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MPTP toxicity in relation to age, dopamine uptake and MAO-B activity in two rodent species
S S Jossan1, E Sakurai, L Oreland
1Department of Pharmacology, University of Uppsala, Sweden.
Abstract:
The effects of single and multidose 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) treatment on mice (NMRI and C-57bl) and rats of different ages have been investigated by using the reduction of striatal dopamine uptake rate as a measure of the neurotoxic effect. The possibility that differences in MAO-B activity or in dopamine (DA) uptake rate might explain differences in MPTP toxicity between species, strains or animals of different age was investigated. Single dose MPTP treatment (45 mg/kg) had no effect on 10 day and 3 week old mice, while there was a significant reduction of DA uptake rate at the age of 12 and 40 weeks (both strains). No neurotoxicity of single dose MPTP treatment was observed in the rats, irrespective of their age. Multidose treatment with MPTP (3 x 20-45 mg/kg) caused a reduction of DA uptake rates both in the mice and in the rats at all dose regimens used. The effect of MPTP increased with increasing doses and was most pronounced in the C-57bl mice. Both DA uptake rate and monoamine oxidase B (MAO-B) activity increased with age. The increase in MAO-B activity was highest between 10 days and 3 weeks both in the mice and in the rats. Rats had higher (MAO-B) activity than the mice, while the two species had about the same DA uptake rates. No obvious correlations were found either between MAO-B activities or DA uptake rates and the neurotoxic effect of MPTP.
Insights
Single-dose 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) did not affect young mice or rats, but reduced dopamine uptake in older mice. Multidose MPTP caused neurotoxicity in both species, with C-57bl mice being most affected.
Area of Science:
- Neuroscience
- Toxicology
- Pharmacology
Background:
- 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) is a neurotoxin that selectively damages dopaminergic neurons.
- Age, species, and strain can influence MPTP neurotoxicity.
- Monoamine oxidase B (MAO-B) activity and dopamine (DA) uptake rates are potential factors in MPTP metabolism and toxicity.
Purpose of the Study:
- To investigate the neurotoxic effects of single and multidose MPTP on mice and rats of different ages.
- To explore the role of MAO-B activity and DA uptake rates in differential MPTP toxicity.
- To determine age- and strain-dependent variations in MPTP-induced neurotoxicity.
Main Methods:
- MPTP administration (single and multidose) to mice (NMRI, C-57bl) and rats at various ages.
- Measurement of striatal dopamine uptake rate as a primary indicator of neurotoxicity.
- Assay of monoamine oxidase B (MAO-B) activity in relation to age and species.
Main Results:
- Single-dose MPTP (45 mg/kg) showed no neurotoxicity in young mice (10 days, 3 weeks) or rats of any age.
- Significant reduction in DA uptake was observed in older mice (12, 40 weeks) after single-dose MPTP.
- Multidose MPTP (3 x 20-45 mg/kg) induced DA uptake reduction in both mice and rats, with C-57bl mice exhibiting the most pronounced effects.
Conclusions:
- MPTP neurotoxicity is age-dependent in mice, with older animals being more susceptible.
- Multidose MPTP is neurotoxic across different ages and species, with strain-specific variations.
- No clear correlation was found between MAO-B activity, DA uptake rates, and MPTP neurotoxicity in this study.