The central mechanism of the depressor-bradycardia effect of "Tinggong(SI 19)-Quchi(LI 11)" 2Hz-electroacupuncture

Roles of central adrenergic receptors and opoid receptors in the depressor- bradycardia effect of 3V, 2Hz "Tinggong-Quchi" electroacupuncture (the EA-D pB, i.e.the depressor bradycardia induced by electroacupuncture) were studi ed by intracerebroventricula (icv) injection of prazosin, yohimbin or propr anol, naloxone or by intra-arachnoid (ith) injection of naloxone. Voltage-d ependent depressor effects were induced by 2Hz "Tinggong-Quchi" acupuncture . The depressor effect of 3V, 2Hz "Tinggong-Quchi" acupuncture was attenuat ed by icy injection of a beta -receptor antagonist-propranalol, but was not blocked by the icy injection of an alpha (1) -or (alpha (2)-receptor antag onist prazosin or yohimbin. Icy injected naloxone but not ith injected nalo xone blocked or reversed the EA-DpB. Results suggest that central P-recepto rs or opoid receptors in the brain are selectively involved in the EA-DpB.