Cerebral metabolic intermediate response following severe canine intrauterine growth retardation.

The effect of intrauterine growth retardation and neonatal hypoglycemia on cerebral metabolic intermediates were determined in newborn dogs subjected to 5 days of maternal canine starvation (MCS) before birth. Birth weight was reduced 23% (232 +/- 6 versus 300 +/- 10 g). Circulating blood glucose was reduced after 3 h of neonatal fasting in MCS pups (2.7 +/- 0.4 +/- versus 5.7 +/- 1.1 mM). Cerebral cortical levels of glucose were also reduced at this time. Cerebral glucose-6-phosphate was not altered; nonetheless fructose-6-phosphate was lower in MCS pups at 6 and 9 h, while fructose 1,6-diphosphate appeared elevated at 3 h. These data suggest that cerebral glycolytic activity may be increased by increased activity of phosphofructokinase. Cerebral glutamine appeared reduced in fasting MCS pups at 3, 6, and 8 h of age. A considerable disturbance of the adenine nucleotide pool was noted between 3-9 h in MCS pups; while the cerebral energy reserve was diminished in MCS pups between 3-24 h. The data of reduced cerebral energy status and reserve suggest that cerebral energy production was diminished. Although glucose levels were low at 3 h, subsequent recovery was not immediate as adenine-nucleotides remained low beyond the period of hypoglycemia. The combined effects of intrauterine growth retardation and transient neonatal hypoglycemia appear to result in reduced cerebral oxidative metabolism; this occurs despite an apparent enhanced utilization of alternate fuels.