Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.
Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.
Cell Calcium. 2021 Jan;93:102319. doi: 10.1016/j.ceca.2020.102319. Epub 2020 Nov 16.
Cerebellar Purkinje cells (PCs) fire spontaneously in a tonic mode, although the precision of this pacemaking activity is disturbed in many abnormal conditions involving cerebellar atrophy, such as many spinocerebellar ataxias (SCAs). In our previous studies we used the single-unit extracellular recording method to analyze spontaneous PC firing in vivo in the anesthetized SCA2-58Q transgenic mice. We realized that PCs from aging SCA2-58Q mice fire much less regularly compared to PCs from their wild type (WT) littermates and this abnormal activity can be reversed with an intraperitoneal (i. p.) injection of SK channel-positive modulator chlorzoxazone (CHZ). Here we used the same single-unit extracellular recording method to analyze the spontaneous firing in vivo in awake SCA2-58Q transgenic mice. For this purpose, we used the Mobile HomeCage (Neurotar, Finland) floating platform to immobilize the experimental animal's head during the recording sessions. We discovered that generally PCs from awake animals fired much more frequently and much less regularly than previously observed PCs from anesthetized animals. In vivo recordings from awake SCA2/WT mice revealed that complex spikes, which are generated by PCs in reply to the excitation coming by climbing fibers, as well as simple spikes, were much less frequent in SCA2 mice compared to their WT littermates. To test the effect of the SK channel positive modulation on the PCs firing activity in awake SCA2 mice and also the effect on their motor coordination, we started the CHZ trial in these mice. We discovered that the long-term i. p. injections of CHZ did not affect the spike generation in SCA2-58Q mice, however, they did recover the precision of this spontaneous pacemaking activity. Furthermore, we also showed that treatment with CHZ alleviated the age-dependent motor impairment in SCA2-58Q mice. We propose that the lack of precision in PC spike generation might be a key cause for the progression of ataxic symptoms in different SCAs and that the activation of calcium-activated potassium channels, including SK channels, can be used as a potential way to treat SCAs on the physiological level of the disease.
小脑浦肯野细胞（PCs）以紧张模式自发放电，尽管在涉及小脑萎缩的许多异常情况下，这种起搏活动的精确性会受到干扰，例如许多脊髓小脑共济失调（SCA）。在我们之前的研究中，我们使用单细胞胞外记录方法在麻醉的 SCA2-58Q 转基因小鼠体内分析自发的 PC 放电。我们意识到，与野生型（WT）同窝仔鼠相比，衰老的 SCA2-58Q 小鼠的 PCs 放电规律要差得多，而这种异常活动可以通过腹腔内（i.p.）注射 SK 通道正变构调节剂氯唑沙宗（CHZ）逆转。在这里，我们使用相同的单细胞胞外记录方法在清醒的 SCA2-58Q 转基因小鼠体内分析自发放电。为此，我们使用移动 HomeCage（Neurotar，芬兰）浮动平台在记录过程中固定实验动物的头部。我们发现，与以前观察到的麻醉动物的 PC 相比，一般来说，清醒动物的 PC 放电频率更高，规律性更差。来自清醒 SCA2/WT 小鼠的体内记录显示，与 WT 同窝仔鼠相比，由 PC 对 climbing 纤维传入的兴奋产生的复杂峰以及简单峰的频率要低得多。为了测试 SK 通道正变构对清醒 SCA2 小鼠 PC 放电活动的影响以及对其运动协调能力的影响，我们开始在这些小鼠中进行 CHZ 试验。我们发现，长期腹腔注射 CHZ 并不影响 SCA2-58Q 小鼠的峰发放，但确实恢复了这种自发性起搏活动的精确性。此外，我们还表明，CHZ 治疗减轻了 SCA2-58Q 小鼠的年龄依赖性运动障碍。我们提出，PC 峰发放缺乏精确性可能是不同 SCA 中共济失调症状进展的关键原因，而激活包括 SK 通道在内的钙激活钾通道可作为一种潜在的方法，从疾病的生理水平治疗 SCA。
