The Dopaminergic Innervation Of The Brain Stem And Spinal Cord An Anatomical Study On The Distribution Of The Neurotransmitter Dopamine And Its D2 Receptor. This study was carried out at the Department of Anatomy of the Erasmus University of Rotterdam, The Netherlands (Head Prof. Dr. J. Voogd). Financial support by NEN-Dupont for the publication of this thesis is gratefully acknowledged. The Dopaminergic Innervation Of The Brain Stem And Spinal Cord An Anatomical Study On The Distribution Of The Neurotransmitter Dopamine And Its D2 Receptor De dopaminerge innervatie van de hersenstam en ruggenmerg Een anatomische studie naar de verdeling van de neurotransmitter dopamine en zijn D2 receptor PROEFSCHRIFf ter verkrijging van de graad van doctor aan de Erasmus Universiteit Rotterdam op gezag van de Rector Magnificus Prof. Dr. P.W.c. Akkermans MA en volgens besluit van het College voor Promoties. De openbare verdediging zal plaatsvinden op donderdag 8 juni 2000 om 13.30 UUf. door Hendrik van Dijken geboren te Emmen Promotiecommissie Promotor Prof. Dr. J. Voogd Overige leden Dr. J.C. Holstege (tevens co-promotor) Prof. Dr. P.G.M. Luiten Dr.P. Voom Prof. Dr. c,r. de Zeeuw Contents Chapter I General Introduction 7 Anatomy of the spinal cord and brain stem 9 Anatomy of the spinal cord 9 Anatomy of the brain stem 14 Chemical anatomy of the central nervous system 16 Monoaminergic transmitters and their receptors 17 Scope ofthe present study 22 Chapterll The Distribution Of Dopamine Immunoreactivity In The Rat, Cat And Monkey Spinal Cord 25 Chapter ill Localization Of Dopamine D2 Receptor In Rat Spinal Cord Identified With Immunocyto­ 47 chemistry And In Situ Hybridization Chapter IV The Distribution Of Dopamine Immunoreactive Fibers And Presumptive Terminals In The 57 Rat Brain Stem. A Comparison With The Distribution Of Dopamine-B-Hydroxylase. Chapter V Distribution Of Dopamine D2 Receptor In The Rat Brain Stem Using Anti-Peptide 83 Antibodies Chapter VI Summary and General Discussion 97 Summary 99 General Discussion 100 Introduction 100 Methodological aspects 100 The anatomical distribution of dopamine and its receptors: the mismatch problem 102 The origin of the dopaminergicjibers in spinal cord and brainstem (the AIl cell group) 103 The relation of dopamine with other monoamines and glutamate 104 The functional role of dopamine in spinal cord and brainstem 105 Conclusions 107 Sarnenvatting 113 Abbreviations 117 References 119 List of publications 132 Nawoord 133 Curriculum Vitae 134 Chapter I General Introduction 7 8 General Introduction Until the first half of the 19"' century, the anatomy of and contains the motor nuclei innervating the muscles the nervous system was studied mainly by means of of the face, eyes, and the cranial parasympathetic macroscopic methods, like dissection, while system. In addition, much of the specialized sensory microscopy was hampered by the lack of adequate information originating from the cochlea and vestibular staining techniques. However, when reliable fixation labyrinth, the eyes, the taste buds, the cardiovascular, and staining techniques (like the Weigert and Golgi respiratory, and digestive systems directly reaches the stains and the silver impregnation technique for brain stem, where it is further processed. Both the brain degenerating fibers) became available, the knowledge stem and spinal cord have a dual function: on the one of the nervous system rapidly increased. Since then a hand they distribute afferent sensory information to multitude of new research methods employed by an higher centers, thereby detennining levels of arousal, ever increasing number of scientists involved in and execute the motor commands from these higher studying the nervous system, have led to a rapid centers, while on the other hand they are capable of progress in our knowledge and - to some extent - our independently organizing and executing a basic motor understanding of the nervous system. response on the basis of afferent sensory information. The classical anatomical studies and especially the findings of Ramon y Cajal (1909), the great advocate of Anatomy of the spinal cord the neuron theory, have laid the foundation of our The spinal cord represents the most caudal part of the present knowledge of the nervous system. central nervous system. It is located within the canal of Cytoarchitectonic studies of this period, made a big the vertebral column surrounded by cerebrospinal fluid. impact on neuroscience and served as the basis of the During its embryonic development there is surprisingly nomenclature of the central nervous system as it is still little change in the internal anatomical organization of used today. Data on the chemical identity and the the spinal cord. Its peripheral nerve fibers are