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Biomedical subjects

M Vergnes

Publications and source records attributed to M Vergnes.

At least 127 records · Page 7Linked to original sources
PubMed1982

Spontaneous paroxysmal electroclinical patterns in rat: a model of generalized non-convulsive epilepsy.

During quiet wakefulness of 63 adult Wistar rats, 24 exhibited synchronous paroxysmal bursts consisting of spikes and spike and wave discharges, recorded in the amygdala and frontoparietal cortex. Discharges were associated with a sudden immobility of the rat and rhythmic twitches of vibrissae or cervicofacial musculature. As soon as the phenomena stopped, the animal resumed its previous behavior. Paroxysmal electroclinical attacks could be observed as long as the animal survived. Similar electrical discharges have been observed previously in rodents by other authors and interpreted as an epileptic phenomenon. Preliminary pharmacological results confirm this interpretation and emphasize the similarity between our findings and the human petit mal epilepsy.

Animals↗
PubMed1982

Effect of hypothalamic injections of 5,7-dihydroxytryptamine on elicitation of mouse-killing in rats.

An overall and marked serotonin (5-HT) depletion of the brain was found to facilitate initiation of mouse-killing behavior in the rat, whereas more selective 5-HT depletions within forebrain structures such as the septum, hippocampus, cingular cortex and amygdala, did not have such an effect. In order to further investigate the topography of the 5-HT pathways and terminals though to be involved in an inhibitory control over this behavior, localized lesions of the serotonergic system(s) were performed by means of bilateral 5,7-dihydroxytryptamine (5,7-DHT) injections (5 microgram/microliter) into the hypothalamus in naive rats. 5,7-DHT injections into the medial hypothalamus did not affect the initiation of mouse-killing behavior, whereas the reflexive startle responses to air puffs were increased. The animals' open-field behavior remained unchanged. Forebrain 5-HT content was reduced by 50% in this group. 5,7-DHT injections into the lateral hypothalamus increased the proportion of killers to 46% as compared to 10% in the control group, in spite of a reduced activity in the open-field and unchanged startle responses. Forebrain 5-HT content was reduced by 88%. As the lateral hypothalamus contains afferents from both the dorsal and the median raphe nuclei, it is likely that 5-HT terminals modulate some hypothalamic mechanism involved in the control of mouse-killing behavior.

5,7-Dihydroxytryptamine↗
PubMed1981

Tryptophan deprivation: effects on mouse-killing and reactivity in the rat.

Following a 5-week maintenance on a low-tryptophan diet, brain 5-HT content was reduced to 75%, whereas NA and DA levels remained unchanged as compared to controls. Reactivity to air-puffs as well as to the novelty of the open-field was increased. Incidence of mouse-killing was examined in 2 groups of Wistar rats maintained on the tryptophan-deficient diet for 2 and 4 weeks, respectively, before being tested with a mouse: 70% and 60% of them killed mice, compared to 20% killers in rats given free access to standard food, and 20% killers in rats given a limited access to standard food so as to reproduce the suppression of weight gain observed in the tryptophan-deficient animals. Prior non-aggressive interactions with mice significantly reduced later incidence of mouse-killing following a 4-week tryptophan-poor diet, thus confirming the suppressant effect of prior familiarization with mice on elicitation of mouse-killing as a result of brain 5-HT depletion. Once initiated, mouse-killing persisted even when the rats were returned to standard food, demonstrating that reduced 5-HT activity is not necessary for the maintenance of this behavior.

Aggression↗
PubMed1979

Interspecies aggression in the rat: the role of the diagonal band of Broca.

Electrolytic lesions of the diagonal band of Broca were made in rats which had previously not killed mice (DBPt) and in rats which had no experience with mice prior to the beginning of the experiment (DBN). The lesions induced killing in 12 of the 20 naive (DBN) rats, but in only 1 of the 16 pretested (DBPt) rats. The region of the diagonal band is projected upon or has extensive projections to many regions of the central nervous system in which lesions have previously been found to induce muricide. The behavior induced by diagonal band lesions and lesions of these other regions was compared.

Aggression↗
PubMed1976

[Shock-induced aggression and reactivity following raphe lesion in rats. Effects of physostigmine (author's transl)].

Shock-induced fighting behavior, flinch-jump thresholds and locomotor open-field activity were studied following dorsal and medial raphe lesions in rats. Attack scores were raised for low-intensity shocks (1 mA) only, whereas they remained unchanged for shocks of higher intensity (2 mA), as compared to controls. The jump threshold is decreased in raphe lesioned animals, but the flinch threshold is unchanged. Physostigmine (0,2-0,5 mg/kg) reduces the lesion-induced hyperreactivity: locomotor open-field activity is reduced to a greater extent than in the controls, and habituation to the open-field situation is restored. Doses of physostigmine (e.g. 0,2 mg/kg), that do not modify shock-induced aggression in controls, reduce aggression in lesioned animals to the level shown by controls for low-intensity shocks. In conclusion, shock-induced aggression is not directly dependent on a serotonergic brain mechanism. The behavioral changes observed are related to the hyperreactivity induced by raphe lesions. This hyperreactivity presumably results from a reduced activity of cholinergic brain mechanisms.

Aggression↗