Role of μ-opioid receptor in attenuation of bone cancer pain by anti-nerve growth factor in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of μ-opioid receptor (MOR) in attenuation of bone cancer pain by anti-nerve growth factor (anti-NGF) in rats. Methods Part Ⅰ Sixty female SD rats weighing 200-220 g were randomly divided into 4 groups (n = 15 each) sham operation group (group S), sham operation + anti-NGF group (group SN), bone cancer pain group (group P) and bone cancer pain+ anti-NGF group (group PN) . Bonecancer was induced by intra-tibial inoculation of 1 × 105 Walker 256 breast cancer cells in group P and PN. Group S and SN received injection of PBS 10 μl. APE 10 catheter was inserted at L2,3 interspace into the epidural space 13 days after cancer cell inoculation. Three days after the catheter was successfully placed, group SN and PN received intrachecal (IT) injection of anti-NGF 10 μg (in normal saline (NS) 10 μl) and group S and P IT injection of NS 10 μl twice a day for 5 consecutive days. The number of spontaneous flinches (NSF), paw withdrawal latency (PWL) and paw withdrawal threshold (PWT) were measured before and 13, 16, 18, 21 day after cancer cell inoculation. The animals were sacrificed at 21 day after cancer cell inoculation and the spinal cord dorsal horn and dorsal root ganglion were removed for determination of MOR and MOR mRNA expression. Part Ⅱ Thirty female SD rats weighing 200-220 g were randomly divided into 2 groups (n = 15 each) bone cancer pain + anti-NGF group (group PN) and bone cancer pain + naloxone + anti-NGF group (group PNN). Bone cancer was induced by intratibial inoculation of 1 × 105 Walker 256 breast cancer cells. APE 10 catheter was inserted at L2-3 interspace into the epidural space 13 days after cancer cell inoculation. Three days after the catheter was successfully placed,group PN received IT injection of anti-NGF 10 μg (in NS 10 μl) and group PNN IT injection of naloxone 10μg (in NS 25 μl) and 0.5 h later IT injection of anti-NGF 10 μg (in NS 25μl) twice a day for 5 consecutive days. NSF,PWL and PWT were measured before and 13, 16, 18, 21 days after cancer cell inoculation. Results Part ⅠCompared with group S, no significant change was found in NSF, PWL and PWT in group SN, and in MOR and MOR mRNA expression in group SN and PN (P ＞ 0.05), NSF was significantly increased, PWL shortened, PWT decreased at 13-21 days after inoculation in group P and PN, and MOR and MOR mRNA expression was down-regulated in group P (P ＜ 0.05 or 0.01). Compared with group P, NSF was significantly decreased, PWL prolonged, PWT increased, MOR and MOR mRNA expression was up-regulated in group PN at 18-21 days after inoculation (P ＜ 0.05 or 0.01). Part Ⅱ Compared with group PN, NSF was significantly increased, PWL shortened, PWT decreased at 18-21 days after inoculation in group PNN (P ＜ 0.05 or 0. 01). Conclusion The mechanism by which anti-NGF attenuates bone cancer pain in rats is related to the activation of MOR.