Visual System Pathology Caused by Clironic Cerebral Hypoperfusion: Loss of Pupillary Reflex, Retinal and Optic Nerve Degeneration, and the Role of Light Toxicity by William Dale Stevens A thesis submitted to the Faculty of Graduate Studies and Research in partial filfilment of the requirements for the degree of Master of Science (Specialitation in Neuroscience) Department of Psychology and the Carleton Institute of Neuroscience Carleton University Ottawa, Ontario September, 2000 Q 2000 William Dale Stevens National Library Bibliothèque nationale of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. rua Wellington Ottawa ON K1A ON4 ûüawaON KIAN Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Cana& to Bibliothèque nationale du Canada de reproduce, loan, dismibute or sell reproduire, prêter, distribuer ou copies of this thesis in microfonn, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fkom it Ni la thèse ni des extraits substantiels may be pniited or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. S prague-Dawley rats undenvent permanent bilateral ligation of the common carotid arteries (ZVO)(~63) or sham surgery (n=20). Half of the rats were post- surgically housed in constant darkness, the other half in a standard 12-hour light/dark environment. Rats were sacrificed at 3, 15, and 90 days post-surgery. 2V0 resulted in loss of the pupillary reflex to light in approximately 58% of rats within 7 days post-2VO. Gallyas silver staining revealed ongoing fibre degeneration of the optic nerve (ON) of eyes that lost the reflex (NO-noflex)at 3, 15, and 90 days post-ZVO. Stereoloçy based counting techniques indicated a reduction of cells of the retinal ganglion ceIl layer in 2VO- nofles eyes by 15, and 90 days post-2V0 relative to eyes that retained the reflex (2VO- fles and sham). By 90 days, the NO-noflex eyes showed an absence of Thy-1 immunoreactivity within the retina, and thinning of the inner and outer plexifonn layers. Severe loss of photoreceptors in 2VO-noflex eyes occurred in the light condition ody. It was concluded that 2V0 likely resulted in ischemic damage to the ON, causing loss of pupiliary refi ex and death of retinal ganglion cells in a subset of rats (-58%). Subsequent light toxicity resulted in death of the photoreceptors in these eyes. My first thanks go to my Morn and Dad. Thank you for having always supponed me in everyt hing I have done, in every way I've needed. You have given me the opportunity to follow my dreams, and the means to stnve for the limits of my potential. Thank you for always being there for me. 1 would also like to extend my warmest gratitude to the amazing team of people 1 have been fortunate enough to cal1 my labmates for the last four years. Thanks Maxine for your friendship. Thanks Nicole, for teaching me what you could, for laughing with me, and for being such a bold gambler. And imrneasurable thanks to you Teresa, for teaching me just about everything I needed to know to get here, and for a11 ofyour assistance with this project. 1 never could have done this without you. Most of all, I wodd like to express my deepest respect, gratitude, and admiration for my advisor and mentor, Dr. Bruce Pappas. Thank you for your patience, your generosity, and your confidence in me. The last four years working under you have afforded me the opponunity to explore my ambitions, and gain the expenence 1 needed to take the next step in rny life. 1 move fonvard with the greatest of optirnisrn and anticipation, but 1 wi11 always look back with the fondest of memones. 1 hope one day to be as accomplished a man as you. Thanks Bruce. TABLE OF CONTENTS Title Page .................................................................................................................. i Acceptance Sheet ...................................................................................................... ii a.. a.. Abstract ..................................................................................................................... 111 Acknowledgements .................................................................................................... iv Table of Contents ...................................................................................................... v ... List of Tables .......................................................................................................... VI" List of Figures ........................................................................................................... ix List of Appendices ..................................................................................................... xl List of Abbreviations .................................................................................................. xii Introduction ............................................................................................................... Cerebral Blood Flow and 2V0 ....................................................................... Retinal Blood Flow and 2V0 ......................................................................... Behavioural Effects of 2VO ............................................................................ 2VO and Vision ............................................................................................. 2VO and Retinal Pathology ............................................................................ Pupillary Reflex .............................................................................................. Clinical Relevance of the 3VO Mode1 ............................................................. Sumrnary and Raiionale .................................................................................. Met hods .................................................................................................................... Anirnals .......................................................................................................... Pupillary Reflex .............................................................................................. Groups ........................... .. .......................................................................... Su rge ry .......................................................................................................... Tissue Preparation .......................................................................................... Stereology ...................................................................................................... Thy- 1 ............................................................................................................. Retinal Sublayers ............................................................................................ Optic Nerve ................................................................................................... Results ...................,............................................................................................... Surgery and Pupitlary Reflex ........................................................................ Retinal Ganglion Cell Layer ............................................................................ S tereology .......................................................................................... Thy- 1 .................................... ..... ........................................................ Retinal Sublayer Pathology ............................................................................. Outer Nuclear Layer ........................................................................... Outer Plexiform Layer ........................................................................ Inner Nuclear Layer ............................................................................ Inner Plexifom Layer ......................................................................... Optic Nerve Pathology .................................................................................... Gallyas Silver Stain ............................................................................ 70 GFAP Immunoreactivity ..................................................................... 70 Discussion ................................................................................................................. Pupillary Reflex .............................................................................................. RGCL Pathology ............................................................................................ Retinai Sublayer Pathology ............................................................................. Outer Nuclear Layer .......................... ............................................. Outer Plexiform Layer ........................................................................ Inner Nuclear Layer ............................................................................ Inner Plexiform Layer ......................................................................... Optic