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Mechanisms of neuronal swelling during spreading depolarization

University of British Columbia

Spreading depolarization (SD) is a wave of intense depolarization that propagates within the gray matter of the brain. It is implicated in migraine and acute brain injuries such as stroke, subarachnoid hemorrhage, and trauma. SD is thought to contribute to the expansions of infarct volume in energy compromised brains. Understanding SD and the associated cellular changes will provide basic knowledge to the field of neurophysiology, and will help identify potential therapeutic targets. The experimental methodologies designed to examine SD properties in acutely prepared brain slices are described in Chapter 2. Techniques used in this study involved simultaneous two photon laser scanning microscopy, intrinsic optical signal (IOS) imaging, electrophysiology, pharmacology, and siRNA delivery by lipid nanoparticles (LNP). In Chapter 3, experimental investigations that tested the contribution of neuronal swelling to the IOS changes in SD, as well as the potential role(s) for SLC26A11 chloride channel to neuronal swelling are described. The pharmacological agent GlyH-101 (an inhibitor of SLC26A11 and other chloride channels) reduced neuronal swelling while other properties of SD were unaltered. This suggests that neuronal swelling likely occurs downstream, or in parallel with other cellular processes. Interestingly, the temporal profiles of neuronal swelling and IOS were not correlated, suggesting that other cellular mechanisms generate IOS changes during SD. I also demonstrated that LNP-mediated delivery of siRNA was effective in gene knock-down in vitro but not in vivo. This was further supported by the lack of functional effect during SD in Slc26a11 siRNA treated samples compared to control siRNAs. Finally, I mimicked situations of mild energy failure in brain slices in parallel to SD induction; however, I observed no differences in SD electrical and optical properties compared to control conditions. These data supported the importance of cellular chloride entry in mediating neuronal swelling associated with SD. However, the role for SLC26A11 and the exact molecular mechanism(s) of swelling that are inhibited by GlyH-101 remain unidentified. My data provide insights into the molecular processes during SD, and work towards identifying potential therapeutic targets in neurological disorders associated with SD.

Text

2018-01-19

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/64412

Neuroscience

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/