Modulation of prepulse inhibition and stereotypies in rodents: no evidence for antipsychotic-like properties of histamine H3-receptor inverse agonists.

Rationale: H(3)-receptor inverse agonists raise a great interest as innovative therapeutics in several central disorders. Whereas their procognitive properties are well established, their antipsychotic-like properties are still debated.

Objectives: We further explored the effect of maximal doses (3-10 mg/kg) of ciproxifan, BF2.

Role of DRD3 in morphine-induced conditioned place preference using drd3-knockout mice.

The dopamine D3 receptor (DRD3) mediates expression of conditioned effects of psychostimulants, but conflicting results have been obtained with opiates. In a conditioned place preference (CPP) procedure, morphine increased the time spent in a compartment previously paired with drug injection. CPP was obtained at morphine doses of 16 and 32 mg/kg in wild-type (drd3+/+) mice and 8, 16 and 32 mg/kg in DRD3-knockout (drd3-/-) mice.

Dopamine D3 receptor ligands modulate the acquisition of morphine-conditioned place preference.

Rationale: The dopamine D3 receptor has been shown to mediate conditioned effects of psychostimulants such as cocaine. The present work was aimed at determining whether drugs acting at D3 receptors alter acquisition of conditioned effects of opiates.

Methods: We have used the conditioned place preference (CPP) in mice, which permits the measurement of approach behaviour to environmental stimuli previously paired with drug effects.

Role of the dopamine D3 receptor in reactivity to cocaine-associated cues in mice.

Environmental stimuli previously associated with drug effects can acquire secondary reinforcing properties, able to maintain drug-seeking behaviour or induce relapse. We have used a classical Pavlovian conditioning procedure to assess the role of the dopamine D3 receptor (D3R) in the expression of drug-conditioned responses. Mice repeatedly receiving cocaine in a particular environment distinct from home-cages displayed hyperlocomotion after subsequent exposure to the drug-paired environment.

Docosahexaenoic acid-rich phospholipid supplementation: effect on behavior, learning ability, and retinal function in control and n-3 polyunsaturated fatty acid deficient old mice.

This study investigated the effects of docosahexaenoic acid (DHA)-rich phospholipid supplementation on behavior, electroretinogram and phospholipid fatty acid (PUFA) composition in selected brain regions and retina in old mice. Two groups of mice were fed a semisynthetic balanced diet or a diet deficient in alpha-linolenic acid. At the age of 8 months, half of each diet group was supplemented with DHA.

Learning and latent inhibition in old mice.

The inhibitory component of selective attention has been compared in young (7-8 weeks) and older (9-10 months) female mice using the latent inhibition (LI) paradigm. LI consists of retardation in conditioning to a stimulus as a consequence of its prior non-reinforced pre-exposure. In the present work, active avoidance of an electric footshock signaled with a sound was used.

Influence of social isolation and 6-OHDA lesion on the effects of quinelorane.

The sensitivity of the response to the preferential dopaminergic D3 (DAD3) receptor agonist, quinelorane, was compared in mice housed socially and in mice isolated for 4 weeks. Quinelorane (1, 5, 10, 50 and 100 microg/kg) was administered intraperitoneally. Motor activity was measured for 60 min posttreatment.

Predominance of HIV type 1 subtype G among commercial sex workers from Kinshasa, Democratic Republic of Congo.

We have investigated the genetic diversity and potential mosaic genomes of HIV-1 during the early part of the HIV-1 epidemic among commercial sex workers (CSWs) in Kinshasa, Democratic Republic of Congo (formerly Zaire). Serologic analysis revealed that 27 (28.7%) of the 94 specimens were seropositive by both peptide and whole-virus lysate EIAs and that 24 were positive by molecular screening assays, using generic primers that can detect all known groups of HIV-1.

Diets containing long-chain n-3 polyunsaturated fatty acids affect behaviour differently during development than ageing in mice.

The effect of a standard diet providing essential fatty acids enriched in fish oil or palm oil was studied in young, mature and old mice. Two groups of pregnant and lactating OF1 mice were fed on diets with or without high levels of long-chain n-3 polyunsaturated fatty acids. Offspring were maintained on these diets after weaning.

Nutritional (n-3) polyunsaturated fatty acids influence the behavioral responses to positive events in mice.

The effect of (n-3) polyunsaturated fatty acid (PUFA) diet deficiency on behavioural responses to appetitive events was assessed in OF1 mice. Pups fed the same diet (deficient in alpha-linolenic acid or a standard control diet) as their dams were used aged 7 to 11 weeks. In a free choice model, the preference for a sucrose solution in both males and females was significantly lower in deficient than in control mice.

Morphine-induced sensitization of locomotor activity in mice: effect of social isolation on plasma corticosterone levels.

This study examined the influence of social isolation on behavioural sensitization to the locomotor effect of morphine and the link between this behaviour and plasma corticosterone concentrations. Four weeks isolation induced an increase in the locomotor effect of morphine. In social and isolated mice, repeated administrations (6) of morphine (one injection every 3 or 4 days) followed by 3 h in an actimeter induced behavioural sensitization to the locomotor effect of morphine.

Phospholipid supplementation reverses behavioral and biochemical alterations induced by n-3 polyunsaturated fatty acid deficiency in mice.

This study investigated the effects of a diet deficient in alpha-linolenic acid followed or not by supplementation with phospholipids rich in n-3 polyunsaturated fatty acids (PUFA) on behavior and phospholipid fatty acid composition in selected brain regions. Three weeks before mating, two groups of mice were fed a semisynthetic diet containing both linoleic and alpha-linolenic acid or a diet deficient in alpha-linolenic acid. Pups were fed the same diet as their dams.

