Neurotransmitters/neuromodulators

No attempt will be made to give an overview of the main pathways of the several dozen neurotransmitters, neuromodulators and co-transmitters which are possibly involved in the aetiology of mental illness. Instead a summary is given of the relevant pathways involved in the synthesis and metabolism of those transmitters which have conventionally been considered to be involved in the major psychiatric and neurological diseases and through which the psychotropic drugs used in the treatment of such diseases are believed to operate. 

Among all panicogens, CCK-4 is the only one that fulfils the criteria for a neurotransmitter/neuromodulator and that, unhke sodiirm lactate and CO2, spares issues such as volume overload and acid base-mediated alterations. Hence, it is hkely that CCK-4 may be among the most suitable panicogenic challenges. 

Neurotransmitter/Neuromodulator Ganglionic Receptor Ganglionic Action Potential... 

Extensive immunohistochemical studies of the basal ganglia have demonstrated the presence of a wide spectrum of classic neurotransmitters, neuromodulators, and neuropeptides. The functional status of a number of these systems has been evaluated in TS. 

Neuropharmacology is the study of drugs that affect the nervous system and its neuronal components. The functions of the nervous system are intimately linked with the synthesis, storage, release, and uptake of many transmitters and their modulators. The beneficial effects or side effects of an extensive number of drugs are brought about through their interaction with these neurotransmitter-neuromodulator systems. 

Another endogenous peptide which has been implicated in pain transmission and the central integration of pain responses is neurotensin (NeT) (Dobner, 2006 Gui et al., 2004 Pettibone et al., 2002). NeT is a brain-gut tridecapeptide that fulfils a dual function as a neurotransmitter/neuromodulator in the nervous system, and as a paracrine and circulating hormone at the periphery. Three NeT receptors, NTRl,... 

In addition to the major neurotransmitteis implicated in psychiatric disorders and targets for drags PA, NA, 5-HT, ACh, GABA and glutamate), Table 1.1 also lists some of the other neurotransmitters/neuromodulators and in particular some of the numerous neuropeptides found in the brain. 

These primary effects are likely to be amplified at different levels (sensory receptors, synapses) through various mechanisms such as potassium accumulation in the vicinity of the nerve membrane, sodium accumulation inside the axons and abnormal release of neurotransmitters, neuromodulators or neurohormones. 

The transfer of information between cells and the subsequent cellular integration of multiple information sources that is necessary to maintain cellular homeostasis and tissue viability—under both normal and adverse, disease-related conditions—involves a variety of different external signaling modalities. These include temperature, membrane potential, mechanical distention and stress, alterations in ion (IT /K ) concentrations, and pheromones and oderants, as well as the more traditional classes of neurotransmitters, neuromodulators, and hormones. These physical stimuli and endogenous chemicals elicit their effects through interactions with cell surface targets, usually proteins, that are classified as receptors (Table 10.1). Once receptors are ac-... 

Receptors on soma, dendrites, and axons of neurons respond to neurotransmitters or modulators released from the same neuron or from adjacent neurons or cells. Soma-dendritic receptors are located on or near the cell body and dendrites when activated, they primarily modify functions of the soma-dendritic region such as protein synthesis and generation of action potentials. Presy-naptic receptors are located on axon terminals or varicosities when activated, they modify functions such as synthesis and release of transmitters. Two main classes c presynaptic receptors have been identified on most neurons, including sympathetic and parasympathetic terminals. Heteroreceptors are presynaptic receptors that respond to neurotransmitters, neuromodulators, or neurohormones released from adjacent neurons or cells. For example, NE can influence the release of ACh from parasympathetic neurons by acting on and receptors, whereas ACh can... 

Radioligands represent the radioactive forms of endogenous neurotransmitters, neuromodulators, hormones or enzyme substrates, or synthetic compounds that interact with the binding sites on receptors or enzymes. Ligands are made radioactive using a number of isotopes (e.g., H, or... 

A mmiber of neurotransmitters, neuromodulators and their respective receptors are involved in the neurotransmission at the dorsal horn. They can be broadly classified into two groups. 

The souree of the hyperpolarization almost definitely includes either a global or regionally speeific alteration in the balance of inhibitory and excitatory neurotransmitters/neuromodulators. In the progressive brain hypoxia model, good... 

Peptides perform many important functions in the CNS as neurotransmitters, neuromodulators, or neurohormones [40]. Neuropeptides are involved in a wide variety... 

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