Effects of Dietary Restriction on Regulation of Energy Metabolism in Male Wistar Rats (Rattus norvegicus)

Laboratory rats are most often fed ad libitum (AL), but dietary restriction (DR) is commonly used to provide appropriate experimental designs. The current methods of DR have shortcomings; animals are often subjected to social isolation, periods of fasting, and disturbed diurnal eating rhythms. The diet board was developed to solve these problems. The diet board offers the possibility of combining group housing with moderate DR without disturbing diurnal eating rhythms or subjecting animals to periods of fasting. In this study, the diet board's validity as a DR method was investigated by assessing possible endocrine effects associated with the previously observed decreases in weight gain and adiposity. Male Wistar rats (n = 30/group) were housed in groups of 3 and fed either with the diet board or AL over a 10-wk study period. Serum ghrelin, leptin, insulin, and adiponectin concentrations and liver triglyceride content and their variance were measured at the end of the study. The diet board showed no reduction potential in energy metabolism parameters. In the serum levels of the adiposity-related hormones leptin, insulin, and adiponectin or liver triglycerides, no statistically significant differences were found. In contrast, levels of ghrelin were significantly lower in the DR rats compared with the controls. In conclusion, diet board feeding induces mild hormonal compensatory changes, thus offering an alternative method of moderate DR in group-housed rats.