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M Ammassari-Teule

Publications and source records attributed to M Ammassari-Teule.

51 records · Page 3Linked to original sources
PubMed1988

The amygdala mediates the impairing effect of the selective kappa-opioid receptor agonist U-50,488 on memory in CD1 mice.

The effect of the selective kappa-opioid receptor agonist U-50,488 on passive avoidance behaviour was studied in CD1 mice bearing lesions of the amygdaloid complex. The results have shown that post-trial injections of U-50,488 in unoperated mice as well as lesions of the amygdaloid complex in untreated mice decreased retention performances. No further impairment was observed in lesioned mice treated with U-50,488, indicating that amygdala is involved in the mediation of the effects of kappa-opioid receptor agonists on memory. The possibility that kappa-opioid receptors could modulate the memory retention of CD1 mice by influencing their emotional state is discussed.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1988

Parallel modifications of spatial memory performances, exploration patterns, and hippocampal theta rhythms in fornix-damaged rats: reversal by oxotremorine.

Learning scores and degrees of divergence of the exploratory patterns (EP) displayed during the acquisition stage of a radial eight-arm maze task were examined in fornix-damaged and sham-operated rats injected either with oxotremorine (0.1 mg/kg) or saline. Modifications of hippocampal rhythmic slow activity (theta) recorded in each condition were analyzed in CA1 and dentate gyrus. Dorsal fornix sections reduced choice accuracy but also induced the adoption of weakly divergent EP. Oxotremorine in animals with lesions reinstates both learning scores and degree of divergence of EP at the levels respectively observed in saline sham-operated animals. Finally, oxotremorine in sham-operated animals did not significantly improve choice accuracy but strongly modified the EP. Preoperatively, theta rhythms indicated a decrease of frequency after oxotremorine administration. Postoperatively, they showed an increase of frequency in animals with lesions that were reinstated at the preoperative level by oxotremorine.

Animals↗
PubMed1986

Avoidance facilitation in adult mice by prenatal administration of the nootropic drug oxiracetam.

CD-1 mice prenatally exposed to saline solution or to the nootropic drug oxiracetam (50 mg/kg during the whole pregnancy) were tested, when adults, for locomotor activity and for shuttle-box avoidance acquisition. Prenatal drug exposure produced long-lasting effects, evident in mature offspring. At the age of two months, mice prenatally exposed to oxiracetam showed a slight but significant reduction in locomotor activity. At the age of three months, these animals exhibited higher performances than control mice in avoidance acquisition.

Animals↗
PubMed1985

Spatial learning and memory, maze running strategies and cholinergic mechanisms in two inbred strains of mice.

The acquisition process of the radial maze task was studied in two inbred strains of mice, C57BL/6 and DBA/2. A quantitative and qualitative evaluation of performance was performed and the pretest level of activity was measured. The results showed a significant correlation between activity and performance since the highly active C57BL/6 mice exhibited better performance of the radial maze task than the less active DBA/2 mice. Moreover, for correct trials, strain-dependent maze-running strategies were observed: while both strains displayed about the same percentage of clockwise and spatial strategies, it was observed that among the spatial strategies C57BL/6 used a larger number of different correct solutions. Subsequently, the effect of scopolamine administration on working memory processes was assessed in sequential and discrete trials. A different reactivity of each strain to anti-cholinergic treatment was found in discrete trials since only DBA/2 mice were impaired. The effect of scopolamine is discussed in relation to the different models of information processing involved in learning and memorizing the experimental rule.

Animals↗
PubMed1985

Improvement of avoidance acquisition by the nootropic drug oxiracetam in mice.

The nootropic drug, oxiracetam (25 or 50 mg/kg i.p.), was tested in two inbred strains of mice, subjected to shuttle-box avoidance training. The drug improved avoidance acquisition in good performers BALB/c mice more than in poor performers C57BL/6 mice. In both cases the avoidance facilitating action was evident only if training was preceded by a five-day pretreatment. The nootropic prototype, piracetam (100 mg/kg), facilitated avoidance acquisition in pretreated BALB/c, but not in C57BL/6 mice.

