Augmented analgesic effects of enkephalinase inhibitors combined with transcranial electrostimulation

The analgesic effects of very low current transcranial electrostimulation are naloxone-reversible and thus presumably mediated by endogenous opioid activity. The present experiments indicate that blocking enkephalinase activity by i.c.v. thiorphan or i.p. acetorphan results in an increased analgesic effect of electrostimulation as measured by the 50 degrees C wet tail flick test. In the case of each drug, rats receiving both drug and electrostimulation displayed significantly more analgesia than rats receiving electrostimulation and injection vehicle alone, rats receiving drug and sham stimulation or rats receiving vehicle and sham stimulation.