| During lactation, lactating animals have an increasing demand for calcium, at this time,which cause the hypocalcemia disease easily. Hypocalcemia is most likely to occur in the metabolic disorders for multiparous dairy goat, and has brought great loss to the dairy goat industry serotonin(5-HT) is a recently discovered regulator of bone turnover during lactation.Tryptophan hydroxylase(TPH) is the rate-limiting enzyme in the biosynthesis of 5-HT by converting tryptophan to 5-hydroxy-L-tryptophan(5-HTP). Research finds that 5-HT regulates the expression of PTHrP by activating Hedgehog(Hh) signaling pathway in mouse.Parathyroid hormone related protein(PTHrP) is a key gene for a regulating calcium transport and is closely related to calcium ion metabolism process. Our laboratory group has indicated that overexpression of PTHrP can regulate Ca2 + in goat mammary epithelial cells. At present,the mechanism of 5-HT and PTHrP in regulating Ca2+ in dairy goat is still not clear.Therefore, we studied the relationship between PTHrP and 5-HT, and the effect of 5-HT on the expression of calcium transport key genes(CaSR,SERCA2,PMCA1,SPCA1 and SPCA2) in dairy goats mammary epithelial cells.The main results are as follows:(1)After obtaining the serum of perinatal period goats, the concentration of 5-HT, PTHrP and Ca2+ were detected. We found that, postpartum 5-HT, PTHrP and Ca2+ concentrations increased significantly(P <0.05). The results showed that the linear relationship between 5-HT and PTHrP was presented using linear equation: y=0.12x+71, correlation coefficient r=0.86(P<0.01); There is a positive correlation between the concentration of 5-HT and Ca2+, the curve equation is: y=2.24(1-e-0.0006x), correlation coefficientr=0.966(P<0.01); The correlation between PTHrP and Ca2+, curve equation: y=2.3(1-e-0.005x), correlation coefficient r=0.902(P<0.01); The results indicated that there is a positive correlation between 5-HT and PTHrP concentration in periparturient dairy goat blood.(2)The goat mammary epithelial cells were treated with 5-HTP and TPH1-Capra-1274 respectively, and we found the mRNA and protein levels of PTHrP increased(P < 0.05).GMECs treated with siRNA, the mRNA and protein levels of PTHrP reduced(P <0.05). Thus,these results showed that 5-HT promoted PTHrP expression in mRNA and protein levels.(3)The goat mammary epithelial cells were treated with 5-HTP and TPH1-Capra-1274 for 24h respectively, and the mRNA levels of calcium transporter gene(CaSR, PMCA1,SERCA2, SPCA1 and SPCA2) were detected.The results showed that: 5-HT promoted the expression of CaSR and inhibited the expression of PMCA1. However 5-HT had no effect on the mRNA level expressions of SPCA1, SPCA2 and SERCA2(P >0.05).In a word, In the serum of perinatal dairy goats, the results indicated that there is a positive correlation between 5-HT and PTHrP concentration in periparturient dairy goat blood and compared with antepartum, postpartum 5-HT, PTHrP and Ca2+ concentrations increased significantly.5-HT promoted PTHrP expression in mRNA and protein levels.5-HT promoted the expression of CaSR and inhibited the expression of PMCA1. |
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