RESUMEN
EEG power variations were evaluated in 9 healthy young adults from 8.45 a.m. to 9 p.m. and at 7 a.m. the next day. EEG signals were obtained from 16 electrodes in closed eyes and open eyes situations. Diurnal power variations were calculated for each frequency component, according to the recording situation (RS) and to the scalp site. Regarding values in the early morning on the first day, the power of almost all the frequency components showed an important diurnal increase. It came back close to initial values at 7 a.m. on the second day, which is in agreement with the existence of EEG circadian variations. Diurnal evolutions were dependent on the frequency components: the higher the frequency, the later was its diurnal maximum. For many frequency components, the diurnal variation was dependent on RS and the scalp topography. All these characteristics could be used to split the classical EEG bands, especially the delta and alpha bands and be useful for physiological and pharmacological research.
Asunto(s)
Ritmo Circadiano/fisiología , Electroencefalografía , Adulto , Ritmo alfa , Mapeo Encefálico , Ritmo Delta , Electrooculografía , Humanos , Masculino , Lóbulo Occipital/fisiología , Valores de Referencia , Cuero Cabelludo/anatomía & histología , Lóbulo Temporal/fisiologíaRESUMEN
One study was performed in 12 patients with presenile Alzheimer's disease (group I), the other one in 16 patients with mild senile dementia of Alzheimer type (group II). In each study, patients were divided into two randomized parallel groups, one receiving placebo, the other piracetam (9 g daily in group I piracetam and 2.4 g daily in group II piracetam) during three months, piracetam induced a decrease in EEG power on the 2-6 Hz range (group I piracetam), 3-5 Hz and 7 Hz (group II piracetam) and an increase of EEG power in the 9-11 Hz range (group I piracetam) and in the 10 Hz and 13 Hz frequencies (group II piracetam). There was also a significant improvement in the Trail Making Test part A in group II piracetam. Correlations between decreased EEG low frequency components and improvement in some psychometric tests were found significant in the two groups. It seems that the main effect of piracetam was to induce increased alertness. The same results were found in both studies; the good reproducibility suggests that EEG spectral analysis is a reliable tool in the assessment of psychotropic drug effects.
Asunto(s)
Enfermedad de Alzheimer/fisiopatología , Encéfalo/fisiopatología , Electroencefalografía/efectos de los fármacos , Piracetam/uso terapéutico , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/psicología , Encéfalo/efectos de los fármacos , Método Doble Ciego , Electroencefalografía/métodos , Femenino , Análisis de Fourier , Humanos , Masculino , Persona de Mediana Edad , Pruebas NeuropsicológicasRESUMEN
During recent years many studies on the electroencephalogram (EEG) changes induced by almitrine-raubasine (Duxil) have been performed in elderly patients and in animals. This article gives an overview of three questions raised by their results. Is there a simple addition of the raubasine and almitrine effects when they are coadministered? Are the EEG effects of this treatment dependent on the patient's disease? To what extent could EEG studies provide some knowledge about the mechanism of action of almitrine-raubasine therapy? In adult (8 months) and aged (22 months) rats the EEG changes induced by the coadministration of almitrine and raubasine were significantly different from the addition of individual almitrine and raubasine EEG effects. In adult rats the coadministration induced slighter EEG changes than those predicted by the addition of almitrine and raubasine effects. In aged rats, the coadministration induced a decrease in delta-theta power not predictable from the effects of almitrine or raubasine. These results could be taken as an indication that some biological targets are common for the two drugs and that the coadministration results in pharmacological effects more complicated than a simple addition of raubasine and almitrine properties. After 3 weeks of treatment in aged healthy subjects, the coadministration induced an increase in the alpha and beta power with a slight decrease of delta and beta-1 powers. In patients with cognitive decline of probable degenerative origin, 3 months of therapy with almitrine-raubasine was mainly associated with a decreased delta and theta power and a slight increase in high frequency components of the alpha band.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Almitrina/farmacología , Electroencefalografía/efectos de los fármacos , Alcaloides de Triptamina Secologanina , Yohimbina/análogos & derivados , Anciano , Envejecimiento/fisiología , Animales , Combinación de Medicamentos , Humanos , Ratas , Yohimbina/farmacologíaRESUMEN
