Biomedical subjects

C Luczak

Publications and source records attributed to C Luczak.

6 recordsLinked to original sources

PubMed1995

Development of the age-related spontaneous spike-wave discharges in rat neocortex and exposure to a model neurotoxin.

In laboratory rats an epileptic-like spontaneous neocortical activity in the form of bursts of spike and wave discharges (SWD) develops gradually with age. High incidence of the SWD episodes is accompanied by other indices characteristic of advanced age: memory disturbances and atrophic changes within basal forebrain structures (Buzsaki et al. 1988b, Gage et al. 1988). Accordingly, it has been proposed that the number and duration of the SWD episodes be regarded as a diagnostic marker to distinguish between young and old brains (Buzsaki et al. 1988a). It is suspected that exposure to neurotoxins may accelerate the progress of age-related neurodegeneration by predisposing neurons to premature death and thus hasten the appearance of the age-related functional deficits (Weiss 1990). Analysing the development of SWD activity in exposed rats may be helpful for an assessment of the potency of the neurotoxin under study to exert such an effect. In the present work the influence of a three-month exposure to a model neurotoxin, ethanol (ETOH), on the development of the SWD activity in imp-DAK rats was investigated. It has been found that in rats given 10% ETOH solution as the only drink for three months, the incidence of the SWD episodes increased markedly. The increase was most clearly seen after ETOH withdrawal and on the 90th day after exposure no tendency to decline could be observed. The obtained data indicate that exposure to exogenous substances may exert a distinguishable long-lasting influence on the development of the SWD activity.

Aging↗

PubMed1994

Changes in cortical and hippocampal EEG activity accompanying spontaneous electrocortical seizures in rats.

The purpose of the present study was to find out whether the occurrence of bursts of spontaneous spike-wave discharges (SWD) in rat neocortex is related to a particular state of vigilance (level of arousal), as some authors suggested, or rather to transitions from one state to another as postulated by others. Patterns of cortical and hippocampal EEG preceding and following the SWD bursts were studied in rats. It has been found that the beginning of an SWD episode is usually preceded by a shift of cortical activity toward synchronization and replacement of the rhythmic slow activity (RSA) in the hippocampus by large irregular activity (LIA). After SWD, the cortical activity is usually more desynchronized and RSA is present more frequently than just before its onset. An analysis of selected episode-free and episode-rich EEG segments revealed that SWD's occur in abundance at the periods characterized by frequent changes of the hippocampal EEG pattern but are absent during the periods in which long-lasting RSA trains dominate in the record. Thus, the data confirm that SWD occurrence is related more to transitions from one state to another than to a particular state as such. They also indicate that the preferable conditions for SWD's appear when arousal is decreasing from a moderate to a lower level.

Animals↗

PubMed1994

Spontaneous seizure electrocortical activity in rats: relation to arousal level.

The relationship between neocortical high voltage spindle activity (HVS) and the level of arousal (state of vigilance) was investigated in imp-DAK rats. Two groups of single records (6 h and 24 h) and one group of repeated ones (6 h daily for three consecutive days) were analysed. Five levels of arousal (states) were distinguished on the basis of hippocampal and neocortical EEG: high arousal (HA), moderate arousal (MA), low arousal (LA), slow wave sleep (SWS) and paradoxical sleep (PS). The number of HVS episodes and the cumulative amount (i.e. summed duration) of each state was calculated for each successive hour of recording. It was found that the number of HVS episodes correlated positively with the amount of the MA state, but not with the amount of the remaining states. The rate of HVS occurrence during the MA state, however, was not stable. It decreased along with the decrease in amount of MA in successive recording hours of the same recording session. However, at the beginning of each successive session, the HVS episodes became more numerous, whereas the MA amount decreased. The accompanying changes in the cumulative amount of the remaining states confirm indirectly the supposition that HVS occurrence is related to transitions from one state to another rather than to a given state itself.

Animals↗

PubMed1993

[Evaluation of the functional observational battery of tests used for neurotoxicity detection based on the effects of exposure to chlorfenvinphos].

Functional observational battery suggested by EPA, was applied to neurotoxicity screening studies. In previous experiments an organophosphorous pesticide, chlorfenvinphos (CVP), was used. It was administered intraperitoneally to male rats at the doses of 1, 3, 6 mg/kg of body weight; edible oil was administered to the control group. Tests were performed 3 hrs, 24 hrs and 7 days after the administration of the these substances. The set of tests concerned motor, sensory and vegetative functions. The influence of the dose of 6 mg/kg on rats was particularly evident. A number of disorders, like tremor, hypersalivation, dysbasia and hypotaxia, not observed in animals to which lower doses of CVP had been administered, were noticed. The mortality rate in this group was 25%. Earlier studies revealed neurotoxicity of CVP administered at the dose of 3 mg/kg, which when compared to the present results of the experiment indicates low sensitivity of this battery of tests taken as a whole. The disadvantage of the battery lies also in applying the quality evaluation scale in many cases, which makes carrying out statistical analysis difficult. Behaviours not formulated in this scale were observed. The observation of animal locomotor activity proved to be the most reliable and objective neurotoxicity evaluation index both in the previous and present studies.

Animals↗

PubMed1992

Tolerance to chlorphenvinphos in rats assessed on the basis of changes in locomotor behavior in rotating wheels.

Spontaneous locomotor activity in rotating wheels was investigated in rats exposed repeatedly (i.p. daily injections, five days a week for two weeks) to an agricultural organophosphorus pesticide, chlorphenvinphos (CVP) at doses of 1.0 and 3.0 mg/kg. After a seven day interval each rat was injected with a single 3.0 mg/kg test dose of CVP in order to assess the stability of tolerance. Concomitant changes in blood and the brain ChE activity were also investigated. It was found that exposure to CVP at a low dose (1.0 mg/kg), resulting in less than 50% reduction of ChE activity in blood and in the brain, did not produce changes in spontaneous locomotion in rotating wheels in the rat. Higher doses (3.0 mg/kg) inhibited blood and the brain ChE by more than 50% and reduced locomotion. Under conditions of repeated exposure to CVP at the symptomatic (3.0 mg/kg) dose ChE activity remained low throughout the exposure period, however, locomotor activity returned to a normal level, i.e. tolerance developed, within less than five days. Seven days after termination of the repeated exposure, the behavioral subsensitivity to CVP still remained. The biochemical data suggest that it may be related, at least partially, to a diminished vulnerability of ChE in some parts of the brain to CVP induced inhibition.

Animals↗

PubMed1982

[Not Available].

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Demography↗