Neurotransmitters function

The compounds used to palliate the mnemonic and cognitive decline associated with dementia include cerebral vasodilators and the so-called nootropic agents. These materials enhance cerebral metaboHsm. Agents which enhance neurotransmitter function are in most cases cholinergic. 

How the different neurotransmitters may be involved in the initiation and maintenance of some brain disorders, such as Parkinson s disease, epilepsy, schizophrenia, depression, anxiety and dementia, as well as in the sensation of pain, is then evaluated and an attempt made to see how the drugs which are used in these conditions produce their effect by modifying appropriate neurotransmitter function (section C). The final section (D) deals with how neurotransmitters are involved in sleep and consciousness and in the social problems of drug use and abuse. 

We have no such pretensions in this book but we do hope to help you to 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 ... 

A glance at the structure of the classical neurotransmitters (Fig. 1.1) shows that apart from the peptides (D) (and purines, E), most of them are fairly simple chemicals. Some authors therefore divide them into small (e.g. A, B, C) and large (peptides, D) molecular NTs. Although we will see that peptides certainly have some properties different from other NTs, in that they rarely have a primary neurotransmitter function and usually just complement the actions of those NTs in groups A-C, to put them in a class of their own and group all the others together simply on the basis of molecular size is inappropriate and misleading since it elevates the peptides to a status that is neither proven nor warranted. 

Basic Pharmacology and Drug Effects on Neurotransmitter Function... 

Table 5.1 Drug modification of the different aspects of neurotransmitter function in synaptic transmission as illustrated in Fig. 5.5...

Dailey, JW (1992) Typical and atypical neuroleptic drug effects on dopamine and other neurotransmitter functions in rodents. PhD thesis, University of London, p. 125. 

Indices of neurotransmitter function on lymphocytes (e.g. )S-adrenoceptor binding) or platelets (e.g. a2-adrenoceptor binding, 5-HT uptake). 

The neural structures involved in the promotion of the waking (W) state are located in the (1) brainstem [dorsal raphe nucleus (DRN), median raphe nucleus (MRN), locus coeruleus (LC), laterodorsal and pedunculopontine tegmental nuclei (LDT/PPT), and medial-pontine reticular formation (mPRF)] (2) hypothalamus [tuberomammillary nucleus (TMN) and lateral hypothalamus (LH)[ (3) basal forebrain (BFB) (medial septal area, nucleus basalis of Meynert) and (4) midbrain ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) (Pace-Schott Hobson, 2002 Jones, 2003). The following neurotransmitters function to promote W (1) acetylcholine (ACh LDT/PPT, BFB) (2) noradrenaline (NA LC) (3) serotonin (5-HT DRN, MRN) (4) histamine (HA TMN) (5) glutamate (GLU mPRF, BFB, thalamus) (6) orexin (OX LH) and (7) dopamine (DA VTA, SNc) (Zoltoski et al, 1999 Monti, 2004). 

Hertz, L. and Schousboe, A. (1987) Primary cultures of GABAergic, and glutamatergic neurons as model systems to study neurotransmitter functions. I. Differentiated cells, in Model Systems of Development and Aging of the Nervous System (Vemadakis, A., Privat, A., Lauder, J. M., Timiras, P. S and Giacobini, E eds.), M. Nijhoff Publishing Company, Boston, MA, pp. 19-31. 

Malaviya M, Husain R, Seth PK et al (1993) Perinatal effects of two pyrethroids insecticides on brain neurotransmitter function in the neonatal rat. Vet Hum Toxicol 35 119-122... 

Many psychoactive drugs act to alter neurotransmitter functions either through effects on their synthesis, metabolism or reuptake or by directly affecting the receptors for naturally occurring compounds. For example, drugs such as prozac increase serotoniner-gic activity by selective serotonin reuptake inhibition (SSRI). 

BASIC ASPECTS OF NEUROTRANSMITTER FUNCTION Measuring neurotransmitter receptors in the brain... 

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