Spinal Serotonergic and Opioid Receptors Are Involved in Electroacupuncture-Induced Antinociception at Different Frequencies on ZuSanLi (ST 36) Acupoint

Figure 8

Pretreatment with 5-HT agonists influences EAc-induced antinociception in different frequencies on the 1st (a, b, c), 3rd (d, e, f), and 7th (g, h, i) days after intrathecal cannulation. (a), (d), (g): 1 mA, 2 Hz EAc; (b), (e), (h): 1 mA, 10 Hz EAc; (c), (f), (i): 1 mA, 100 Hz EAc; ↓: initiation point of EAc except sham group. ○: sham group. ⚫: ACSF (artificial CSF). ▲: DOI (R(+)-2,5-dimethoxy- 4-iodoamphetamine HCl, 5-HT_2/1C agonist, 10 μg/10 μL, i.t.). ▼: 2-methyl-5-HT (2-methylserotonin maleate, 5-HT₃ agonist, 50 μg/10 μL, i.t.). Data are shown as mean ± S.E. ^∗𝑃<0.05, ^∗∗𝑃<0.01, and ^∗∗∗𝑃<0.001 compared to the ACSF group (𝑛=10).

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