Perinatal development of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in rat lung, liver and brain.

The developmental pattern of microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34), which catalyzes the rate-limiting step of cholesterol biosynthesis, was studied in lung, liver and brain of Sprague-Dawley rats. Each tissue exhibited a distinct pattern. Reductase activity in the fetal lung reached a peak at 19 days of gestation, which corresponds to the onset of active surfactant production. This observation is consistent with the suggestion that the fetal lung synthesizes all surfactant components including cholesterol. In the liver, reductase activity varied in a reciprocal fashion with serum cholesterol levels. The peak of brain reductase activity occurred at 3 days after birth at the onset of rapid brain growth despite rapidly rising serum cholesterol levels.