Study On The Developmental Changes Of The Genes Related To Intramusculat Fat Expression Level In Muscles In Hu Sheep And Association With Intramusculat Fat Content

The objectives of this study were to investigate the developmental changes of adipocyte differentiation,accumulation and metabolize genes mRNA expression in different part of muscles in Hu sheep and its effect on intramuscular fat(IMF) accumulation. Male Hu lamb at 0 to 6 months old and male Hu grown sheep were selected to investigate the developmental changes of these genes mRNA expression and its effect on intramuscular fat content in four different part of muscles.Five animals were slaughtered at 0,1,2,3,4, 5,6 months and thirteen animals were slaughtered at grown sheep to collect samples from longissimus dorsi muscle,Psoas major muscle,biceps femoris muscle,biceps brachii muscle for the purpose of determining the IMF content and extracting total RNA in order to investigate the developmental changes of these genes mRNA expression by real-time PCR. The results were as follows:1)With growing,the IMF content increased with the progress of development,the term of 4-5 month was the most time for IMF accumulation in Hu lamb,then IMF content kept steadily level in grown Hu sheep.Longissimus dorsi muscle and psoas major muscle were higher than biceps femoris muscle(p＜0.05) at the same age.2)With growing,adipocyte differentiation genes PPARγ,ADD1 andC/EBPαmRNA expression were different patterns in different part of muscles at 0-6 months Hu lamb and grown Hu sheep,but their common ground was increasing-decreasing.①For PPARγmRNA expression,in longissimus dorsi muscle its mRNA expression was highest(p＜0.01) on 4 month,then continued declining and kept steadily level;In Psoas major muscle and biceps femoris muscle,its mRNA expression presented increasing-decreasing-increasing-decreasing with growing;In biceps brachii muscle,its mRNA expression was highest(p＜0.01) on 5 month.②ADD1 mRNA expression was a similar pattern in different part of muscles with growth,its mRNA expression was highest on 3 month,then decreasing.Whereas in longissimus dorsi muscle its mRNA expression was no significant changes with growing.③C/EBPαmRNA expression was a different pattern in different part of muscles with growth.In longissimus dorsi muscle its mRNA expression was highest(p＜0.01) on 3 month, then continued decreasing and its expression was lowest on grown Hu sheep;From 0-5 monthC/EBPαmRNA expression was no significant differences,on 6 month its mRNA expression was highest,whereas in grown Hu sheep its mRNA expression was lowest;In biceps femoris muscle,its mRNA expression was highest(p＜0.01) on 3 month,then decreased on 4 month,ascended on 5 month and continued decreasing;In biceps brachii muscle,its mRNA expression presents increasing-decreasing-increasing-decreasing.On 5 month the level was the highest and significantly higher than 0,3 month and grown sheep(p＜0.05),then in grown Hu sheep its mRNA expression was the lowest.In the same month PPARγ,ADD1 andC/EBPαmRNA expression have no significant differences in four different part of muscles in Hu sheep,excepting several months.In the early to old development stage,PPARγand ADD1 mRNA expression were negatively related to IMF content.C/EBPαmRNA expression was positively related to IMF content.3) H-FABP mRNA expression was different in different part of muscles from 0 month to grown in Hu sheep and has tissues-dependent.In longissimus dorsi muscle and Psoas major muscle their mRNA expression was highest(p＜0.01) on 2 month in Hu sheep,presenting increasing-declining-increasing-declining with growth;In biceps femoris muscle and biceps brachii muscle,their mRNA expression were same model and on 1 month the levels were the highest.In the same month H-FABP mRNA expression have no significant differences in four different part of muscles in Hu sheep,excepting 2,3 months. In longissimus dorsi muscle,Psoas major muscle,biceps femoris muscle,H-FABP mRNA expression was positively related to IMF content,it showed that the H-FABP gene expression in sheep muscle may promote IMF accumulation.4) The hypothalamus MC4R mRNA expression was steadily from birth to grown Hu sheep.MC4R mRNA expression was different in different part of muscles from birth to grown Hu sheep.Model was increasing-declining,its mRNA expression was highest (p＜0.05) on 3 month(excepting Psoas major muscle).With growing MC4R mRNA expression was steadily.In the same month MC4R mRNA expression have no significant differences in four different part of muscles in Hu sheep,excepting 2,3 months.In longissimus dorsi muscle, Psoas major muscle,biceps femoris muscle,MC4R mRNA expression was negatively related to IMF content,it showed that the MC4R gene expression in sheep muscle may restrain IMF accumulation.