Impulse activity of bulbar respiratory neurons in myocardial ischemia in cats

Acute experiments on cats anesthetized with nembutal, using a microelectrode technique, have demonstrated that pinching of the coronary artery involves changes in the patterns of impulse activity in all types of bulbar respiratory neurons, up to the appearance of ischemic shifts on the ECG. Progression of myocardial ischemia is paralleled by changes in all the bulbar respiratory neurons.     

Impulse activity of the nodose ganglion neurons in myocardial ischemia

Standard microelectrode techniques were used to study the impulse activity of different types of nodosal ganglion neurons in the course of the development of myocardial ischemia. The cardiopulmonary late inspiratory and inspiratory-expiratory neuronal responses were estimated upon ligation of the coronary artery during the first respiratory cycle after blood flow stoppage. Spontaneous activity of cardiopulmonary neurons was not dependent on coronary circulation disturbances at the moment of coronary artery ligation. Later on, however, during the development of myocardial ischemia, there occurred substantial changes in all the types of nodosal ganglion neuronal activity, excluding real inspiratory neurons.     

Hemodynamic changes during electrical stimulation of some bulbar cardiovascular structures

The effect of electrical stimulation was studied on the nucleus of the tractus solitarius, the nucleus cuneatus, and the dorsal motor nucleus of the vagus nerve, i.e., structures of the bulbar cardiovascular sector in which it has been postulated that impulses from the sinoaortic reflexogenic zone are relayed to the cardiovascular system. Stimulation of all the structures tested in acute experiments on cats under chloralose-Nembutal anesthesia evoked depressor responses of varied degree, the hemodynamic basis of which was a decrease in the cardiac output (CO). The effect of stimulation of the nucleus cuneatus on the development of the negative chronotropic effect was observed. The dorsal motor nucleus of the vagus nerve in cats is not the only or even the principal zone from which negative chronotropic influences are exerted on the heart.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol.3, No.6, pp.631–636, November–December, 1971.     

Integrative properties of the microsystem of cortical neurons during repeated local stimulation

Small groups of neighbouring neurons in neocortex are able to form separate microsystem in model situation of habituation during the local repetitive action of acetylcholine. This new functional unit exhibits a number of main properties which are characteristic of systemic processes of habituation. Only some of the properties don't reproduce in microsystem of cortical neurons. There is no effect of full extinction of responses and no direct relationship between the decrease of speed quantity of responses and stimulus action frequency. The data obtained are considered as significant argument for identification of special intermediate level of integrative processes--microsystem level.     

Ca and acidosis synergistically lead to the dysfunction of cortical GABAergic neurons during ischemia

Cell death in cerebral ischemia is presumably initiated by neural excitotoxicity resulted from the dysfunction of inhibitory neurons in early stage. Molecular processes underlying the ischemic injury of inhibitory neurons remain to be elusive, which we investigated by biochemical manipulations with cellular imaging and patch clamp at GFP-labeled GABAergic cells in cortical slices. Ischemia induces Ca²⁺ elevation, acidosis and dysfunction in GABAergic cells. An elevation of cytoplasmic Ca²⁺ or H⁺ impairs the encoding of action potentials in these neurons. The effects of Ca²⁺ and H⁺ are additive in nature and occlude ischemic outcomes. Ischemia impairs spike production through prolonging spike refractory periods and raising threshold potentials. Therefore, calcium toxicity and acidosis during ischemia synergistically impair the dynamics of sodium channels and function of cortical GABAergic neurons, which lead to neural excitotoxicity. Our results also suggest that the cocktail therapeutics is needed to prevent neuronal death from ischemia.     

Comparative analysis of discharge frequency of right and left sensorimotor cortical neurons in rabbits during tonic immobility

Multiunit activity was recorded in left and right sensorimotor cortex of rabbits in the state of tonic immobility. After the first immobilization session, the discharge frequency changed in 47% cells in the right hemisphere: 30% decreased their frequency, and 17% increased. In the left hemisphere, only 18% cells changed their discharge frequency (13% decreased and 5% increased). Reciprocal changes in discharge frequency could be observed in the neighboring neurons (recorded by the same electrode). Several days later, after the second immobilization session, the interhemispheric difference in the number of neurons, whose activity changed, almost disappeared (21% neurons in the right and 24% neurons in the left hemispheres). The relationship between the number of cortical neurons, which increased and decreased their activities in the state of "hypnosis" also became similar in the right and left hemispheres. A suggestion about the involvement of cortical neurons in organization of the state of "animal hypnosis" was made.     

