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Estrogen alters MPTP-induced neurotoxicity in female mice: effects on striatal dopamine concentrations and release
D E Dluzen1, J L McDermott, B Liu
1Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown 44272-0095, USA.
Abstract:
The effects of estrogen on MPTP-induced neurotoxicity of the nigrostriatal dopaminergic system were examined in C57Bl and CD-1 mice. Ovariectomized mice with and without estrogen were treated with MPTP or its vehicle. The effects of these treatments on striatal dopamine concentrations and L-DOPA-stimulated dopamine and L-3,4-dihydroxyphenylacetic acid (DOPAC) release in vitro were determined. Dopamine concentrations of C57Bl mice receiving estrogen before MPTP were significantly greater than those of non-estrogen-treated MPTP mice as well as estrogen-treated mice receiving the MPTP vehicle. Dopamine concentrations of the CD-1 mice did not differ with these treatments. L-DOPA-evoked dopamine release values of estrogen-treated C57Bl mice were significantly increased compared with non-estrogen-treated mice. No such differences were observed in the MPTP-treated C57Bl mice. DOPAC release rates were similar to that of dopamine in these C57Bl mice. In the CD-1 mice estrogen also produced a significant increase in L-DOPA-evoked dopamine release; however, this response was unaltered by MPTP treatment. A significant increase in L-DOPA-evoked DOPAC output was obtained only for estrogen-treated CD-1 mice. Both strains show very similar responses to the estrogen treatment, but differential responses of dopamine release to L-DOPA between the C57Bl and CD-1 mice were obtained with regard to the interactive effects of estrogen and MPTP. Our results suggest that in addition to its role as modulator, estrogen may also function as a neuroprotectant against MPTP neurotoxicity of the nigrostriatal dopaminergic system in the C57Bl mouse.
Insights
Estrogen may protect the nigrostriatal dopaminergic system from MPTP neurotoxicity in C57Bl mice. This neuroprotection was observed through increased dopamine concentrations and L-DOPA-stimulated release, suggesting a potential therapeutic role for estrogen.
Area of Science:
- Neuroscience
- Endocrinology
Background:
- MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) is a neurotoxin that selectively damages the nigrostriatal dopaminergic system, a pathway implicated in Parkinson's disease.
- Estrogen is a hormone known to have various effects on the central nervous system, including potential neuroprotective properties.
Purpose of the Study:
- To investigate the neuroprotective effects of estrogen against MPTP-induced neurotoxicity in the nigrostriatal dopaminergic system of C57Bl and CD-1 mice.
- To determine how estrogen influences dopamine concentrations and L-DOPA-stimulated dopamine release in response to MPTP treatment.
Main Methods:
- Ovariectomized C57Bl and CD-1 mice were treated with or without estrogen, followed by administration of MPTP or its vehicle.
- Striatal dopamine concentrations were measured.
- In vitro release of dopamine and DOPAC (3,4-dihydroxyphenylacetic acid) in response to L-DOPA stimulation was assessed.
Main Results:
- In C57Bl mice, estrogen treatment significantly increased striatal dopamine concentrations and L-DOPA-evoked dopamine release, particularly when administered before MPTP.
- CD-1 mice showed increased L-DOPA-evoked dopamine release with estrogen, but this effect was not significantly altered by MPTP.
- Differential responses regarding the interactive effects of estrogen and MPTP on dopamine release were observed between the two mouse strains.
Conclusions:
- Estrogen demonstrates neuroprotective effects against MPTP-induced neurotoxicity in the nigrostriatal dopaminergic system of C57Bl mice.
- Estrogen's modulatory role extends to neuroprotection, potentially offering a therapeutic strategy for conditions involving dopaminergic neurodegeneration.