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Temporal Resolution and Determination of the Mechanism of Ethanol-Induced Taurine Efflux

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Temporal Resolution and Determination of the Mechanism of Ethanol-Induced Taurine Efflux TEMPORAL RESOLUTION AND DETERMINATION OF THE MECHANISM OF ETHANOL-INDUCED TAURINE EFFLUX By ANTHONY DONALD SMITH A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2005 Copyright 2005 by Anthony Donald Smith ACKNOWLEDGMENTS The first person I would like to thank would be Dr. Joanna Peris. Her scientific wisdom, unique perspective on life and enjoyable demeanor has made this journey a very smooth one. She has exposed me to many very interesting ideas and people and I simply cannot thank her enough. I would like to thank my supervisory committee for their ideas, suggestions and (occasionally) lab equipment: Drs. Michael King, William Millard, Michael Meldrum and Maureen Keller-Wood. I would also like to thank Dr. Robert Kennedy and his lab for all their help, materials and lab space at the University of Michigan. I would also like to thank Dr. Bärbel Eppler for help/advice throughout the years. I would like to thank the late Dr. Ralph Dawson. He was a great scientist and an expert in the taurine field and I appreciated his input into my experiments. He was the first to congratulate me when I passed my qualifiers and I regret that he is not here to congratulate me now. His advice and expertise will be greatly missed as well as his wit. Most importantly I thank my parents for all of their love and support. iii TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iii LIST OF FIGURES ......................................................................................................... viii ABSTRACT....................................................................................................................... xi 1 LITERATURE REVIEW .............................................................................................1 Alcoholism....................................................................................................................1 Addiction ......................................................................................................................1 The Neuronal Effects of Ethanol ..................................................................................3 The Biochemistry of Taurine........................................................................................7 Taurine Synthesis ..................................................................................................8 Taurine Transport ..................................................................................................8 Taurine as a Neuromodulator .....................................................................................10 Taurine and GABA..............................................................................................10 Taurine and Glutamate ........................................................................................11 Taurine and Dopamine ........................................................................................11 Taurine as an Osmolyte ..............................................................................................12 The Mechanism of Taurine Release ...........................................................................13 Taurine Release Due to Neurotransmission ........................................................14 Taurine Release Due to Osmoregulation.............................................................16 Microdialysis and CE-LIF ..........................................................................................19 Summary.....................................................................................................................21 Objectives ...................................................................................................................22 2 GENERAL METHODS..............................................................................................25 Animals.......................................................................................................................25 Chemicals ...................................................................................................................25 Surgeries for CHAPTER 3 .........................................................................................26 Microdialysis for CHAPTER 3 ..................................................................................26 Microdialysis and Surgeries for Anesthetized Rats....................................................27 Microdialysis and Surgeries for Freely-moving Animals in CHAPTER 4 ................28 CE-LIF for CHAPTER 3............................................................................................29 CE-LIF for CHAPTER 4............................................................................................32 Flow-gated Interface and CE System .........................................................................36 iv Neurotransmitter Derivatization .................................................................................36 Laser-induced Fluorescence Detection System..........................................................37 HPLC ..........................................................................................................................38 Dialysate Ethanol Determinations ..............................................................................40 Histology.....................................................................................................................40 Data Analysis..............................................................................................................40 3 DIFFERENTIAL INCREASE IN TAURINE LEVELS BY LOW DOSE ETHANOL IN THE NUCLEUS ACCUMBENS AND CAUDATE-PUTAMEN REVEALED BY MICRODIALYSIS WITH ON-LINE CAPILLARY ELECTROPHORESIS ....42 Introduction.................................................................................................................42 Methods ......................................................................................................................44 Animals................................................................................................................44 Chemicals ............................................................................................................45 Surgeries..............................................................................................................45 Microdialysis .......................................................................................................45 CE-LIF.................................................................................................................47 HPLC...................................................................................................................48 Dialysate Ethanol Determinations.......................................................................49 Data Analysis.......................................................................................................49 Results.........................................................................................................................50 Ethanol-induced Taurine Efflux ..........................................................................50 Ethanol-induced Glutamate Efflux......................................................................51 Ethanol-induced Glycine Efflux..........................................................................54 Ethanol-induced Serine Efflux ............................................................................56 Basal Efflux.........................................................................................................58 Ethanol-induced Taurine Efflux Measured by HPLC .........................................60 Ethanol-levels in Dialysate..................................................................................60 Direct Perfusion of Ethanol.................................................................................63 Discussion...................................................................................................................65 4 ETHANOL-INDUCED TAURINE EFFLUX IN THE NUCLEUS ACCUMBENS IS MEDIATED VIA CALCIUM-DEPENDENT OSMOTICALLY ACTIVATED CHANNELS...............................................................................................................73 Introduction.................................................................................................................73 Methods ......................................................................................................................76 Animals................................................................................................................76 Chemicals ............................................................................................................76 Neurotransmitter Derivatization..........................................................................77 Flow-gated Interface and CE System..................................................................77 Laser-induced Fluorescence Detection System...................................................78 Microdialysis and Surgeries for Anesthetized Rats.............................................79 Microdialysis and Surgeries for Freely-moving Animals ...................................80 v Results.........................................................................................................................81
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