Abstract: Objective To investigate the role of glucose-dependent insulinotropic polypeptide (GIP) receptors in central sensitization of pain with the plantar incision model of rats. Methods Rats were randomly divided into five groups: Control group (group Ctrl), sham operation group (group Sham), incisional pain group (group P), incisional pain + intrathecal normal saline group (group I), and incisional pain + intrathecal antagonist (Pro3)GIP group (group M). Cumulative pain score (CPS) and paw-withdrawal threshold to von Frey stimuli (PWT) were measured before incision and at 3 h and day 1, 3 and 5 after incision. The expression of GIPR in spinal cord dorsal horn was determined by Western blot analysis. The location of GIPR was examined by immunofluorescence staining. Results The CPS was significantly increased at 3 h after incision (P<0.05), the PWT was significantly decreased at the same time after incision (P<0.05). The expression of GIPR was up-regulated obviously 1 d after incision (P<0.001). Antagonist (Pro3)GIP increases the PWT of rats, and the best analgesic effects occurs at 30 minutes after intrathecal injection (P<0.001). Spinal GIPR was specifically expressed on neurons, and did not locate on astroglias or microglial cells. Conclusions GIPR plays a significant role in central sensitization of pain, and it provides a potential therapeutic target for incision pain.

Key words: Receptors, GIP, Pain, Central sensitization