Leptin's Crucial Modulatory Role in Regulating Body Mass Homeostasis of High- Fat- Fed Striped Field Mice (Apodemus Agrarius)：Insight into the Physiology and Biochemistry

Abstract

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, digestive metrics, and physiological parameters of food consumption and energy metabolism 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 the 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 uncoupling protein 1 content, T45'-deiodinaseII activity, and cytochrome C oxidase activity in brown adipose tissue, increased serum triiodothyronine, 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.

Note:
Funding declaration: This work was supported by the Basic Research Program of Shanxi Province, China (Project No. 202303021221093 and 202303021212109); China Postdoctoral Science Foundation Funded Project (Project No. 2024M761890); Excellent Doctoral Award of Shanxi Province for Scientific Research (Project No. SXBYKY2022123), and the Grant from Shanxi Agricultural University (Project No. 2023BQ46, 2023BQ47, and ZBXY23B-14) , and Cute pet · Ingenuity: Flower branch rat daily and specimen art co-creation.

Conflict of Interests: The authors declare no competing financial interests.

Ethical Approval: All animal operations follow the guidelines established by the Animal Care and Use Committee of Shanxi Agricultural University's College of Veterinary Medicine. The committee approved this study.

Keywords: Apodemus agrarius, leptin, body mass, high-fat food, AMPK