Schneider Justus, Lewen Andrea, Ta Thuy-Truc, Galow Lukas V, Isola Raffaella, Papageorgiou Ismini E, Kann Oliver
Institute of Physiology and Pathophysiology and Interdisciplinary Center for Neurosciences, University of Heidelberg, Heidelberg, Germany.
J Neurosci Res. 2015 Jul;93(7):1067-78. doi: 10.1002/jnr.23590. Epub 2015 Mar 24.
Gamma oscillations (30-100 Hz) reflect a fast brain rhythm that provides a fundamental mechanism of complex neuronal information processing in the hippocampus and in the neocortex in vivo. Gamma oscillations have been implicated in higher brain functions, such as sensory perception, motor activity, and memory formation. Experimental studies on synaptic transmission and bioenergetics underlying gamma oscillations have primarily used acute slices of the hippocampus. This study tests whether organotypic hippocampal slice cultures of the rat provide an alternative model for cortical gamma oscillations in vitro. Our findings are that 1) slice cultures feature well-preserved laminated architecture and neuronal morphology; 2) slice cultures of different maturation stages (7-28 days in vitro) reliably express gamma oscillations at about 40 Hz as induced by cholinergic (acetylcholine) or glutamatergic (kainate) receptor agonists; 3) the peak frequency of gamma oscillations depends on the temperature, with an increase of ∼ 3.5 Hz per degree Celsius for the range of 28-36 °C; 4) most slice cultures show persistent gamma oscillations for ∼ 1 hr during electrophysiological local field potential recordings, and later alterations may occur; and 5) in slice cultures, glucose at a concentration of 5 mM in the recording solution is sufficient to power gamma oscillations, and additional energy substrate supply with monocarboxylate metabolite lactate (2 mM) exclusively increases the peak frequency by ∼ 4 Hz. This study shows that organotypic hippocampal slice cultures provide a reliable model to study agonist-induced gamma oscillations at glucose levels near the physiological range.
γ振荡（30 - 100赫兹）反映了一种快速的脑节律，它为海马体和体内新皮层中复杂的神经元信息处理提供了一种基本机制。γ振荡与更高层次的脑功能有关，如感觉感知、运动活动和记忆形成。关于γ振荡背后的突触传递和生物能量学的实验研究主要使用海马体的急性切片。本研究测试大鼠的器官型海马切片培养物是否能在体外为皮层γ振荡提供一个替代模型。我们的研究结果表明：1）切片培养物具有保存良好的分层结构和神经元形态；2）不同成熟阶段（体外培养7 - 28天）的切片培养物在胆碱能（乙酰胆碱）或谷氨酸能（ kainate）受体激动剂诱导下能可靠地表达约40赫兹的γ振荡；3）γ振荡的峰值频率取决于温度，在28 - 36°C范围内，每摄氏度约增加3.5赫兹；4）在电生理局部场电位记录期间，大多数切片培养物显示持续约1小时的γ振荡，随后可能会发生变化；5）在切片培养物中，记录溶液中浓度为5 mM的葡萄糖足以支持γ振荡，额外供应单羧酸代谢物乳酸（2 mM）作为能量底物仅使峰值频率增加约4赫兹。这项研究表明，器官型海马切片培养物提供了一个可靠的模型，用于在接近生理范围的葡萄糖水平下研究激动剂诱导的γ振荡。
