Neurotransmitters glutamate receptors

Repeated exposure to cocaine increases the release of glutamate, the excitatory neurotransmitter. Glutamate receptors, such as NMDA, in postsynaptic neurons, are activated by glutamate. Each of the several types of glutamate receptors is transcribed by different genes and their mRNA. 

The neurotransmitter, glutamate, is a major excitatory neurotransmitter. Glutamate receptors are called ionotropic receptors. The effect of glutamate is to cause charged ions such as Na and Ca " to pass through a channel in the centre of the receptor complex, which results in a depolarization of the plasma membrane and the generation of an electrical current that is propagated down the dendrites and axons of the neuron. Kandel found that cyclic AMP increased when these effects were retained in the neurons, to provide a chemical foundation of short-term memory. Cyclic AMP activates an enzyme, protein kinase, which acts like a neuronal switch. Serotonin increases this reaction. 

MSG is used to give a meaty, savory, or brothy taste to foods by stimulating the glutamate receptors on the tongue. There are glutamate receptors in other parts of the body, notably the brain, where glutamate is a neurotransmitter. 

Opiates produce more discreet inhibitory effects since they bind to and activate inhibitory opioid receptors which, due to their restricted distribution, cause less widespread effects than those of the barbiturates and alcohol. Activation of the opioid receptors leads to a decrease in release of other neurotransmitters (glutamate, NA, DA, 5-HT, ACh, many peptides, etc.) and direct hyperpolarisation of cells by opening of K+ channels and decreasing Ca + channel activity via predominant actions on the mu opiate receptor (see Chapter 12). 

L-Glutamate acts as an excitatory neurotransmitter at many synapses in the mammalian central nervous system. Electrophysiological measurements and the use of various selective agonists and antagonists indicate that different glutamate receptors co-exist on many neurons. 

Cartmell, J. Schoepp, D. D. (2000). Regulation of neurotransmitter release by metabotropic glutamate receptors. J. Neurochem. 75, 889-907. 

TABLE 23-3 Examples of proteins regulated by phosphorylation Enzymes involved in neurotransmitter biosynthesis Tyrosine hydroxylase Tryptophan hydroxylase Neurotransmitter receptors Adrenergic receptors Dopamine receptors Opioid receptors Glutamate receptors Many others... 

Fas ligand and interleukin-ip), the neurotransmitter glutamate and thrombin. Like tumor necrosis factor (TNF) receptors, Fas is coupled to downstream death effector proteins that ultimately induce caspase activation (Ch. 22). Fas and TNF receptors recruit proteins called FADD and TRADD respectively FADD and TRADD then activate caspase-8, which, in turn, activates caspase-3 (Fig. 35-4). Calcium ion influx mediates neuronal apoptosis induced by glutamate receptor activation calcium induces mitochondrial membrane permeability transition pore opening, release of cytochrome c and caspase activation. Interestingly, in the absence of neurotrophic factors some neurotrophic factor receptors can activate apoptotic cascades, the low-affinity NGF receptor being one example of such a death receptor mechanism [23],... 

DNLM 1. Neuopharmacology-methods. 2. Receptors, Neurotransmitter. 3. Neurotransmitters. 4. Receptors, GABA. 5. Receptors, Glutamate. WL 102.8 M7179 2004]... 

Several neurotransmitter and receptor changes are observed in Alzheimer s disease (Nordberg 1992). Losses occur in nicotinic receptors, but muscarinic receptors are relatively preserved. Reductions are also seen in serotonin 5-HTl and 5-HT2 receptors. Glutamate NMDA receptors decrease, while kainate receptors increase. j8-adrenergic and dopamine receptors are preserved. Decreases occur in receptors for somatostatin and neuropeptide Y, but corticotrophin-releasing factor receptors increase. Across all receptor subtypes for which there is a loss, the number of receptors decrease but the affinity constant remains unchanged. 

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