[...]... here Neurotransmitters, Drugs and Brain Function Edited by R A Webster &2001 John Wiley & Sons Ltd 4 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION CHEMICAL TRANSMISSION We might start by considering what we understand by the term `neurotransmitter' According to the Oxford English Dictionary (2nd edition) it is: A substance which is released at the end of a nerve fibre by the arrival of a nerve impulse and. .. Zolmitriptan 458 Zolpidem 405, 496 Zonisamide 348 Zopiclone 405, 496 Neurotransmitters, Drugs and Brain Function Edited by Roy Webster Copyright & 2001 John Wiley & Sons Ltd ISBN: Hardback 0-471-97819-1 Paperback 0-471-98586-4 Electronic 0-470-84657-7 Section A BASIC ASPECTS OF NEUROTRANSMITTER FUNCTION Neurotransmitters, Drugs and Brain Function Edited by Roy Webster Copyright & 2001 John Wiley & Sons... biological function Ð becomes ever harder to understand and predict The system is reduced to its elements, but it is not clear how to integrate it again Yet this is the ultimate functional goal (Brezina and Weiss 1997) The molecules referred to are the neurotransmitters (NTs) and their receptors, found in the brain; the biological function is the activity of the brain itself Our understanding of that... understand how neurotransmitters may be involved in brain function and more particularly how their activity is modified by disease and drugs As the above quotation implies, this will mean considering the synaptic characteristics of each neurotransmitter, but before we do so, it is important to consider some more general and basic aspects of neurotransmitter function Thus: What is a neurotransmitter and. .. narrower, almost nonexistent, in brain capillaries and it is likely that any filtering is further reduced by the manner in which astrocytes pack around the capillaries This constraint is known as the NEUROTRANSMITTER SYSTEMS AND FUNCTION: OVERVIEW 11 blood brain barrier (BBB) It protects the brain from inappropriate substances, including all NTs and many drugs To enter the brain as a whole is therefore... action potentials without the neuron having to do anything special 12 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION Figure 1.3 Some possible basic neurotransmitter±synaptic arrangements for the excitation and inhibition of different neurons (a) The single NT activates neuron B and inhibits neuron C by being able to activate both excitatory and inhibitory receptors or, more probably, acting on one receptor... G-proteins linked to the activation (Gs) or 14 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION Figure 1.4 Ionic basis for excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) Resting membrane potential (770 mV) is maintained by Na‡ influx and K‡ efflux Varying degrees of depolarisation, shown by different sized EPSPs (a and b), are caused by increasing influx of Na‡... Exp Brain Res 126: 369±382 (1999) NEUROTRANSMITTER SYSTEMS AND FUNCTION: OVERVIEW 9 (b) Figure 1.2 (b) Schematic representation of a neuron The main features of a neuron are shown together with different synaptic arrangements (A) axo-dendritic, (B) axo-somatic, (C) axo-axonic and (D) dendro-dendritic For more detail see section on `Morphological correlates of synaptic function' and Fig 1.7 10 NEUROTRANSMITTERS,. .. astocytes Neurons and glia are bathed in an ion-containing protein-free extracellular fluid which occupies less of the tissue volume (20%) in the brain than in other organs because of the tight packing of neurons and glia In fact the whole brain is really suspended in fluid within its bony casing The brain and spinal cord are covered by a thin close-fitting membrane, the pia mater and a thicker loose... Systems and Function: Overview R A WEBSTER INTRODUCTION Analysis of Biological Function generally presumes that function at one level arises from the interactions of lower-level elements It is often relatively straightforward to identify elements that may be involved and their individual interactions Modern cell and molecular biology, in particular, is very efficient at identifying new molecules, and establishing . x0 y0 w0 h0" alt=""