Age-related changes of serum leptin, insulin, IGF-I and thyroid hormones levels in growing Jinhua and Landrace gilts

Abstract

The present study was aimed to investigate the age-related changes of the serum IGF-I, leptin, insulin, triiodothyronine (T 3 ) and thyroxine (T 4 ) levels in pigs of different breeds. Jinhua and Landrace gilts were sampled at 35, 80 and 125 days of age, respectively. Serum hormone levels were measured with RIA. Serum IGF-I, leptin levels increased with age and displayed breed differences. Jinhua gilts showed lower (P<0.05) serum IGF-I and higher (P<0.05) leptin levels compared with Landrace gilts. In contrast, serum T 3 , T 4 levels decreased with age, Jinhua gilts had lower serum T 4 levels at 80 days of age. Meanwhile, Jinhua gilts had higher (P<0.01) serum insulin levels. Serum leptin, IGF-I, insulin and T 4 levels correlated with carcass fat content (P<0.05), which suggested that the breed differences of serum hormone levels may contribute to the different phenotypes in adipose tissue deposition.

Mapping, expression and regulation of the TRα gene in porcine adipose tissue

“…In our study, the mRNA levels of TRa in subcutaneous adipose tissue were associated with the fat percentage, Jinhua pigs had significantly lower TRa mRNA expression levels compared to Yorkshire pigs. Miao et al (2008) also found a negative relationship between serum thyroid hormone levels and carcass fat content of pigs. These results indicate that thyroid hormone and its receptor TRa may have a negative relationship with body adiposity in growing pigs, and subcutaneous fat expression of TRa may directly influence functions of adipocytes.…”