Neuron central

Figure 8-1J. Training ofa Kohonen neural network with a chirality code, The number of weights in a neuron is the same as the number of elements in the chirality code vector, When a chirality code is presented to the network, the neuron with the most similar weights to the chirality code is excited (this is the ivinning or central neuron) (see Section 9.5,3),...

The neuron for which this distance gives the minimum is called the winning neuron or central neuron c (see Eq. (5)). 

Opioids G-protein coupled p-, 5-, k-receptors l cAMP l Ca2+ currents t K+ currents l Excitability of peripheral and central neurons l Release of excitatory neurotransmitters p, 5 sedation, nausea, euphoria/re-ward, respiratory depression, constipation k dysphoria/aversion, diuresis, sedation... 

Antidepressants Noradrenaline/5-HT transporters Na+, K+ channels l Noradrenaline/ 5-HT reuptake l Na+ currents t K+ currents l Excitability of peripheral and central neurons Cardiac arrhythmia, myocardial infarction, sedation, nausea, dry mouth, constipation, dizziness, sleep disturbance, blurred vision... 

Central neuronal blockers (reserpine) Depression, sedation, nasal congestion... 

Nowak L, Bregestovski P, Ascher P, Herbet A, Prochiantz A. Magnesium gates glutamate-activated channels in mouse central neurones. Nature 1984 307 462-465. 

Tyramine is produced by decarboxylation of tyrosine and is present in the CNS in higher (threefold) concentrations than m-tyramine, the hydroxylated derivative of phenylethylamine. In the periphery / -tyramine is easily hydroxylated to octopamine, which has some direct effects on ai adrenoceptors, unlike tyramine which functions by releasing NA. When tested on central neurons tyramine always produces the same effects as NA but they are slower and less marked, implying an indirect action. By contrast octopamine often produces the opposite effect to NA and it is probable that octopamine may have a functional role in the invertebrate CNS where it is found in higher concentrations (5pg/g) than in the mammalian brain (0.5ng/g). Neither tyramine nor octopamine have distinct behavioural effects, unlike phenylethylamine,... 

Although histamine has mixed excitatory and inhibitory effects on central neurons, those antihistamines (Hi-receptor antagonists) that enter the brain produce sedation this indicates that the predominant overall effect of histamine is excitatory. The preferred explanation for this rests on evidence that histaminergic neurons in the posterior hypothalamus are active in waking and silent in deep SWS and REM sleep. 

Ascher P. and Nowak L., The role of divalent cations in the IV-methyl-D- aspartate responses of mouse central neurones in culture, J. Physiol., 399, 247-266, 1988. 

In addition to direct enhancement of channel activity, PTKs can indirectly increase GABA-evoked inhibitory current by recruiting intracellular GABAaR to the surface of postsynaptic membrane. Insulin has been shown to increase surface expression GABAaR in transfected human embryonic kidney cells. In central neurons insulin rapidly increases the expression of functional postsynaptic GABAaR in a tyrosine kinase-dependent manner, resulting in an increase in the amplitude of the miniature inhibitory postsynaptic currents. 

Rauwolfia derivatives became available in the 1950s in western medicine for the treatment of hypertension. The antihypertensive effects of rauwolfia alkaloids occur from their depletion of monoamines in adrenal chromaffin cells and sympathetic ganglia, and perhaps central neurons as well (Oates 1996). 

Most, but not all, of the axons of both peripheral and central neurones are wrapped in a sheath of material known as myelin (which is a complex of protein and phospho-... 

Reserpine lowers elevated blood pressure as a result of neuro-transmitter depletion in peripheral postganglionic sympathetic neurons, as discussed in detail in a separate paragraph. In addition, reserpine also causes neurotransmitter depletion in central neurons involved in the regulation of sympathetic activity and blood pressure. For this reason it may be assumed that this central mechanism contributes to the antihypertensive activity of reserpine. The mechanism of the central antihypertensive action of reserpine has not been analysed in detail. 

Apart from their anti-inflammatory activity the NSAIDs also show, dependent on the condition and the type of pain, considerable analgesic efficacy. In some forms of postoperative pain the NSAID s can be as efficacious as opioids, especially when prostaglandins, bradykinin and histamine, which are released by inflammation, have caused sensitization of pain receptors to normally painless stimuli. In Table 4 some advantages and disadvantages of NSAID s and opioids are compared. Although analgesic effects at peripheral or central neurons cannot be excluded completely, most studies indicate that... 

Schwarcz R, Kohler C (1983) Differential vulnerability of central neurons of the rat to quinolinic acid. Nemosci Lett 38 85-90... 

Evidence of a behavioral role for central neuronal nitric oxide synthetase has been reported. A knockout mouse deficient in the gene encoding for this enzyme... 

Study RE, Barker JL Diazepam and pentobarbital fluctuation analysis reveals different mechanisms for potentiation of gabaaminobutyric acid responses in cultured central neurons. Proc Natl Acad Sci U S A 78 7180-7184, 1981... 

Peripheral tissue markers include high-molecular-weight complex biomolecules (receptors) and enzyme systems that can be obtained from outside the CNS (e.g., in platelets, lymphocytes, skin fibroblasts, and erythrocytes) and are thought to reflect or parallel central neuronal activity. 

Williams, J. T., Eagan, T. M., North, R. A. Enkephalin opens potassium channels in mammalian central neurons, Nature 1982, 299, 74-77. 

L-type Ca2+ channels can be detected in peripheral neurons, central neurons, synaptosomes as well as in non-neuronal cells (review Tsien et al., 1988). In general the following gene products were found to be expressed, at least in part, in the central nervous system (CNS) (Birnbaumer et al., 1994 Alexander and Peters, 2000) ... 

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