Animals↗
PubMed1985

Interaction between nootropic drugs and methamphetamine on avoidance acquisition but not on locomotor activity in mice.

Two nootropic drugs, oxiracetam and piracetam, were tested, alone or in combination with methamphetamine, on locomotor activity and shuttle-box avoidance acquisition in mice of the C57BL/6 strain. Oxiracetam (50 mg/kg/day) and piracetam (100 mg/kg/day) had no effect when given alone, but significantly increased avoidance responses when combined with methamphetamine (0.5, 1 and 2 mg/kg). On the contrary, the two nootropic agents did not affect locomotor stimulation induced by methamphetamine. The results suggest that nootropic drugs may interact with methamphetamine in behavioural tests in which learning and memory processes are involved.

Animals↗
PubMed1984

Facilitation of generalization performances in spatial learning problems by posttrial stimulation of the mesencephalic reticular formation.

The effects of low posttrial stimulation of the mesenphalic reticular formation (MRF) on spatial learning problems were studied in two consecutive stages. First, the performances of stimulated (S) and no-stimulated (NS) subjects were assessed in a reconvergent three-arm maze. Secondly, the same animals were tested in a generalization paradigm, since they had to solve a similar task in a radial four-arm maze, each group being divided into newly stimulated (S-S, NS-S) or no-stimulated (S-NS, NS-NS) subjects. In the first experiment, no differences were found between the acquisition processes of groups S and NS. Conversely, in the second experiment, previously stimulated animals (S-S and S-NS) showed better generalization of the experimental rule. The results are discussed in terms of preservation of the neural activity after the early MRF stimulation. From a functional point of view, our data indicate that an enhancement of the neural activity during acquisition facilitates not only a high accessibility of memories concerning the experimental rule in a subsequent similar situation but also the capability to apply a previously elaborated response system in a more complex situation.

Animals↗
PubMed1984

Prenatal exposure to morphine in mice: enhanced responsiveness to morphine and stress.

Some behavioral effects of prenatal morphine administration were studied in CD1 mice. Two sets of experiments were carried out. In a first set, which was performed during development: (a) measures of postnatal reflexes revealed only a light deficit in tests involving motor control, (b) activity measures showed a significant reduction of spontaneous activity which was evident only in the course of the first postnatal days. In a second set of experiments, in which adult mice were tested for activity, analgesia and passive avoidance learning: (a) no difference was observed, in baseline conditions, between the performances of the mice prenatally exposed to saline and those preexposed to morphine, (b) as compared with controls, enhanced responsiveness to morphine administration (for the activity and passive avoidance measures), and to morphine and stress (for the analgesic measures) were found.

Analgesia↗
PubMed1983

Different mossy fiber patterns in two inbred strains of mice: a functional hypothesis.

Quantitative and qualitative evaluations of the distribution of mossy fiber terminals in the hippocampal region inferior were performed in two inbred strains of mice, SECRe/J and C57BL/6, known to have different learning abilities. The results confirmed previous observations showing that there are fewer mossy fiber terminals along basal dendrites of the CA3 pyramidal cells in the high performer strain (SECRe/J). One additional, qualitative difference between the strains was found near the hilus and in particular at dorsal levels. Thus strands of mossy fiber terminals connecting the infra- and suprapyramidal mossy fiber layers were more significant and more randomly oriented in the C57BL/6 strain than in SECRe/J. In an otherwise laminar structure like the hippocampus this might have a similar functional importance as the quantitative differences.

Animals↗
PubMed1983

Ontogenic and genetic variability in the morphology of the somatosensory cortex in developing C57BL/6 and SEC/Re1J mice.

