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Updated: Aug 24, 2026
Microglia as a Surrogate Biosensor to Determine Nanoparticle Neurotoxicity
Published on: October 25, 2016
Microglial activation precedes dopamine terminal pathology in methamphetamine-induced neurotoxicity
Matthew J LaVoie1, J Patrick Card, Teresa G Hastings
1Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Abstract:
Previous studies have demonstrated methamphetamine (METH)-induced toxicity to dopaminergic and serotonergic axons in rat striatum. Although several studies have identified the nature of reactive astrogliosis in this lesion model, the response of microglia has not been examined in detail. In this investigation, we characterized the temporal relationship of reactive microgliosis to neuropathological alterations of dopaminergic axons in striatum following exposure to methamphetamine. Adult male Sprague-Dawley rats were administered a neurotoxic regimen of methamphetamine and survived 12 h, or 1, 2, 4, and 6 days after treatment. Immunohistochemical methods were used to evaluate reactive changes in microglia throughout the brain of methamphetamine-treated rats, with a particular focus upon striatum. Pronounced morphological changes, indicative of reactive microgliosis, were evident in the brains of all methamphetamine-treated animals and were absent in saline-treated control animals. These included hyperplastic changes in cell morphology that substantially increased the size and staining intensity of reactive microglia. Quantitative analysis of reactive microglial changes in striatum demonstrated that these changes were most robust within the ventrolateral region and were maximal 2 days after methamphetamine administration. Analysis of tissue also revealed that microglial activation preceded the appearance of pathological changes in striatal dopamine fibers. Reactive microgliosis was also observed in extra-striatal regions (somatosensory and piriform cortices, and periaqueductal gray). These data demonstrate a consistent, robust, and selective activation of microglia in response to methamphetamine administration that, at least in striatum, precedes the appearance of morphological indicators of axon pathology. These observations raise the possibility that activated microglia may contribute to methamphetamine-induced neurotoxicity.
Insights
Methamphetamine (METH) causes neurotoxicity by activating microglia, immune cells in the brain. This microglial activation in rats precedes damage to dopamine axons, suggesting a role in METH-induced neurotoxicity.
Area of Science:
- Neuroscience
- Neurotoxicology
- Immunology
Background:
- Methamphetamine (METH) is known to cause neurotoxicity, particularly to dopaminergic and serotonergic axons in the rat striatum.
- While reactive astrogliosis has been studied, the detailed response of microglia to METH-induced neurotoxicity remains less understood.
Purpose of the Study:
- To investigate the temporal dynamics of reactive microgliosis in relation to neuropathological changes in dopaminergic axons following METH exposure.
- To characterize the morphological and temporal aspects of microglial activation in the striatum and other brain regions after METH administration.
Main Methods:
- Adult male Sprague-Dawley rats were administered a neurotoxic dose of METH.
- Immunohistochemistry was employed to assess reactive microglial changes at various time points (12 h, 1, 2, 4, and 6 days) post-treatment.
- Quantitative analysis focused on microglial morphology and distribution, particularly in the striatum.
Main Results:
- Significant reactive microgliosis, characterized by hyperplastic changes in microglia morphology and increased staining intensity, was observed in METH-treated rats compared to controls.
- Microglial activation was most pronounced in the ventrolateral striatum and peaked at 2 days after METH administration.
- Crucially, microglial activation was observed to precede the onset of pathological alterations in striatal dopamine fibers.
Conclusions:
- Methamphetamine administration induces a robust and selective activation of microglia in the brain.
- This microglial response, particularly in the striatum, occurs before observable damage to dopamine axons.
- These findings suggest that activated microglia may play a significant role in the neurotoxic mechanisms of methamphetamine.
