KAPPA-OPIOID RECEPTOR-MEDIATED DEPRESSION OF ACTIVITY EVOKED IN CONVERGENT DORSAL HORN CELLS BY THERMAL AND NONTHERMAL NOXIOUS-STIMULATION

The response of convergent dorsal horn cells to tonic and phasic noxiuos heating and to noxious pinching was studied and after topical application of a solution (30 nmol) of the κ agonist U-50,488H to the dorsal surface of the spinal cord. U-50,488H depressed the discharge of convergent units evoked by thermal and mechanical nociceptive stimuli. The opiate antagonist WIN 44,441-3 reversed the effect of U-50,488H. It is concluded that κ opioids are effective in preventing the depolarization of convergent dorsal horn neurons evoked by either thermal or non-thermal noxious stimuli. © 1990.