Here, we reveal a novel analgesic mechanism for electroacupuncture. Low frequency electroacupuncture at the PC6 (Neiguan) acupoint (EA-PC6), but not electro-stimulation at a non-acupoint location (NAP) or needle insertion alone, increased the number of c- Fos expressing-orexin neurons in the lateral hypothalamus and orexin A levels in the ventrolateral periaqueductal gray (vlPAG), and induced antinociception in mice. EA-PC6-induced antinociception was signi ? cantly attenuated by systemic or intra-vlPAG pretreatment with the OX1 or CB1 receptor antagonist, and by intra-vlPAG inhibition of the synthesizing enzyme of 2-arachidonoylglycerol (2-AG), but not by systemic pretreatment with opioid receptor antagonists. EA-PC6 elicited a weak antinociceptive effect in Cnr1 / mice. EA-PC6-induced antinociception is not a phenomenon of stress-induced analgesia since EA-PC6 decreased the plasma corticosterone level. These ? ndings suggest that EA-PC6 activates hypothalamic orexin neurons, releasing orexins to induce analgesia through an opioid-independent but CB1 receptor-dependent cascade mediated by an OX1 receptor-initiated 2-AG retrograde disinhibition mechanism 1 in the vlPAG.
Date:
2014-08
Relation:
Journal of Neurochemistry. 2014 Aug;130(Suppl. s1):38.
