Search PubMed⌕ Search

Biomedical subjects

J M Gaillard

Publications and source records attributed to J M Gaillard.

At least 91 records · Page 5Linked to original sources
PubMed1983

Relationships between brain concentrations of desipramine and paradoxical sleep inhibition in the rat.

Desipramine (DMI), like many antidepressant drugs, inhibit the production of paradoxical sleep (PS). In the present experiment, we have investigated the relationships between brain level of DMI and PS inhibition. Groups of rats had their sleep monitored after 1, 2 or 4 mg/kg of DMI. In other animals, the brain concentration of DMI was assayed at various times after the same treatments. The results indicate that a critical threshold concentration of 300 ng/g DMI in the brain is necessary for complete PS inhibition. This stage reappears only when the DMI level falls below this value, and its production resumes at a normal rate, provided the DMI level reached initially was not largely in excess of the threshold concentration. The results are discussed with regard to the present knowledge of specific binding of tricyclics in brain and their "ex vivo" action on norepinephrine uptake resulting in enhancement of collateral inhibiton of noradrenergic cells.

Animals↗
PubMed1983

Paradoxical sleep rebound without previous debt: the effect of minute doses of clonidine in man.

This report describes an experimental condition in which clonidine administration does not modify paradoxical sleep (PS) directly, but is followed by a secondary rebound. After oral consumption of minute doses of clonidine (CLN), 12 subjects showed no direct effect of CLN, but showed a significant increase of PS production in the following placebo night. Four other subjects experienced a decrease of PS under CLN and no rebound the next night. In addition, these four subjects had mechanisms of slow wave sleep production significantly weaker than the first 12 subjects.

Adolescent↗
PubMed1983

Effect of the benzodiazepine antagonist Ro 15-1788 on flunitrazepam-induced sleep changes.

1 The modifications of human sleep induced by benzodiazepines, and particularly by flunitrazepam, are complex. Stage 4 and paradoxical sleep are both decreased; however, these two effects have a different evolution during and after single or short-term drug administration. 2 The benzodiazepine antagonist Ro 15-1788 also tends to depress stage 4, but with immediate recovery in the post-drug night, and does not modify paradoxical sleep. 3 In combined administration, this drug totally reverses the hypnogenic effect of flunitrazepam, as well as its effect on paradoxical sleep but not the decrease of slow wave sleep. 4 Some of the benzodiazepine-induced alterations of sleep may be related to receptors different from central benzodiazepine receptors, or to mechanisms not directly connected to this type of receptors.

Adult↗
PubMed1983

Biochemical pharmacology of paradoxical sleep.

The role of noradrenergic cells in the regulation of paradoxical sleep is still controversial, and experimental data have given rise to contradictory interpretations. Early investigations focused primarily on chemical neurotransmissions. However, the process of information transmission between cells involves many other factors, and the cell surface is an important site for transduction of messages into modifications of the activity of postsynaptic cells. alpha-adrenoceptors are believed to play an important role in the control of wakefulness and paradoxical sleep. Experimental evidence suggests that physiological modulation of receptor sensitivity, possibly by specific neuro-modulators, may be a key mechanism in synaptic transmission. In the investigation of the mechanisms involved in paradoxical sleep regulation, lesions of the locus coeruleus have given equivocal results. Collateral inhibition, probably mediated by alpha 2-adrenoceptors, appears to be a powerful mechanism. The exact temporal relationship between noradrenergic cell activation and paradoxical sleep production is not established, but 5-HT appears to be involved. Differences between paradoxical sleep and waking may be related to a physiological modulation of alpha 2-adrenoceptor sensitivity.

Animals↗
PubMed1983

[Clinical characteristics of a representative group of hospitalized depressed patients].

In order to define some principal clinical characteristics of the hospitalised depressives, the authors have examined a group of 100 depressed patients consecutively admitted to the Psychiatric University Clinic of Lausanne. The clinic is at the same time a sector hospital. The depressives constituted 21% of all hospitalised patients. The number of depressives admitted during the duration of the study (6 months) permitted to calculate a hospitalisation rate of 86 patients per 100 000 inhabitants and per year. The 100 patients were subclassified in patients with a short depressive reaction, neurotic depressives, and endogenous depressives. Each of the 3 subgroups had about the same size. A modified version of the ICD 9 was used for the diagnostic classification. As a whole, the patients showed serious psychiatric manifestations and the majority presented suicidal tendencies. Besides, there were found characteristics which are not considered to be associated with depressions in general: an elevated proportion of unmarried persons in the total group, psychopathic traits among the reactive and neurotic depressives, and a considerable proportion of parental loss in early childhood in these two last mentioned subgroups. Furthermore, an accumulation of chronic and therapy resistant cases was observed in the group of neurotic depressives. A third of the endogenous depressives had been resistant to the ambulatory antidepressive treatment; a part of these patients responded well to the treatment in the hospital.

Adjustment Disorders↗
PubMed1982

Exchange mechanism of tyrosine between plasma and red blood cells in normal subjects and psychiatric patients.

