Plasma hormones and expression of growth hormone receptor and insulin-like growth factor-I mRNA in hepatic tissue of periparturient dairy XXXX .

@entity1420 @entity4208 @entity53 @entity1718 @entity291 @entity413
Growth hormone plays a central role in the change in nutrient metabolism that occurs during the initiation of lactation. The actions of growth hormone are mediated by the growth hormone receptor (GHR) whose mRNA is present in three alternatively spliced forms (GHR 1A, 1B, and 1C). Liver-specific GHR 1A mRNA is transiently decreased around parturition, but the exact timing of the decline is not known. Our objective was to generate a daily profile for total GHR (GHRtot; all GHR transcripts), GHR 1A, and @entity4208 mRNA expression in liver of periparturient Holstein @entity291 and evaluate these daily mRNA profiles relative to daily profiles for periparturient hormones and metabolites. Liver biopsies and blood samples (n = 139) were collected from 65 Holstein @entity291 at the University of Missouri Dairy Farm. At least two @entity291 were sampled on each day from 14 d before to 14 d after parturition. Total cellular RNA was isolated and reverse transcribed to cDNA. Target cDNA were measured by quantitative real-time polymerase chain reaction. Plasma was assayed for @entity1420 , @entity53 , insulin, growth hormone, @entity4208 , @entity413 , and nonesterified @entity1718 . The GHR 1A mRNA declined 2 d before parturition, was lowest 3 to 4 d after parturition, and then increased. The @entity4208 mRNA declined 1 d after parturition, was lowest 2 to 5 d after parturition and then increased. Total GHR mRNA was not affected by day. The decrease in GHR 1A mRNA was associated with a decrease in @entity1420 and an increase in @entity53 shortly before parturition. A detailed profile of GHR 1A, @entity4208 , and GHRtot mRNA expression during the periparturient period was provided. The decreases in GHR 1A and @entity4208 during the transition period occurred immediately before (GHR 1A) or shortly after ( @entity4208 ) parturition. Rapid changes in placental and ovarian steroids before parturition were coincident with changes in GHR 1A mRNA.
