Regional distributions of choline acetyltransferase and acetylcholinesterase activities in layers of rat cerebellar vermis.

Entire sagittal sections of rat cerebellar vermis were dissected into microgram-sized samples of molecular, granular, and white matter layers. Assayed activities of choline acetyltransferase and acetylcholinesterase were plotted back onto sectional maps of exact sample locations. On the average, the activities of choline acetyltransferase and acetylcholinesterase in the granular layer were about four and five times, respectively, those in the molecular layer. The highest activity of both enzymes was in the granular layer of the vestibulocerebellum, the nodulus and ventral uvula (lobules X and IXc of Larsell). This activity might be related to the secondary vestibulocerebellar projection, terminating as mossy fibers in the granular layer of this region. Intermediate levels of activity were found in the granular layer of the dorsal uvula (lobule IX, a and b). The lowest activities of both enzymes in the granular layer were in the culmen (lobule V). A 7.1-fold difference in choline acetyltransferase activity and a 4.5-fold difference in acetylcholinesterase activity were found between the granular layer of lobules V and X. The numerical density of aggregates of acetylcholinesterase staining product in the granular layer correlated much better with assayed acetylcholinesterase activity than with choline acetyltransferase activity.