Abstract：The metabolism of adipose tissue is known to regulated by gonadal steroid hormones such as testosterone. Castrated and intact male pigs(Sus scrofa) demonstrate striking difference in body fatness, but up to now, the molecular mechanisms underlying such difference are still not clear. To determine whether the increased body fat mass in castrated male pigs is associated with the changes of gene expression in adipose tissues, we compared the mRNA expression levels of genes related to fat deposition in both subcutaneous and abdominal fat adipose tissue depots between intact and castrated male pigs using Real-time PCR method. Moreover, effects of castration on body fatness trait and serum hormones concentrations were also investigated in the present study. The results showed that castration could significantly reduce serum testosterone concentrations (P<0.01), while serum leptin concentrations were significantly increased by castration in male pigs (P<0.01). The castrated male pigs had lower body weight compared to the intact male pigs (120.6±4.77) kg vs (133.29±7.25) kg(P<0.05), but the levels of adiposity were higher in castrated male pigs than in intact male pigs. For example, the carcass fat weight, leaf fat weight, back fat thickness at shoulder and back fat thicknesses at buttock were all significantly higher in castrated male pigs than those in intact male pigs (P<0.05). Additionally, castration of male pigs caused a significant increase in peroxisome proliferator-activated receptor γ(PPARγ), fatty acid synthase(FAS), acety-CoA carboxylase(ACC), steraroyl-CoA desaturase(SCD) and malic enzyme 1(ME1) mRNA expression in subcutaneous fat adipose tissue (SAT) (P<0.05). The mRNA expression levels of sterol regulatory binding protein-1C (SREBP-1C) gene was not significant different in SAT adipose tissue between intact and castrated male pigs (P>0.05). The expression changes of lipogenic genes in castrated male pigs were different between adipose tissue depots. In abdominal fat adipose tissue (ATT), only the mRNA expression levels of FAS and ACC genes were significantly induced by castration in male pigs (P<0.05). However, no significant changes of PPARγ, SREBP-1C, SCD and ME1 mRNA expression level in AAT adipose tissue were induced by castration in male pigs (P>0.05). In conclusion, our results demonstrated that castration could increased body fat accumulation in male pigs, and castrated male pigs had higher expression levels of PPARγ, FAS, ACC, SCD and ME1 in both SAT and ATT adipose tissue. These results suggest that the increased fat accumulation in castrated male pigs is partly caused by the increased of expression levels of lipogenic genes in adipose tissues.
