ABSTRACT
Objective:To evaluate the role of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in striatum in paclitaxel-induced neuropathic pain and the relationship with GABA B receptors in rats. Methods:Healthy clean-grade male Sprague-Dawley rats, aged 6-9 weeks, weighing 180-220 g, were used in this study.The neuropathic pain model was established by intraperitoneal injection of paclitaxel 2 mg/kg once every 2 days for 7 consecutive days in anesthetized rats, and then intrathecal catheterization was performed.Fifty rats in which intrathecal catheters were successfully implanted were divided into 5 groups ( n=10 each) using a random number table method: paclitaxel group (P group), paclitaxel plus normal saline group(N group), paclitaxel plus lentivirus empty vector group (BV group), paclitaxel plus HCN4 channel lentivirus group (H group), and paclitaxel plus HCN channel inhibitor ZD7288 group (I group). Ten rats of the same age were selected as the blank control group (C group). At 15 days after intraperitoneal injection of paclitaxel, normal saline 20 μl was intrathecally injected in group N, group BV received intrathecal injection of HCN4 channel lentivirus empty vector 1×10 8 TU/ml, 20 μl, group H received intrathecal injection of HCN4 channel lentivirus 1×10 8 TU/ml, 20 μl, and group I received intrathecal injection of ZD728830 μg, 20 μl.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before paclitaxel injection and 14 and 21 days after injection.The cerebral striatum tissues were obtained at T 2, and the expression of HCN4 channel and GABA B receptors was determined by immunohistochemistry and Western blot. Results:Compared with group C, the MWT was significantly decreased, HCN4 channel expression was up-regulated, and GABA B receptor expression was down-regulated in group P ( P<0.05). Compared with group P, the MWT was significantly increased, HCN4 channel expression was down-regulated, and GABA B receptor expression was up-regulated in group H and group I ( P<0.05), and no significant change was found in the parameters mentioned above in group N and group BV ( P>0.05). Conclusion:Up-regulation of expression of HCN4 channels in striatum can induce down-regulation of GABA B receptor expression, which is involved in the pathophysiological mechanism of paclitaxel-induced neuropathic pain in rats.
ABSTRACT
Aim To investigate the effect of 2-deoxy-D-glucose(2-DG)on the sensitivity of leukemia multi-drug resistant K562/ADMcells to adriamycin by inhib-iting glycolytic pathway as well as its molecular mecha-nisms.Methods The leukemia drug-resistant K562/ADM cells and parental K562 cells were used as the target cell models.The cell proliferating activity was assessed with an MTT colorimetric assay,and the gly-colysis including glucose consumption,lactate export, and hexokinase activity was determined by glucose, lactic acid and hexokinase (HK)testing kits.The ex-pression and phosphorylation of mammalian target of rapamycin(mTOR)and glucose transporter-4 (GLUT-4)expression were analyzed by western blot.Results K562/ADM drug-resistant cells possessed higher HK activity,GLUT-4 expression level and aerobic glycolic ability than K562 sensitive cells. 2-DG treatment markedly inhibited HK activity,glucose consumption, and lactate export both in K562 cells and K562/ADM cells,and suppressed the proliferation of the two cells in a time-and concentration-dependent manner.Low concentration of 2-DG or adriamycin could increase the expression and phosphorylation of mTOR.However, the co-administration of 2-DG and adriamycin markedly counteracted adriamycin-mediated enhancement of mTOR expression and phosphorylation and down-regu-lated GLUT-4 expression in K562/ADM cells,and 2-DG dramatically improved the sensitivity of K562/ADM cells to cytotoxicity.Conclusion 2-DG inhibits the proliferation of drug-resistant K562/ADM cells and en-hances the sensitivity to adriamycin by blocking aerobic glycolysis pathway through inhibiting hexokinase activi-ty,counteracting adriamycin-stimulated increased ex-pression and phosphorylation of mTOR and downregu-lating GLUT-4 expression.