有髓传入神经纤维相应DRG神经元中Cav3.2通道N-糖基化在DPN触诱发痛发生发展中的作用机制研究

The pathogenetic difference between painful and painless diabetic peripheral neuropathy (DPN) remained elusive. Tactile allodynia is the common hallmark of painful DPN and its pathogenesis still remained unclear. In our previous research, higher excitability of neurons in myelinated primary afferents-associated dorsal root ganglion (DRG) was found in DPN rats with tactile allodynia when compared with those without. In addition, Cav3.2 T-type calcium channels was reported to play an important role in shaping the excitability of DRG neurons, and its membrane expression as well as kinetic activity were regulated by asparagine-linked glycosylation. Therefore, we hypothesized that the distinct manifestation of tactile allodynia in DPN might be attributed to different extent of asparagine-linked glycosylation of Cav3.2 T-type calcium channels in myelinated primary afferents-associated DRG neurons. In this study, the asparagine-linked glycosylation and membrane expression of Cav3.2 T-type calcium channels on myelinated primary afferents-associated DRG neurons as well as the cell electrophysiology mediated by Cav3.2 T-type calcium channels would be compared between DPN rats with and without tactile allodynia. This study aims to confirm that the membrane expression on myelinated primary afferents-associated DRG neurons and the kinetic activity of Cav3.2 T-type calcium channels were regulated by asparagine-linked glycosylation, being involved in the development of tactile allodynia in DPN. The findings in this study would contribute to a new insight into the identification of the difference of painful and painless DPN, and also provide experimental evidence and theoretical basis for exploration of pathogenetic study of tactile allodynia in DPN as well as further development of new therapeutic modalities in the future.

痛性与非痛性糖尿病性周围神经病变（DPN）的病理机制差异尚不明确。触诱发痛是痛性DPN常见的特征性表现，机制未明。我们前期研究发现，触诱发痛阳性的DPN大鼠中有髓传入纤维相应背根神经节（DRG）神经元的兴奋性较阴性组显著升高，而Cav3.2通道对DRG神经元的兴奋性具有重要调控作用，且其蛋白表达与电生理特性受N-糖基化调节。据此我们提出假设：DPN中触诱发痛的差异性表现可能与有髓传入纤维相应DRG神经元中Cav3.2通道的N-糖基化程度相关。本课题拟从Cav3.2通道的N-糖基化、蛋白表达及其介导的细胞电生理改变等环节对触诱发痛阳性与阴性的两组DPN大鼠进行对比性研究，证实N-糖基化可通过改变Cav3.2通道的表达及其电生理特性从而影响DPN大鼠触诱发痛的发生发展。为鉴别DPN疼痛的差异性表现提供新思路，为DPN触诱发痛病理机制的研究和相关诊疗方式的进一步研发提供实验证据与理论依据。

触诱发痛是神经病理性疼痛的特征表现，常见于糖尿病周围神经病变（DPN）。本课题组前期研究发现，DPN大鼠中有髓传入纤维相应背根神经节（DRG）神经元的兴奋性与其触诱发痛的发生密切相关，而Cav3.2通道对DRG神经元的兴奋性具有重要调控作用，且其蛋白表达与电生理特性受N-糖基化调节。本项目从疼痛行为学、周围神经形态学、分子生物学角度，在外周神经、神经节和脊髓中枢水平，对DPN触诱发痛阳性和阴性大鼠在疼痛行为模式、外周神经脱髓鞘病变及Cav3.2通道N-糖基化蛋白修饰等方面进行对比性研究，发现DPN大鼠触诱发痛与有髓传入纤维的损害、DRG神经元的Cav3.2通道N-糖基化程度及脊髓背角神经元的激活密切相关。本项目结果为临床上甄别DPN疼痛的差异性表现提供新思路，为DPN触诱发痛病理机制的研究和相关诊疗方式的进一步研发提供实验证据与理论依据。