Other second messengers Arachidonic acid

Arachidonic acid and its metabolites, collectively known as eicosanoids, were known for a long time to be important in modulation of nervous signals, but the identification of these substances as second messengers came only in the 1980s when Axelrod's group determined that their production involved the action of a G protein.(!2) Arachidonic acid can be produced directly from a variety of phospholipids by the action of phospholipase A 2, or indirectly by the action of the enzyme diglyceride lipase on diglycerides produced as a result of the hydrolytic action of phospholipase C on either phosphoinositides or phosphatidylcholine ( Fig. 6). Free arachidonic acid and some of its metabolites such as prostaglandin E 2, the leucotrienes and lipoxin A can elevate cytosolic calcium concentrations independently of inositol-1,4,5-trisphosphate, and may also act as physiological regulators of guanylate cyclase. Arachidonic acid may also leave the cell and act as a first messenger for adjacent cells.

One pathway of arachidonic acid metabolism (Fig.6) involves lipoxygenase enzymes that introduce an oxygen molecule into one of the polyunsaturated pentadiene moieties to form a hydroperoxyeicosatrienoic acid. Depolarization of brain slices with high concentrations of extracellular potassium ions, glutamate or N-methyl-D-aspartate has been shown to greatly increase 12-lipoxygenase activity. 12-Hydroperoxyeicosatrienoic acid and some of its metabolites act to modulate the actions of ion channels at specific synapses.

Funny Wiring Autism

Funny Wiring Autism

Autism is a developmental disorder that manifests itself in early childhood and affects the functioning of the brain, primarily in the areas of social interaction and communication. Children with autism look like other children but do not play or behave like other children. They must struggle daily to cope and connect with the world around them.

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