Expression of the insulin-like growth factor system in skeletal muscle during embryonic and postnatal development in the first filial generation pigs from Erhualian and Yorkshire reciprocal crosses.

In this study, we detected the expression of IGF-I, IGF-II, IGF-IR, IGF-IIR, and IGFBP-3 mRNA at 50 (E50), 70 (E70), and 90 (E90) days of gestation, and 1 (D1), 20 (D20), 70 (D70), 120 (D120), and 180 (D180) days of age in the longissimus dorsi (LD) and the semitendinosus (ST) of pigs from a Yorkshire boar×Erhualian sow (YE) cross as well as a Erhualian boar×Yorkshire sow (EY) cross. We found that the expression of IGF-I and IGF-II mRNA in skeletal muscle tissues differed based on developmental age and reciprocal cross type (P<0.05). The expression of IGF-I mRNA exhibited a fluctuant ascending trend. In contrast, IGF-II showed a fluctuant descending trend after birth. The levels of IGF-IR mRNA were higher before birth compared with after birth except for the ST of EY pigs at D120 (P<0.05). The expression of IGF-IIR and IGFBP-3 mRNA remarkably changed with age and reciprocal cross type (P<0.05). IGF-I, IGF-II, and IGFBP-3 mRNA were positively correlated with IGF-IR from 50E to 180D. These data suggest that the expression of IGF-system genes exhibits specific developmental patterns in the skeletal muscle tissues of pigs from reciprocal crosses at different developmental stages and may show linked expression during certain periods of development. Our results may provide a valuable resource for the molecular breeding of pigs. Crown