Spinal Serotonergic and Opioid Receptors Are Involved in Electroacupuncture-Induced Antinociception at Different Frequencies on ZuSanLi (ST 36) Acupoint
Antinociceptive effects of electroacupuncture (EAc) in different frequencies on the 1st, 3rd and 7th days after intrathecal cannulation by tail-flick test. : initiation point of EAc except sham group. ○: sham group. ▲: 2 Hz, 1 mA. ▼: 10 Hz, 1 mA. ■: 100 Hz, 1 mA. (a) Determined on 1st day; (b) determined on 3rd day; (c) determined on 7th day (described as text). Data are shown as mean ± S.E. compared with sham group ().