Cai Wen Ting, Han Joonyeup, Kim Wha Young, Kim Jeong-Hoon
Department of Physiology, Graduate School of Medical Sciences, Yonsei University College of Medicine, Seoul 03722, Korea.
Korean J Physiol Pharmacol. 2021 Jan 1;25(1):79-85. doi: 10.4196/kjpp.2021.25.1.79.
α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors are differentially regulated in the nucleus accumbens (NAcc) of the brain after cocaine exposure. However, these results are supported only by biochemical and electrophysiological methods, but have not been validated with immunohistochemistry. To overcome the restriction of antigen loss on the postsynaptic target molecules that occurs during perfusion-fixation, we adopted an immersion-fixation method that enabled us to immunohistochemically quantify the expression levels of the AMPA receptor GluA1 subunit in the NAcc. Interestingly, compared to saline exposure, cocaine significantly increased the immunofluorescence intensity of GluA1 in two sub-regions, the core and the shell, of the NAcc on withdrawal day 21 following cocaine exposure, which led to locomotor sensitization. Increases in GluA1 intensity were observed in both the extra-post synaptic density (PSD) and PSD areas in the two sub-regions of the NAcc. These results clearly indicate that AMPA receptor plasticity, as exemplified by GluA1, in the NAcc can be visually detected by immunohistochemistry and confocal imaging. These results expand our understanding of the molecular changes occurring in neuronal synapses by adding a new form of analysis to conventional biochemical and electrophysiological methods.
可卡因暴露后，大脑伏隔核（NAcc）中的α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体受到不同程度的调节。然而，这些结果仅得到生化和电生理方法的支持，尚未通过免疫组织化学进行验证。为了克服灌注固定过程中突触后靶分子上抗原丢失的限制，我们采用了一种浸泡固定方法，使我们能够通过免疫组织化学定量NAcc中AMPA受体GluA1亚基的表达水平。有趣的是，与生理盐水暴露相比，在可卡因暴露后第21天戒断时，可卡因显著增加了NAcc核心和壳两个亚区域中GluA1的免疫荧光强度，这导致了运动敏化。在NAcc的两个亚区域的突触后致密区（PSD）外和PSD区域均观察到GluA1强度增加。这些结果清楚地表明，通过免疫组织化学和共聚焦成像可以直观地检测到NAcc中以GluA1为例的AMPA受体可塑性。这些结果通过在传统生化和电生理方法之外增加一种新的分析形式，扩展了我们对神经元突触中发生的分子变化的理解。
