Department of Pharmacology, Creighton University School of Medicine, Omaha, NE 68178, United States.
Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, United States.
Neurobiol Dis. 2018 Jun;114:45-52. doi: 10.1016/j.nbd.2018.01.017. Epub 2018 Mar 20.
Adenosine participates in maintaining the excitatory/inhibitory balance in neuronal circuits. Studies indicate that adenosine levels in the cortex and hippocampus increase and exert sleep pressure in sleep-deprived and control animals, whereas in epilepsy reduced adenosine tone promotes hyperexcitability. To date, the role of adenosine in pathological conditions that result in both seizures and sleep disorders is unknown. Here, we determined adenosine tone in sleep and seizure regulating brain regions of K1.1 knockout (KO) mice, a model of temporal epilepsy with comorbid sleep disorders.
RP-HPLC indicated a non-significant decrease in adenosine (~50%, p = 0.23) in whole brain homogenates of KO mice. Regional examination of relative levels of adenine nucleotides indicated decreased ATP and increased AMP in the cortex and hippocampus and increased adenosine in cortical tissue. Using electrophysiological and pharmacological techniques, estimated adenosine levels were ~35% lower in the KO hippocampal CA1 region, and 1-2 fold higher in the KO LH. Moreover, the increased adenosine in KO LH contributed to lower spontaneous firing rates of putative wake-promoting orexin/hypocretin neurons.
This is the first study to demonstrate a direct correlation of regionally distinct dichotomous adenosine levels in a single model with both epilepsy and comorbid sleep disorders. The weaker inhibitory tone in the dorsal hippocampus is consistent with lower seizure threshold, whereas increased adenosine in the LH is consistent with chronic partial sleep deprivation. This work furthers our understanding of how adenosine may contribute to pathological conditions that underlie sleep disorders within the epileptic brain.
腺嘌呤核苷参与维持神经元回路中的兴奋/抑制平衡。研究表明，在睡眠剥夺和对照动物中，皮质和海马中的腺嘌呤核苷水平增加并产生睡眠压力，而在癫痫中，降低的腺嘌呤核苷张力会促进过度兴奋。迄今为止，腺嘌呤核苷在导致癫痫发作和睡眠障碍的病理状况中的作用尚不清楚。在这里，我们确定了睡眠和癫痫调节脑区中 K1.1 敲除（KO）小鼠（一种伴有睡眠障碍的颞叶癫痫模型）的腺嘌呤核苷张力。
1）采用反相高效液相色谱法（RP-HPLC）对脑组织进行分析，以确定腺嘌呤核苷和腺嘌呤核苷酸的水平。2）多电极阵列细胞外电生理学用于确定海马 CA1 区和外侧下丘脑（LH）中的腺嘌呤核苷张力。
RP-HPLC 表明 KO 小鼠全脑匀浆中的腺嘌呤核苷水平无显著降低（~50%，p = 0.23）。对腺嘌呤核苷酸相对水平的区域检查表明，皮质和海马中的 ATP 减少，AMP 增加，皮质组织中的腺嘌呤核苷增加。使用电生理和药理学技术，KO 海马 CA1 区的估计腺嘌呤核苷水平降低约 35%，KO LH 的水平增加 1-2 倍。此外，KO LH 中增加的腺嘌呤核苷导致促觉醒的食欲素/下丘脑分泌素神经元的自发放电率降低。
这是第一项研究，证明了单个模型中具有癫痫和共病睡眠障碍的区域独特的二分腺苷水平之间的直接相关性。背侧海马中的抑制性张力较弱与较低的癫痫发作阈值一致，而 LH 中增加的腺苷与慢性部分睡眠剥夺一致。这项工作进一步加深了我们对腺嘌呤核苷如何有助于癫痫大脑中潜在睡眠障碍的病理状况的理解。
