[Effect of opiate agonists administered intrathecally on the behavioral and hemodynamic manifestations of pain].

An agonist of mu-opiate receptors, D-Ala2-Gly-ol5-enkephalin (DAGO, 0.5 mcg), administered intrathecally, was found to inhibit behavioral and hemodynamic reactions induced by thermal and electrical stimulation of conscious male rats. D-Ala2-D-Leu-enkephalin (DADL, 0.5 mcg), acting on delta-receptors, was shown to potentiate nociceptive shifts of arterial blood pressure. Phencyclidine and bremazocine failed to exert any significant effect on the opioidergic mechanisms of the spinal cord.