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Updated: May 22, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Sustained activation of microglia in the hypothalamic PVN following myocardial infarction
Melissa Dworak1, Martin Stebbing, Andrew R Kompa
1School of Medical Sciences, and Health Innovations Research Institute, RMIT University, Melbourne, Australia.
Abstract:
Microglia are the immune cells in the central nervous system and can produce cytokines when they are activated by an insult or injury. In the present study, we investigated in detail the time frame of the activation of microglia in the hypothalamic paraventricular nucleus (PVN) following myocardial infarction in rats. Morphological changes and immunohistochemistry to detect CD11b (clone OX-42) were used to identify activated microglia. Compared to rats that had undergone sham surgical procedures, there was a significant increase of between 40 and 50% in the proportion of activated microglia in the PVN 4-16 weeks following myocardial infarction (P<0.001, One way ANOVA). At 24h or 1 week post myocardial infarction, however, there was no significant increase in the proportion of activated microglia. Echocardiography and haemodynamic parameters after myocardial infarction indicated significantly reduced left ventricular function. In conclusion, following myocardial infarction, activation of microglia in the PVN does not occur immediately but once manifested, activation is sustained. Thus, activated microglia may contribute to the chronic elevation in cytokine levels observed following myocardial infarction. Since cytokines elicit sympatho-excitatory effects when locally microinjected into the PVN, activated microglia may contribute to the mechanisms mediating the chronic increase in sympathetic nerve activity in animals with reduced left ventricular function induced following myocardial infarction.
Insights
Following myocardial infarction, microglia activation in the brain
Area of Science:
- Neuroscience
- Immunology
- Cardiovascular Science
Background:
- Microglia are central nervous system immune cells that release cytokines upon activation.
- Myocardial infarction (MI) can lead to changes in the central nervous system.
- The hypothalamic paraventricular nucleus (PVN) regulates sympathetic nerve activity.
Purpose of the Study:
- To investigate the temporal profile of microglial activation in the PVN after myocardial infarction in rats.
- To determine if sustained microglial activation contributes to chronic sympathetic hyperactivity post-MI.
Main Methods:
- Rats underwent myocardial infarction or sham surgery.
- Microglial activation in the PVN was assessed using morphological analysis and immunohistochemistry for CD11b (OX-42).
- Echocardiography and hemodynamic measurements evaluated cardiac function.
Main Results:
- No significant microglial activation was observed at 24 hours or 1 week post-MI.
- A significant increase (40-50%) in activated microglia in the PVN was detected 4-16 weeks after MI (P<0.001).
- Myocardial infarction led to significantly reduced left ventricular function.
Conclusions:
- Microglial activation in the PVN following MI is delayed but sustained.
- Sustained microglial activation may contribute to chronic cytokine elevation and sympathetic nerve activity post-MI.
- This suggests a role for neuroinflammation in the long-term cardiovascular consequences of MI.
