Brain distribution signal transduction

Some members of this family have been shown to mediate the dephosphorylation of MAPKs under physiological conditions. Others dephosphorylate Cdc-2 and related CDKs. However, relatively little is known to date about the regional distribution of these dual-functioning phosphatases in the brain and the specific function these enzymes serve in the regulation of neuronal signal transduction. Considerable interest has focused on one particular MAPK phosphatase, which can be induced very rapidly, at the level of gene transcription, in target cells in response to cellular activation [44]. 

The actions of U-II are mediated by a G protein-coupled receptor referred to as the UT receptor. UT receptors are widely distributed in the brain, spinal cord, heart, vascular smooth muscle, skeletal muscle, and pancreas. Some effects of the peptide including vasoconstriction are mediated by the phospholipase C, IP3-DAG signal transduction pathway. 

Demyelination. The role of myelin in the nervous system is to aid in signal transduction. Myelin acts like an electrical insulator by preventing loss of ion current, and intact myelin is critical for the fast saltatory nerve conduction discussed above. Neurotoxicants that target the synthesis or integrity of PNS myelin may cause muscle weakness, poor coordination, and paralysis. In the brain, white matter tracts that connect neurons within and between hemispheres may be destroyed, in a syndrome known as toxic leukoencephalopathy. A multifocal distribution of brain lesions is reflected in mental deterioration, vision loss, speech disturbances, ataxia (inability to coordinate movements), and paralysis. 

In vitro, urotensin II is a potent constrictor of vascular smooth muscle its activity depends on the type of blood vessel and the species from which it was obtained. Vasoconstriction occurs primarily in arterial vessels, where urotensin II can be more potent than endothelin 1, making it the most potent known vasoconstrictor. In vivo, urotensin II has complex hemodynamic effects, the most prominent being regional vasoconstriction and cardiac depression. The extent to which the peptide is involved in the regulation of vascular tone and blood pressure in humans is not clear recent studies have produced conflicting results. The actions of urotensin II are mediated by G protein-coupled receptors that are widely distributed in the brain, spinal cord, heart, vascular smooth muscle, skeletal muscle, and pancreas. Some effects of the peptide including vasoconstriction are mediated by the phospholipase C/IP3/DAG signal transduction pathway. 

Table 1.3 Dopamine receptors. The distribution, function, signal transduction and pharmacology of dopamine receptors in the brain...

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