At seven days of age, inbred strains such as SEC/Re1J and C57BL/6 present clear variations of a number of behavioral and electrophysiological parameters. The present investigation was carried out in order to provide anatomical evidence of the interstrain variability in maturation during the first postnatal week by analysing the morphological characteristics of cortical areas in seven day old SEC/Re1J and C57BL/6 mice. The somatosensory cortex was chosen on the basis of its easy localization in histological preparations, its postnatal plasticity and its functional importance during ontogeny. Different measures were performed in areas 1, 3 and 40: cortical depth, depth of layers, grey/cell coefficient, and cellular volumes. The main interstrain differences were observed in areas 1 and 40 and interpreted either in terms of ontogenic variability or, alternatively, in terms of phenotypic characteristics of the brain cortex in inbred mice. Conversely, the level of maturation in area 3 was found remarkably similar in both strains. The relationship between morphological parameters and other measures of the postnatal development is discussed.

Animals↗
PubMed1982

Selective effects of hippocampal and frontal cortex lesions on a spatial learning problem in two inbred strains of mice.

The effects of dorsal hippocampal and medial frontal lesions of the cortex on a spatial learning problem were studied in two inbred strains of mice (C57BL/6 and DBA/2) which present both neuroanatomical differences of such structures and various patterns of spontaneous exploration. The results showed that hippocampal lesions produced impairments of the learning performance in each strain of mouse, but the temporal distribution of the errors over the experiment was found to be strain dependent. On the other hand, medial frontal cortex lesions selectively affected the learning performances since the acquisition process of only the C57BL/6 lesioned mice differed significantly from the other groups. The effects of these lesions are discussed in terms of genetically associated differences of brain structures and functions. It is suggested that investigations of such differences can provide an experimental model for the study of functional and structural recovery.

Animals↗
PubMedDate not supplied

Effects of kappa-opioid receptor agonists on locomotor activity and memory processes in mice.

The effects of the kappa-opioid receptor agonists tifluadom, bremazocine and U-50,488 on locomotor activity (test: toggle-floor box) and memory (test: passive avoidance) were assessed in C57BL/6 (C57) and DB/2 (DBA) mice. The drugs administration resulted in activity depression in both strains, the effect was higher in DBA mice and was enhanced by pretreatment with haloperidol and with muscimol. Memory impairment was observed in DBA mice following posttraining administration of all drugs. This effect was enhanced by immobilization stress and decreased by familiarization with the apparatus. Memory improvement was evident in C57 mice (U-50,488 experiments). In a research carried out with CD1 mice, amygdaloid lesions decreased the memory impairing effect of U-50,488. The results are compared with those previously obtained with mu agonists and, as concerns memory, are discussed in terms of the involvement of emotional factors in mice responses to kappa agonists administration.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMedDate not supplied

Effects of oxiracetam-scopolamine combinations on shuttle-box avoidance acquisition in mice.

The nootropic drug oxiracetam and the anticholinergic agent scopolamine were tested, alone or in combination, on shuttle-box avoidance acquisition and locomotor activity in mice of the CD-1 strain. Both drugs, given separately, slightly but significantly enhanced avoidance performance, but only scopolamine increased locomotor activity. Combinations of the 2 drugs, in some instances, enhanced avoidance performance more than drugs given separately, but the disinhibitory property of scopolamine makes it difficult to understand the role played by cholinergic mechanisms in these effects.

Animals↗
PubMedDate not supplied

The effect of chronic administration of trazodone on the acquisition of avoidance behavior in mice.

An atypical antidepressant trazodone, given in doses of 5 or 10 mg/kg ip during the period of avoidance training (15 min before the beginning of each of 5 consecutive daily sessions) significantly depressed the rate of acquisition of the conditioned avoidance response. However, in mice pretreated with trazodone, 10 mg/kg daily for the preceding 14 consecutive days, the treatment with 10 mg/kg before each session did not impair the acquisition of the conditioned avoidance response, and the treatment with a dose of 5 mg/kg improved the acquisition over the control level. The data show that the pattern of action of trazodone on the acquisition of conditioned avoidance response is the same as that of other antidepressant agents, desipramine and mianserin, and indicate that chronically administered antidepressant agents do not impair learning.

Analysis of Variance↗