阿片诱导痛觉过敏伤害性杏仁核突触强化神经环路解构及分子调控

Opioid induced hyperalgesia (OIH) is a paradoxical phenomenon, which hindered the clinical treatment for pain, and it can only be partially explained by peripheral and spinal mechanism. After induction, the maintaining of OIH is not dependent on opioid receptor only, probably, synaptic plasticity has occurred in the pain circuit. Our research group first proved that nociceptive amygdala (CeLC) was the key superspinal central for OIH modulation. The main finding of our research including:1) Synaptic potentiation in CeLC is the key mechanism for OIH; 2) Extracellular-signaling regulated kinase (ERK) and calcium/ calmodulin kinaseⅡalpha can modulate this synaptic potentiation; 3) There exist a ‘CeLC-PAG-RVM-Spine’ descending facilitating pathway for OIH. However, the local circuit in amygdala for OIH modulation is still not fully understood. Here, based on the upper study we propose that the local circuit in amygdala for synaptic potentiation in CeLC may include: 1) PB-CeLC excitatory synaptic potentiation, 2) BLA-CeLC excitatory synaptic potentiation, and 3) disinhibition of BLA-ITC-CeLC inhibitory synapse. To test this hypothesis, patch clamp recording on brain slices will be used to recording evoked excitatory /inhibitory post synaptic currents. In addition, pharmacological, molecular and behavior test will be used to explore the underling molecular mechanism for OIH. This study will facilitate the development of new interventions to cure OIH in clinic.

阿片诱导的痛觉过敏（opioid induced hyperalgesia, OIH）是临床镇痛治疗的难题，外周及脊髓机制不足以完全解释OIH现象。前期研究发现伤害性杏仁核（CeLC）是脊髓上游调控OIH的重要中枢，其突触兴奋性增强可通过“CeLC-PAG-RVM-脊髓”下行易化通路调控OIH。但OIH时CeLC突触兴奋性增强的局部神经环路机制尚待阐明，本项目针对CeLC突触兴奋性增强的机制提出假说：1） PB-CeLC兴奋性突触传递增强；2）BLA-CeLC兴奋性突触传递增强；3）BLA-ITC-CeLC抑制性突触脱抑制；拟主要通过脑片双电极膜片钳记录刺激诱发的兴奋性/抑制性突触后电流验证上述假说，并对其分子调控进行探索，为最终寻找治疗OIH的方法、解决临床镇痛治疗的难题提供科学依据。

阿片诱导的痛觉过敏（OIH）是临床镇痛治疗的难题，外周及脊髓机制不足以完全解释OIH现象。前期研究证明OIH时伤害性杏仁核（CeLC）突触兴奋性增强，但OIH时CeLC突触兴奋性增强的局部神经环路机制尚待阐明。本课题提出CeLC突触兴奋性增强机制的假说：PB-CeLC及BLA-CeLC兴奋性突触传递增强，BLA-ITC-CeLC抑制性突触脱抑制。为验证以上假说，我们首先确认然后利用Western blot检测到OIH大鼠CeLC mGluR5表达上调，在CeLC区立体定位注射相应的mGluR5和CaMKIIα抑制剂可翻转OIH大鼠的痛敏行为；随后离体脑片膜片钳记录到OIH大鼠CeLC区微小兴奋性突触后电流（mEPSCs）和自发性兴奋性突触后电流（sEPSCs）的频率和强度均增强，微小抑制性突触后电流（mIPSCs）和自发性抑制性突触后电流（sIPSCs）的频率和强度均减弱，mGluR5和CaMKIIα抑制剂可逆转这种突触可塑性变化；同时双电极膜片钳技术记录到OIH时PB-CeLC和BLA-CeLC环路刺激诱发的兴奋性突触后电流（eEPSC）幅值增强，BLA-ITC-CeLC环路刺激诱发的抑制性突触后电流（eIPSC）幅值减弱，mGluR5和CaMKIIα抑制剂可逆转eEPSC幅值的升高，即抑制PB-CeLC和BLA-CeLC环路兴奋性突触传递的增强。由此我们的假说基本得到验证，而且发现了mGluR5和CaMKIIα是调制OIH局部神经环路机制的重要分子基础。以上研究部分揭示了OIH CeLC突触兴奋性增强的局部神经环路机制，为最终寻找治疗OIH的方法、解决临床镇痛治疗的难题提供科学依据。