A comparison of neuroinflammation to implanted microelectrodes in rat and mouse models.

Rat models have emerged as a common tool to study neuroinflammation to intracortical microelectrodes. While a number of studies have attempted to understand the factors resulting in neuroinflammation using rat models, a complete understanding of key mechanistic pathways remains elusive. Transgenic mouse models, however, could facilitate a deeper understanding of mechanistic pathways due to an ease of genetic alteration. Therefore, the goal of the present study is to compare neuroinflammation following microelectrode implantation between the rat and the mouse model. Our study suggests that subtle differences in the classic neuroinflammatory markers exist between the animal models at both two and sixteen weeks post implantation. Most notably, neuronal densities surrounding microelectrodes were significantly lower in the rat model at two weeks, while similar densities were observed between the animal models at sixteen weeks. Physiological differences between the species and slight alterations in surgical methods are likely key contributors to the observed differences. Moving forward, we propose that differences in the time course of neuroinflammation between the animal models should be considered when trying to understand and prevent intracortical microelectrode failure.