REGIONAL DISTRIBUTION AND RATE OF PRODUCTION OF FREE FATTY ACIDS IN RAT BRAIN

Abstract

Abstract— We have found the levels of free fatty acids (FFA) in rat brain to be much lower than had been previously supposed. An unusually rapid and linear production of FFA occurred in brains of adult rats during the period from 30 s to 4 min after decapitation. Under the same conditions the production of FFA in the brain of the newborn rat or in the liver or spleen of the adult rat was much slower. The major sources of the FFA produced in the brain of the adult rat under these conditions were lipids other than triglycerides. FFA, like norepinephrine, occurred in much higher concentration in the hypothalamic region and the brain stem than in the remainder of the brain. We have proposed a hypothesis suggesting that norepinephrine might regulate membrane‐associated processes in the central nervous system by stimulating the enzymic splitting of the polar lipids of neuronal membranes. This action of norepinephrine might be mediated by adenosine 3′,5′‐phosphate in a manner analogous to that by which norepinephrine stimulates the enzymic splitting of triglycerides in adipose tissue. Liquid nitrogen and Freon‐12 have been compared for their respective efficacies in the rapid freezing of rat brain in situ.