Specific phospholipid fatty acid composition of brain regions in mice. Effects of n-3 polyunsaturated fatty acid deficiency and phospholipid supplementation.

This study examined the effects of dietary alpha-linolenic acid deficiency followed or not by supplementation with phospholipids rich in n;-3 polyunsaturated fatty acid (PUFA) on the fatty acid composition of total phospholipids in 11 brain regions. Three weeks before mating, mice were fed a semisynthetic diet containing both linoleic and alpha-linolenic acid or deficient in alpha-linolenic acid. Pups were fed the same diet as their dams.

Leptomeningeal melanoma in childhood.

Background: Malignant melanoma (MM) is one of the least common types of childhood cancer, accounting for less than 1% of all pediatric malignancies. Neurocutaneous melanosis (NCM) is a rare phakomatosis consisting of congenital abnormal pigmentation of the skin and meninges. The meningeal lesions are particularly prone to malignant change.

Effect of social isolation on the metabolism of morphine and its passage through the blood-brain barrier and on consumption of sucrose solutions.

Rationale: We have previously shown that place preference conditioning to morphine was observed in social mice at the dose of 8 mg/kg, whereas 4 weeks of isolation impairs the place preference conditioning to morphine (8-100 mg/kg).

Objective: The present study, aimed at explaining this phenomenon, tested three hypotheses: firstly, a reduced sensitivity to reinforcers induced by isolation; secondly, a difference in morphine disposition in isolated and social mice; thirdly, an altered blood-brain barrier transport of morphine in isolated mice.

Methods: In the sucrose experiments, mice had the choice (for 24 h) between a bottle containing tap water and a bottle containing a sucrose solution.

Age-induced cognitive alterations in OF1 mice.

Female OF1 mice aged 17-18 months were compared with female OF1 mice aged 7-11 weeks for locomotor activity, pain sensitivity, and cognitive performance using the Morris water maze, passive and active avoidance, and the elevated plus-maze learning protocol. Performance of old mice was impaired compared to those of young mice for both locomotor activity, pain sensitivity, and the four cognitive tests including the elevated plus-maze not previously used in studies on aging. Using complementary experiments and a detailed analysis of the results, we have shown that the reduction of learning and memory do not result from a decline of sensory and motor capacities.

Learning deficits in first generation OF1 mice deficient in (n-3) polyunsaturated fatty acids do not result from visual alteration.

The effects of (n-3) polyunsaturated fatty acids (PUFA) diet deficiency on learning, electroretinogram and retinal fatty acid composition were assessed for the first time in OF1 mice. Pups fed the same diets (deficient in alpha-linolenic acid or a control) as their dams were used aged 7 weeks for passive avoidance test and fatty acid analysis of retinal phospholipids. Visual function was measured by electroretinography in 4- and 7-week-old mice.

Use of alternate splice sites in granule-bound starch synthase mRNA from low-amylose rice varieties.

The rice Waxy gene encodes a granule-bound starch synthase (GBSS) necessary for the synthesis of amylose in endosperm tissue. We have previously shown that a CT microsatellite near the transcriptional start site of the GBSS gene can distinguish 7 alleles that accounted for more than 80% of the variation in apparent amylose content in an extended pedigree of 89 US rice cultivars (Oryza sativa L.).

Effect of isolation on pain threshold and on different effects of morphine.

1. The effect of three periods of isolation (8, 15 and 30 days) were studied in mice on the pain threshold and the sensitivity to morphine. 2.

Mice selected for low and high blood magnesium levels: a new model for stress studies.

Extra- and intracellular magnesium levels have previously been shown to be genetically controlled in humans and in the mouse. To further study this genetic regulation, mice were selected from a heterogeneous population, for low (MGL mice) and high (MGH mice) red blood cell (RBC) magnesium values. These values diverged rapidly in the two strains, to reach a stable difference between the 14th and 18th generations.

Isolation impairs place preference conditioning to morphine but not aversive learning in mice.

Morphine (8-100 mg/kg IP) induces place preference conditioning in mice. The effect of two different periods of isolation (15 and 30 days) was examined. Mice isolated for 15 days but not 30 days exhibited place preference conditioning to morphine (8 mg/kg).

Effect of isolation on morphine-induced running and changes in body temperature.

1. The influence of isolation of three durations 8, 15 and 30 days has been examined in mice on the effects of morphine on rectal temperature and on locomotor activity. Isolated mice were compared to non isolated mice with the same age.

Influence of a dietary alpha-linolenic acid deficiency on learning in the Morris water maze and on the effects of morphine.

Female OF1 mice were fed on a diet deficient in alpha-linolenic acid or on a control diet 3 weeks before mating and throughout pregnancy and lactation. Pups fed on the same diet as their mothers were used for experiments. The effects of dietary alpha-linolenic acid deficiency were studied in a model of learning, the Morris water maze, and on the following effects of morphine: increase in locomotor activity, modifications of rectal temperature and analgesia.

Effect of dietary alpha-linolenic acid deficiency on habituation.

Three weeks before mating, two groups of SWISS OF1 mice were fed a diet that was similar but contained either peanut oil poor in alpha-linolenic acid [18:3(n-3)] (n-3 deficient = deficient mice = (n-3)-) or peanut + rapeseed oil rich in alpha-linolenic acid (n-3 nondeficient = controls = (n-3)+). Pups, fed the same diet as their dams, aged 45 to 62 days were used for brain lipid analysis and for behavioral experiments, aimed at determining whether there is a relation between the dietary intake of alpha-linolenate and a simple form of learning: habituation. The behavior of mice was compared using four models: exploration recorded in a photocell actimeter, activity in an open-field, duration of immobility in the forced swimming test and number of escape attempts from a small closed space.