Signal Transduction of Opiate Receptors in Spinal Cord Cells

Abstract

AbstractThe spinal cord plays an important role in opiate-induced analgesia and in the development of opiate tolerance. We have shown that the majority of the opiate receptors in the spinal cord (> 70%) are of the K type. We have also demonstrated that cocultures consisting of neurons of spinal cord and dorsal root ganglia express primarily the K type of opiate receptors. Using these cocultures, we found that activation of k-opiate receptors leads to inhibition of the basal-and forskolin-stimulated adenylate cyclase, as well as to the inhibition of the activity of voltage-dependent Ca2+ channels. In addition, activation of the k-opiate receptor led to stimulation of the phosphatidylinositol turnover in these cells. All these opiate-induced activities could be blocked by opiate antagonists, as well as by pretreatment of the cells with pertussis toxin, demonstrating the involvement of authentic opiate receptors and pertussis toxin-sensitive GTP-binding protein(s) in the transduction pathways. We found that ...