Nutrient supply enhances both IGF-I and MSTN mRNA levels in chicken skeletal muscle
2004
Guernec, A. | Chevalier, B. | Duclos, M.J.
Nutrient supply may control muscle growth directly and indirectly through its influence on regulatory factors. The present study focuses on its effects on muscle insulin-like growth factors (IGF-I and -II) and myostatin (MSTN). Their mRNA levels were quantified by real time RT-PCR in pectoralis major (PM) and sartorius (SART) muscles from broiler chickens submitted to different feeding regimens (fed or fasted for 48 h) between hatch and 2 days of age and at 4 weeks of age. In the PM of 4 weeks old broilers, mRNA levels were also evaluated after a 16 h-fast and a refeeding period (refed 24 or 48 h after a 48 h-fast). In the PM muscle, both IGF-I and MSTN mRNA levels increased between 0 and 2 days of age in the fed group, while they remained low in the unfed one. A comparable trend was observed in the SART, but with lesser amplitude. In both muscles of 4 weeks old chickens, a 48 h-fast induced a significant reduction in MSTN mRNA levels (20% of fed state). In the PM, this effect required more than 16 h of fasting to occur and was fully reversed by only 24 h of refeeding. IGF-I mRNA levels also varied with nutritional state. They decreased significantly with fasting in the SART muscle. By contrast, IGF-II mRNA levels did not vary significantly. Our data shows for the first time that two major paracrine regulators of muscle growth, IGF-I and MSTN, are sensitive to nutrient supply in hatching chicks, and also that fasting reduced IGF-I and MSTN mRNA levels in muscles of older chickens.
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