Meeting Abstract
S9.11 Tuesday, Jan. 6 The Injured Nervous System: a Darwinian Perspective WEIL, Z.M.*; NORMAN, G.; DEVRIES, A.C.; NELSON, R.J.; Ohio State University zacharymweil@gmail.com
Much of the permanent damage that occurs in response to nervous system damage (trauma, ischemia, etc.) is mediated by endogenous secondary processes that can contribute to cell death and tissue damage. For humans to evolve mechanisms to minimize secondary pathophysiology, selection must occur for individuals who survive such insults. Two major factors limit the selection for beneficial responses to CNS insults: for many CNS disease states the principal risk factor is advanced age and virtually all severe CNS traumas are fatal in the absence of medical intervention. An alternative hypothesis for the persistence of apparently maladaptive responses to CNS damage is that the secondary exacerbation of damage is an unavoidable evolutionary constraint. That is, the CNS could not function without the mechanisms that caused secondary damage in response to injury. However, some vertebrates inhabit environments (e.g., hypoxia in underground burrows) that could potentially damage their CNS. Yet, neuroprotective mechanisms have evolved in these animals indicating that natural selection can occur for traits that protect animals from CNS damage. Many of the secondary processes that exacerbate injuries likely persist because they have been adaptive over evolutionary time in the healthy CNS. Therefore, it remains important that researchers consider the role of these processes in the healthy CNS to understand how they become dysregulated following injury. For instance, death from cardiovascular disease in humans peaks during the winter. Siberian hamsters housed in short day lengths (simulating winter) are more prone to hippocampal cell death than hamsters housed in long days after experimental ischemia. Proinflammatory cytokine expression is elevated following cardiac arrest in short- but not long-day, hamsters suggesting that there is a tremendous opportunity to investigate human disease patterns in a comparative context.
