EFFECT OF MATERNAL GLUCOSE-INFUSION ON BROWN ADIPOSE-TISSUE AND LIVERDEVELOPMENT IN THE NEONATAL LAMB

The effect of maternal glucose infusion over the final 5-7 days of ges tation in under-fed ewes on perirenal brown adipose tissue (BAT) and l iver development in lambs over the first month of neonatal life was ex amined. During glucose infusion, higher maternal plasma concentrations of glucose and thyroid hormones, and lower plasma concentrations of n on-esterified fatty acids and 3-hydroxybutyrate were observed, compare d with saline-infused controls. These differences were not observed 1- 1.5 h before parturition when plasma concentrations of glucose, lactat e, cortisol and thyroid hormones all increased in control ewes. Lamb b irthweight and liver and BAT weights were similar between groups, but lambs born to glucose-infused ewes had a higher hepatic glycogen conte nt and greater iodothyronine 5'deiodinase activities in liver and BAT. The norepinephrine, epinephrine and dopamine contents were also great er in BAT sampled from lambs born to glucose infused ewes. Three lambs born to glucose-infused ewes failed to survive beyond the second week of life and exhibited abnormally low plasma triiodothyronine concentr ations. It is concluded that maternal glucose infusion stimulates deve lopment of the fetal sympathetic nervous system during late gestation but this adaptation does not appear to improve postnatal survival.