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V Leviel

Publications and source records attributed to V Leviel.

61 records · Page 4Linked to original sources
PubMed1979

Catecholaminergic depressant effects on bulbar respiratory mechanisms.

On the basis of histochemical and pharmacological studies, catecholamines have been implicated in central mechanisms controlling respiration. This hypothesis was tested in iontophoretic studies on neurones located in bulbar respiratory centres. Adrenaline and noradrenaline had a predominantly depressant effect on respiratory as well as on closely situated non-respiratory units. These depressions were mimicked by the application of isoproterenol and clonidine; acetylcholine and serotonin had inconsistent effects on these neurones. In control experiments, microinjections, using a Hamilton syringe, were made in the area of bulbar respiratory centres: noradrenaline, but not serotonin, depressed the central respiratory activity reflected in the phrenic nerve discharge. These results suggest that specific adrenergic and noradrenergic depressant mechanisms could affect both respiratory and other physiological centres at the bulbar level.

Acetylcholine↗
PubMed1979

In vivo release of substance P in the cat substantia nigra.

Push-pull cannuale were implanted into the substantia nigra (SN) and the caudate nucleus (CN) of the cat to study the in vivo release of substance P (SP), using a radioimmunoassay and high pressure liquid chromatography (HPLC) analysis. The spontaneous release of SP could be detected in the SN and the CN. Potassium (50 mM) locally applied stimulated SP release in both structures. Furthermore an important evoked release of SP was observed in the SN during depolarization of striato-nigral SP fibers with potassium (50 mM) applied in the CN.

Animals↗
PubMed1977

A study of the action of valproic acid on the kindling effect.

The effect of an antiepileptic drug, valproic acid (VPA), on an experimental form of epilepsy, the kindling phenomenon, is described. In cat, 50 mg/kg i.p. per day is sufficient to block the progressive establishment of generalized seizures produced normally by repetitive electrical stimulation of the amygdala. However, a focal afterdischarge persists during the entire treatment. Higher doses (75-150 mg/kg) are necessary to protect the animal against the generalized tonic-clonic seizure when the kindling phenomenon is established. These effects and the action of barbiturates, which was also tested, seem to attribute to VPA a complex role in the mechanism of this action.

Amygdala↗
PubMedDate not supplied

Afferent connections of the rat substantia nigra pars lateralis with special reference to peptide-containing neurons of the amygdalo-nigral pathway.

The afferent connections of the rat substantia nigra pars lateralis have been studied using the retrograde axonal transport of fluorescent latex microspheres. The most numerous groups of retrogradely labelled nerve cell bodies were observed bilaterally in the parabrachial complex and several hypothalamic nuclei, whereas the parietal neocortex, the fundus striati, the central nucleus of the amygdala and the bed nucleus of the stria terminalis were labelled on the injected side only. The neuronal projections from the central amygdaloid nucleus to the substantia nigra pars lateralis and lateral part of the rostral pars compacta have additionally been confirmed by anterograde tracing using wheat-germ agglutinin coupled to horseradish peroxidase. The presence of some peptides in this pathway was studied by combining the use of the same retrograde tracer with immunofluorescence after intra-amygdaloid injections of colchicine. With this method, we have demonstrated that Met-enkephalin, dynorphin and neurotensin are probably utilized as neurotransmitters or co-transmitters in the neurons of the amygdalo-nigral pathway.

Afferent Pathways↗
PubMedDate not supplied

[Preliminary study of the comparative action of 1 methyl-2 (2 naphtyl) aziridine on kindling effect and on paradoxical sleep (author's transl)].

Methyl-2 (2 Naphtyl) Aziridine (MNA) is a new agent which has been demonstrated to have effects on paradoxical sleep (PS) and on the levels of cerebral noradrenaline (Yamamoto, 1975). It has been tried on a experimental model of epilepsy, the kindling effect, produced in the cat by repetitive stimulation of the amygdala. The results obtained in the cat confirmed blockage of paradoxical sleep (PS) and revealed a marked reduction in the number of stimuli required to produce the effect. The shortening of the time before the first generalised seizure did not seem attributable to privation of paradoxical sleep. The role of cerebral catecholamine reduction, however, is discussed.

Animals↗