Cholesterol synthesis in the rat brain in course of late development as determined by 3-hydroxy-3-methylglutaryl CoA...

The activity of 3-hydroxy-3-methylglutaryl-CoA reductase (E.C. 1.1.1.88), the key regulatory enzyme in the process of cholesterol biosynthesis was evaluated in different development stages of rat brain. The obtained results have shown an almost twofold increase of HMG-CoA reductase activity in one year old rats compared to the reference 4 months old animals. The activity of the cerebral HMG-CoA reductase in two years old animals dropped to the level observed in the reference group. The enhancement of activity of the regulatory enzyme for cholesterol biosynthesis occurs in parallel with an appearance of quantitatively minor, other than cholesterol, free sterol normally absent in the brains of young animals.