GDNF靶向纳米脂质体鼻腔给药对神经病理性疼痛的镇痛效果和机制研究

Glial cell line-derived neurotrophic factor (GDNF) can produce analgesic effect on the level of spinal medulla and supra- spinal centre while combined with its receptor. However, this analgesic effect sharply decreases when GDNF is intravenous administered because of its rapid metabolism and inability to cross blood brain barrier (BBB) as a macromolecule protein. Our previous experiments have confirmed intrathecal injection of GDNF can reduce thermal allodynia in a rat model of neuropathic pain. However, it's also found that repeated intrathecal injections can increase risk of central nervous system (CNS) infection. Thus, how to prolong GDNF vivo circulation and enhance the passage through BBB by altering its dosage form and administration route is the crucial problem we are going to point out. A handful studies have confirmed intranasal delivery of liposome encapsulated peptides and protein is a convenient and effective way in treating CNS diseases. In this study, we first transformed liposome encapsulated GDNF into GDNF targeted sterically stabilized nanoliposomes (GDNF-SSNL-T) by adding PEG and RMP-7. Then, GDNF-SSNL-T was administered though nasal cavity in order to prolong its vivo circulation and enhance BBB permeability. Pain behavior of chronic constriction injury (CCI) rats pre-and post- drug administration was recorded to evaluate analgesic effect and immunohistochemical method adopted to explore analgesic mechanism, providing convincing scientific evidence for intranasal delivery of GDNF-SSNL-T in treating neuropathic pain.

胶质细胞源性神经营养因子(GDNF)可在脊髓水平和脊髓上中枢发挥镇痛作用。由于GDNF是一种大分子蛋白质在体内代谢快且难以通过血脑屏障(BBB)，静脉注射给药的镇痛效果差。前期实验证实，蛛网膜下腔注入GDNF可有效缓解坐骨神经慢性缩窄性损伤(CCI)模型鼠在热刺激试验中的痛觉过敏现象，但反复蛛网膜下腔穿刺给药有增加CNS感染的危险。因此，如何通过改变剂型、给药途径等手段延长GDNF在体内循环时间和增加通过BBB能力是本课题拟要解决的关键科学问题。大量研究已证实，采用脂质体包载蛋白多肽类药物后经鼻腔给药是治疗CNS疾病的一种简便、有效的方法。本研究拟先采用脂质体包载GDNF，并经修饰形成GDNF靶向纳米脂质体(GDNF-SSNL-T)，采用鼻腔给药途径，观察给药前、后CCI模型鼠的疼痛行为学变化，并通过免疫组化方法探讨镇痛机制，为GDNF靶向纳米脂质体鼻腔给药治疗神经病理性疼痛提供基础依据。

神经病理性疼痛是外周或中枢神经系统损伤或功能障碍引起的疼痛综合征,以痛觉过敏、痛觉超敏和自发性疼痛为特征，在临床上十分常见。胶质细胞源性神经营养因子(GDNF)可在脊髓水平和脊髓上中枢发挥镇痛作用；但由于GDNF是一种大分子蛋白质在体内代谢快且难以通过血脑屏障(BBB)，静脉注射给药的镇痛效果差。大量研究已证实，采用脂质体包载蛋白多肽类药物后经鼻腔给药是治疗中枢神经系统疾病的一种简便、有效的方法。. 主要研究内容：⑴采用脂质体包载GDNF，并经修饰形成GDNF靶向纳米脂质体(GDNF-SSNL-T)；⑵采用鼻腔给药途径，观察给药前、后CCI模型鼠的疼痛行为学变化，并通过免疫组化方法探讨镇痛机制，为GDNF靶向纳米脂质体鼻腔给药治疗神经病理性疼痛提供基础依据。. 本课题基本按原计划书进行和完成。已取得的重要结果和关键数据如下：⑴采用反相蒸发法制备GDNF-L，及DSPE-PEG-RMP-7插入后获得具有脑靶向性GDNF-SSNL-T；并通过体外细胞模型、体内静脉注射证实，GDNF-SSNL-T通过BBB能力明显高于GDNF。此结果已发表在Int J Mol Sci,2014,15:3612-3623（已标注基金号）。⑵GDNF-SSNL-T鼻腔给药，可明显缓解CCI模型大鼠患侧下肢的痛觉过敏；此部分实验结果文章在投稿中。. 本课题的科学意义：GDNF-SSNL-T可通过鼻腔给药这一便捷的方式，经由嗅神经和嗅粘膜上皮通路进入中枢神经系统，与额皮质、丘脑、纹状体等区域的相应受体结合发挥镇痛作用，利于临床应用。