Effect of maternal nutrition on brown adipose tissue and its prolactin receptor status in the fetal lamb

We investigated the influence of maternal nutritional enhancement during th e second half of gestation on prolactin receptor (PRLR) abundance in fetal brown adipose tissue (BAT) and liver close to term (i.e. 141-144 d gestatio n). Ewes were provided with 100% (i.e. control; n = 8) or 150% (i.e. well-f ed; n = 7) of their metabolic requirements from 80 to 144 d gestation. Crud e plasma membranes were prepared from fetal BAT and hepatic tissue, and ind ividual molecular weight isoforms for the long and short forms of the PRLR were detected by immunoblotting. Mitochondrial preparations were prepared f rom BAT to measure the amount of the BAT-specific mitochondrial uncoupling protein-1 and its thermogenic activity (i.e. guanosine 5'-diphosphate bindi ng). Fetuses sampled from well-fed ewes were heavier (controls, 3927 +/- 19 6 g; well-fed, 4783 +/- 219 g; p = 0.01) but possessed less BAT per kilogra m body weight (controls, 5.92 +/- 0.43 g/kg; well-fed, 3.85 +/- 0.19 g/kg; p = 0.001), which had a greater uncoupling protein-1 abundance (controls, 5 6 +/- 5% of reference; well-fed, 78 +/- 9% of reference; p < 0.01) and high er thermogenic activity (controls, 157 +/- 41 pmol guanosine 5'-diphosphate per milligram mitochondrial protein; well-fed, 352 +/- 36 pmol guanosine 5 '-diphosphate per milligram mitochondrial protein; p < 0.01) than controls. Multiple isoforms of the long and short forms of the PRLR were detected in all tissues. BAT from well-fed fetuses had a higher abundance of the 15-kD isoform of the long form of the PRLR (controls, 1.6 +/- 0.4 densitometric units; well-fed, 16.3 +/- 2.0 densitometric units; p < 0.001). This isoform was not detected in hepatic tissue. Maternal nutrient intake had no effect on any other isoforms of the PRLR in BAT or liver. In conclusion, increasi ng the quantity of feed provided in late gestation acts to promote fetal we ight and BAT maturation, the combination of which will enhance neonatal via bility.