Expression Patterns of the Cannabinoid Receptor 1 Gene in Pig Skeletal Muscle and Skeletal Satellite Muscle Cells

摘要

The Cannabinoid Receptor type 1 (CNR1) is a key component of the endocannabinoid system which has been reported to play a pivotal role in modulating feeding behavior and energy balance. While a large number of researches have showed clearly that CNR1 is expressed in skeletal muscle of mice and human beings, detailed analysis of CNR1 gene expression in pig muscles and muscle cells has not been reported. Here, quantitative PCR were used to characterize the CNR1 in different muscles of pig and isolation of porcine myogenic satellite cells. Results showed that the expression of CNR1 mRNA was greatest in longissimus dorsi muscle (p<0.01) among that in the gastrocnemius (mix), soleus muscle (slow-type) and longissimus doris muscle (fast-type). As to age-related changes of CNR1 gene in different pig muscles, the higher expression was found at the 30th day, then declined (p<0.05) in all three kinds of muscles to the 90th day. At the 150th day, the expression of CNR1 steadily decreased (p<0.05) in the gastrocnemius compared to the 90th day but not in longissimus doris muscle and soleus. Meanwhile the breed differences in the expression of CNR1 mRNA between Jinhua pig and Landrace were also identified. The mRNA abundance of CNR1 in Landrace was higher compared with that of Jinhua pigs and strong differences were observed in longissimus doris muscle (p<0.05) and soleus (p<0.01). In vitro with the differentiation of the satellite cells, the mRNA expression of the CNR1 was significantly down-regulated (p<0.05). The lowest mRNA expression was observed at the 9th day. These data provide a framework of CNR1 gene expression patterns and implicate a novel gene for regulating muscle fiber types.