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Updated: Aug 16, 2026
The 6-hydroxydopamine Rat Model of Parkinson's Disease
Published on: October 27, 2021
Differential survival patterns among midbrain dopaminergic cells of MPTP-treated monkeys and 6OHDA-lesioned rats
Emily Fitzpatrick1, Keyoumars Ashkan, Bradley A Wallace
1Department of Anatomy & Histology, University of Sydney, Australia.
Abstract:
We explore the patterns of survival among dopaminergic cells of the midbrain in MPTP-treated macaque monkeys and 6OHDA-lesioned Sprague-Dawley rats. For the monkeys, animals were injected intramuscularly with MPTP for 8 days consecutively and then allowed to survive for 21 days. For the rats, 6OHDA was injected into the midbrain and then allowed to survive for either 7, 28 or 84 days. Brains were processed for tyrosine hydroxylase (TH) and calbindin immunocytochemistry to label populations in the ventral and dorsal tiers of midbrain dopaminergic cells. In monkeys, while there was a decrease in the TH+ cell number in the ventral tier of MPTP-treated cases (65%), there was an overall increase (22%) in the TH+ and calbindin+ cell number in the dorsal tier. Double labelling studies indicate that approximately 50% of TH+ cells of the dorsal tier contain calbindin also. In rats, there was a decrease in TH+ cell number in the ventral tier of 6OHDA-lesioned cases (97%), and to a lesser extent, in the TH+ and calbindin+ cell number in the dorsal tier ( approximately 40%). In conclusion, we show a surprising increase in TH+ and calbindin+ cell number in the dorsal tier in response to MPTP insult; such an increase was not evident after 6OHDA insult. We suggest that the increase in antigen expression relates to the dopaminergic reinnervation of the striatum in MPTP-treated cases. We also suggest that the greater loss of dopaminergic cells in the ventral tier when compared to the dorsal tier relates to glutamate toxicity.
Insights
MPTP-treated monkeys surprisingly showed increased dorsal midbrain dopaminergic cells, while rats treated with 6OHDA experienced significant cell loss in both ventral and dorsal tiers. This highlights differential neurotoxic effects.
Area of Science:
- Neuroscience
- Cell Biology
Background:
- Dopaminergic cell loss in the midbrain is implicated in neurodegenerative diseases.
- Understanding differential cell survival patterns is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the survival patterns of midbrain dopaminergic cells following MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and 6OHDA (6-hydroxydopamine) insults.
- To compare the effects of MPTP and 6OHDA on tyrosine hydroxylase (TH) and calbindin positive cells in ventral and dorsal midbrain tiers.
Main Methods:
- MPTP was administered to macaque monkeys over 8 days, followed by a 21-day survival period.
- 6OHDA was injected into Sprague-Dawley rats with survival times of 7, 28, or 84 days.
- Immunocytochemistry for TH and calbindin was used to label and quantify dopaminergic cell populations.
Main Results:
- MPTP-treated monkeys exhibited a 65% decrease in ventral TH+ cells but a 22% increase in dorsal TH+ and calbindin+ cells.
- Approximately 50% of dorsal TH+ cells in monkeys co-expressed calbindin.
- 6OHDA-lesioned rats showed a 97% decrease in ventral TH+ cells and a 40% decrease in dorsal TH+ and calbindin+ cells.
Conclusions:
- MPTP insult surprisingly increased TH and calbindin expression in dorsal midbrain dopaminergic cells, an effect not seen with 6OHDA.
- Differential cell loss between ventral and dorsal tiers may relate to glutamate toxicity.
- Increased antigen expression in MPTP-treated cases might be linked to dopaminergic reinnervation of the striatum.
