Relationship Between the mRNA Expression Level of TGF-β Receptor Genes in Tissues and Ovulation Rate in Hu Sheep

Eight ewes of Hu sheep which bred multi-lamb were used as the high-fecundity group and the other eight ewes of Hu sheep which bred single lamb were used as the control group to investigate the relationship between the mRNA expression level of TGF-β receptor genes in tissues and ovulation rate in Hu sheep. Cloprostenol sodium was injected to make the synchronization of estrus treatment, then all ewes were slaughtered within 24–36 h after empathema and the ovaries were collected. Furthermore, the number of ovulation points was counted to determine ovulation rate for each sheep. Tissue expression analysis was conducted by RT-PCR for one ewe form the high-fecundity group and the relationship between the mRNA expression of genes encoding TGF-β receptors and ovulation rate was detected by real-time fluorescent quantitative PCR. The results showed that the relative expression level of TGF-βR I gene in the reproductive organ was significantly higher than in the lung and muscle (P < 0.01), while relative expression level of TGF-βR II in reproductive organ was significantly higher than that of other tissues (P < 0.01), indicating that these are highly expressed genes in the ovary. In addition, mRNA expression level of TGF-βR I and TGF-βRII in the ovaries of the high-fecundity group were significantly higher (P < 0.01) and obviously higher (P = 0.011) than the control group, respectively. The mRNA expression level of TGF-βR I and TGF-βR II had a positive correlation with ovulation rate and the correlation coefficients were 0.562 (P > 0.05) and 0.711 (P < 0.05), respectively. It is suggested that TGF-β receptors have close relationship with high-fecundity in Hu sheep.