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Biomedical subjects

J Costentin

Publications and source records attributed to J Costentin.

At least 217 records · Page 12Linked to original sources
PubMed1981

Hypokinesia in mice and catalepsy in rats elicited by morphine associated with antidopaminergic agents, including atypical neuroleptics.

The interaction of morphine with agents displaying antidopaminergic properties (low dose of apomorphine, alpha-methyl-p-tyrosine, the "classical" neuroleptic haloperidol as well as the "atypical" neuroleptics sulpiride, thioridazine, clozapine and mezilamine) has been studied both on locomotor activity in mice and catalepsy in rats. At the tested doses most of the drugs induced neither catalepsy nor akinesia, but when they were associated with morphine these effects were plainly observed. It is suggested that a hyperactivity of dopaminergic systems mask the cataleptic effect of morphine.

Animals↗
PubMed1980

Evidence for thermoregulatory dopaminergic receptors located in the preopticus medialis nucleus of the rat hypothalamus.

Systemic administration of apomorphine induces hypothermia in anaesthetized rats as well as in conscious rats exposed to an ambient temperature of 22 degrees C. The central nature of this effect is confirmed by the antagonism exerted by haloperidol and the lack of antagonism with domperidone. Dopamine receptors involved in the hypothermic effect of apomorphine seem to be located in the preopticus medialis nucleus (p.o.m.n.) of the hypothalamus since: (i) injections of apomorphine (5 ng), dopamine (100 ng) or (+)-amphetamine (50 ng) into this nucleus induce hpothermia, (ii) haloperidol injected into the p.o.m.n. antagonizes the hypothermic effect of a systemic administration of apomorphine, (iii) heat lesions of the p.o.m.n. strongly reduce the hypothermic effect of a systemic injection of apomorphine.

Amphetamine↗
PubMed1979

[Modulation of dopaminergic receptor sensitivity in the central nervous system: important parameters in synaptic function regulation].

Modulation in sensitivity of dopamine receptors in the central nervous system are reviewed. Three main types differing by their behavioural and biochemical characteristics are described: -- Disuse hypersensitivity to dopamine agonists, induced by an interruption of dopaminergic transmission, seems to depend on an increased number of post-synaptic dopamine receptors; -- Hyposensitivity to dopamine agonists, induced by an overstimulation of dopamine receptors, could depend on their qualitative or quantitative modifications; -- Behavioural facilitation, elicited by a previous administration of dopaminergic agonists in low dosage, could be associated with an hyposensitivity of dopaminergic autoreceptors. They seem to constitute important parameters in adaptation of synaptic efficacy in physiological as well as pathological states.

Acetylcholine↗
PubMed1977

[Facilitation of a stereotyped motor behavior (climbing behavior) by previous stimulation of dopaminergic receptors: hyposensitivity of autoreceptors?].

The sensitivity of dopamine receptors in Mouse striatum has been evaluated both behaviourally (responsiveness to apomorphine as regarviour) and biochemically (striatal level of homovanillic acid and its decrease induced by apomorphine) After a single administration of apomorphine (0.25 mg.kg-1 or 5 mg.kg-1) or piribedil, another dopamine agonist, a state of "behavioural facilitation" develops which differs from the state of hypersensitivity following blockade. This state of facilitation is characterized by a lower threshold dose of apomorphine eliciting the stereotyped behaviour, without modification of the response to higher doses. In contrast with the state of hypersensitivity, the level of homovanillic acid is not modified and the decrease of this level by a low dose of apomorphine is less important. The hypothesis is put forward that "behavioural facilitation" results from the hyposensitivity of a class of dopamine receptors, possibly autoreceptors, mediating an impaired activity of dopaminergic neurons and, consequently, inhibitory behavioural effects.

Animals↗
PubMed1976

Climbing behavior induced by apomorphine in mice: a simple test for the study of dopamine receptors in striatum.

Mice treated with low doses of apomorphine tend to adopt a vertical position along the walls of their cage. Optimal conditions have been defined to obtain a reliable dose-response relationship. This peculiar behavior appears to be elicited by stimulation of dopamine receptors in the striatum: it is suppressed after coagulation of this structure while it is facilitated when these receptors are made hypersensitive by previous treatments with 6-hydroxy-dopamine or haloperidol; on the other hand, it is not modified by coagulation of the nucleus accumbens. The relative efficacy of various agonists and antagonists of dopamine receptors have been determined on this test. It appears that this stereotyped behavior might represent a convenient mean to assess the stimulation of striatal dopamine receptors in mice.

Animals↗
PubMed1976

[Rapid and prolonged facilitation of stereotyped motor behavior (verticalization) induced by apomorphine in mice previously submitted to stimulation of dopaminergic receptors].

The climbing behaviour, a stereotyped motor behaviour, is elicited in mice by stimulation of striatal dopamine receptor by low doses of apomorphine. The action of apomorphine is unexpectedly enhanced in animals pretreated with a single dose of this agent (5 mg/kg). This enhancement occurs as early as 2 h following the first administration and persists for at least 3 days. It is also observed after pretreatments with a combination of L-DOPA and dexamphetamine. This effect seems independent from the desensitization of the dopaminergic receptors involved in thermoregulation that we have previously reported.

Animals↗