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Updated: Jun 25, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Microglial activation is inhibited by corticosterone in dopaminergic neurodegeneration
Shuei Sugama1, Takato Takenouchi, Hiroshi Kitani
1Department of Physiology, Nippon Medical School, Tokyo, Japan. sugama@nms.ac.jp
Abstract:
The present study compared 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced microglial activation in 3 different groups, sham-operated (SHM) mice, adrenalectomized mice (ADX), and ADX mice administered with corticosterone (ADX + CORT), to investigate the roles of glucocorticoids on microglial activation and dopaminergic neurodegeneration. Acute MPTP treatment induced moderate tyrosine hydroxylase (TH)-immunoreactive neuronal loss in the substantia nigra (SN) of SHM mice; this neuronal loss was significantly enhanced in ADX mice, but eventually recovered following the administration of corticosterone. Consistent with neuronal findings, acute MPTP treatment induced microglial activation in the SN from 1-3 days post injection in SHM mice. Interestingly, microglial activation was further enhanced and occasionally showed a phagocytic morphology in ADX mice that showed no circulating corticosterone. Furthermore, the activated microglia was significantly suppressed by the administration of corticosterone to ADX mice. Moreover, a confocal microscopic study demonstrated that the expression of inducible nitric oxide synthase protein, exclusively colocalized with activated microglia in the SN in ADX mice, was substantially decreased by the administration of corticosterone. Thus, the present study, using in-vivo adrenalectomy for a dopaminergic neurodegeneration model, successfully demonstrated the neuroprotective effects of corticosterone by microglial inhibition.
Insights
Glucocorticoids, like corticosterone, protect against MPTP-induced neurodegeneration by inhibiting microglial activation in the substantia nigra. Adrenalectomy exacerbates this damage, highlighting corticosterone's neuroprotective role.
Area of Science:
- Neuroscience
- Immunology
- Pharmacology
Background:
- Microglial activation and dopaminergic neurodegeneration are key features of Parkinson's disease.
- Glucocorticoids play a role in neuroinflammation and neuronal survival.
- The specific role of corticosterone in MPTP-induced neurodegeneration requires further elucidation.
Purpose of the Study:
- To investigate the role of glucocorticoids, specifically corticosterone, in modulating microglial activation and dopaminergic neurodegeneration.
- To compare the effects of MPTP in sham-operated, adrenalectomized, and corticosterone-replaced adrenalectomized mice.
Main Methods:
- Utilized the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model for dopaminergic neurodegeneration.
- Employed adrenalectomy (ADX) to manipulate endogenous glucocorticoid levels.
- Administered corticosterone (CORT) to ADX mice to assess its neuroprotective effects.
- Quantified tyrosine hydroxylase (TH)-immunoreactive neuronal loss in the substantia nigra (SN).
- Assessed microglial activation using morphological criteria and inducible nitric oxide synthase (iNOS) expression via confocal microscopy.
Main Results:
- MPTP induced significant dopaminergic neurodegeneration and microglial activation in the SN.
- Adrenalectomy (ADX) exacerbated MPTP-induced neuronal loss and microglial activation, indicating a lack of circulating corticosterone.
- Corticosterone administration to ADX mice significantly ameliorated neuronal loss and suppressed microglial activation.
- Corticosterone treatment markedly reduced iNOS expression in microglia within the SN of ADX mice.
Conclusions:
- Corticosterone exhibits significant neuroprotective effects against MPTP-induced dopaminergic neurodegeneration.
- Glucocorticoids, via corticosterone, inhibit microglial activation and subsequent neuroinflammation.
- This study highlights the potential therapeutic role of corticosterone in neurodegenerative conditions characterized by microglial involvement.
