Effects of fasting on glucose turnover rate and metabolite levels in conscious pregnant guinea pigs.

Abstract

The effect of fasting during pregnancy is of particular interest in the guinea pig because of the large fetal mass carried to term. The present studies examined the effect of acute and chronic starvation on maternal glucose turnover in the guinea pig. In the first experiment, 7 near-term pregnant guinea pigs were fasted for 6 h. The maternal glucose concentration and glucose production decreased rapidly, falling to about 65-70% of fed levels at 4 h of starvation. Mothers demonstrated a 2.6-fold elevation in ketoacids after 2, 4 and 6 h starvation. In a second experiment, 5 non-pregnant and 11 near-term pregnant animals were studied in the control period and after 24 h of fasting. The maternal glucose concentration in the control state was independent of fetal mass. The maternal glucose turnover rate in the fed state correlated linearly with fetal mass. After 24 h of fasting, the glucose concentration and glucose turnover rate both decreased, with the magnitude of each decrease proportional to fetal mass. We conclude that, in the pregnant guinea pig, the fetal mass impacts significantly on maternal glucose metabolism in the fed and fasting states.