Abstract:
Acetylcholinesterase (AChE), the enzyme which catalyzes hydrolysis of the neurotransmitter acetylcholine, is located in cholinergic neurons, cholinoceptive neurons, and extracellularly in the synaptic clefts of cholinergic synapses. In the rat cochlear nucleus, high activities of AChE have been found in locations rich in granule cells. In the rat dorsal cochlear nucleus (DCN), light microscopic histochemistry for AChE is characterized by stained dots and some patches, especially in its middle, fusiform soma layer, which contains a dense population of granule cells. The fine structure of AChE staining in the DCN has not previously been described. Electron microscopic histochemistry for AChE was performed on perfusion-fixed rat brains. Preliminary results indicate that AChE is distributed differentially across DCN layers. In the molecular layer, AChE staining was found in the extracellular space between nerve fibers and inside the cytoplasm of some dendrites. In deeper layers, extracellularly located AChE was less common, but staining was found inside some of the larger dendrites, some large neuron somata (probably fusiform cells), and some glomeruluslike structures. There appeared to be some labeled fibers coursing in the acoustic striae. [Supported by NIH Grant No. DC00172.]