脊髓水平GR-NPAS4信号通路对GABA能抑制性突触的调节在术前焦虑加重术后疼痛中的作用

术前焦虑加重术后疼痛是临床常见现象，其机制尚未明确。我们前期实验发现，术前焦虑可使切口痛大鼠术后疼痛明显加重，且持续时间延长，该现象同时伴随脊髓水平抑制性神经递质GABA释放减少及GABAA受体γ2亚基表达下调。研究提示，转录因子NPAS4在抑制性突触形成和维持的功能依赖性调节中具有关键作用。应激可通过激活糖皮质激素受体（GR）而显著下调海马NPAS4的表达水平，从而抑制GABA能抑制性突触的形成和功能，参与应激诱导的神经功能失调。我们提出假说：术前焦虑通过脊髓神经元GR-NPAS4信号通路，抑制GABA能抑制性突触的形成及突触囊泡释放GABA，最终导致术后疼痛的加重和延长。我们拟通过干预上述信号通路中的关键靶点，检测GABA囊泡释放量及GABA能抑制性突触相关蛋白的表达，在离体和在体水平探讨术前焦虑加重术后疼痛的分子机制，为临床防治与焦虑相关的术后疼痛提供新的策略。

Preoperative anxiety is a clinically significant problem for many patients undergoing surgery, and is associated with the prolonged and exacerbated postoperative pain. However, the molecular mechanisms are still unclear. Our previous studies demonstrated that preoperative anxiety resulted in exacerbated and prolonged mechanical allodynia that lasted up to 30 postoperative days in a rat model of incisional pain. The decrease in inhibitory neurotransmitter GABA release and the down-regulation of GABAA receptor γ2 subunit in spinal cord may participate in the mechanism of this phenomenon. Studies in vitro indicated that transcription factor Neuronal Per Arnt Sim (PAS) domain protein 4 (NPAS4) palys an important role in the activity-dependent regulation of inhibitory synapse. Stress can down-regulate the expression of NPAS4 via glucocorticoid receptor (GR) in hippocampus, inhibit the development and function of GABAergic inhibitory synapse, and contribute to the stress-induced brain dysfunction. As mentioned above, we hypothesize that preoperative anxiety can derectly inhibit the release of GABA and the development of GABAergic inhibitory synapse via the neuron GR-NPAS4 signaling pathway in spinal cord. The imbalance of inhibitory synapse function and excitatory synapse function results in the exacerbated and prolonged postoperative pain. The spinal neuron cultivation, pain behaviors measurement, microdialysis, western blot, chromatin immunoprecipitation assay and immunofluorescence technique will be applied to investigate the release of GABA and the expression of the inhibitory synaptic proteins, and to investigate the spinal mechanisms of preoperative anxiety-induced exacerbated and prolonged postoperative pain in vivo and in vitro. The implementation of this project provides novel intervention targets for the prophylaxis and treatment of preoperative anxiety-related postoperative pain.