Gene expression related to cholesterol metabolism in mouse brain during development

Although a large amount of cholesterol is known to be needed for brain maturation and differentiation, cholesterol metabolism during these periods remains unclear. To elucidate the developmental regulation of cholesterol metabolism in the brain, we investigated the expression of 3-hydroxy-3-methyglutaryl-coenzyme A (HMG-CoA) reductase (EC 1.1.1.34), low-density-lipoprotein (LDL) receptor and very-low-density-lipoprotein (VLDL)/apolipoprotein E (apo E) receptor (VLDL receptor) using RNase protection assay (RPA) to quantitate mRNA levels in mouse brain, liver and kidney during development. Messenger RNA levels of HMG-CoA reductase in the brain decreased with age, and those levels at -5 (5 days before birth) and 5 days after birth were significantly higher than the control level of adult mice. The period from -5 to 5 days might correspond to stages of active biogenesis of the membranes of brain cells. The mRNA level of HMG-CoA reductase in the liver was also high at -5 days; a finding that correlated with cell proliferation. On the other hand, mRNA levels of the LDL and VLDL receptors in the brain did not change markedly during development. These results suggest that de novo cholesterol biosynthesis in brain cells plays a major role in the supply of cholesterol to the developing brain, rather than the uptake of cholesterol from serum lipoproteins through lipoprotein receptors.