Zh Vyssh Nerv Deyat+
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Zh Vyssh Nerv Deyat+ · May 2008
[The remote effects of neonatal injections of caffeine and piracetam on audiogenic seizure susceptibility in mice of three genotypes].
Neonatal DBA/2J, 101/HY and CBA/Lac/Sto mice (2-7-day-old) were subcutaneously injected with caffeine (200 mg/kg), piracetam (50 mg/kg) or distilled water. At the age of 1 month, they were tested for audiogenic seizure susceptibility (SS). The neonatal injections changed SS in 1-month-old mice in a genotype-dependent manner. ⋯ Caffeine neonatal injections induced slight changes in DBA/2J, no changes in CBA and increased SS in 101/HY mice. Piracetam reduced fit intensity in DBA/2J mice but increased it in CBA and, especially, in 101/HY strain. Genotype-dependent differences in physiological mechanisms of audiogenic seizures may be responsible for different remote effects of early treatment.
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Zh Vyssh Nerv Deyat+ · Mar 2004
[Dopaminergic regulation of theta activity of septohippocampal neuron in the awake rabbit].
The effects of dopamine reuptake blocker nomifensine and nonselective antagonist of dopamine receptors haloperidol on the theta rhythmicity of the medial septal neurons and hippocampal EEG were investigated in the rabbit. Bilateral intracerebroventricular infusion of nomifensine (9 micrograms in each ventriculus) produced an increase in both the rate of firing and the theta modulation of medial septal neurons; the theta power of the hippocampal EEG also augmented. The degree of neuronal theta stability (time constant of damping, tao theta) significantly increased. ⋯ Effects of both drugs built up rapidly and then gradually attenuated. Nomifensine infusion against the background of exposure to haloperidol provoked neither increasing neuronal firing rate, nor elevating theta activity. These finding suggest that dopaminergic system produces activation of the septohippocampal system in situations that require selective attention to functionally important information.
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Zh Vyssh Nerv Deyat+ · Mar 2004
[The influence of neonatal ketamine injection on pain sensitivity and audiogenic seizures in adult rats].
The remote effects of neonatal (on the 3d-to-9th postnatal days) ketamine injections (10 and 50 mg/kg in 20 microliters of distilled water, s.c.) were analyzed in adult Wistar, WAG/Rij, and KM (a strain with high audiogenic sensitivity) rats. Both ketamine and water injections increased pain sensitivity in adult rats. ⋯ In highly sensitive KM rats the neonatally injected ketamine (50 mg/kg) significantly shortened the mean latency of the fit onset, and fit stages developed faster. Thus, the neonatal ketamine injection increased the audiogenic seizure susceptibility of brain structures in KM rats.
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Zh Vyssh Nerv Deyat+ · Nov 2003
[Sensory responses of neurons in the medial septal area to modulation of the theta-activity by alpha2-adrenergic receptor agonist clonidine].
It was shown by us earlier that bilateral intracerebroventricular injection of alpha2-adrenoreceptor agonist clonidine produced a dose-dependent effect on theta oscillations in the septohippocampal system of awake rabbits. A relatively low dose of clonidine (0.5 microgram) attenuated and a high dose (5 micrograms) significantly enhanced the rhythmic activity. It was suggested that the effect of the low dose of clonidine is mediated by presynaptic alpha2-adrenoreceptors were as postsynaptic alpha2-adrenoreceptors. ⋯ Persisted excitatory and inhibitory responses became less distinct than the initial ones except single excitatory reactions. The results suggest that alpha2-adrenoreceptors are involved in the control of the sensory reactivity of MS neurons. A sharp decrease in neuronal reactivity during stable rhythmical oscillations developing under the influence of high dose of clonidine confirm the role of the theta rhythm in the septohippocampal system as an active filter in information selection and registration.
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Zh Vyssh Nerv Deyat+ · Mar 1998
Comparative Study[The characteristics of the spatial organization of the human EEG in ketamine-altered consciousness].
Spatial organization of human EEG was studied by means of topographic mapping methods with the multiparametric data estimations in the state altered by ketamine in terms of the concept of coherent structures of brain electrical activity. Two main features of the altered state of consciousness were reflected in the opposite shifts: an increase in the spatial synchronization in the left hemisphere (especially, in the posterior area) and its decrease in the left frontal and right temporal one. The obtained data are discussed from the viewpoint of dissociative effects of ketamine at the neurochemical and neurophysiological levels.