G. Mack

Contrôle inhibiteur du comportement d'agression interspécifique du rat: système sérotoninergique du raphéet afférences olfactives

Destruction of the dorsal and medial raphenuclei induces mouse-killing behaviour in about one-third of the lesioned rats. A lesion limited to either the dorsal or the medial nucleus very seldom induces interspecies aggression, whereas it results in most instances in a clearly increased activity in the open field. In rats whose behaviour had remained unchanged following removal of the olfactory bulbs, a combined lesion of the two raphenuclei induces mouse-killing in 73% of the lesioned animals. The percentage of killer-rats reaches 91% when in addition PCPA (p-chlorophenylalanine) is administered, whereas 5-HTP transiently abolishes interspecies aggression. 5-HT levels in the amygdala are greatly reduced in raphe-lesioned rats irrespective of whether they started killing mice following the lesion. Mouse-killing behaviour appears to be controlled by two different inhibitory mechanisms, one originating from the olfactory bulbs, the other involving serotonergic neurones of the raphenuclei.

Regional studies of brain serotonin and norepinephrine in the hibernating, awakening or active European hamster, Cricetus cricetus, during winter

Abstract 1. 1. Serotonin and norepinephrine were determined in six different regions of the brain of the hibernating, awakening or active European Hamster in Winter. 2. 2. In all parts of the brain serotonin is lower in the hibernating animal as compared with the awakening and especially active animal. Major differences occur in hypothalamus and limbic system. The concentration of norepinephrine does not vary. Whole brain content of 5-hydroxyindole acetic acid is higher in hibernating and awakening animals than in active animals. 3. 3. These results suggest that serotonin is involved in the entrance into hibernation.

Effects of apomorphine and sodium Di-n-propylacetate on the aggressive behaviour of three strains of mice.

1. The effects of apomorphine and sodium Di-n-propylacetate (DPA, sodium valproate) on pain-induced aggressive behavior were investigated in three inbred strains of mice: BALB/c, C57B1/6 and DBA/2, which exhibited spontaneously low levels of aggression. 2. Apomorphine elicited aggressive behavior in the three strains, the range of effective doses being different for each strain of mice. 3. Di-n-propylacetate was effective in inhibiting apomorphine elicited aggression but the three strains exhibited a different sensitivity to this drug. 4. The effects of Di-n-propylacetate were not related to pain sensitivity, posture and locomotion. Only C57 strain exhibited a slight postural and locomotor impairment when injected with a higher dose of Di-n-propylacetate. 5. The results are discussed in terms of a genetic inference and of biological differences existing between these three strains.

Effect of valproic acid on brain serotonin metabolism in isolated and grouped rats

The effect of the GABA transaminase inhibitor valproic acid (DPA) on serotonin (5HT) metabolism of different brain regions were studied in both grouped and isolated rats. One hour after DPA injection 5HT levels in the amygdala were increased in grouped and isolated rats. In the hypothalamus of grouped rats, changes in 5HT metabolism were also found. The alteration in 5HT metabolism in grouped rats was reversed 150 min after injection of DPA. At this same time, a large and significant increase in 5HT turnover was observed in all brain areas examined in isolated rats. It can be concluded that prolonged isolation induces a differential sensitivity to the effects of DPA leading to differences in 5HT metabolism: the drug effect being more intense in isolated rats.

Seasonal changes in the levels and the turnover of brain serotonin and noradrenaline in the European hamster kept under constant environment.

Seasonal changes in the content and the turnover of noradrenaline and serotonin are shown in various parts of the brain of the European hamster kept under constant conditions of light and temperature.

Turnover of brain adrenergic transmitters in Quaking mice

Quaking mice, neurological mutants of the C57 BL/6J strain have a markedly deficient myelination of the CNS(Sidman, Dickie and Appel, 1964). Many studies have been carried out on their lipids (Jacque, Harpin and Baumann, 1969; Neskovic, Nussbaum and Mandel, 1969, 1970; Kurihara, Nussbaum and Mandel, 1970; Sarlieve, Neskovic and Mandel, 1971; Singh, Spritz and Geyer, 1971) for this reason, but little attention has been paid to other aspects of their aminergic transmitters metabolism. During the course of our work, Tillement, Debarle, Simon and Boissier (1970) reported on the transmitter levels in Quaking mice. The reasons for thinking that the monoamine metabolism of these mice might be altered are as follows. The trembling might be associated with a change in the activity and therefore metabolism of dopaminergic structures. Chronic stress due to permanent tremor might induce changes in norepinephrine metabolism. Since there are changes in the sleep patterns of Quaking mice (Valatx and Jouvet, 1971), there might be changes in brain serotonin metabolism. This study of the turnover of norepinephrine, dopamine and serotonin in the whole brains of control and Quaking mice is the preliminary to detailed examination of the turnover of the transmitters in well‐defined brain regions.

