Influence of curcumin on expression of cAMP response element-binding protein phosphorylation (p-CREB) in spinal dorsal horn and dorsal root ganglion in a rat model of herpes zoster postherpetic neuralgia

Abstract

Objective To evaluate the influence of curcumin on expression of phosphorylated cAMP response element-binding protein (p-CREB) in spinal dorsal horn and dorsal root ganglion in a rat model of herpes zoster postherpetic neuralgia. Methods Eighty male SD rats were randomly divided into 4 groups (n=20): control group (group C), model group (group D), curcumin 1 group (DCur1) and curcumin 2 group (DCur2). Rats received injection of 0.9% sodium chloride solution in posterior claw in group C, received injection of human papillomavirus-1 (HSV-1) (concentration of 106/100 μl, injection volume 50 μl) on the hind paws of rats in group D. Intraperitoneal curcumin (100, 200 mg/kg, once a day for 7 days) was injected respectively at 5 days after establishment of the model in group DCur1 and group DCur2. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were tested after 5 d (before treatment) and 1, 7, 14 d after the treatment. Eight rats were sacrificed on 14 days after the treatment, and the expression of p-CREB was detected in the dorsal horn of the spinal cord and the dorsal root ganglion (DRG) in all groups. Results Compared with group C, MWT was significantly decreased, TWL was significantly shortened at each time point in the other three groups (P<0.05). Compared with group D, MWT was significantly increased, TWL was significantly extended at 7, 14 d after the treatment in group DCur1 and group DCur2, especially in group DCur2 (P<0.05). Compared with group C, the expression of p-CREB was up-regulated in spinal dorsal horn and dorsal root ganglion in the other three groups (P<0.05). Compared with group D, the expression of p-CREB was down-regulated in group DCur1 and group DCur2, especially in group DCur2 (P<0.05). Conclusion Curcumin can alleviate herpes zoster postherpetic neuralgia in rats, and down-regulation of p-CREB over-expression in spinal dorsal horn and dorsal root ganglion is involved in the mechanism. Key words: Curcumin; Neuralgia, postherpetic; CREB-binding protein