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Ovarian steroids and raloxifene prevent MPTP-induced dopamine depletion in mice
M Grandbois1, M Morissette, S Callier
1Oncology and Molecular Endocrinology Research Center, Laval University Medical Center, Sainte-Foy, Québec, Canada.
Abstract:
The activity of steroids was studied in 1-methyl-phenyl-1,2,3,6-tetrahydropyridine (MPTP) lesioned retired breeder C57BL/6 male mice as a model of Parkinson's disease. Steroids were injected daily for 5 days before MPTP (4 injections, 15 mg/kg i.p., at 2 h intervals) and hormonal treatment continued for 5 more days. Mice that received 17beta-estradiol or progesterone or raloxifene (a selective estrogen receptor modulator) and MPTP had striatal concentrations of dopamine (DA) and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) similar to those in control animals, whereas mice that received MPTP alone or with 17alpha-estradiol (the isomer with weak estrogenic activity) had an extensive decrease of DA and its metabolites. These results suggest stereospecific prevention of MPTP-induced dopamine loss by 17beta-estradiol, which is also observed with progesterone and raloxifene.
Insights
Certain steroids, including 17beta-estradiol, progesterone, and raloxifene, protect against dopamine loss in a Parkinson
Area of Science:
- Neuroscience
- Pharmacology
- Endocrinology
Background:
- Parkinson's disease is a neurodegenerative disorder characterized by the loss of dopaminergic neurons.
- 1-methyl-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin used to model Parkinson's disease in rodents.
- Steroid hormones and their modulators are being investigated for potential neuroprotective effects.
Purpose of the Study:
- To investigate the neuroprotective potential of specific steroids against MPTP-induced dopamine depletion in a mouse model.
- To determine if the neuroprotective effects of steroids are stereospecific.
Main Methods:
- Retired breeder C57BL/6 male mice were used as a model for Parkinson's disease.
- Mice were treated with MPTP to induce dopaminergic neurotoxicity.
- Animals received daily injections of 17beta-estradiol, 17alpha-estradiol, progesterone, or raloxifene before and after MPTP administration.
- Striatal concentrations of dopamine (DA) and its metabolites (DOPAC, HVA) were measured.
Main Results:
- MPTP administration significantly decreased striatal DA, DOPAC, and HVA levels.
- Pre-treatment with 17beta-estradiol, progesterone, or raloxifene prevented the MPTP-induced reduction in DA and its metabolites.
- The stereoisomer 17alpha-estradiol did not show significant neuroprotective effects.
- These findings indicate a stereospecificity in the neuroprotective action of estradiol.
Conclusions:
- 17beta-estradiol, progesterone, and raloxifene exhibit stereospecific neuroprotective effects against MPTP-induced dopamine loss.
- These findings suggest potential therapeutic strategies for Parkinson's disease involving these compounds.