导水管周围灰质内注射黑皮质素受体4型拮抗剂HS014抑制乳腺癌骨转移模型大鼠骨癌痛

Intra-periqueductal gray injection of melanocortin-4 receptor antagonist HS014 inhibits bone cancer pain in rats

目的 观察导水管周围灰质内注射黑皮质素受体4型（MC4R）拮抗剂对骨癌痛模型大鼠疼痛行为学及腰段脊髓星形胶质细胞活化的影响,探讨其治疗骨癌痛的机制.方法 选择雌性SD大鼠18只,随机分为3组（n=6）：A组（对照组）：左侧胫骨上段骨髓腔注入3μl生理盐水（NS）;B组（模型组）：左侧胫骨上段骨髓腔注入3μl MRMT-1大鼠乳腺癌细胞（1×10^3/μl）,导水管周围灰质（PAG）内注射NS 0.5μl;C组（HS014组）：造模同B组,PAG内注射MC4R拮抗剂HS0140.5μl.术后每24 h在PAG内注射HS014（0.5 μg/0.5μl）或NS 1次,连续注射至术后13 d.大鼠与术前及术后1、3、7、14 d给药后60 min内,采用热板测痛仪测试大鼠的热痛阈值.第14天取大鼠脊髓L4～L6节段,采用免疫组织化学方法观察骨癌痛大鼠腰段脊髓星形胶质细胞阳性产物分布及变化.结果 A组大鼠对热痛阈值在术后各时间点组内比较差异无统计学意义（P＞0.05）;B、C组大鼠对热痛阈值在术后的前6d与A组比较升高（P＜0.05）;术后7～14d,与B组大鼠对热痛阈值比较,C组明显降低（P＜0.05）.大鼠腰脊髓背角胶质纤维酸性蛋白（GFAP）免疫反应吸光度值C组（50.15 ±1.98）比B组（59.46 ±2.55）降低（P＜0.05）.结论 导水管周围灰质内注射MC4R拮抗剂HS014抑制乳腺癌骨转移模型大鼠骨癌痛,其机制可能是抑制脊髓星形胶质细胞激活.

Objective To investigate the effects of melanocortin-4 receptor antagonist HS014 on astrocyte activation of spinal cord in bone cancer pain rats.Methods Eighteen SD female rats weighing 180-220 g were randomly divided into 3 groups （n =6 each）：A group（control group）：intra-tibial injection of 3 μl saline;B group （model group）：intra-periqueductal gray （PAG） injection of 0.5 μl saline after intra-tibial injection of 3 μl MRMT-1 cells （1 × 10^3/μl） ; C group （HS014 group）：intra-PAG injection of 0.5 μl MC4R antagonist HS014 after intra-tibial injection of 3 μl MRMT-1 cells.From 1h of intra-tibial operation,0.5 μl saline or HS014 were injected into PAG respectively per day for 14 days.Heat threshold of rats＆#39; hind paws were measured every other day from one day before operation until 14 days later.The lumbar 4-6 spinal cord was removed on 14d after operation.The changes of the spinal glial fibrillary acidic protein （GFAP） immunoreactivity were detected by immunohistochemistry method.Results No significant differences in heat threshold were found at all time points in A group.During the first 6 days of postoperation there were obvious differences in heat stimulus between A and the other groups （P 〈 0.05） ; During 7-14 d after operation,heat threshold in A and C group were significantly different from those of B group （P 〈 0.05）,but the differences were not remarkable between A and C group.The absorbance value of GFAP immunoreactivity in B group （59.46 ± 2.55） showed stronger staining than that in C group （50.15 ± 1.98） （P 〈 0.05）.No significant difference of GFAP immunoreactivity was found between C group and A group （P 〉 0.05）.Conclusion Intra-PAG injection of MC4R antagonist HS014 inhibits bone cancer pain in rats by repressing spinal astrocyte activation.