Fetal and Neonatal Cerebral Metabolism Following Maternal Canine Starvation

Abstract

Summary: Pregnant dogs were starved for 72 hr before a term delivery. Maternal (1.68 ± 0.39 versus 0.74 ± 0.20 mM) and fetal (0.39 ± 0.03 versus 0.22 ± 0.07) circulating free fatty acids and maternal (2.99 ± 0.79 versus 1.04 ± 0.84) and fetal (2.53 ± 0.35 versus 1.01 ± 0.32) ketones were elevated whereas blood glucose values remained unchanged at the time of delivery. After birth, pups born to starved mothers had significantly lower blood glucose values during 3, 6, 9, and 24 hours of neonatal fasting. Intracerebral glucose concentrations paralleled those in the blood as they were depressed at 3, 6, and 9 hours of age. Cerebral glycogen content was lower in pups born to starved mothers at 6 (2.72 ± 0.43 versus 4.32 ± 0.56 μmoles/g) and 24 (2.31 ± 0.17 versus 3.48 ± 0.39 μmoles/g) hr, whereas UDP-glucose concentrations were significantly elevated in these pups during fetal, 3, 9, and 24 hr of age. Phosphoenolpyruvate was higher after maternal starvation in the fetus and at 6 and 9 hr, whereas cerebral pyruvate concentrations were elevated at 3, 6, and 9 hr of age. The elevation of pyruvate with no alteration of lactate concentration resulted in an elevated cytoplasmic NAD/NADH ratio at 3 hr of age (1381 ± 194 versus 792 ± 198). Cerebral α-ketoglutarate and calculated oxaloacetate concentrations were elevated throughout the day after maternal starvation whereas malate concentrations were depressed at 3 and 9 hr of age. Cerebral energy charge was unaffected, whereas the calculated energy reserve was lower at 3, 6, and 24 hours. Cerebral amino acids demonstrated elevated aspartate concentrations at 3 and 6 hr. Cerebral glutamine concentrations were lower during fetal stage (7.86 ± 0.52 versus 10.01 ± 0.41 μmoles/g) and 3, 6, and 9 hr of life. Speculation: These data suggest that cerebral glycogen synthesis was diminished and that the oxidation of cerebral amino acids, in particular glutamine, may contribute to maintain cerebral energy production during the relative fasting neonatal hypoglycemia which develops in pups after maternal starvations.