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Commissural Projections of the Nuclei of the Lateral Lemniscus and Keuronal Degeneration Following Midline Transections in the Adult Rat By

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Commissural Projections of the Nuclei of the Lateral Lemniscus and Keuronal Degeneration Following Midline Transections in the Adult Rat By Commissural Projections of the Nuclei of the Lateral Lemniscus and Keuronal Degeneration Following Midline Transections in the Adult Rat by Brian Anthony van Adel B .Sc. (Hons) Carleton University, 1995 A thesis subrnitted to the faculty of Graduate Studies and Research in partial fulnllment of the requirements of the degree of Master of Science Specialization in Neuroscience Deparûnent of Biology Ottawa-Carleton Institutes of Biology and Neuroscience Carleton University Ottawa, Ontano May, 1998 O copyright 1998, Brian Anthony van Adel National Library Bibliothèque nationale 1+1 .,nad, du Canada Acquisitions and Acquisitions et Bibliographie Services seMces bibliographiques 395 Wellington Street 395, rue Wellington OttawaON KtAW ûuawaON KtAON4 canada CaMda The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, 10- disûiiute or sen reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette these sous paper or electronic formats. la forme de microfiche/fïlm, 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 fiom it Ni la thèse ni des extraits substantiels may be printed or otheMrise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. ABSTRACT The normal neuroanatomical organization of the rat's nuclei of the lateral lemniscus (nLL) was investigated (Experiment 1) as a prerequisite for a time course analysis of retrograde changes in commissural projec~glemniscd neurons following midline surgical transection of their axons (Expriment 2). In ExpeRment 1, conventional neuroanatomical nct tracing techniques were employed to determine the efferent and afferent projections of the nLL. The results suggest that in the rat the nuclei of the lateral Iemniscus (nLL) cm be divided into three distinct ceiI groups (DU,WLL, and VNLL) based on the differential patterns of innemation each receives from auditory brainstem nuclei. Of the three lemniscal nuclei, only the DNLL receives bilateral inputs from lower auditory nuclei. Furthemore, it is the only nucleus within the LL that projects bilaterally to the ICC and to the opposite LL through the commissure of Probst (CP). In Experiment 2, the anatomical consequence of surgical tansection of the commissure of Probst was investigated. Responses to injury were investigated for survival times ranging from 1 day to 12 weeks after complete CP transection. Transection of the CP completely eliminated the transport of Ruorogold (FG) from the central nucleus of the inferior colliculus (ICC)to the opposite DNLL. and blocked the anteropde transport of biocinylated dextran (BD) to both contralateral DNLL and ICC. Axotomized DNLL neurons prelabeled with FG appeared normal 2 weeks post-transection, but by 4 weeks a significant loss of FG-prelabeled contralaterally projecting DNLL neurons was observed. Some fluorescent labehg was observed in animals that survived for 4 weeks or longer, but this was attributed to rnicrogha which sequestered FG via phagocytosis. Ceil counts of FG-prelabeled neurons in the DNLL indicated that no contralateraily projecting neurons suniived CP uansection. Immunoreactive astrocytes were labeled with anti-GFAP, reveahg a pattern of anisomorphic fibrous gliosis at the wound site, dong the CP and bilaterally in DU.These results suggest that transection of the CP is a valuable in vivo mode1 of neuronal degeneration and time-dependent responses to traumatic brain injury. ACKNOWLEDGEMENTS 1would like to thank my supervisor, Dr. Jack B. Kelly for his excellence in guiding me through ail aspects of my research and academic studies. In addition, 1 would also like thank Dr. M. Tenniswwd for aIlowing me to carry out a portion of my snidies in his laboratory and for the input into this research, and Dr. J.J. Cheetham for many thought provoking conversations. Cheng Huang for ail the help with the electron microscopy work involved in this thesis. Adam Baker and Cheng Huang for aU the help preparing many of the photographic figures presented in this thesis. 1 also wish to thank the members of our laboratory, and support staff in Life Sciences Research Building (LSRB)who have made my studies enjoyable and rewarding; and Dr. Makoto Ito kom Kanazawa, Japan, who refined my neuroanatomical techniques and more importantly, for his fiiendship; Christine McGregor, Patrice Jacobson and Teresa Fortin for their excellent assistance in histology for making the lab seem so friendly and cheerful. In addition, 1 would like to thank the following people: Heather iMcNeely, my siblings, my mom and grandparents, Sean Kidd, Rose Labelle, Colm Momssey, Chns Davidson, Yves Bureau, Liang Li, Jeder Arnold, Heather Lemox. Jim Carleton, the fobat Vittoria's on Bank Street, and every single person who has been through the LSRB since my fint day - 1have gained insight (scientific or otherwise) from each of you. Many thanks to aIl the Columbi of the world. 