Professor, Department of Pharmacology, Kanak Manjari Institute of Pharmaceutical Sciences, Chhend, Rourkela 769015, Orissa, India. chandrakanti_12@rediffmail.com
Telephone: +91-661-2480752 Fax: +91-661-2480752
Received: May 26, 2015
Peer-review started: May 29, 2015
First decision: June 18, 2015
Revised: September 26, 2015
Accepted: October 20, 2015
Article in press: October 27, 2015
Published online: November 15, 2015

Due to the grave pathological role of obesity, worldwide research is being continued to find out the causative factors involved in it. Recent advances in this field reveal a possible relationship between the compositional pattern of gut microbiota and genesis of obesity. Several study results have shown that short-chain fatty acids (SCFAs, microbiota-induced fermentation products) and lipopolysaccharides (LPS, an integral component of Gram negative microorganisms) play the key role in linking the two. Though several SCFAs are produced as microbiota-fermentation products, three of them, i.e., butyrate, propionate and acetate have been found to be definitely involved in obesity; though individually they are neither purely obesogenic nor antiobesogenic. Out of these, butyrate and propionate are predominantly antiobesogenic. Butyrate, though a major energy source for colonocytes, has been found to increase mitochondrial activity, prevent metabolic endotoxemia, improve insulin sensitivity, possess anti-inflammatory potential, increase intestinal barrier function and protect against diet-induced obesity without causing hypophagia. Propionate has been found to inhibit cholesterol synthesis, thereby antagonizing the cholesterol increasing action of acetate, and to inhibit the expression of resistin in adipocytes. Moreover, both these SCFAs have been found to cause weight regulation through their stimulatory effect on anorexigenic gut hormones and to increase the synthesis of leptin. Unlike butyrate and propionate, acetate, which is substantially absorbed, shows more obesogenic potential, as it acts as a substrate for hepatic and adipocyte lipogenesis. High fat diet increases the absorption of LPS, which, in turn, has been found to be associated with metabolic endotoxemia and to induce inflammation resulting in obesity. Multiple independent and interrelated mechanisms have been found to be involved in such linking processes which are discussed in this review work along with some possible remedial measures for prevention of weight gain and obesity.

Keywords: Microbiota, Obesity, Butyrate, Propionate, Acetate

Core tip: The objective of this article is to relate gastrointestinal microbiota with obesity positively. This idea itself is most innovative. In this article, probable mechanisms involved in relating microbiota with obesity have been discussed. Its key findings are: (1) The gut microbiota play a definite role both in genesis and retardation of obesity; (2) Microbiota-derived lipopolysaccharides and short-chain fatty acids mediate the obesogenic action; (3) Fatty diet not only adds calories but also shifts microbiota compositional pattern in favour of obesity; and (4) The obesogenic actions are mediated through receptor activation, modification of cytokine and endocrine function and gene expression.