脑缺血和缺血再灌注大鼠皮层神经元自噬的动态变化

目的：探讨脑缺血和缺血/再灌注不同时间大鼠大脑皮层神经元自噬的变化。方法：健康雄性SD大鼠60只,随机分为：假手术（Sham）组（n=10）,脑缺血和缺血/再灌注模型组（n=50）.模型组分别在缺血30min、2h,缺血2h再灌注1h、6h、24h五个时间点,随机抽取10只大鼠,测定脑梗死体积和脑含水量,同时采用Western印迹法测定各组大鼠大脑皮层中微管相关蛋白轻链3-Ⅱ（LC3-Ⅱ）的水平,透射电镜检测大脑皮层神经细胞自噬情况。结果：脑缺血30min时LC3-Ⅱ/Ⅰ比值未见明显上升,缺血2h时LC3-Ⅱ/Ⅰ比值开始升高,明显高于Sham组（P<0.01）;缺血/再灌注1h、6h时LC3-Ⅱ/Ⅰ比值虽较缺血2h组有所下降,但仍明显高于Sham组（P<0.05）;缺血/再灌注24h时LC3Ⅱ/Ⅰ比值达高峰,明显高于Sham组（P<0.01）。透射电镜观察进一步证实该现象。缺血/再灌注6h和24h时大鼠脑梗死体积明显增加,与Sham组比较有统计学差异（P<0.01）。缺血/再灌注24h大鼠脑组织含水量明显增加,明显高于Sham组（P<0.05）。HE染色显示：仅在缺血/再灌注24h组大鼠皮层见组织水肿、疏松,部分细胞变性、凋亡,海马区见大量神经元细胞核皱缩、深染呈变性凋亡状。结论：局灶性脑缺血和缺血/再灌注模型中大脑皮层缺血2 h神经元自噬即明显激活,缺血/再灌注1 h、6 h自噬均持续增高,缺血/再灌注24 h自噬达高峰。     

Impulse activity of neurons in the nucleus pontis oralis in cats during sleep--wakefulness cycle

The nucleus pontis oralis contains several populations of neurons showing distinct sleep-waking discharge patterns. PS-on, PS-off cells, and neurons that discharged in association with phasic movements during paradoxical sleep and/or waking, were found. The findings suggest that different populations of the nucleus pontis oralis neurons take a distinct part in paradoxical sleep control.     

Plasticity and its physiological markers in the microsystem of cortical neurons during repeated local stimulation

Separate neuronal microsystems in the sensomotor cerebral cortex are able to exhibit the functional plasticity under conditions of repeated action of acetylcholine applied microiontophoretically. The characteristic properties of dynamics in activity of single cortex neurones are determined mainly by the initial reactivity to transmitter and by the state of nervous cells of the surrounding microsystem. The composition and succession of response components as well the duration of excitatory stage of reaction to acetylcholine serve as physiological markers of plastic properties of neurones in cortical microsystem.     

Responses of cortical neurons to viscero-somatic stimulation

Responses of cortical neurons in the posterior sigmoid gyrus of cats anesthetized with chloralose to electrical stimulation of somatic and visceral nerves were recorded. Bimodal viscero-somatic neurons are predominant in this part of the cortex and some of them also respond to light. Besides the polysensory modally-specific neurons it was also possible to distinguish a group of modally nonspecific cells (27%), whose responses to different stimuli did not differ statistically from each other. Simultaneous stimulation of visceral and somatic nerves led to facilitation of activity of the long-latency neurons; this was reflected in a decrease of 10 msec in the latent period of the response and an increase in the number of spikes per discharge.A. A. Zhdanov Leningrad University. Tadjik University, Dushanbe. Translated from Neirofiziologiya, Vol. 3, No. 6, pp. 574–581, November–December, 1971.     

Ultrastructural characteristics of the biological action of an endotoxin on sensorimotor cortical neurons

The work is devoted to the ultrastructural investigation of the state of the sensomotor cortex neurons after intravenous and intracisternal administration of endotoxin. The evidences are presented concerning ultrastructural alterations in mitochondria and the presence of compensatory reaction in them after intravenous injection of endotoxin. Besides, coated vesicles and subsurface cisternae whose formation is induced by the endotoxin action have been studied.