Neuronal activity

Anticonvulsant. A compound that depresses the central nervous system, thus decreasing frequency and severity of uncontrolled bursts of neuronal activity. 

Antiepileptics are used in neuropathic pain resulting from lesions to the peripheral (e.g., diabetes, heipes) or central nervous system (e.g., stroke). Such syndromes have been attributed to ectopic activity in sensitized nociceptors from regenerating nerve sprouts, recruitment of previously silent nociceptors, and/or spontaneous neuronal activity. This may result in sensitization... 

Primary generalized seizures are also heterogeneous with respect to their clinical features. Such seizures can impose as absence epilepsy, which is characterized by a brief interruption of consciousness due to highly synchronized neuronal activity involving thalamocortical networks without increases in neuronal firing rate. On the other hand, tonic-clonic convulsions with loss of consciousness are often also primarily generalized. 

Substantia nigra pars reticulata is the area with highest neuronal activity and metabolic rate in the brain. This region also shows highest expression rates of SUR1/ Kir6.2 channels. These KATP channels are present... 

Episodic ataxia (EA) is an autosomal dominant disorder that brief episodes of ataxia can be triggered by physical or emotional stress. The symptom can occur several times during the day, last for seconds to minutes, and be associated with dysarthria and motor neuron activity, which causes muscle rippling (myokymia) between and during attacks. It is caused by a mutation in a neuronal voltage dependent Ca2+ channel. 

Hi-receptors in the adrenal medulla stimulates the release of the two catecholamines noradrenaline and adrenaline as well as enkephalins. In the heart, histamine produces negative inotropic effects via Hr receptor stimulation, but these are normally masked by the positive effects of H2-receptor stimulation on heart rate and force of contraction. Histamine Hi-receptors are widely distributed in human brain and highest densities are found in neocortex, hippocampus, nucleus accumbens, thalamus and posterior hypothalamus where they predominantly excite neuronal activity. Histamine Hrreceptor stimulation can also activate peripheral sensory nerve endings leading to itching and a surrounding vasodilatation ( flare ) due to an axonal reflex and the consequent release of peptide neurotransmitters from collateral nerve endings. 

The localization of transporter molecules on the cell surface is dynamic rather than constitutive, such that transport capacity may be adapted to neuronal activity. Obviously, the mechanisms regulating uptake are of principal importance in pharmacology just as pharmacological transport inhibitors can regulate the density of transporters. 

Prostaglandins are a group of lipid autacoids known as eicosanoids. They are produced from membrane phospholipids and found in almost every tissue and body fluid. They are involved in a number of physiological processes including inflammation, smooth muscle tone and gastrointestinal secretion. In the central nervous system they have been reported to produce both excitation and inhibition of neuronal activity. 

Cornelius JR, Salloum IM, EhlerJG, et al Fluoxetine in depressed alcoholics a doubleblind, placebo-controlled trial. Arch Gen Psychiatry 54 700—705, 1997 Cornelius JR, Salloum IM, Haskett RF, et al Fluoxetine versus placebo for the marijuana use of depressed alcoholics. Addict Behav 24 111—114, 1999 Cui S-S, Bowen RC, Gu G-B, et al Prevention of cannabinoid withdrawal syndrome by lithium involvement of oxytocinergic neuronal activation. J Neurosci 21 9867— 9876, 2001... 

The Effect of CXCR4-Mediated Signaling Pathway on Neuronal Activity and Neurotransmitter Release... 

The findings recently reported can be relevant to understand the functional role of transmitter release from astrocytes in brain function. Interestingly, a recent report shows for the first time the occurrence in vivo of fast astrocytic calcium events in response to neuronal activity, peaking with millisecond time-scale from sensory stimulation (Winship et al. 2007). 

Dani JW, Chernjavsky A, Smith SJ (1992) Neuronal activity triggers calcium waves in hippocampal astrocyte networks. Neuron 8 429 40... 

Schipke CG, Kettenmann H (2004) Astrocyte responses to neuronal activity. Gha 47 226-232 Schneggenburger R, Neher E (2005) Presynaptic calcium and control of vesicle fusion. Curr Opin Neurobiol 15 266-274... 

Winship IR, Plaa N, Murphy TH (2007) Rapid astrocyte calcium signals correlate with neuronal activity and onset of the hemodynamic response in vivo. J Neurosci 27 6268-6272 Wu MM, Buchanan J, Luik RM, Lewis RS (2006) Ca store depletion causes STIMl to accumulate in ER regions closely associated with the plasma membrane. J Cell Biol 174 803-813 Wyss-Coray T (2006) Inflammation in Alzheimer disease driving force, bystander or beneficial response Nat Med 12 1005-1015... 

Guyon A, Nahon JL (2007) Multiple actions of the chemokine stromal cell-derived factor-la on neuronal activity. J Mol Endocrinol 38 365-376... 

Guyon A, Nahon JL (2007) Multiple actions of the chemokine stromal ceU-derived factor-lalpha on neuronal activity. J Mol Endocrinol 38 365-376 Haribabu B, Richardson RM, Fisher I, Sozzani S, Peiper SC, Horuk R, Ah H, Snyderman R (1997) Regulahon of human chemokine receptors CXCR4. Role of phosphorylahon in desen-sihzahon and intemahzahon. J Biol Chem 272(45) 28726-28731... 

How do neurotransmitters work What effects do they have on neuronal activity What is known about the receptors to which they bind ... 

Figure 1.9 Comparison of the effects of an endogenously released and exogenously applied neurotransmitter on neuronal activity (identity of action). Recordings are made either of neuronal firing (extracellularly, A) or of membrane potential (intracellularly, B). The proposed transmitter is applied by iontophoresis, although in a brain slice preparation it can be added to the bathing medium. In this instance the applied neurotransmitter produces an inhibition, like that of nerve stimulation, as monitored by both recordings and both are affected similarly by the antagonist. The applied neurotransmitter thus behaves like and is probably identical to that released from the nerve...

Many people consider this to be the most important of all the criteria. Obviously a substance must have an effect of some kind if it is to be a NT but not all substances that have an effect on neurons need to be NTs. It may seem unnecessary to say this but the literature contains many accounts of the study of various substances on neuronal activity from which a NT role is predicted without any attempt to compare its effect with that of physiologically evoked (endogenous NT) effects. The importance of this safeguard is highlighted by the ease with which both smooth muscle and neurons will respond to a range of substances that are not released onto them as NTs. Thus the value of this criterion depends very much on the rigour with which it is applied and on its own is no more or less important than any other approach. 

There is no room within the definition for nitric oxide, the prostaglandins and steroids mainly because they are not released in a controlled manner by neuronal activity and only the last are preformed. Thus if they are to be classified as NTs then the definition must be simplified so that a NT becomes ... 

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