Effects of Acute and Subchronic Anodal Transcranial Direct Current Stimulation (tDCS) on Morphine-Induced Responses in Hotplate Apparatus.

BACKGROUND: The endogenous opioid system plays a basic role in pain suppression. The opiate analgesia is the most powerful and useful technique for reducing severe pain in many medical conditions. Transcranial direct current stimulation (tDCS) is a neuromodulator technique by which the cerebral cortex is stimulated with a weak and constant electrical current by the painless and non-invasive method. MATERIALS AND METHODS: In this experimental study, we investigated the effect of tDCS on morphine (1.25, 2.5 and 5 mg/kg)-induced pain responses; as we applied left prefrontal anodal stimulation with 0.2 mA intensity and 20 minutes. RESULTS: our results revealed that the acute (One-time electrical stimulation 24 hours after the last administration of morphine three days) and subchronic (three times electrical stimulation; one session/day before each administration of morphine three days) left prefrontal anodal tDCS does not alter pain perception induced by different dose of morphine significantly. CONCLUSION: Finally, our data indicated that there is no potentiated effect between acute tDCS or subchronic tDCS and morphine administration with tested parameters significantly.