Activity of pyruvate dehydrogenase complex in the mammary gland of normal and diabetic rats.

After parturition there is a 10 fold increase in the actual and total activity of the PDH complex in the mammary gland, which can be explained by an increased amount of enzyme protein. There is a marked difference between the activity state of the PDH complex in the suckled and unsuckled gland of the same animals. In fasting rats the active form of the PDH complex is decreased. This effect is further enhanced by inhibition of suckling. In the diabetic state the PDHa activity is reduced, but the change is statistically insignificant. The decreased milk production during diabetes results from the reduction of the total mass of gland. The total activity of the PDH complex is the same in fetal and neonatal liver of the rat. Whereas the PDH complex is fully activated before parturition, there is a significant decrease in the active form of the pyruvate dehydrogenase complex in the liver of the newborn rats.