Assessment of Neuroinflammation in Cognitive and Motor Brain Regions in Female Rats Exposed to Chronic Intermittent Hypoxia




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Sleep apnea increases the risk of neurodegenerative disorders in postmenopausal women. In this study, we tested whether chronic intermittent hypoxia (CIH), a preclinical model of sleep apnea-associated cyclical hypoxia, can be used to identify early changes in the brain that might contribute to impair neurological function in intact (INT) and ovariectomized (OVX) female rats. To test this hypothesis, we conducted immunohistochemistry studies using markers for glial activation and neuroinflammation. We hypothesize that CIH will increase glial activation in ovariectomized (OVX) relative to intact (INT) female rats.

Adult female Sprague Dawley INT (n=4) or OVX (n=4) rats that were part of a larger study and underwent 7 days of CIH (10% O2 and 21% O2 cycle, every 6 mins, 8h/day during the light phase) or continuous normoxia (CON) were euthanized on day 8, and their brains were collected. Brains were processed for microglia (IBA1) and astrocytes (GFAP) activation markers in (CA1) hippocampus, medial prefrontal cortex (mPFC), and caudate putamen (CP) striatum.

Confocal images from each region are being used to optimize a fractal analysis protocol to test for changes in glial morphology. Raw images will be linearly processed in Huygens Essentials software to limit noise and optimize quality for further analysis in ImageJ. Skeletal and fractal analyses will be performed on randomly selected cells in the photomicrographs to determine cell ramification (branching, junctions, endpoint voxels, branch lengths) and complexity (fractal dimension, cell span ratio, density) to complement cell counts of immunohistochemical markers of activation.

Our preliminary analysis has allowed us to determine the appropriate parameters needed for image capture and subsequent analysis. We have observed some possible qualitative changes indicative of increased activation in the CA1, CP, and mPFC regions following CIH in OVX rats relative to intact rats. The results of this study aim to contribute to our understanding of the potential impact of CIH in female rats of differing ovarian function, providing insights into sleep apnea-associated CNS dysfunction in women.


Research Appreciation Day Award Winner - School of Biomedical Sciences, 2024 Department of Physiology & Anatomy (Integrative Physiology) Award - 2nd Place