Related Experiment Videos
Prematurity in the rat. I. Fuels and gluconeogenic enzymes
Insights
Neonatal hypoglycemia may drive liver glycogenolysis post-cesarean delivery in rats. Preterm neonates exhibit transient lactate utilization resistance, which resolves within the first hour of extrauterine life.
Area of Science:
- Biochemistry
- Neonatal Physiology
- Comparative Physiology
Background:
- Cesarean delivery necessitates rapid metabolic adjustments in neonates.
- Understanding neonatal metabolic responses is crucial for clinical care, especially in preterm infants.
- Liver glycogenolysis and substrate utilization are key to maintaining energy homeostasis after birth.
Purpose of the Study:
- To investigate metabolic changes in term and preterm rats during the initial 2 hours after cesarean delivery.
- To compare the rates of liver glycogenolysis, plasma glucose, lactate, alanine, and glycerol concentrations between term and preterm neonates.
- To elucidate the role of neonatal hypoglycemia in promoting glycogenolysis and assess lactate utilization capacity.
Main Methods:
- Cesarean delivery was performed on term and preterm rats.
- Concentrations of liver glycogen, plasma glucose, lactate, alanine, and glycerol were measured at intervals up to 2 hours post-delivery.
- Rates of metabolic substrate utilization and production were calculated.
Main Results:
- Liver glycogenolysis was initiated in both term and preterm rats immediately after delivery, at approximately 50 mumol/h/g wet weight.
- Low plasma glucose concentrations suggested that neonatal hypoglycemia may promote glycogenolysis.
- Plasma alanine concentrations decreased similarly in both groups, indicating enhanced utilization.
- Plasma glycerol increased in preterm rats but remained unchanged in term rats.
- Term rats showed a progressive decrease in plasma lactate, while preterm rats exhibited a transient resistance to lactate utilization in the first hour, followed by a decrease.
Conclusions:
- Preterm rats demonstrate a transient resistance to lactate utilization immediately after birth via cesarean section.
- This resistance is overcome within the first hour of extrauterine life.
- Hypoglycemia may play a role in stimulating liver glycogenolysis in the immediate neonatal period.
Abstract:
Changes in liver glycogen, plasma glucose, lactate, alanine and glycerol concentrations during the first 2 h after delivery by cesarean section in term and preterm rats were studied. Liver glycogenolysis initiated in both groups just after delivery, the rates of glycogenolysis being about 50 mumol/h/g wet weight. Glycogen breakdown came along with very low plasma glucose concentrations suggesting that glycogenolysis could be promoted by neonatal hypoglycemia. Plasma alanine concentrations decreased in both groups at similar rates suggesting that alanine utilization was enhanced during the first 2 h of extrauterine life. The plasma glycerol concentration increased in preterm rats but no changes were observed in term rats. The plasma lactate concentration progressively decreased during the first 2 h in term rats. However, preterm rats showed no changes in plasma lactate concentrations during the first hour, then decreased during the second hour at similar rates to those observed in term rats. These results suggest that preterm rats showed a transient resistence to lactate utilization at delivery which was overcome during the first hour of extrauterine life.