Effect of 3-acetylpyridine on the content of myelin in the developing rat brain.

Suckling rats were given 3-acetylpyridine, an antagonistic agent of nicotinic acid, on the 6th day after birth. The quantity of myelin and cerebroside, total lipid synthesis, and activities of fatty acid synthetase and fatty acyl-CoA elongating enzyme were measured in rats which received 3-acetylpyridine. At both 20 days and 30 days of age, rats which had received 3-acetylpyridine showed lower values in body weight, myelin yield, cerebroside level and specific activity of brain 2',3'-cyclic nucleotide-3-phosphohydrolase, when compared with those of the controls. Biosynthetic activity of lipid in brain slices of rats which had received 3-acetylpyridine was about 50% less than that of the controls. Moreover, activities of the microsomal palmitoyl-CoA, stearoyl-CoA and arachidyl-CoA elongating systems in the brain of rats which had received 3-acetylpyridine were about 80%, 50% and 50% those of the controls, respectively. These findings imply that 3-acetylpyridine affects the synthesis of long chain fatty acid in the developing rat brain. Therefore, nicotinic acid may play an important role in myelination associated with the synthesis of cerebrosides which contain high levels of long chain fatty acids.