DRD2 and insomnia: In conclusion, we found here that EA could increase DA in the hypothalamus, increase D1R and D2R in the HPA axis, and decrease CRH, ACTH, and CORT in the hypothalamus in rats after cage change, suggesting that EA may regulate hypothalamus DA and DA receptors in the HPA axis and alleviate changes in neurotransmitters induced by stress to improve sleep-wake cycles in rats with acute insomnia.