Cholinergic involvement in ethanol intoxication and withdrawal-induced seizure susceptibility

The enzymes of the cholinergic system have been investigated in discrete brain areas in alcohol-dependent rats, which were still intoxicated or were undergoing withdrawal.The ethanol intoxication resulted in a slight, but significant increase in choline acetyltransferase (CAT) activity in the caudate nucleus both 1 and 7 h after the last dose of ethanol. We also found a significant decrease in CAT activity in the temporal limbic cortex while rats were highly intoxicated. All other brain regions investigated, e.g., cerebellum, pons-medulla, frontoparietal cortex, hypothalamus and septum showed unchanged CAT activity.Rats were also analysed immediately following the onset of a withdrawal-induced audiogenic convulsive seizure where, in addition to the striatum, depressed CAT activity was observed in the hippocampus.In all the analysed situations acetylcholinesterase activity remained unchanged.These results show that ethanol intoxication leads to a perturbation in the synthetic capacity of acetylcholine in certain defined brain structures and that this may have some correlation to the observed behavioural impairments.

Function of the Central Catecholaminergic Neuron: Synthesis, Release, and Inactivation of Transmitter

The term “catecholamine” refers to a series of organic compounds which have a benzene nucleus with two adjacent hydroxyl groups (the catechol nucleus) and amine group. Thus dopamine (dihydroxyphenylethylamine), noradrenaline (β-hydroxy dihydroxyphenylethylamine), and adrenaline (N-methyl-β-hydroxy dihydroxyphenylethylamine) and certain of their metabolites are catecholamines.

Genetically determined cholinergic involvement in morphine-induced behavioural responses in mice

Abstract Cholinergic involvement in morphine-induced motor effects has been investigated by measuring choline acetyltransferase (CAT) and acetylcholinesterase (AChE) activities in several brain areas of two inbred mouse strains differing in their motor reaction to opiates. A significant decrease in CAT activity was observed in the corpus striatum of the C57BL/6J mice which exhibit a characteristic locomotor hyperactivity after morphine treatment whereas no differences were found in this area in the DBA/2J strain whose motor activity was depressed. This observation pertains to both acute and chronic morphine administration. The activity of CAT was still significantly depressed in C57B1 striatum following 24 hr withdrawal. It is suggested that the decreased CAT activity in the striatum reflects an imbalance of the striatal dopaminergic-cholinergic equilibrium required for the integrity of motor function.

Aortic mucoproteins. Biochemical study of their qualitative variations in the course of aging in cattle

Cette masse g6latineuse, homog6ne en apparence, est, en fait, un amalgame de substances macromol6culaires diverses qui jouent un role fondamental, non seulement dans tous les ph6nom6nes de diffusion et de nutrition des cellules qui y baignent, mais encore dans l’organisation meme de la texture des syst6mes fibrillaires et le maintien de l’int6grit6 du tissu. Dans un travail ant6rieur,l nous avons 6tudi6 le comportement quantitatif global des mucopolysaccharides acides et neutres, au niveau de 1’aorte thoracique de bovides jeunes d’une part, Ag6s d’autre part. Rappelons que les mucopolysaccharides, aussi bien acides que neutres, baissent avec 1’age de fa~on tr6s significative (tableau 1) alors qu’inversement au cours de I’ath6rome experimental du lapin ces deux composantes augmentent tres nettement. Mais, si la technique prot6olytique a la papaine utilis6e dans le premier travail permet une telle etude quantitative, elle severe incapable d’aborder les mucopolysaccharides sous leur forme native, c’est-A-dire de complexe mueoprot6ine. Voila pourquoi nous nous sommes servis d’une nouvelle technique pour les extraire, les purifier et les fractionner, dans le but d’en 6tudier les modifications structurales au cours du vieillissement et d’y trouver d’6ventuels parall6les avec