Excessive fat deposition compromises the health of companion animals and the carcass quality of food-producing livestock. Follicle-stimulating hormone (FSH) has been demonstrated to play a critical regulatory role in fat deposition, with its function dependent on binding to its cognate receptor (FSHR) in target organs. In this study, female Sprague-Dawley (SD) rats were immunized with subunit vaccines targeting FSHβ and FSHR, respectively, and obesity was induced by a high-fat diet (HFD) to investigate the effects of these vaccines on adipose deposition in female mammals. The results revealed that active immunization against FSHβ and FSHR effectively suppressed HFD-induced obesity and the elevated serum triglyceride levels. Histological observations found that FSHβ and FSHR immunity decreased adipocyte hypertrophy and increased the cross-sectional area of skeletal muscle fibers caused by HFD, partially ameliorated HFD-associated hepatic sinusoidal spaces and vacuolated steatosis in the cytoplasm. RT-qPCR results indicated that FSHβ and FSHR immunization inhibited lipid synthesis by downregulating adipogenic-related genes, including C/ebpα, Creb, Pparγ, Lpl, and Perilipin. These findings suggest that both vaccines can mitigate HFD-induced adipose deposition in rats, with the FSHR vaccine exhibiting more pronounced effects. This study provides a novel strategy to mitigate pet health deterioration caused by excessive obesity and the decline in carcass quality of food-producing livestock.
