Effect of repeated MDMA exposure on rat brain and behaviour by Ross van de Wetering A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Victoria University of Wellington, New Zealand 2020 Table of contents Absract ........................................................................................................................... 5 List of abbreviations ...................................................................................................... 7 CHAPTER 1: GENERAL INTRODUCTION ............................................................ 10 Introduction ........................................................................................................................ 10 Behavioural fundamentals of addiction ........................................................................... 12 Studying addiction ........................................................................................................... 13 Self-administration. ...................................................................................................... 14 Behavioural sensitisation. ............................................................................................ 18 Neurocircuitry of addiction ............................................................................................... 20 Ventral tegmental area and nucleus accumbens .............................................................. 20 Dopamine and reinforcement. ...................................................................................... 20 Dopamine and incentive motivation. ........................................................................... 22 Amygdala ......................................................................................................................... 26 Dorsal striatum ................................................................................................................. 27 Prefrontal cortex............................................................................................................... 29 MDMA ................................................................................................................................ 31 MDMA/ecstasy use disorders .......................................................................................... 31 MDMA self-administration ............................................................................................. 32 Pharmacology of MDMA ................................................................................................ 33 Role of serotonin in self-administration .......................................................................... 35 Effect of repeated MDMA exposure on serotonin and dopamine ................................... 37 Serotonin, dopamine, and MDMA self-administration ................................................... 39 The current thesis .............................................................................................................. 40 ∆FosB and immunohistochemistry .................................................................................. 40 Microdialysis and LC-MS................................................................................................ 45 Aims and objectives ......................................................................................................... 51 CHAPTER 2: ∆FOSB AND IMMUNOHISTOCHEMISTRY ................................... 52 Introduction ........................................................................................................................ 52 Methods ............................................................................................................................... 53 Subjects ............................................................................................................................ 53 Surgical procedures .......................................................................................................... 53 Apparatus ......................................................................................................................... 53 2 Self-administration ........................................................................................................... 54 FosB-like immunohistochemistry .................................................................................... 54 Statistical analysis ............................................................................................................ 57 Results ................................................................................................................................. 57 Discussion ............................................................................................................................ 66 CHAPTER 3: LOCAL MDMA INFUSION ............................................................... 71 Introduction ........................................................................................................................ 71 Methods ............................................................................................................................... 72 Subjects ............................................................................................................................ 72 Surgical procedures .......................................................................................................... 72 Apparatus ......................................................................................................................... 73 Drugs ................................................................................................................................ 73 Pretreatment and intra-striatal microinjections ................................................................ 73 Statistical analysis ............................................................................................................ 75 Results ................................................................................................................................. 76 Discussion ............................................................................................................................ 80 CHAPTER 4: MICRODIALYSIS AND LC-MS ........................................................ 82 Introduction ........................................................................................................................ 82 Methods 1 ............................................................................................................................ 84 Subjects ............................................................................................................................ 84 Drugs and reagents ........................................................................................................... 84 Surgical procedures .......................................................................................................... 85 Microdialysis.................................................................................................................... 85 LC-MS ............................................................................................................................. 85 Data analysis .................................................................................................................... 86 Results 1 .............................................................................................................................. 86 Method development 1 ...................................................................................................... 89 Chromatography gradient ................................................................................................ 89 BzCl concentration........................................................................................................... 89 Probe implantation ........................................................................................................... 93 Method 2 ............................................................................................................................. 94 Results 2 .............................................................................................................................. 94 3 Method development 2 ...................................................................................................... 95 BzCl concentration........................................................................................................... 95 LC-MS injection volume ............................................................................................... 100 Microdialysis.................................................................................................................. 100 Quantification of MDMA .............................................................................................. 103 Methods 3 .......................................................................................................................... 104 MDMA pretreatment and locomotor sensitisation ........................................................ 104 Statistical analysis .......................................................................................................... 104 Results 3 ............................................................................................................................ 105 Discussion 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