EEG effects of l-fenfluramine (l-F) (2.5, 5 and 10 mg/kg) and haloperidol (0.1, 0.25 and 0.5 mg/kg) were studied in 20 adult rats. The EEG signals of two prefrontal (A = +4, L = 2.5) and two sensorimotor (A = -4, L = 4) transcortical electrodes were analyzed in each rat during three 60-min periods, 1, 3 and 5 h after the intraperitoneal (IP) administration of the drugs. In the prefrontal cortex haloperidol induced a decreased power for the 1-3 Hz components and an increase in power for frequencies higher than 8 Hz, with a maximum around 13 Hz. These effects were already observed after 0.1 mg/kg. In this cortical area l-F administration was essentially associated with a decrease of power maximum for 3-8 Hz, an increased power for the 10-19 Hz band being present only after 10 mg/kg. In the sensorimotor cortex haloperidol appeared less potent than in the prefrontal site; a significant power increase for the frequencies higher than 8 Hz was only observed with 0.5 mg/kg. On the contrary, l-F appeared more effective in this area, its action being characterized by a decreased power from 2-8 Hz and a power increase already significant with 2.5 mg/kg for the frequencies higher than 10 Hz, with a maximum lying around 15 Hz. These results suggest that haloperidol induced cortical sedation (increased power) on the two recording sites. l-F also induced a net cortical sedation in sensorimotor cortex but up to 5 mg/kg acted in the opposite direction on the prefrontal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Electroencefalografía , Fenfluramina/farmacología , Haloperidol/farmacología , Animales , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/fisiología , Relación Dosis-Respuesta a Droga , Habituación Psicofisiológica , Masculino , Ratas , Ratas Endogámicas , Factores de TiempoRESUMEN
A new method for quantification of electroencephalographic (EEG) signals was used to study the effects of almitrine and raubasine, alone and in combination, in two groups of six unanesthetized rats, aged 8 months (young) and 22 months (old). Coadministration of almitrine (7.5 mg/kg-1 i.p.) and raubasine (2.5 mg/kg-1 i.p.) induced an increased EEG power from 7 to 30 Hz; the frequencies concerned were identical in young and old rats, but the degree of their power variations was more marked in old rats. Almitrine induced a 20 to 50% increase in EEG power in young rats on nearly all spectral components. The effects of almitrine were only seen in the low-frequency range in old rats. Raubasine increased the EEG power in the 10 to 20 Hz frequency range; these effects were significantly greater in old rats. In both age groups, the effects on EEG power observed with coadministration of almitrine and raubasine were significantly different from those expected if raubasine and almitrine add their individual effects. These results show that a) almitrine and raubasine modify cortical electrical activity in a different manner as a function of age; b) the modification of the EEG activity induced by the coadministration is suggestive of an interaction between the cortical effects of each drug; and c) the modification of EEG power induced by the coadministration is qualitatively identical in young and old rats but quantitatively more marked in old rats.
Asunto(s)
Envejecimiento/fisiología , Electroencefalografía , Piperazinas/farmacología , Alcaloides de Triptamina Secologanina , Yohimbina/farmacología , Almitrina , Animales , Encéfalo/efectos de los fármacos , Combinación de Medicamentos , Inyecciones Intraperitoneales , Masculino , Piperazinas/administración & dosificación , Distribución Aleatoria , Ratas , Ratas Endogámicas , Yohimbina/administración & dosificaciónRESUMEN
The purpose of this study was to investigate the role of four doses of apomorphine (0.01, 0.05, 0.25, 1 mg/kg s.c.) on the cortical activity by a quantified electroencephalography (EEG) method recently developed in our laboratory. The EEG-effects of apomorphine were changed significantly according to the dose and the time. When initial effects were considered an opposition in the apomorphine-induced variations between low (0.01 mg/kg) and higher doses were observed. In the time course with 0.01, 0.25 and 1 mg/kg SC, EEG variations changed the direction in 6-17 Hz and diminished in the other spectral components. Qualitatively, this tardive change with 0.01 mg/kg may show a feed-back response of the dopaminergic system to the initial low dose-induced depressant effects of apomorphine. On the other hand higher doses-induced tardive EEG pattern may show a possible changed balance in the stimulated D1 and D2 receptors.
Asunto(s)
Apomorfina/farmacología , Corteza Cerebral/efectos de los fármacos , Electroencefalografía , Animales , Corteza Cerebral/fisiología , Relación Dosis-Respuesta a Droga , Inyecciones Subcutáneas , Masculino , Ratas , Ratas Endogámicas , Factores de TiempoRESUMEN
Computerized quantification of electroencephalograms enables pharmacological compounds designed to counteract pathological cerebral aging to be evaluated. The results obtained by this method when substances which sedate or stimulate the central nervous system are used suggest the existence of a negative correlation between neuronal activity and electroencephalographic power. More precisely, the application of this method to pharmacology suggests a relation with the activity of one or several neurotransmission systems. By extension, studies of cerebral aging may benefit from this new technique of cerebral exploration because it allows the demonstration of age related changes in the EEG effect of drugs studied in physiological conditions. Thus we have demonstrated an interaction between the almitrine-raubasine combination and the noradrenergic system in rats. In clinical pharmacology, the evaluation of these two compounds is still liable to numerous experimental biases. The almitrine-raubasine combination was tested in controlled trials in elderly people complaining of intellectual deterioration; the results obtained were fairly similar to those observed in old rats, thus demonstrating an effect on the central nervous system and perhaps also an action on the noradrenergic system in human.
