Effect of intrathecal resveratrol on activation of CaMKII in spinal dorsal horn neurons of rats with bone cancer pain

Abstract

Objective To evaluate the effect of intrathecal resveratrol on activation of Ca2+/calmodulin-dependent protein kinase Ⅱ (CaMKⅡ) in spinal dorsal horn neurons of rats with bone cancer pain. Methods Thirty-two adult female Sprague-Dawley rats, weighing 180-220 g, were equally randomized into 4 groups using a random number table: sham operation group (group S), bone cancer pain group (B group), and bone cancer pain + solvent control group (BD group). Walker 256 mammary gland cancer cell suspension (4×105 cells/ml) 5 μl was injected into the medullary cavity of the right tibia in B, BR and BD groups.Normal saline 5 μl was given in group S. On 12, 13 and 14 days after injection of mammary gland cancer cells, resveratrol 200 μg/10 μl was injected intrathecally once a day in group BR, and 1% dimethyl sulfoxide 10 μl was intrathecally injected once a day in group BD.Before injection of mammary gland cancer cells (T0) and on 3, 5, 7, 10, 12 and 14 days after injection of mammary gland cancer cells (T1-6), mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured.The rats were then sacrificed and L4, 5 segments of the spinal cord were removed for confirmation of the location of phosphorylated CaMKⅡ (p-CaMKⅡ) in spinal dorsal horn neurons (by immunofluorescence) and for detection of p-CaMKⅡ expression (using Western blot). Results Compared with group S, MWT and TWL were significantly decreased at T2-6, and p-CaMKⅡ expression was up-regulated at T6, and p-CaMKⅡ was mainly co-expressed with neurons in B, BR and BD groups.Compared with group B, MWT and TWL were significantly increased at T5, 6, and p-CaMKⅡ expression was down-regulated at T6 in group BR.There was no significant difference in MWT, TWL, and p-CaMKⅡ expression at each time point between group B and group BD. Conclusion Resveratrol can alleviate hyperalgesia in rats with bone cancer pain and inhibited activation of CaMKⅡ in spinal dorsal horn neurons may be involved in the mechanism. Key words: Phenols; Injections, spinal; Bone neoplasms; Pain; Spinal cord; Neurons; Calcium-calmodulin-dependent protein kinase type 2