Intrathecal injection of monocarboxylate transporter inhibitor α-cyano-4-hydroxy-cinnamate attenuates neuropathic pain in rats

Objective To investigate the effects of intrathecal injection of α-cyano-4-hydroxy-cinnamate(4-CIN) in rats with neuropathic pain induced by chronic constriction injury of sciatic nerve(CCI). Methods Eighteen male SD rats were divided randomly into 3 groups(n=6): sham group (group S), CCI model group (group C0) and 4-CIN group ( group C1). Group C0 and C1 were operated with the model of neuropathic pain induced by chronic constriction injury of sciatic nerve; and group S were treated as sham operated rats. Two days after operation, group C1 received intrathecal injection of 100 μmol 4-CIN dissolved in 10% DMSO 10 μl, while group C0 received intrathecal injection of 10% DMSO 10 μl only.The paw withdrawal thermal latency(PWTL) and paw withdrawal mechanical threshold(PWMT) were tested 1 d before operation and 1 d, 3 d, 7 d, 10 d, 14 d after operation(T0-5). Results The basic values of PWMT and PWTL before operation showed no statistically significant differences among the three groups.On T1-5, the PWMT((11.71±2.81)g, (9.76±1.00)g, (8.22±1.33)g, (6.50±1.48)g, (4.67±1.03)g) and PWTL((11.36±2.18)s, (11.60±2.54)s, (8.54±1.42)s, (7.59±1.00)s, (6.88±0.42)s) in group C0 were significantly lower than those in group S (P 0.05). Conclusion Intrathecal administration of 4-CIN can attenuate neuropathic pain in rats induced by CCI. Key words: Monocarboxylate transporter; Inhibitor 4-CIN; Neuropathic pain; Spinal cord