The vagus nerve plays a crucial role in the development of the brain, and its efferent and afferent effects have been studied to understand their impact on microglial plasticity. In this study, researchers used the sheep model of human fetal development to investigate the effect of vagotomy on microglial phenotype. They found that vagotomy alters microglial phenotype and that this effect is hormetic under conditions of mild systemic inflammation, such as chorioamnionitis. The team also presented a methodology for assessing both biomarker-based microglial activation and morphometric features of the microglia, providing a more comprehensive toolbox for investigating locoregional vagal control of glial function. The findings support earlier discoveries in preclinical and clinical models of adult physiology where vagotomy appeared neuroprotective for Parkinson's disease, explained by its effects on microglia. Additionally, the team presented an approach to measure regional cerebral blood flow changes in relation to vagus nerve manipulation. The body of evidence underscores the importance of both efferent and afferent pathways via the vagus nerve in programming microglial phenotype in developing brains. Following animal experimentation, fetal brain tissue samples were taken from various regions for fluorescence analysis. The researchers analyzed all cortical and subcortical regions together before calculating group averages. Statistical analysis was performed using Graphpad Prism 9.4.1 software with unpaired nonparametric T-tests used to compare differences between experimental groups. The results showed that systemic inflammation caused by LPS had an impact on cytokine levels while accounting for repeated measurements on fetal rCBF using generalized estimating equations modeling. The study also reported that not all measurements were obtained in each animal, which was explicitly stated when sample sizes were affected. In summary, this study provides new insights into how the vagus nerve impacts microglial plasticity during fetal development and highlights potential implications for early susceptibility to neuroinflammatory and neurodegenerative disorders in later life. The presented methodology for assessing microglial activation and morphometric features of the microglia provides a more comprehensive toolbox for investigating locoregional vagal control of glial function. Further studies are needed to fully understand these relationships and their potential implications for developing treatments against neurodegenerative disorders.
The vagus nerve is important for brain development and can affect microglial plasticity. Microglia are cells in the brain that help protect it. Vagotomy, which is a surgery to cut the vagus nerve, can change how microglia look and act. This surgery may help protect against Parkinson's disease by affecting microglia. Scientists can measure changes in blood flow in the brain when manipulating the vagus nerve. The study found that the vagus nerve affects how microglia develop before birth, which could impact later health problems like Alzheimer's disease. More research is needed to fully understand these relationships and how they could be used to treat brain diseases."
Definitions
- Vagus nerve: A long nerve that connects the brain to many different parts of the body.
- Microglial plasticity: The ability of microglia cells in the brain to change their shape and function.
- Hormetic: A term used to describe a positive response to a low dose of something that would normally be harmful at higher doses.
- Biomarker-based: Using specific markers or indicators in the body to measure changes or responses.
- Neuroprotective: Something that helps protect or prevent damage to the nervous system.
- Parkinson's disease: A disorder of the nervous system that causes tremors, stiffness, and difficulty with movement.
- Cerebral blood flow: The amount of blood flowing through the brain at any given time.
- Neuroinflammatory: Inflammation (swelling
Vagus Nerve and Microglial Plasticity During Fetal Development
The vagus nerve plays a crucial role in the development of the brain, and its efferent and afferent effects have been studied to understand their impact on microglial plasticity. In this study, researchers used the sheep model of human fetal development to investigate the effect of vagotomy on microglial phenotype. The team presented an approach to measure regional cerebral blood flow changes in relation to vagus nerve manipulation. Additionally, they provided a methodology for assessing both biomarker-based microglial activation and morphometric features of the microglia, providing a more comprehensive toolbox for investigating locoregional vagal control of glial function.
Experimental Design
The experiment was conducted using sheep fetuses at different gestational ages (GA). The animals were divided into two groups: one with sham surgery (control) and another with bilateral transection of the cervical vagus nerves (vagotomy). Following animal experimentation, fetal brain tissue samples were taken from various regions for fluorescence analysis. The researchers analyzed all cortical and subcortical regions together before calculating group averages. Statistical analysis was performed using Graphpad Prism 9.4.1 software with unpaired nonparametric T-tests used to compare differences between experimental groups.
Results
The results showed that systemic inflammation caused by LPS had an impact on cytokine levels while accounting for repeated measurements on fetal rCBF using generalized estimating equations modeling. Vagotomy altered microglial phenotype under conditions of mild systemic inflammation such as chorioamnionitis; this effect was hormetic in nature—meaning it had protective qualities against neurodegenerative disorders like Parkinson's disease due to its effects on microglia activity within developing brains. However, not all measurements were obtained in each animal; sample sizes were affected when this occurred but it was explicitly stated when reporting results from each group average calculation or comparison test statistic value reported by Graphpad Prism 9.4.1 software’s unpaired nonparametric T-test calculations
Conclusion
In summary, this study provides new insights into how the vagus nerve impacts microglial plasticity during fetal development and highlights potential implications for early susceptibility to neuroinflammatory and neurodegenerative disorders in later life. The body of evidence underscores the importance of both efferent and afferent pathways via the vagus nerve in programming microglial phenotype in developing brains as well as presenting an approach to measure regional cerebral blood flow changes related to these manipulations . Further studies are needed to fully understand these relationships and their potential implications for developing treatments against neurodegenerative disorders
The efferent and afferent effects of the vagus nerve on the developing brain have remained enigmatic. Here we review the evidence of such effects on microglial plasticity in the sheep model of human fetal development, one of the most recognized and deployed models of human fetal physiology. We show that vagotomy alters microglial phenotype and that this effect is hormetic under conditions of mild systemic inflammation, as may occur antepartum with chorioamnionitis. We present the methodology to assess not only biomarker-based microglial activation but also the morphometric features of the microglia. Together, these assessments provide a more comprehensive toolbox of glial phenotypical characterizations, especially in the context of investigating the locoregional vagal control of glial function. The presented findings support the earlier discoveries in preclinical and clinical models of adult physiology whereby vagotomy appeared neuroprotective for Parkinson disease, explained, at least in part, by the effects on microglia. In addition, we present the approach to measure and the findings on regional cerebral blood flow changes in relation to vagus nerve manipulation. In summary, the body of evidence underscores the importance of both the efferent and the afferent vagal pathways, via the vagus nerve, in the programming of microglial phenotype in the developing brain. The significance of these relationships for developing and treating early susceptibility to neuroinflammatory and neurodegenerative disorders in later life requires further studies.
