Role of leptin on body mass in high fat feeding striped field mouse (Apodemus agrarius)

Leptin is a hormone that regulates a variety of physiological processes. To investigate into the role of leptin in body mass in high-fat-fed animals. Male striped field mice (Apodemus agrarius) fed high-fat diets were given leptin (0.5μg/g.d) via intraperitoneal injection for 28 days. Their body mass, food intake, daily fecal output, apparent digestibility, hormone and enzyme activity, and hypothalamic neuropeptide expression were compared to those of the control and high-fat food groups, which received PBS injections. Firstly, it is worth noting that the high-fat diet did not cause weight gain in A. agrarius, and the animals on the diet ate less and had higher apparent digestibility. Furthermore, compared to animals fed a high-fat diet, peripheral leptin injection in A. agrarius reduced food intake, increased fecal content, and reduced apparent digestibility. Additionally, peripheral leptin injection inhibits the activity of AMPK in the hypothalamus, increased the activity of malonyl-CoA, inhibits the expression of phagotrophic neuropeptide mRNA, promoted the expression of phagotrophic neuropeptide mRNA, and thus reduces food intake and weight. Finally, exogenous leptin injection increased UCP1 protein content, T45'-DII activity, and COX activity in BAT, increased serum T3, and increased animal energy consumption. In conclusion, our data indicate that leptin affects body mass in animals on a high-fat diet in two ways: by inhibiting food intake and increasing energy expenditure.