METHODS TO QUANTIFY DIVERSE MICROGLIA MORPHOLOGIES IN THE HEALTHY AND INJURED BRAIN

Abstract

Microglia have a measurable morphologic response to injury, reflecting their cell function as well as the health-status of the cells in their micro-domains. We postulate that microglia morphology could be a biomarker of brain physiology/pathophysiology. Early Infantile Epileptic Encephalopathy was modeled using SCN8a mutated mice where the gain of function in neuronal sodium channels leads to neuronal hyperexcitability and intractable seizures. We aim to determine the usefulness of computer-aided methods to quantify microglia morphologies in the epileptic brain. We hypothesize that 1) microglia morphology in the CA1 and entorhinal regions are significantly different among SCN8a wild-type, heterozygous and mutant mice and 2) that increases in microglia ramification will correlate to increases in seizure activity. TALEN SCN8atm1768DMm mice were observed for epileptic seizures, euthanized at 20-days and brain tissue was collected. Microglia ramified morphology and complexity were quantified from photomicrographs imaged from brain regions after immunohistochemistry. ImageJ was used to quantify cell ramification, complexity and shape. Our data shows that microglia morphology and size are different among mice at post-natal day 20 in the hippocampal and entorhinal regions, but is inconclusive due to sample size. We present simple and highly-sensitive computer-aided methodologies useful in quantifying microglia morphologies in the healthy and injured brain.