Transcranial direct current stimulation (tDCS) prevents chronic stress-induced hyperalgesia in rats

Abstract Background Chronic stress (CS) is associated with a decrease in pain threshold caused by the changes in neural pain circuits. It can be associated to glucocorticoid imbalance with alterations in neural circuitry. Inhibition of stress-induced pain-related neural changes by using techniques that safely induce neuroplasticity such as transcranial direct current stimulation (tDCS) may prevent hyperalgesia triggered by CS. Objective This study aimed to verify the effect of tDCS performed prior to CS exposure on nociceptive response. Methods Thirty-two rats were distributed in the following groups: control; stress; sham-tDCS + stress; and tDCS + stress. Bicephalic active tDCS was performed for 8 consecutive days before the CS exposure. The pain threshold was evaluated using a hot plate and tail flick latency (TFL) tests. Results The tDCS exposure increased the pain threshold on stressed rats. Conclusion The data obtained indicate that the treatment with bicephalic active tDCS before chronic stress exposure prevents stress-induced hyperalgesia.