Biomedical subjects

Daniel Beracochea

Publications and source records attributed to Daniel Beracochea.

5 recordsLinked to original sources

PubMed2006

Long-term behavioral consequences of soman poisoning in mice.

We investigated the long-term (up to 90 days) consequences of soman intoxication in mice on weight, motor performances (grip strength, rotarod) and mnemonic cognitive processes (T-maze, Morris water maze test). First, a relative weight loss of 20%, measured 3 days after intoxication, was evidenced as a threshold beyond which neuropathological damage was observed in the hippocampus. Animals were then distributed into either low weight loss (LWL) or high weight loss (HWL) groups according to the relative 20% weight loss threshold. Compared to controls, both groups of poisoned mice quickly exhibited a decrease in their motor performance subsequent to an acute soman toxicity phase. Then, total motor recovery occurred for the LWL group. Comparatively, HWL mice showed only transient recovery prior to a second decrease phase due to soman-induced delayed toxicity. One month after intoxication, mnemonic cognitive performances of the LWL group were similar to controls while the HWL group did not exhibit any learning skill. Three months after poisoning, compared to controls, the LWL group showed similar mnemonic performances in the maze test but a mild deficit in the Morris water maze task. At the same time, learning skills slightly recovered in the HWL group. Mnemonic cognitive data are discussed in relation to the neuropathology, neurogenesis and sprouting occurring in the hippocampus of soman-intoxicated animals.

Animals↗

PubMed2006

Anterograde and retrograde effects of benzodiazepines on memory.

Benzodiazepines are known as "acquisition-impairing" molecules, and their effects on anterograde memory processes are well described. In contrast, the impact of benzodiazepines on retrograde memory and, more particularly, on retrieval processes, is only marginally studied. This mini-review provides an overlook of the main studies evidencing an effect of benzodiazepines on retrograde memory, both in humans and animals, with special emphasis on retrieval processes. The conditions for the emergence of the benzodiazepine-induced retrieval impairments are also discussed.

Animals↗

PubMed2006

Mouse lines selected for difference in sensitivity to beta-CCM also differ in memory processes.

Methyl-beta-carboline-3-carboxylate (or beta-CCM) is a benzodiazepine receptor ligand with inverse agonist properties. Two strains of mice were selected, one for sensitivity (BS) and one for resistance (BR) to a convulsive dose of beta-CCM. These two strains were then shown to differ in several biochemical, pharmacological and behavioral characteristics; specifically BS mice were less anxious than BR mice. The present work provides evidence of differences in the learning abilities of the two strains. Three different learning tasks were used: spatial delayed discrimination on the 4-hole board, a learned choice between a lit and a dark compartment in a T-maze, and place-learning in an 8-arm radial maze. In all three tasks, BS mice had consistently better performance levels than BR mice.

Animals↗

PubMed2004

Effects of ibotenic acid lesions of the dorsal hippocampus on contextual fear conditioning in mice: comparison with mammillary body lesions.

The goals of the present study were to determine if ibotenic acid lesions of the dorsal hippocampus (dHPC) or of mammillary body (MB) of the hypothalamus would induce similar contextual conditioning deficit in a fear-conditioning paradigm, previously developed in mice [Eur. J. Neurosci. 12 (2000) 2575]. Results showed that ibotenic acid lesions of the dHPC or of the MB both induced severe deficits on contextual conditioning but spared auditory conditioning, as compared to controls. This study provides direct evidence for an involvement of dHPC neurones in contextual fear conditioning and is first to demonstrate an involvement of the MB in the mediation of contextual fear conditioning.

Acoustic Stimulation↗

PubMed2004

BetaCCM but not physostigmine enhancement of memory retrieval depends on emotional processes in mice.

RATIONALE: The effects of methyl beta-carboline-3-carboxylate (betaCCM, an inverse agonists of GABA/benzodiazepine receptors) or physostigmine (a cholinesterase inhibitor) on retrieval processes and relationships with anxiety have been only marginally studied. OBJECTIVE: This study investigates in mice the effects of acute betaCCM or physostigmine injections on retrieval of previously acquired discriminations involving distinct contextual cues (serial contextual discrimination; SCD) in a four-hole-board. Animals submitted to SCD were also evaluated for emotional reactivity in an elevated-plus maze. METHODS: Mice were injected before the learning session began with a saline solution. Twenty-four hours later, mice were replaced on the context of the initial acquisition and a single dose of saline or betaCCM (0.5 or 1.5 mg/kg) or physostigmine (0.05 and 1.0 mg/kg) was injected 20 min before testing. RESULTS: The highest dose of either betaCCM or physostigmine improved performance of the first discrimination in the SCD task. The higher dose of betaCCM produced anxiety-like reactivity in the plus maze, and scores of "anxiety" were significantly correlated with memory scores; in contrast, memory performance of physostigmine-treated subjects were totally independent of emotional reactivity. CONCLUSION: These results show that, as opposed to physostigmine, betaCCM acts on retrieval processes specifically through its emotional component.

Animals↗