Quantitative immunohistochemical distribution of choline acetyltransferase in the rostral forebrain of the rat

The immunohistochemical distribution of choline acetyltransferase (CAT) in the rat rostral forebrain was analyzed quantitatively and minutely by means of a microphotometry system. The CAT concentrations varied greatly depending on the brain region. Within the neostriatum, CAT tended to be distributed with a lateral (high) to medial (low) gradient of approximately 1.2:1 and a caudal (high) to rostral (low) gradient of approximately 1.4:1, with the highest level in the medius lateralis. In the cortex cerebri, the CAT concentration in the area cinguli was high, while those in the area frontalis, area parietalis and area pyriformis were relatively low. High levels of CAT were also localized in other regions: e.g., hippocampus pars posterior, nucleus preopticus, nucleus anterior hypothalami, nucleus interstitialis striae terminalis, nucleus suprachiasmaticus and nucleus accumbens septi. The quantitative data obtained from the present microphotometric examination can be useful for analysis of a dynamic aspect of neurochemical substances under physiological as well as pathological conditions of the brain.