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Late-onset cerebellar degeneration in mice induced transplacentally by methylnitrosourea
S B Smith1, C B Brown, M E Wright
1Department of Anatomy, University of South Alabama, College of Medicine, Mobile.
Abstract:
A late-onset degenerative disease in the cerebellum was produced in the offspring of mice exposed to 1 mg/kg of the direct-acting DNA alkylating agent methylnitrosourea (MNU) on day 16 of gestation. This intrauterine exposure to MNU also provoked a progressive retinal degeneration that was described elsewhere. Mild ataxia in the MNU-exposed animals was expressed by 20 weeks of age. Although animals appeared normal in the immediate post-natal period, quantitative histological evaluation of cerebellar coronal sections indicated that MNU-exposed animals had a significantly greater number of pyknotic Purkinje cells than age-matched controls. The number of pyknotic Purkinje cells declined with age in the drug exposed animals; however, the percentage of pyknotic Purkinje cells to total number of Purkinje cells still was greater in MNU-induced animals at 36 weeks than in controls, suggesting that a slow degenerative process was ongoing in the MNU-exposed animals. Furthermore, the folia were grossly disrupted in 90% of the older MNU-exposed animals (ages greater than 12 weeks), suggesting permanent cerebellar disruption macroscopically. Such intrauterine exposure to low doses of alkylating agents may be potentially useful in modeling degenerative neuronal diseases.
Insights
Intrauterine exposure to methylnitrosourea (MNU) induced late-onset cerebellar degeneration and Purkinje cell loss in mice offspring. This study suggests MNU may model neurodegenerative diseases.
Area of Science:
- Neuroscience
- Developmental Biology
- Toxicology
Background:
- Prenatal exposure to certain chemicals can induce developmental abnormalities.
- Neurodegenerative diseases often have complex etiologies with potential environmental influences.
Purpose of the Study:
- To investigate the effects of intrauterine exposure to methylnitrosourea (MNU) on cerebellar development and function in mice offspring.
- To assess the potential of MNU as a model for studying late-onset degenerative neuronal diseases.
Main Methods:
- Pregnant mice were administered 1 mg/kg of methylnitrosourea (MNU) on day 16 of gestation.
- Offspring were monitored for neurological signs, including ataxia.
- Quantitative histological evaluation of cerebellar Purkinje cells and gross morphology was performed at various ages.
Main Results:
- MNU-exposed offspring exhibited mild ataxia by 20 weeks of age.
- Histological analysis revealed a significantly higher number of pyknotic Purkinje cells in MNU-exposed animals compared to controls.
- Gross disruption of cerebellar folia was observed in 90% of older MNU-exposed animals, indicating permanent cerebellar damage.
Conclusions:
- Intrauterine MNU exposure induces a late-onset degenerative disease in the mouse cerebellum.
- The observed Purkinje cell loss and cerebellar disruption suggest MNU is a potential model for studying neurodegenerative conditions.
- This model may be valuable for investigating the mechanisms and potential treatments for degenerative neuronal diseases.