Effect of transganglionic degenerative atrophy on opiate receptors in the dorsal horn of the spinal cord.

We investigated alterations in opiate-binding sites in the upper dorsal horn after transection of the related peripheral sensory nerve in rats. The binding of (3H)diprenorphine was measured autoradiographically. The findings indicated a shift of the binding sites, rather than a degenerating disappearance, with a decrease in nerve fibers but an increase in nerve cells. This may be due to latent opiate-binding sites becoming manifest.