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Biomedical subjects

J Oehler

Publications and source records attributed to J Oehler.

At least 37 records · Page 2Linked to original sources
PubMed1987

The influence of long-term treatment with haloperidol on neuronal activity and sensitivity in several brain structures of the rat.

The influence of long-term haloperidol pretreatment on neuronal spontaneous activity and transmitter sensitivity was investigated in prefrontal cortex, hippocampus and locus coeruleus. The changes are different in all areas as well as in the transmission systems involved. In particular cases, analogies exist between haloperidol- and isolation-induced changes, reflecting a comparable dopaminergic supersensitivity.

Action Potentials↗
PubMed1987

The influence of social isolation, hypoxia and immobilization on potassium-stimulated dopamine release from telencephalon slices of mice.

Dopamine release from mice telencephalon slices was investigated following immobilization or hypobaric hypoxia exposure during periods of social isolation of different length which itself affects dopamine release in a characteristic manner. Isolation initially results in a decreasing release, which is compensated at the end by adaptive processes. The decrease of dopamine release induced by immobilization is highly dependent on the foregoing isolation. On the other hand, a hypoxia-induced decrease of release always dominates the results. Adaptive processes in consequence of social isolation are supposed to be important in relation to immobilization effects but not to hypoxia-induced changes.

Adaptation, Physiological↗
PubMed1986

Altered neurobiological responses to acute immobilization in social-isolated mice.

Social isolation results in dynamic changes of neurobiological functions. The altered internal state of the CNS is reflected in changes in spontaneous behavior, changed responses to transmission-related substances and changed responsiveness to an additional impairment of normal relations between the organism and its environment. We analysed the influence of an acute 2-hour immobilization on such isolation-dependent changes. Whereas the susceptibility to pentetrazole-induced seizures increased continuously with lengthening of isolation and was not affected by the additional impairment, the responsiveness to transmission-related substances changed dynamically depending upon isolation-induced alterations. An immobilization-induced increase in responsiveness to LSD and propranolol was demonstrable in grouped controls and after short-term isolation. The apomorphine stimulation during prolonged isolation experienced a down- and an upregulation which were repeated in a stronger manner by immobilization responses especially after long-term isolation. It is suggested that the dynamics of isolation-induced changes coincided with changed acute adaptive functions.

Animals↗
PubMed1985

Posthypoxic transmitter release from brain slices and behavioural consequences of hypoxia in rats and mice.

Subsequent to a hypoxic exposure of adult rats and mice the stimulus induced release of dopamine from striatum slices is inhibited for several days. The posthypoxic release inhibition is not restricted to the striatal dopaminergic transmission system especially, but hypoxia causes comparable changes also in other brain regions regarding further transmitter systems. The transmitter release inhibition reflects a significant caudo-rostral gradient of increasing vulnerability of phylogenetically younger brain regions. The consequences of these biochemical changes in the brain following cessation of hypoxia are investigated with regard to behavioural manifestations. Corresponding in time with the inhibition of transmitter release and its restitution the seizure susceptibility is increased when pentetrazol is given in subconvulsive doses. On the other hand, the results of further tests (climbing behaviour, open field, rotarod test, forced-swimming test) do not point to behavioural changes induced particularly by a mild hypoxia.

Animals↗
PubMed1985

[Effect of lithium, carbamazepine, ca-valproate and diazepam on changes in social isolation-induced behavior in mice].

Neurobiological changes induced by social isolation of mice are used to characterize pharmacological influences of lithium and several other drugs. Lithium is able to prevent not only early serotoninergic changes but also enhanced aggressiveness and enhanced spontaneous locomotion, seen after long term isolation. Very similar to lithium are the effects of carbamazepine, whereas Ca-valproat and diazepam prevent the early serotoninergic (stress like) changes, but not later changes in aggressivity and locomotion.

Aggression↗
PubMed1985

[The dynamics of behavioral changes in mice induced by social isolation].

Various behavioural patterns such as spontaneous locomotion, open-field behaviour and aggressivity undergo typical changes in socially isolated mice. Each of them shows a specific course depending on the duration of isolation. Differences in time courses and quantitative changes demonstrate that not only a general mechanism such as decreased arousal threshold is responsible for the complex alterations. It seems that many different mechanisms in the CNS underly the isolation syndrome, but the functional connections between the different alterations are unknown.

Aggression↗
PubMed1984

Inhibition of isolation-induced changes in aminergic transmission by chronic lithium treatment.

