Kinetics of [3H]choline and [3H]acetylcholine metabolism in several regions of rat brain following intracerebroventricular injection of [3H]choline. Effects of haloperidol.

Intracerebroventricular (icv.) injection of [3H]choline in conscious rats produced a rapid, efficient labeling of brain choline and acetylcholine (ACh) stores without altering steady-state levels of endogenous ACh. The kinetics of [3H]choline and [3H]ACh metabolism were measured in seven brain regions for up to 10 min following icv. administration of [3H]choline. The initial rate of formation of [3H]ACh varied in different brain areas, being greatest in the striatum and least in the hypothalamus. In contrast, the rate of [3H]choline metabolism was similar in all regions of the brain. Pretreatment of rats with haloperidol resulted in an increase in the apparent synthesis rate of ACh only in the striatum and rostral hypothalamus, pointing to possible dopaminergic-cholinergic interaction in these regions.