Expression of PC, PCK1, PCK2, LDHB, FBP1 and G6PC genes in the liver of cows in the transition from pregnancy to lactation

The effect of the transition of dairy cows from pregnancy to lactation on the expression of genes encoding enzymes involved in hepatic glucose metabolism was studied. Six Holstein-Friesian heifers were used for this study. Liver samples were collected by biopsy on day 7 before expected parturition (-7) and days 3 and 21 after parturition (+3 and +21, respectively). The mRNA levels of pyruvate carboxylase(PC),phosphoenolpyruvate carboxykinase 1 (PCK1), phosphoenolpyruvate carboxykinase 2 (PCK2), lactate dehydrogenase B (LDHB),fructose-1,6-bisphosphatase 1 (FBP1) and glucose-6-phosphatase (G6PC) were measured using quantitative real-time PCR. The expression of PC and PCK2 mRNA on day 3 of lactation was significantly higher than that on day 7 before parturition (P<0.05) and slightly higher than on day 21 postpartum. The LDHB gene showed the highest expression level on day 3 of lactation, as compared with day 7 prepartum (P<0.001) and day 21 postpartum (P<0.001). No differences were shown in PCK1, FBP1 and G6PC expression levels between pregnancy and early lactation.