ORGANIZATION OF THE NUCLEUS OF THE SOLITARY TRACT IN THE HAMSTER - ACETYLCHOLINESTERASE, NADH DEHYDROGENASE, AND CYTOCHROME-OXIDASE HISTOCHEMISTRY

The distribution of acetylcholinesterase (AChE), NADH dehydrogenase (N ADHd), and cytochrome oxidase (CO) was determined in the nucleus of th e solitary tract (NST) in the golden hamster. Histochemical staining w as compared to cytoarchitectonic subdivisions of the NST (Whitehead: J . Comp. Neurol. 276:547-572, 1988) and to terminal fields of primary a fferents of the nerves that innervate the tongue. These three histoche mical methods resulted in differential staining patterns within the NS T that were related to certain subdivisions. Transganglionic transport of horseradish peroxidase (HRP) was used to determine the central pro jections of the chorda tympani (CT), the lingual branch of the trigemi nal (L-V), and the lingual-tonsilar branch of the glossopharyngeal ner ves (L-IX). Alternate or the same brain sections were processed to rev eal transported HRP, and NADHd or AChE levels. Increased staining of t he neuropil with NADHd and AChE was coincident with the dense part of the afferent terminal fields of all three nerves in the NST and the la terally adjacent dorsomedial part of the spinal trigeminal nucleus. CO showed this pattern only for the most rostral part of the CT field. T he densest AChE staining coincided with gustatory afferent terminal fi elds. The histochemical staining facilitated the interpretation of the organization of the NST. For example, at caudal levels of the gustato ry NST, it is suggested that taste processing is localized predominate ly in the medial part of the rostral central, and somatosensory proces sing in the rostral lateral subdivision. AChE or NADHd staining should facilitate studies of connections, topography, and neuroplastic chang es of the gustatory NST. (C) 1993 Wiley-Liss, Inc.