Asunto(s)
Antiinflamatorios no Esteroideos/uso terapéutico , Estimulantes del Sistema Nervioso Central/uso terapéutico , Demencia/tratamiento farmacológico , Electroencefalografía/métodos , Piperazinas/uso terapéutico , Alcaloides de Triptamina Secologanina , Yohimbina/uso terapéutico , Almitrina , Animales , Antiinflamatorios no Esteroideos/farmacología , Estimulantes del Sistema Nervioso Central/farmacología , Corteza Cerebral/fisiopatología , Clonidina/antagonistas & inhibidores , Demencia/fisiopatología , Combinación de Medicamentos , Evaluación de Medicamentos , Humanos , Piperazinas/farmacología , Ratas , Yohimbina/farmacologíaRESUMEN
The EEG-effects induced by intraperitoneal administration of clonidine, prazosin and yohimbine to 8 and 22 month old rats were compared. Clonidine (0.01 mg/kg) and prazosin (1 mg/kg) increased spectral powers, yohimbine (0.5 mg/kg) decreased them. In the older rats, EEG variations were smaller for prazosin and yohimbine, but larger for clonidine. These findings show that alpha receptor mediated influences on EEG are changed during aging and show that quantified EEG gives a picture of age related changes in the functional state of the neurotransmitter systems.
Asunto(s)
Envejecimiento , Encéfalo/fisiología , Clonidina/farmacología , Prazosina/farmacología , Yohimbina/farmacología , Animales , Electroencefalografía , Electrofisiología/efectos de los fármacos , RatasRESUMEN
The role of the heart and its working conditions on the shape of aortic pressure curves was studied by analysis of pressure signals produced at the input of an artificial ejection circuit by 25 isolated working hearts of rats aged 4-22 months. The hearts were paced at five successive heart rates and three levels were imposed for the left auricular perfusion pressure (LAPP). With ageing of the myocardium, increased LAPP and low heart rates, there was an alteration of the pressure wave visual aspect towards a tele-systolic maximum. This modification was regularly associated with significant differences in the harmonic content of the pressure signal. More precisely, there was a bigger increase in the first harmonic amplitude than in the second and third harmonic amplitudes. Because of the physical linearity of the artificial ejection circuit and the controlled working conditions for the heart, it is possible to explain these changes in the pressure wave shape. Lowering of the heart rate is associated with an involvement of a more left part of the circuit impedance curve. Ageing of the myocardium and increased LAPP change the pressure wave shape because they were associated with an increase in left ventricular ejection time.
Asunto(s)
Envejecimiento , Corazón/fisiología , Animales , Presión Sanguínea , Gasto Cardíaco , Electrofisiología , Frecuencia Cardíaca , Técnicas In Vitro , Ratas , Función VentricularRESUMEN
The effects of age, pre-load and heart rate on the juxta-aortic pressure wave form in an artificial ejection circuit were studied in 25 isolated perfused rat hearts beating at a controlled rate. The hearts were taken from male Wistar rats aged 4, 8, 12, 16 and 22 months. Each heart was submitted to 3 pre-loads by adjusting the level of left atrium perfusion to 15, 20, 25 cm H2O. Five different heart rates (300, 240, 198, 174 and 150/min) were imposed at each level of pre-load by pacing the interatrial septum after destroying the sinoatrial node. Age, increasing pre-load and bradycardia produced similar changes in the systolic part of the wave characterised by a delayed peak. The effects of these three factors were significant and independent and corresponded to significant changes of the harmonic composition of the pressure wave. In these three conditions, the amplitude of the first harmonic of the pressure increased significantly compared with the second, third and fourth harmonics. The predominance of the amplitude of the first harmonic is characteristic of pressure waves with delayed systolic summits . The linear character of the physical properties of the circuit was tested experimentally. A change in the wave form at a fixed rate is explained by a modification of ventricular ejection which is therefore necessarily present when pre-load is increased and the age of the heart varies. On the other hand, the effect of rate changes on the wave form are explained essentially by the interplay of different zones of the impedence curve of the circuit.(ABSTRACT TRUNCATED AT 250 WORDS)