Substance P as a neuromodulator of cerebellar cholinergic systems

Substance P in low concentrations (10 -7 M) activates rat cerebellar neurons (in slices), while in high concentrations (10 -6 and 10 -5 M) this compound causes a biphasic response (excitation-inhibition). Substance P probably acts as the excitatory neurotransmitter in the cerebellum and produces modulatory effects (triggering and facilitation) on cerebellar cholinergic structures. Substance P reactivates cholinergic excitatory processes, while acetylcholine prevents substance P-induced inhibitory phase. The data suggest that the modulatory effects of substance P are realized via the feedback mechanisms

Maturation of cerebellar neuronal elements in a tissue culture

The process of differentiation of neurons was traced on an organotypic cerebellar culture of newborn mice. Cerebellar cells reach morphological maturity by the 18-21st day of culturing. An increase of the membrane potential begins on the 6-7th day of culturing. It reaches values characteristic for the definitive stage of the neuron (65-75 mV) by the 9-10th day of culturing. Spontaneous action potentials begin to be recorded on the 10-12th day of culturing. At this time they markedly differ in their characteristics from the action potential of the mature neuron. The differences become less noticeable by the 16-18th day of culturing. However, final maturation of the action potential occurs at later times. The formation of specific sensitivity of cerebellar neurons to acetylcholine correlates with the time of formation of the action potential. © 1986 Plenum Publishing Corporation

INFLUENCE OF INFRALOW-FREQUENCY MAGNETIC-FIELD ON THE NERVOUS CELLS RHYTHM AND THEIR TOLERANCE TO HYPOXIA

The direct effect of infralow-frequency (0,05, 0,1, 0,25 Hz, 100 nT) magnetic fields (MF) was demonstrated on the brain cellular-tissue model-surviving slices of mouse cerebellum. MF influence is a trigger for the nervous cells. MF-5 Hz revealed two-phases response: inhibition and excitation of the impulse activity of neurons. Besides that we recorded convulsive effect of MF. The experiments with simultaneous exposure of hypoxia and MF revealed a prohypoxia effect of MF, when the oxygen concentration was very low and also after reoxygenation. The surviving slices may be used as a model for studying the fine mechanisms of influence of different intensity MF on the nervous cells

Individual resistance of the organism and nerve cell to hypoxia

The correlation between the pattern of a neuron's reaction to acute hypoxia and individual resistance to oxygen deficit is studied on rats in vivo as well as on surviving slices of their cerebellum in vitro. According to the survival time in a pressure chamber simulating an altitude of 11 km all the rats were divided into groups of high resistance, medium resistance, and low resistance to hypoxia. Survival time was 4.2 times longer in the high resistance group than in the low resistance group. In the cerebellar slices of high resistance animals 61.5% high-resistance neurons and 38.5% low-resistance neurons were recorded. On the other hand, in the high resistance animals the percentage of high-resistance neurons and low-resistance neurons was 31.2 and 68.8, respectively. The period of hypoxia development was 4.32 times longer in the high-resistance neurons as compared to low-resistance neurons. It is speculated that individual differences in the resistance to O2 deficit are of a hereditary nature and manifest themselves not only on the level of the whole organism, but also in the individual nerve cell. © 1995 Plenum Publishing Corporation

Biorhythmologic aspects of seizure activity

Seasonal and circadian rhythms of neuronal and organism resistance to convulsive effect of strychnine and penicillin were studied in vivo on mice and rats and in vivo on cultured mouse cerebellar sections. Resistance was assessed by the latency of seizures in mice and neuronal response to convulsants in sections. In the night and morning time (0:00-9:00) seizure resistance in mice increased: it manifested in longer latency and lower mortality compared to those in the day and evening time (12:00-21:00). Seizure resistance was minimum in autumn and maximum in winter. Neurons in cerebellar section were most resistant to the convulsive effect of penicillin in autumn and winter and least resistant in spring and summer. Circadian rhythms of cerebellar neuron resistance to convulsants were opposite, which attests to reciprocal relations between epileptogenic and antiepileptic (cerebellar) cerebral structures

Maturation of cerebellar neuronal elements in a tissue culture

The process of differentiation of neurons was traced on an organotypic cerebellar culture of newborn mice. Cerebellar cells reach morphological maturity by the 18-21st day of culturing. An increase of the membrane potential begins on the 6-7th day of culturing. It reaches values characteristic for the definitive stage of the neuron (65-75 mV) by the 9-10th day of culturing. Spontaneous action potentials begin to be recorded on the 10-12th day of culturing. At this time they markedly differ in their characteristics from the action potential of the mature neuron. The differences become less noticeable by the 16-18th day of culturing. However, final maturation of the action potential occurs at later times. The formation of specific sensitivity of cerebellar neurons to acetylcholine correlates with the time of formation of the action potential. © 1986 Plenum Publishing Corporation

Biorhythmologic aspects of seizure activity

Seasonal and circadian rhythms of neuronal and organism resistance to convulsive effect of strychnine and penicillin were studied in vivo on mice and rats and in vivo on cultured mouse cerebellar sections. Resistance was assessed by the latency of seizures in mice and neuronal response to convulsants in sections. In the night and morning time (0:00-9:00) seizure resistance in mice increased: it manifested in longer latency and lower mortality compared to those in the day and evening time (12:00-21:00). Seizure resistance was minimum in autumn and maximum in winter. Neurons in cerebellar section were most resistant to the convulsive effect of penicillin in autumn and winter and least resistant in spring and summer. Circadian rhythms of cerebellar neuron resistance to convulsants were opposite, which attests to reciprocal relations between epileptogenic and antiepileptic (cerebellar) cerebral structures

INFLUENCE OF INFRALOW-FREQUENCY MAGNETIC-FIELD ON THE NERVOUS CELLS RHYTHM AND THEIR TOLERANCE TO HYPOXIA

The direct effect of infralow-frequency (0,05, 0,1, 0,25 Hz, 100 nT) magnetic fields (MF) was demonstrated on the brain cellular-tissue model-surviving slices of mouse cerebellum. MF influence is a trigger for the nervous cells. MF-5 Hz revealed two-phases response: inhibition and excitation of the impulse activity of neurons. Besides that we recorded convulsive effect of MF. The experiments with simultaneous exposure of hypoxia and MF revealed a prohypoxia effect of MF, when the oxygen concentration was very low and also after reoxygenation. The surviving slices may be used as a model for studying the fine mechanisms of influence of different intensity MF on the nervous cells