PARADOXICAL STATE-DEPENDENT EXCITABILITY OF THE MEDIAL SEPTAL NEURONS IN BRAIN-SLICES OF GROUND-SQUIRREL, CITELLUS-UNDULATUS
PARADOXICAL STATE-DEPENDENT EXCITABILITY OF THE MEDIAL SEPTAL NEURONS IN BRAIN-SLICES OF GROUND-SQUIRREL, CITELLUS-UNDULATUS
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DOI：
10.1016/0306-4522(90)90054-8
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发表时间：
1990-01-01
期刊：
影响因子：
3.3
通讯作者：
PAKHOTIN, PI
中科院分区：
文献类型：
--
作者：
BELOUSOV, AB;VINOGRADOVA, OS;PAKHOTIN, PI
研究人员在细胞外切片中研究了内侧隔膜-对角带复合体的自发和诱发神经元活动，切片取自三组动物的大脑：冬眠的地松鼠、苏醒的地松鼠和豚鼠。所有切片均在 31-32°C 下孵育。 C.将地松鼠大脑切片在2-4℃冰箱中保存15-36小时后重新测试。 C.在所有实验组中，大多数内侧隔膜-对角带复合体神经元具有较高的规则或节律性突发自发活动，其中一半的神经元群体在突触阻断的条件下持续存在。在这些条件下，周围结构（外侧隔膜、尾状核、伏隔核、内侧视前区）的低频不规则活动被完全抑制。切片中自发活动神经元的密度以及冬眠地松鼠内侧隔膜-对角带复合体中放电的平均频率显着高于清醒时的地松鼠和豚鼠。刺激内侧前脑束引起了大多数内侧隔膜-对角带复合体单元活动的最初抑制；在许多情况下，抑制之后会发生爆发放电。具有背景节律性爆发活动的神经元总是通过重置自发爆发来做出反应。总的来说，苏醒的地松鼠和豚鼠的内侧隔膜诊断带复合体神经元中约有 50-60% 对内侧前脑束的刺激产生后抑制性爆发反应，而在冬眠的地松鼠中，几乎所有神经元都观察到了这种反应。冬眠地松鼠组的刺激电流阈值显着较低，初始抑制的平均持续时间较短，尖峰的内爆发密度和/或爆发持续时间增加。因此，基于各种标准对自发活动和诱发活动的评估揭示了两组活跃动物之间惊人的相似性，而冬眠动物中内侧隔膜-对角带复合体神经元的活动和兴奋性大约加倍。活跃和冬眠的地松鼠之间的这种差异在切片深度和长时间冷却后的重新测试中得以保留。实验表明，冬眠地松鼠内侧隔膜-对角带复合体神经元的活性和兴奋性矛盾地稳定增加。讨论了内侧隔膜在控制冬眠-恒温觉醒周期中的作用以及这种调节机制与恒温动物睡眠-觉醒周期的可能相关性。
Spontaneous and evoked neuronal activity of the medial septum-diagonal band complex was investigated extracellularly in slices, taken from the brain of the three groups of animals: hibernating ground squirrels, waking ground squirrels, and guinea-pig. All slices were incubated at 31-32.degree. C. The slices of the ground squirrels'' brain were retested after keeping them for 15-36 h in the refrigerator at 2-4.degree. C. In all experimental groups the majority of the medial septum-diagonal band complex neurons had higher regular or rhythmic burst spontaneous activity, which in half of the neuronal population persisted in conditions of synaptic blockade. The low-frequency irregular activity of the surrounding structures (lateral septum, caudate, accumbens, medial preoptic area) was completely suppressed in these conditions. The density of the spontaneously active neurons in the slices, as well as the mean frequency of discharges in the medial septum-diagonal band complex of hibernating ground squirrels, was significantly higher than that in waking ground squirrels and guinea-pigs. Stimulation of the medial forebrain bundle evoked initial suppression of activity in majority of the medial septum-diagonal band complex units; in many of them the suppression was followed by a burst discharge. The neurons with background rhythmic burst activity always responsed by resetting the spontaneous bursts. In total, about 50-60% of the medial septum-diagnoal band complex neurons of waking ground squirrels and guinea-pigs responded by post inhibitory bursts to the stimulation of medial forebrain bundle, while in hibernating ground squirrels such responses were observed in nearly all neurons. The threshold values of the stimulating current were significantly lower in the hibernating ground squirrels'' group, the mean duration of the initial suppression was shorter, the intraburst density of spikes and/or duration of the bursts was increased. Thus, evaluation of spontaneous and evoked activity on the basis of various criteria revealed surprising similarity between the two groups of active animals, while the activity and excitability of the medial septum-diagonal band complex neurons was approximately doubled in the hibernating animals. This difference between active and hibernating ground squirrels was preserved during retesting after deep and prolonged cooling of the slices. The experiments demonstrate paradoxical stable increase of activity and excitability of the medial septum-diagonal band complex neurons in the hibernating ground squirrels. The role of the medial septum in control of hibernation-euthermic waking cycle and possible relevance of this regulatory mechanism to sleep-waking cycle of homotothermic animals is discussed.