Localization of high affinity choline transporter in the primate nervous system.

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1.Localization in the central nervous systemUsing in situ hybridization and immunohistochemistry, we have determined the localization of high affinity choline transporter (CHT) messenger RNA and protein in the macaque monkey central nervous system. Signals for CHT mRNA and protein are localized in neurons in the motor nuclei of the cranial nerves (somatic motor and parasympathetic preganglionic), laterodorsal tegmental nucleus, parabrachial nucleus, pedunculopontine tegmental nucleus, globus pallidus, neostriatum, nucleus accumbens, nucleus of the diagonal band of Broca, nucleus basalis of Meynert, medial septal nucleus, and olfactory tubercle. Parasympathetic preganglionic neurons exhibited significantly lower density of CHT mRNA and protein than other positive neurons. In the spinal cord, motor neurons in the ventral horn showed both signals for CHT mRNA and protein. Putative gamma-motor neurons always showed strong immunoreactivity for CHT, while putative alpha-motor neurons showed … More wide variety of immunoreactivity intensities. Of putative alpha-motor neurons, neurons innervating principal dorsal muscles demonstrated higher content of CHT than neurons innervating limb muscles.2.Ultrastructural localization at the synapseTo determine whether CHT is located at the presynaptic membrane or at the membrane of synaptic vesicles, we analyzed the localization of CHT at the monkey neuromuscular junction using post-embedding immunocytochemistry with electronmicroscopy. Although immunoreactivity was weaker than reported in the rat, most of the immunoreactivity for CHT was located inside the nerve terminal rather than on the presynaptic membrane. The findings are compatible with the CHT localization on the vesicular membrane reported in the rat, but for the exact localization at the vesicular membrane, further study will be necessary to determine the optimal condition that preserve both the immunoreactivity for CHT and the structure of vesicular membrane. These electron microscopic studies were performed in collaboration with Professor Seiji Matsuda at Ehime University. Less