Immunocytochemical localization of muscarinic m2 receptor in the rat spinal cord.

Muscarinic receptors have been implied in the regulation of spinal cord functions. The m2 subtype has been found to be one of the major muscarinic receptors expressed in the spinal cord. In order to determine the precise cellular localization of m2 receptor in the rat spinal cord, immunocytochemistry was performed using a commercially available specific antibody. In the dorsal horn, strong m2 immunoreactivity was detected in the substantia gelatinosa. In the ventral horn, m2 immunoreactivity was detected in patches that were associated with cell groups of motor neurons. At higher magnification, m2 immunoreactivity was detected in neuronal processes and many of them were seen in close apposition to m2-negative perikarya and proximal dendrites of motor neurons. These results indicate that m2 receptor immunoreactivity is localized in different neuronal elements of the spinal cord.