Meta-Analysis of Experimental Studies of Diet-Dependent Effects of Melatonin Monotherapy on Body Weight Gain and Eating Behavior in Rats.

In a previous meta-analysis, we showed that long-term melatonin administration minimizes diet-induced changes in lipid profiles. The present work was aimed to use a meta-analysis to study the diet-denendent effect of melatonin monotherapy on body weight gain (BWG) and eating behavior in rats. We carried out a meta-analysis of 43 publications examining the effects of melatonin monotherapy on BWG, blood leptin levels, food and water intake in rats fed a standard diet (37 publications), as well as high-fructose (5 publications) and high-fat (9 publications) diets. Our findings suggest that although melatonin reduced triglyceride, total cholesterol and leptin levels in rats fed high-fructose and high-fat, but not a standard, diets, melatonin therapy prevented BWG in rats on either diet. Increasing the dose of melatonin did not enhance the effect of therapy on any diet. We did not obtain convincing evidence that the effect of melatonin depends on the initial body weight and age of rats. On a standard diet, melatonin has been found to reduce food and water intake. Melatonin did not reduce BWG with a standard diet when administered intraperitoneally. Our research suggests that melatonin may be beneficial in diet-induced metabolic disorders as it improves lipid profiles and prevents BWG. However, a decrease in appetite and BWG when taking melatonin may also be due to negative side effects of the drug, which requires further research. [ABSTRACT FROM AUTHOR]