Social isolation of mice leads to changes in aminergic transmission systems. After 6 weeks of isolation, an increase of apomorphine-stimulated climbing behavior is seen, reflecting an isolation-induced dopaminergic supersensitivity. After 1-3 weeks of isolation, a decrease of clonidine sedation is detectable, suggesting the development of noradrenergic alpha 2-receptor subsensitivity. The isolation-induced changes of both drug effects are prevented by lithium given over the time of isolation.

Animals↗
PubMed1984

[Development of tolerance to haloperidol in the rat striatum].

Microiontophoretic application of dopamine effects in the rat's striatum a dose-dependent inhibition of the glutamate-induced pulse activities. Acute systemic applications of haloperidol are able to abolish this dopamine-induced inhibition. After chronic pretreatment with haloperidol, however, acute administration of haloperidol can no longer antagonize the dopamine-induced inhibition of the pulse activity. Hence, it is likely that tolerance to haloperidol , as described in individual behavioral studies can develop also on the cellular level.

Animals↗
PubMed1983

[Effect of desipramine and social isolation on neuronal activity in rat hippocampus].

Chronic treatment of rats with desipramine leads to an increase of hippocampal neurons with low spontaneous activity. After an isolation rearing period of three months an increased spontaneous activity is seen in the hippocampus of rats. Furthermore the hippocampal spontaneous activity is related to age. Opposite alterations of spontaneous activity in desipramine treated and socially isolated rats, respectively, as well as their relations to noradrenergic transmission processes are discussed. The isolation syndrome as a model to test substances with antidepressive properties is also reviewed.

Animals↗
PubMed1980

[Changes of neuronal activity in the rat's hippocampus under long-term treatment with desipramine].

Long-term treatment of rats with the antidepressive desipramine increase in the hippocampus the number of neurons with low spontaneous discharges and affects the animals' response to microiontophoretically applied noradrenalin. Additional acute administration of desipramine causes, after long-term treatment with the antidepressive, a stronger increase in noradrenalin induced inhibition of the firing rates as compared with controls.

Action Potentials↗
PubMed1980

[Effect of social isolation on the transmitter sensitivity of striatal and hippocampal neurons of the rat].

Rats kept in isolation for 3 months from the 4th week onward show increased sensitivity of striatal neurons for dopamine and acetylcholine, as well as of the hippocampal neurons for noradrenalin administered microiontophoretically, in comparison to animals maintained collectively. The results are discussed as reflecting a supersensitivity of central dopaminergic and noradrenergic receptors caused by the social isolation.

Acetylcholine↗
PubMed1980

[Locomotor activity of rats following chronic pretreatment with haloperidol].

The spontaneous locomotor activity, the nocturnal action profile and exploratory behavior following chronic pretreatment with haloperidole was measured (2 mg/kg daily i. p. for 3 weeks). After this treatment all 3 parameters showed significant changes. The mean values of spontaneous activity during the night and the exploratory behavior during the day were strongly enhanced. The nocturnal action profile showed both amplification and a shift of the activity moves. The results give evidence of an increase and alteration of spontaneous motor actions, correlated with a relatively increased activity of the dopaminergic system due to the pretreatment.

Animals↗
PubMedDate not supplied

The influence of social isolation on ethanol preference behavior and dopamine release in telencephalon slices in mice.

We examined the relation between the duration of social isolation and alterations in ethanol preference behavior and the dopamine release in telencephalon slices in mice. Ethanol preference developed only after an isolation period of 2 weeks and a further ethanol treatment of 2 weeks. It did not appear after an isolation period of 6 weeks, in mice without ethanol treatment, and in group-housed mice. The dopamine release was lowered in mice isolated for 2 weeks and is normalized in combination with ethanol treatment. The dopamine release inhibition evoked by social isolation of 2 weeks probably reflects a functional state with high sensitivity for induction of an ethanol preference behaviour.

Animals↗
PubMedDate not supplied

The influence of chronic treatment with psychotropic drugs on behavioral changes by social isolation.

Neurobiological changes induced by social isolation of mice are affected by several drugs in different manner. Lithium is able to prevent changes in head-twitches seen after short term isolation as well as enhanced aggressivity and enhanced spontaneous locomotion demonstrable after long term isolation. Similar to lithium are the effects of carbamazepine, whereas the other tested substances: Ca-valproate, diazepam, desipramine, clomipramine as well as piracetam, methylglucaminorotate and meclofenoxate show different effects. The model of social isolation is discussed in view of its ability to differentiate the qualities of chronic drug administration during functional dynamic changes of the CNS in animals.

Aggression↗