Effect of dorsal rhizotomy on the autoradiographic distribution of opiate and neurotensin receptors and neurotensin-like immunoreactivity within the rat spinal cord.

The distributions of neurotensin and opiate receptors within the dorsal horn of the rat spinal cord were studied with quantitative autoradiographic techniques and compared with the immunohistochemical localizations of neurotensin and methionine-enkephalin-like immunoreactivity in this region. High densities of both neurotensin and opiate receptors were found within the superficial layers of the spinal cord, paralleling the distribution of neurotensin and enkephalin-containing interneurons and nerve terminals. Dorsal root section produced a 40% loss of opiate receptors throughout layers I and II of the spinal cord whilst no change in neurotensin receptor density or distribution was found. At the electron microscopic level the presence of neurotensin-like immunoreactivity within vesicle-containing profiles in the dorsal horn was demonstrated; however, no interaction of these terminals with primary afferent boutons was seen.