Effets de lésions de l'hypothalamus et du globus pallidus et d'injections d'apomorphine dans le globus pallidus,le noyau caudé, la substantia nigra et le septum sur le 〈comportement d'agressivité induit par l'apomorphine〉 chez le rat

Intraspecific apomorphine-induced aggressive behavior in the rat was not affected following electrolytic lesions of the ventromedial hypothalamus. Some inhibition of the aggressive behavior was found after lateral lesions and an almost total suppression after destruction of globus pallidus.These results, as well as those following localized injections of apomorphine into the septum, substantia nigra, caudate nucleus, and globus pallidus suggested that the latter anatomical region may be the major site of the action of apomorphine in the behavior studied. The role of acetylcholine is discussed.

     

Facilitation de réactions nociceptives par la naloxone chez la souris et chez le rat

The effects of graded doses of naloxone on nociceptive reactions of mice and rats of different strains were studied using a hot plate technique.Enhancements were observed provided the control reaction times were long enough, a condition which was fulfilled for the jumping reaction at different temperatures of the hot plate (50 C, 55 C, 65 C, 80 C in mice-55 C in rats) but for the licking reaction only at the lowest temperature (50 C in mice). Enhancement was dose-related up to a ceiling effect. Nalorphine had no such overt action. As low doses of naloxone (0.1–1 mg/kg s.c.) were effective, the enhancement is most simply accounted for by interactions at the level of the specific opioid receptors, some of which are suggested. The phenomenon might be relevant to the interpretation of the mechanisms of precipitated abstinence.

     

Effects comparés du muscimol et du diazépam sur les inhibitions du comportement induites chez le rat par la nouveauté, la punition et le non-renforcement

Diazepam and muscimol, a direct GABA agonist, were compared on behavioral inhibition induced in rats by (1) novelty, (2) punishment, and (3) nonreward.(1) Muscimol (0.03–0.25 mg·kg^-1 i.p. 30 min before testing, or i.v. immediately before testing) failed to enhance food intake consistently in a nonfamiliar situation and (0.125–0.5 mg · kg^-1 i.p. or i.v.) to increase the ingestion of an unknown food (chocolate); (2) muscimol (0.125–0.5 mg · kg^-1 i.p. or 0.25 i.v. 10 min before testing) was ineffective in reducing the inhibition of lever presses for food elicited by the delivery of an electric shock at every eighth press; (3) muscimol (0.125–0.5 mg · kg^-1 i.p.) failed to attenuate the inhibitory effects on responding induced by the suppression of the reinforcement during extinction.Contrastingly, diazepam (2 mg · kg^-1 i.p. 30 min before testing) was found to reduce each type of behavioral inhibition.These data lend no support to the hypotheses of GABA control of behavioral inhibition and of GABA involvement in the action of benzodiazepines on inhibition induced by novelty, punishment, or nonreward.

     

Amines cérébrales et comportement d'agressivité intraspécifique induit par l'apomorphine chez le rat

In rats sensitive to apomorphine-induced aggression, similar, but less pronounced aggressive reactions were induced by ET-495, a specific stimulant of dopaminergic receptors and, to a very slight extent by l-Dopa, whereas clonidine was ineffective. In these rats the apomorphine-induced aggressiveness was nearly completely inhibited by phenoxybenzamine, only partially by DDC, 5-HTP, and FLA 63. Conversely it was altered slightly or not at all by PCPA, alpha-mmT, reserpine, alpha-mDopa, iproniazide, and JB-516.In rats not sensitive to the action of apomorphine, simultaneous administration of clonidine and apomorphine induced aggressive reactions, as did a combination of clonidine-ET 495, but to a lesser degree. Pretreatment with reserpine or MAO inhibitors, or to a lesser extent, alpha-mDopa, sensitized these rats to the action of apomorphine. 5 HTP, l-Dopa, PCPA, DDC, and alpha-mmT did not have this inductive effect. The inductive effect of reserpine was completely inhibited by DDC, partially by l-Dopa, but not at all by 5-HTP. That of iproniazid was inhibited by DDC, but not modified by PCPA.On the basis of these data, it was concluded that the aggressive behavior induced by apomorphine might result from a stimulation of dopaminergic receptors, stimulation that would itself induce the setting of noradrenergic structures.

L'auteur remercie vivement le Docteur J. Jacob pour les précieux conseils, qu'il lui a apporté au cours de ce travail et de la rédaction de ce manuscrit et Madame S. Bizeul pour son aide technique; il remercie également le Docteur Baille-Barrelle (Laboratoire Boehringer), le Docteur Régnier (Laboratoire Servier) qui lui ont aimablement fourni, respectivement, de la clonidine et du ET 495.     

Inhibiteurs β-adrénergiques et stéréotypies provoquées par l'amphétamine ou l'apomorphine chez le rat

The influence of three beta-adrenergic blocking agents was studied on the stereotyped behavior induced in rats by a range of doses of d-amphetamine or apomorphine. The stereotyped behavior was assessed either clinically (quotation from 0 to 3 at various times for each rat) or using the confinement motor activity test. From 8 mg/kg (i.p.) onwards, propranolol and prinodolol clearly potentiated the amphetamine-induced stereotyped behavior without any modification of the apomorphine-induced stereotyped behavior. Practolol, known for its poor passage through the blood-brain barrier had only a slight effect.

     

Effets de lésions du septum,de l'amygdale,du striatum,de la substantia nigra et de l'ablation des bulbes olfactifs sur le comportement d'agressivité intraspécifique induit par l'apomorphine chez le rat

Lesions of the septal region have been found to enhance apomorphine-induced aggressive behavior, without however facilitating its appearance in non-aggressive rats. This effect has been observed following bulbectomy or destruction of the anterior part of the striatum. Conversely, lesions of the amygdala or substantia nigra have been shown to produce an inhibitory effect on this behavior. It has also been observed that the septal syndrome was the most clear-cut one in those rats which were the most sensitive to the aggresion inducing effect of apomorphine. These results have been compared with those related to other aggressive behaviors, and the site of action of apomorphine has been discussed.

L'auteur remercie vivement le Docteur J. Jacob pour les précieux conseils qu'il lui a apporté au cours de ce travail et de la rédaction de ce manuscrit. Il remercie également le Professeur D. Albe-Fessard pour son aimable acceuil à l'Institut Marey et le Docteur J. Delacour qui l'a si obligeamment initié aux techniques stéréotaxiques.