grouped specific function of (groups of) nerve cells became into segmental spinal nerves that emerge from the available more recently. Often the data complemented, vertebral canal between the individual vertebrae. As a but sometimes it conflicted with, the cytoarchitecture result, the rat spinal cord is subdivided into 8 cervical based subdivisions of the brain. This induced the (CI-C8), 13 thoracic (Thl-Th13), 6 lumbar (Ll-L6), 4 introduction of alternative nomenclatures, not based on sacral (S I-S4) and 3 coccygeal segments. In the center cytoarchitecture, but on pharmacological or functional of the spinal cord lies the central canal, which is a characteristics. This thesis, which describes an remnant of the space within the primitive neural tube. anatomical study of the dopamine innervation of the The spinal cord is bilaterally symmetrical. It consists of brain stem and spinal cord and one of the receptors a centrally located gray matter, which is characterized involved, i.e. of a chemically identified system by a large number of neuronal cell bodies, and is characterized by containing the transmitter dopamine, surrounded by white matter, which is characterized by a reflects some of these great changes, which transformed large nwnber of nerve fibers. Sensory information from classical neuroanatomy into a dynamic, functional the skin, joints, muscles and, to some extent, the viscera science. In this chapter the subject will be introduced by of the trunk and limbs enters the spinal cord by way of a short description of the anatomy of the spinal cord and the dorsal roots. The motoneurons in the spinal cord the brainstem, followed by a description of the chemical constitute the final common pathway for issuing anatomy of the nervous system, with the main emphasis commands for muscle contraction by way of the ventral on the doparninergic system and its receptors. roots. In the spinal cord there is an orderly arrangement Subsequently, we will provide insight into the scope of of the sensory and motor nuclei controlling the limbs this thesis. and trunk. ill addition, the spinal cord contains various ascending pathways, that convey sensory information Anatomy of the spinal cord and brain stem towards the brain, and descending pathways which The central nervous system is composed of the spinal originate in higher parts of the brain and terminate cord, the brain stem (which consists of the within the spinal cord. myelencephalon, the metencephalon and the mesencephalon) and the forebrain (cerebrum, which The spinal gray matter The spinal gray matter, in cross section, is more or less consists of the telencephalon and diencephalon). The butterfly-shaped. The dorsal protrusions on each side spinal cord, the most caudal part of the central nervous are known as dorsal horns and the ventral protusions as system, receives sensory information from the entire the ventral horns. The area in between the ventral and body below the face, by way of the dorsal divisions (the dorsal horns, where the left and right side of the spinal dorsal roots) of the spinal nerves, and activates muscle cord are interconnected, is termed the intermediate fibers as part of a motor command for reflex or zone. Based on cytoarchitectonic criteria, first presented voluntary movement, by way of the ventral divisions by Rexed in cat (1952, 1954), the gray matter can be (the ventral roots) of the spinal nerves. The brain stem further subdivided into ten different cell layers or is a complex rostral continuation of the spinal cord and lantinae, numbered I to IX from dorsal to ventral, with contains several collections of cell bodies, among which lamina X representing the area that surrounds the the cranial nerve nuclei. Similar to the spinal cord, the central canal (fig. I). brain stem receives sensory infonnation from the face, 9 Chapter One C4 C7 Th3 L5 L6 81 Figure 1: Diagrams of cross-sections of the spinal cord at cervical (C), thoracic (Th), lumbar (L) and sacral (8) levels. CeC, central cervical nucleus; LCN, lateral cervical nucleus; PHR, phrenic nucleus; 0, dorsal nucleus (Clarke); IML, intermediolateral cell column; CRE, cremaster nucleus; OM, dorsomedial motor nucleus (8NB, spinal nucleus of the bulbocavernosus); VE, ventral motor nucleus; DL, dorsolateral nucleus; numerals I-X show the layers of Rexed. In the classical nomenclature, lamina I is known as and the underlying gray matter of the dorsal horn. the marginal zone, lamina II as the substantia Lamina I contains many relatively small neurons of gelatinosa. laminae III and IV as the nucleus proprius, various types as well as large horizontal neurons (the laminae V-VI as the base of the dorsal hom, laminae marginal cells ofWaldeyer), which are relatively sparse VII and VIII as the intermediate