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Cell death and cell number in the developing cerebral cortex of MAM treated mice
S Ciaroni1, T Cecchini, P Ambrogini
1Institute of Morphological Sciences, University of Urbino, Italy.
Abstract:
The postnatal cell death decline in microencephalic mice produced after methylazoxymethanol-acetate injection during embryonic development may adjust the final cell number of treated animals in the mature neocortex. Quantitative observations of cortical cell number in normal and treated mice, from 5 days to adult age were carried out. The proportion of cortical dead cells per 1000 live cells in a standardized cortical column and the cumulative cell death across time were studied in mice aged 5-10-20-30 days. Two main results were obtained. First, the mature neocortex of treated animals shows a number of cells which is significantly lower with respect to the controls but the difference is less accentuated than in the developing neocortex. Secondly, the proportion of cortical dead cells per 1000 live cells at every date studied and the cumulative cell death across time decreased in cerebral cortex of treated mice when compared with age-matched controls. Our data show that decreasing initial cell number by prenatal MAM injection is correlated to an increase in the survival of cortical cells.
Insights
Prenatal exposure to methylazoxymethanol-acetate (MAM) in mice reduces the number of cortical cells. However, this reduction is compensated by decreased postnatal cell death, leading to increased cell survival in the mature neocortex.
Area of Science:
- Neuroscience
- Developmental Biology
- Toxicology
Background:
- Methylazoxymethanol-acetate (MAM) exposure during embryonic development causes microencephaly in mice.
- This prenatal insult affects the developing neocortex, leading to reduced cell numbers.
Purpose of the Study:
- To investigate the impact of prenatal MAM exposure on postnatal cell death and final cortical cell numbers.
- To quantify the proportion of dead cells and cumulative cell death in the developing and mature neocortex of MAM-treated mice.
Main Methods:
- Quantitative observations of cortical cell numbers in normal and MAM-treated mice from 5 days to adulthood.
- Analysis of the proportion of cortical dead cells per 1000 live cells in standardized cortical columns.
- Assessment of cumulative cell death over time in mice aged 5, 10, 20, and 30 days.
Main Results:
- The mature neocortex of MAM-treated mice had significantly fewer cells than controls, but the difference was less pronounced than in the developing neocortex.
- The proportion of cortical dead cells and cumulative cell death decreased in MAM-treated mice compared to controls at all studied time points.
- Prenatal MAM injection, which decreases initial cell number, correlated with increased cortical cell survival.
Conclusions:
- Postnatal cell death decline in MAM-exposed mice helps to adjust the final cell number in the mature neocortex.
- Prenatal MAM-induced reduction in cell number is associated with enhanced cortical cell survival during postnatal development.