1 now realize that exploring new territory inevitably evokes the Columbus response: shaking heads and muttering as you disappear over the horizon and a hero's welcome when (if)you rem. Thanks are also extended to Graduate Studies at Carleton University for hancial support of my M.Sc. snidies. In memory of Raymond J. van Adel. Thanks for teaching me how to fly Grandpa. TABLE OF CONTENTS Page Title Page Acceptance sheet Abs trac t Achow ledgments Table of Contents List of abbreviations List of Figures List of Tables List of Appendices Chapter 1 Introduction Chapter 2 Neuroanatomical investigation of the nuclei of the lateral lemniscus: a search for subdivisions and commissural projections using anterograde and retrograde tract tracing techniques in the addt rat, norvegicw (Experiment 1) Chapter 3 Neuronal degeneration in the dorsal nucleus of the lateral lemniscus after surgical msection of the commissure of Robst in the adult rat, Rattus norvegicw (Experiment 2) General Conclusions Appendix 1 Surgical procedure for transection of the commissure of Probst Appendix 2 Publication List References LIST OF ABBREVlATIONS MA a-amino-3-hydroxy-5-methyl4isoxazolepr~pio~c CAMP adenosine 3'.5',-cyclic monophosphate 4 aqueduct (cerebral) ATP Adenosine triphosphate AVCN anterovend cochlear nucleus BBB blood-brain barrier\ BC brachium conjunctim BD biotinylated dextran BK brachium of the infenor colliculus C condateral cic commissure of the inferior collicuius CN cochlear nucleus CP commissure of Probst DNLL dorsal nucleus of the Iateral lemniscus DCIC dorsal cortex of the inferior colliculus Dm dorsal cochlear nucleus ECIC extemal cortex of the inferior colliculus EE (EE/F) binaural response type - ceil excited by stimulation of either ear alone. EEA excitatory amino acids EEACI excitatory amino acid transporter EI (Em bina4 response srpe - ceil excited by condaterd stimulation and inhibited by ipsilateral stimulation. EO (EOIO) binad response type - cell excited by conualateral sumulation and ipsilateral stimulation has no effect. FI3 Fast Blue FG Fluoro-Gold FR Fluoro-Ruby GABA y-gamma-aminobut~cacid GAD glutamic acid decarboxylase GFAP glial fibrillary acid protein GS glutamine synthetase GLAST glutamate asmxyte specific transporter GLT-1 glutamate transporter vii H202 hydrogen peroxide HRP honeradish peroxidase 1 ipsilateral IC inferior colliculus ICC central nucleus of the idenor colliculus IID interaural intensity difference INLL intermediate nucleus of the lateral lemniscus ITD interaural time difference KYNA kynurenic acid LL lateral lemniscus LSO lateral superior olivary nucleus MGB medial geniculate body MLF medial longitudinal fasciculus MSO medial superior olivary nucleus nLL nuclei of the lateral lemniscus NMDA N -methyl-D-aspartic acid NO nitric oxide riru-os neuronal NOS NOS NO synthase 02- superoxide radical ON00 peroxynitrate PARS poly (ADP-ribose) synthase PCD programmeci cell death PL paralemniscal zone PS phosphatidylserine PVCN posteroventral cochlear nucleus sag saguium SC superior colliculus SOC superior olivary nucleus SfN superior paraolivary nucleus trapezoid body ventral nucleus of the lateral lemniscus ventral nucleus of the trapezoid body LIST OF FIGURES Figure Page 2.1 A schernatic illustration of the anteropde and retrograde 46 tract ~ingprocedures used for each experimental group fiom Experiment 1. Cresyl violet shedcoronal section through the rat's ICC, 18 nLL and sumounding structures. Anterograde labehg in a normal animal afier a unilateral 50 injection of BD into the left ICC. hterograde labeling in a normal animal after a unilateral 52 injection of BD into the left DNLL. The extent of efferent fibers contained within the 54 commissure of Probst after an injection of BD into the right DNLL of a normal animal. The pattern of retrograde labellhg in a normal animal afier 56 a unilateral injection of FG into the left ICC. Low power photomicrographs of the rostral-to-caudai 58 extent of retrograde labeling, bilaterally in the ILL after a unilateral injection of FG into the left ICC of a nomial animal. Low power photornicrographs of the rostral-tocaudal 60 extent of retrograde labeling in the ipsilateral nLL after a unilateral injection of FG into the left ICC. Percentage of ipsilaterally and contralaterally labeled DNLL
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