It has been shown that the endogenous compound, acetyl-L-carnitine (ALCAR), acts in the brain as a metabolic cofactor in the synthesis of acetylcholine. In these studies, ALCAR was injected into the brain of developing rats every other day for the first three weeks after birth in order to assess its effect on forebrain cholinergic neurons. The results showed that intracerebroventricular (icv) administration of ALCAR causes an increase of choline acetyltransferase (ChAT) activity and of nerve growth factor receptor expression in the striatum. Biological assays of brain tissues revealed that the level of nerve growth factor (NGF) in the hippocampus also increases. The ability of brain cholinergic tissues to respond to exogenous administration of ALCAR is discussed.