Chronic exposure to mercuric chloride during gestation affects sensorimotor development and later behaviour in rats

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Free versus forced exposure to an elevated plus-maze: evidence for new behavioral interpretations during test and retest

International audienceRationale The rodent elevated plus-maze is based on an approach/avoidance conflict between secure closed arms and aversive open arms that can be measured to assess anxiety. Despite this apparent simplicity, several discrepancies emerge from the interpretation of an animal's behavior in the maze, especially when considering the one-trial tolerance effect. Objectives and methods In order to bring new elements of interpretation, we compared the behavior of rats exposed to the standard version of the test (forced exposure) to the behavior of rats that were allowed to freely explore the apparatus. We also compared the effects of testing/retesting and chlordiazepoxide in these two situations. Results Our results confirm that open-arm avoidance is a natural tendency and therefore that it is not learned during initial exposure to the maze. In addition, comparison of the two situations suggests that some of the open-arm entries during a forced confrontation with the maze are better interpreted as attempts to avoid the whole situation, rather than as indications of a low level of anxiety. Finally, the one-trial tolerance effect was partially reduced in the free-exposure situation. Conclusions Our results contradict the hypothesis that there is acquisition of a phobic-like response to open arms during trial 1. Rather, they are discussed in line with the hypotheses by Rodgers and Shepherd (Psychopharmacology (Berl) 113:237–242, 1993) and Bertoglio and Carobrez (Behav Brain Res 108:197–203, 2000) concerning the acquisition of spatial information about the whole apparatus, leading on trial 2 to an unbalanced approach/avoidance conflict and to the inefficiency of anxiolytic drugs

ALUMINIUM OXIDE NANOPARTICLES COMPROMISE SPATIAL LEARNING AND MEMORY PERFORMANCE IN RATS

International audienceRecently, the biosafety and potential influences of nanoparticles on central nervous system have received more attention. In the present study, we assessed the effect of aluminium oxide nanoparticles (Al 2 O 3-NPs) on spatial cognition. Male Wistar rats were intravenously administered Al 2 O 3-NP suspension (20 mg/kg body weight/day) for four consecutive days, after which they were assessed. The results indicated that Al 2 O 3-NPs impaired spatial learning and memory ability. An increment in malondialdehyde levels with a concomitant decrease in superoxide dismutase activity confirmed the induction of oxidative stress in the hippocampus. Additionally, our findings showed that exposure to Al 2 O 3-NPs resulted in decreased acetylcholinesterase activity in the hippocampus. Furthermore , Al 2 O 3-NPs enhanced aluminium (Al) accumulation and disrupted mineral element homoeostasis in the hippocampus. However, they did not change the morphology of the hippocampus. Our results show a connection among oxidative stress, disruption of mineral element homoeostasis, and Al accumulation in the hippocampus, which leads to spatial memory deficit in rats treated with Al 2 O 3-NPs

Impairment of emotional behavior and spatial learning in adult Wistar rats by ferrous sulfate

International audienceThe aim of this study was to investigate the effects of FeSO 4 on the behavior of adult Wistar rats. Rats were treated with moderate doses of iron (1.5 or 3.0 mg/kg) for 5 consecutive days, and the effects of iron supplementation on emotional behavior were studied. One group of rats was tested in elevated plus-maze and in open field, and other group was tested for learning abilities in water maze and for motor skills in rotarod task. Iron level in the brain was measured in the frontal cortex, cerebellum, basal ganglia and hippocampus. The effects of the iron treatment (in particular, a dose of 3.0 mg/kg) on emotional behavior in the elevated plus maze and in the open field were significant. The effects of iron on spatial learning were less pronounced, but significant impairments due to the treatment were observed during the probe test. Motor skills and procedural learning in the rotarod task were not significantly affected by the treatment. These behavioral impairments were associated with significant iron accumulations in the hippocampus and basal ganglia of rats treated with 3.0 mg/kg iron and are discussed in terms of possible neuronal impairments of these structures. Thus, FeSO 4 administration at 3.0 mg/kg for 5 consecutive days in adult rats overcomes the mechanisms that shield the brain from iron intoxication and leads to behavioral impairments, in particular with respect to emotional behavior

Acute exposure to zinc oxide nanoparticles does not affect the cognitive capacity and neurotransmitters levels in adult rats

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