The saturable mechanism of tyrosine (TYR) uptake by the membrane of red blood cells incubated at 37 degrees C has been studied in normal subjects and psychiatric patients. This uptake is markedly inhibited by incubation at 0 degree C, and weakly inhibited by iodoacetic acid and ouabain. The uptake of TYR is significantly lower in unipolar- and bipolar-depressed patients, and significantly higher in schizophrenics compared to normal controls. These results indicate a possible disturbance of functional capacity of membrane transport in some psychiatric diseases.

Biological Transport↗
PubMed1982

On the role of brain alpha-adrenergic systems in the production of paradoxical sleep.

In order to reinvestigate the role of brain alpha-adrenergic systems in the regulation of paradoxical sleep (PS), we recorded chronically implanted rats under the effect of various neuroactive substances. The functions describing the evolution of PS during sleep were calculated. The following substances were studied at different doses, alone and in various combinations: clonidine, phenoxybenzamine, chlorpromazine, yohimbine, piperoxane and desipramine. Chlorpromazine, yohimbine, piperoxane and desipramine were also studied after pretreatment with alpha-methylparatyrosine. The results are discussed in terms of the known pharmacological properties of these compounds, and indicate that brain alpha-adrenergic systems, probably mainly noradrenergic systems, are positively involved in the maintenance of PS. However, the activity of these systems is controlled by powerful regulatory mechanisms: inhibitory control of transmitter release at the effector site, collateral inhibition within the locus coeruleus and control of transmitter release at the site of collateral inhibition.

Animals↗
PubMed1981

[Decrease of paradoxical sleep in the rat under tricyclic antidepressant: the role of collateral inhibition (author's transl)].

The present study investigated the mechanisms of the action of a tricyclic antidepressant, desmethylimipramine, upon paradoxical sleep in the rat in acute administration. Desmethylimipramine induces an increase in paradoxical sleep latency, as well as a decrease of its total duration; these two modifications are dose-dependent. Different mechanisms may be evoked: inhibition of catecholamine synthesis, inhibition of locus coeruleus by adrenergic collaterals, or an anticholinergic effect. The results show that inhibition of synthesis is not quantitatively sufficient to induce the observed effects. It appears more probable that this decrease in paradoxical sleep results from a collateral inhibition, with the possible participation of an anticholinergic effect. The contributions of these different factors are discussed.

Animals↗
PubMed1981

Relationship between plasma-levels of chlorpromazine and effects on EEG and evoked potentials in healthy volunteers.

The effect of chlorpromazine (CPZ) was studied at four different doses in a group of 10 normal subjects. Blood levels of CPZ were assayed by gas chromatography and showed wide interindividual variations. Spontaneous brain electrical activity (EEG) was recorded from 8 leads and submitted to spectral analysis. Evoked responses (ER) to flashes, pattern reversals and clicks were averaged, and measured by their amplitude and variability. Several subjects presented marked side-effects (responders, R) and showed differences in many EEG parameters with respect to subjects without side-effects (non-responders, NR). A cluster analysis permitted to distinguish very clearly these two groups of subjects. The differences in the effects of CPZ between the R and NR groups involved mainly EEG, and appeared with a systematic topography over the scalp. Within the R group, many differences were observed as a function of the dose of CPZ; they consisted mainly in a decrease of alpha and an increase of theta activity in the EEG, decrease of amplitude and increase of variability in the ER measures. These modifications had also a typical topography over the scalp. Finally, many variables of EEG (relative power only) were correlated with plasma level of CPZ, while no such correlation appeared for ER. These results are discussed in terms of individual sensitivity to drugs, relationships between EEG parameters and plasma level, and topographical differences in the effect of CPZ.

Adult↗
PubMed1981

Spindle density in sleep of normal subjects.

We studied sleep spindle activity in ten normal young subjects, five males and five females. The subjects were recorded on magnetic tapes according to standard procedures, and the tapes were scored automatically by a system described previously. Spindle activity was analyzed on the C4-T4 lead of electroencephalogram, using a bandpass filter and discrimination of the integrated output of the filter. Results indicated that spindle density was the same in stages 2, 3, and 4, and was much lower in rapid eye movement (REM) sleep. In stage 2, K potentials were less abundant than spindles and exhibited a much smaller individual variability. Whereas spindle density was very stable across two nights in the same subject, there was wide variation between subjects. In addition, there was a sex difference; female subjects presented more than twice as many spindles as males. The density of spindles during non-REM sleep was constant throughout the recording and did not show any cyclic variation.

Adult↗
PubMed1980

Electrophysiological semeiology of sleep.

The main characteristics of electroencephalograms, electro-oculograms and electromyograms in human sleep are described. This electrophysiological semeiology permits the identification of the different stages in normal sleep. In animals, sleep is generally less differentiated; the possibility of recording subcortical structures allows the observation of additional phenomena such as hippocampal theta activity and PGO spikes. Evoked brain electrical activity is less well known than the spontaneous activity in sleep. Recent technological developments offer many interesting possibilities in the processing of the EEG and other physiological signals.

Animals↗