tropisetron and Obesity

Obesity is a major cause for nonalcoholic fatty liver disease (NAFLD). Previous studies suggested that alterations in intestinal motility and permeability contribute to the development of NAFLD. Serotonin and serotonin receptor type 3 (5-HT(3)R) are key factors in the regulation of intestinal motility and permeability. Therefore, we studied the effect of the 5-HT(3)R antagonists tropisetron and palonosetron on the development of NAFLD in leptin-deficient obese mice. Four-week-old ob/ob mice and lean controls were treated for 6 weeks orally with tropisetron or palonosetron at 0.2 mg/kg per day. We determined markers of liver damage and inflammation, portal endotoxin levels, and duodenal concentrations of serotonin, serotonin-reuptake transporter (SERT), occludin, and claudin-1. Tropisetron treatment significantly reduced liver fat content (-29%), liver inflammation (-56%), and liver cell necrosis (-59%) in ob/ob mice. The beneficial effects of tropisetron were accompanied by a decrease in plasma alanine aminotransferase and portal vein plasma endotoxin levels, an attenuation of enhanced MyD88 and tumor necrosis factor-α mRNA expression in the liver, and an increase of tight junction proteins in the duodenum. Tropisetron treatment also caused a reduction of elevated serotonin levels and an increase of SERT in the duodenum of ob/ob mice. Palonosetron had similar effects as tropisetron with regard to the reduction of liver fat and other parameters. Tropisetron and palonosetron are effective in attenuating NAFLD in a genetic mouse model of obesity. The effect involves the intestinal nervous system, resulting in a reduction of endotoxin influx into the liver and subsequently of liver inflammation and fat accumulation.

Topics: Actins; Animals; Azo Compounds; Drug Evaluation, Preclinical; Duodenum; Endotoxins; Fatty Liver; Indoles; Inflammation; Isoquinolines; Leptin; Liver; Mice; Mice, Obese; Non-alcoholic Fatty Liver Disease; Obesity; Palonosetron; Proteins; Quinuclidines; Serotonin; Serotonin 5-HT3 Receptor Antagonists; Tropisetron; Tumor Necrosis Factor-alpha

Sugar consumption has increased markedly over the last few decades and parallels the dramatic increase in overweight and obesity. Data obtained from animal studies suggest that the intestinal serotonergic system and herein particularly the serotonin receptor 3 (5-HT3R) may be involved in sugar detection and short-term control of food intake. Using a mouse model, we tested the hypothesis that blocking 5-HT3R prevents the development of sugar-induced obesity.. For 8 weeks, C57BL/J6 mice were offered either water containing 30% glucose or plain water in addition to normal chow. The effect of oral treatment with the 5-HT3R antagonist, tropisetron (0.2 mg kg(-1) body weight), on body weight and caloric intake was studied.. Total caloric intake and weight gain were significantly increased in mice fed glucose compared with the control group. Tropisetron treatment reduced intestinal motility and almost completely blocked weight gain associated with glucose feeding; however, total caloric intake was not affected. The effect of tropisetron was not associated with a decreased expression of the intestinal and hepatic glucose transporters, SGLT1 (sodium-dependent glucose cotransporter) and Glut2 (glucose transporter 2); instead, the expression of these transporters was slightly increased by the 5-HT3R antagonist. However, expressions of carbohydrate responsive element binding protein and fatty acid synthase, as well as triglyceride levels in the liver were only enhanced in mice fed glucose, but remained unchanged at the level of the control group when mice were treated concomitantly with tropisetron. At the same time, beta-hydroxybutyrate dehydrogenase mRNA expression and plasma levels of ketone bodies were significantly increased.. Our results suggest that 5-HT3R is a new target for the modulation of hepatic glucose metabolism and for the prevention of obesity.

Topics: Animals; Body Weight; Gastrointestinal Motility; Glucose; Glucose Transport Proteins, Facilitative; Indoles; Mice; Mice, Inbred C57BL; Obesity; RNA, Messenger; Serotonin Antagonists; Tropisetron; Weight Gain