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J Y Bertholet

Publications and source records attributed to J Y Bertholet.

13 recordsLinked to original sources
PubMed1997

Hippocampal morphology and open-field behavior in Mus musculus domesticus and Mus spretus inbred mice.

Mus spretus is extensively used in interspecific mouse backcross analyses employed to generate genetic linkage maps. However, little is known about its behavior and neuroanatomy, phenotypes for which large interstrain differences have been observed in Mus musculus domesticus. Behavioral and hippocampal neuroanatomical variables were measured in adult male mice from the inbred strains C57BL/6J (Mus musculus domesticus) and SEG (Mus spretus). Clear differences were found for behavioral responses to novelty in an open field, SEG being much less active than C57BL/6J. Morphometrical analysis of hippocampal terminal fields, visualized with Timm's stain, revealed strain differences only for the size of the intra- and infrapyramidal mossy fiber terminal fields, which were about 3 x larger in C57BL/6J than in SEG. In addition, absolute left-right differences were larger in SEG for the stratum radiatum and stratum oriens. In spite of these behavioral and neuroanatomical differences, the phenotypical scores obtained for SEG do not exceed the range observed for Mus musculus domesticus inbred strains.

Animals↗
PubMed1996

Age-related morphological changes in the hippocampus in two mouse strains.

The granule cell number (nGR) in the dentate gyrus (DG) has been reported to vary considerably among inbred strains of mice, thus providing proof of some genetically associated components to this variation. Furthermore, several authors have described age-related morphological changes in the DG in both humans and animals, but there is no general agreement in the literature about the occurrence of such changes. The purpose of this study was to investigate for strain differences in hippocampal structure changes in old C57BL/6J (B) and DBA/2J (D) mice as compared with younger ones. The nGR in the DG, as well as other structural parameters of the hippocampus, were determined in female B and D mice of 4 and 24 months. The two-way analysis of variance indicated a significant interaction between 'strain' and 'age' for the nGR, suggesting that this parameter changes differently with age in B and D mice. This finding indicates that these strains could present a differential susceptibility in granule cell aging raising the possibility that age effects on the granule cell population in the DG could be influenced by some hereditary factors.

Aging↗
PubMed1994

Neuroanatomical divergence between two substrains of C57BL/6J inbred mice entails differential radial-maze learning.

Compared to the parental strain C57BL/6J, male mice from the mutated substrain C57BL/6JNmg show smaller hippocampal intra- and infrapyramidal mossy fiber projections and a correlated inability to master a simple spatial radial-maze task. Possibly, these two substrains differ for only one single gene, making them a valuable model to investigate the physiological pathways leading from genotype to neurobehavioral phenotype.

Animals↗
PubMed1993

Hippocampal mossy fiber changes in mice transgenic for the human copper-zinc superoxide dismutase gene.

The copper-zinc superoxide dismutase (SOD-1) gene, located on chromosome 21 and triplicated in Down's syndrome (DS), is suspected to be involved in the neuropathology observed in Alzheimer's disease (AD), DS and physiological aging. In order to explore the effect of an overproduction of SOD-1 in the mouse hippocampus, we investigated the Timm-stained mossy fiber (MF) innervation in the hippocampus of transgenic mice for the human SOD-1 gene (hSOD-1 mice). The results showed a decrease of the MF projection area in the hSOD-1 mice overexpressing the SOD-1 protein. These findings suggest that free radicals could play a role in this particular synaptic loss.

Animals↗
PubMed1991

Spatial and non-spatial spontaneous alternation and hippocampal mossy fibre distribution in nine inbred mouse strains.

Ten male mice from each one of nine inbred strains were tested for spontaneous alternation in a T-maze, which was placed in a spatially richly structured room. Each test consisted of two trials, the first choice to be made was forced, the second one free. By turning the maze 180 degrees between choices during 8 of the 16 tests, 3 variables could be measured: total alternation, spatial alternation, and non-spatial alternation. After Timm's staining, the sizes of the intra- and infrapyramidal mossy fibre terminal fields (iip-MF) were measured. Significant strain differences were found for all variables, but none of the behavioural variables correlated with hippocampal variation. These results disagree with earlier experiments, where large correlations between the iip-MF and spatial working memory were found. Some hypotheses to explain this discrepancy are presented.

Animals↗
PubMed1990

No correlations between spatial and non-spatial reference memory in a T-maze task and hippocampal mossy fibre distribution in the mouse.

Two reference memory tasks were tested in a T-maze, which was placed in a spatially richly structured environment and turned 180 degrees between trials following a semi-random schedule. Male mice from 9 different inbred strains were either trained always to go to the same place (spatial task) or always to make the same turn (non-spatial task). Animals were subsequently processed for Timm's stain and the sizes of their intra- and infrahippocampal mossy fibre terminal fields (ipp-MF) were measured. Significant strain differences were found for this variable and in both learning tasks, but learning and hippocampal variation did not correlate. This disagrees with earlier findings in a radial maze, where significant correlations between the iipMF and spatial reference memory were obtained. Two hypotheses are brought forward to explain this discrepancy. First, in radial mazes (multiple choices) different memory capabilities might be used than in T-mazes (only two choices). Second, a considerable amount of stress appeared to be present in our subjects, possibly induced by the large size of the T-maze. This might have interfered negatively with acquisition. Further experiments will be needed to test these hypotheses.

Animals↗
PubMed1980

Proliferative activity and cell migration in the adrenal cortex of fetal and neonatal rats: an autoradiographic study.

The aim of this experiment was to examine, using autoradiograhic techniques, proliferative activity in the adrenal cortex of rats on day 20 of fetal life, and to follow the fate of labelled cells 48, 168, 336 and 672 h after injection of [3H]thymidine. On day 20 of fetal life, labelled cells were more numerous in the zona glomerulosa than in the other zones. The fate of the labelled cells in each cell compartment showed centripetal migration, but their displacement from day 20 of pregnancy up to 5 days post partum, combined with a reduction in the size of the adrenal gland, suggested a real migration. The centripetal movement was found in the cortex when growth had effectively ceased.

Adrenal Cortex↗
PubMedDate not supplied

No aging effect on hippocampal type II glucocorticoid receptors in two inbred mouse strains.

We report here on the type II glucocorticoid receptor concentration in the hippocampal cytosol of two inbred strains of mice, C57BL/6J and DBA/2J, aged 2 and 24 months. Glucocorticoid receptors are usually considered as mediating cytotoxic effects of glucocorticoids on hippocampal neurons and modulating hippocampus-dependent behaviors. Either a decrease in glucocorticoid receptors with aging or no effect of aging have been reported previously. In order to test whether strain differences may explain these conflicting results, we have measured, using [3H]RU 28362, the hippocampal glucocorticoid receptor concentrations in two inbred strains of mice showing differential modifications of some hippocampus-dependent behaviors with aging. Our results show that there is neither a strain nor an age effect.

Aging↗