Study On Plasma Leptin Level In Dairy Cows With Ketosis And Transiciptional Level Of Leptin And Leptin Receptors In Adipose Tissue

The postpartum dairy cow could develop to a so-called negative energy balance stage, which massive adipose depots were mobilized.From this point forward,the status would proceed to cause ketosis. Affected cows had poor performances in both production and fertility, more seriously, affected ones could be culled. Leptin was a kind of hormone derived from white adipose tissue,which could inhibit the feeding behavior and regulate energy balance and lipometabolism. The point of this study is to understand the relationship between plasma leptin and ketosis, along with the effect of ?- hydroxybutyric acid(BHBA), leptin, insulin on transcription of adipose leptin-related genes.Blood sample of 16 multiparous Holstein Cows around parturition were obtained weekly, beginning from week-1 to week 7.Analytic data indicated that plasma metabolic profile of ketosis was low leptin, low glucose, high ketone bodies and high NEFA level.Leptin level started to elevate after birth. During the period of postpartum week 2 to week 4, leptin level of cattle suffering from ketosis was higher than unaffected ones, but there was no significant difference between them. However ketone bodies and NEFA level was very significant higher than unaffected ones.In vitro study, mRNA level of gene leptin,ObRa,ObRb and ObRc were detected among the subcutaneous adipose, mesenteric adipose and perirenal adipose tissue, which was treated with different concentrations of BHBA(0.5,1.0,3.0,5.0 mM/L),Leptin(10,50,100 ng/ml) and Insulin(10,50,100 nM/L)respectively. ObRa mRNA was not found in the above three adipose tissue, subcutaneous adipose was the most sensitive one to BHBA. The lower BHBA dose(0.5,1.0 mM/L) upregulated leptin, ObRb and ObRc very significantly. The higher dose of BHBA(3.0,5.0 mM/L) downregulated leptin mRNA, moreover very significantly reduced the upregulated effect on ObRb and ObRc.In perirenal adipose ObRc was the only one could respond to the change of BHBA concentration.Regulation on leptin and leptin receptor gene with each concentration of leptin was shown to be a point of convergence in subcutaneous adipose and perirenal adipose tissue.In subcutaneous adipose gene leptin, ObRb, ObRc transcriptional level decreased with the increase of insulin concentration, in perirenal adipose they acted in an opposite ways. All three medicine downregulated above three mRNA in mesenteric adipose, furthermore,insulin had a significant effect.In Conclusion, conecentration of BHBA can directly effect on leptin-related genes'transcription. Low plasma leptin level was associated with ketosis. The secretion and self-regulation of leptin in different adipose depots was varied, the subcutaneous adipose is the main spot of leptin synthesis and secretion, which has the greatest sensitivity to BHBA. In perirenal adipose tissue, leptin-related genes' transcription was not much changed and maintained at an acceptable level.