OBJECTIVETo investigate the changes in the levels of monocarboxylate transporter-2 in spinal cord horn in a rat model of chronic inflammatory pain.

METHODSMale SD rats weighting 180 - 220 g were randomly divided into two groups(n = 48): normal saline group (NS group), complete Freund's adjuvant group (CFA group). Rats were given injections of CFA 100 µl in left hind paw in group CFA, and an equal volume of saline was given injection in group NS. Mechanical withdraw threshold(MWT) and thermal withdraw latency(TWL) were measured at before injection(T0 and 3 h, 1 d, 3 d, 7 d, 14 d, and 21 d after injection(T1-7). Four rats were chosen from each group at T0-7 and sacrificed, and L4-5 segments of the spinal cord horn were removed for measurement of the expression of monocarboxylate transporter-2 by Western blot analysis.

RESULTSIn CFA group, mechanical hyperalgesia and allodynia appeared on the 3 h after CFA injection, then until the day 14. The expression of monocarboxylate transporter-2 in the spinal dorsal horn of rats in CFA group was significantly higher than that in normal control group at T1-6(P <0.05). The protein level of monocarboxylate transporter-2 was apparently correlated with MWT and TWL(P <0.01 and P <0.05) in CFA group.

CONCLUSIONThe level of monocarboxylate transporter-2 in spinal dorsal horn is significantly increased in a rat model of chronic inflammatory pain and the change may involve in the formation and maintenance of central sensitization in spinal cord of chronic inflammatory uain.