The Developmental Changes and Effect on IMF Content of H-FABP and PPARγ mRNA Expression in Sheep Muscle

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Male Kazak sheep and Xinjiang fine wool sheep of different ages were selected to investigate the developmental changes and effect on intramuscular fat (IMF) content of heart fatty acid-binding protein ( H-FABP) and peroxisome proliferator-activated receptor γ ( PPARγ) mRNA expression in muscle. Longissimus dorsal muscle was sampled to measure IMF content; and total RNA was extracted to determine H-FABP and PPARγ mRNA expression levels by real-time PCR. The results showed that: (1) The IMF content increased continuously with growing and showed significant differences ( P<0.05) between ages in male Kazak sheep, but no such differences ( P>0.05) existed in Xinjiang fine wool sheep. Furthermore, the IMF content in Kazak sheep was very much higher ( P<0.01) than that of the other breed from day 30 to 90; (2) H-FABP mRNA expression level was the highest on day 2 and showed significant differences ( P<0.05) between ages in male Kazak sheep as well as in Xinjiang fine wool sheep. In the former breed, the expression reached the lowest point at day 30, and then rose continuously. But in the latter breed, it declined continuously from day 2 to 90, and then increased; (3) Significant differences ( P<0.05) of PPARγ mRNA expression between ages occurred in both breeds. In male Kazak sheep, PPARγ mRNA expression declined from day 2 to 90, while in the other breed it increased continuously from day 2 to 60, but reached the lowest level at day 90, then increased; (4) In male Kazak sheep, the mRNA expression level of H-FABP was highly positively correlated ( r=0.737, P<0.01) with IMF content from day 30 to 90, but that of PPARγ was highly negatively correlated ( r=−0.835, P<0.01) with IMF content from day 2 to 90.