Acupuncture manipulation enhances anti-nociceptive effect on formalin-induced pain in rats.

Objectives: In order to apply appropriate acupuncture stimulation, different needle manipulation techniques are required. These manipulations are performed in many ways such as twirling the needle, varying the insertion angle, etc. The present study was designed to evaluate the antinociceptive effect of these manipulations to the acupuncture point ST36 on formalin-induced pain in rats. Methods: Animals were divided into four groups: non-treated control (CON), acupuncture without manipulation (AT), acupuncture with twirling manipulation (TM) and acupuncture with lifting–thrusting manipulation (LM) group. Level of pain was measured in formalin-injected rats in the early (0–10 minutes) and the late (10–60 minutes) phase. Several pain-related gene expressions were investigated in the spinal cord using reverse transcriptase-polymerase chain reaction analysis. Results: Formalin-induced pain was significantly reduced in the TM and the LM groups, compared with the CON and the AT groups. TM was more effective than LM in both phases. Needle manipulation was also effective in suppressing the mRNA expression of pain-related genes such as Fos, opioid receptor-like 1, tachykinin 1, tachykinin receptor 1, μ-opioid receptor and 5-hydroxytryptamine receptor 2A in the spinal cord. Discussion: The TM and the LM groups showed enhanced analgesia, compared with the AT group. This effect might be related to the suppression of the transcription of pain-related genes. [ABSTRACT FROM AUTHOR]