Arachidonic Acid Pathway.ppt.pptx

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1. Arachidonic Acid Pathway

2. The arachidonic acid pathway, also known as the arachidonic acid cascade or the eicosanoid pathway, is a biochemical pathway involved in the production of various signaling molecules called eicosanoids . Arachidonic acid is a polyunsaturated fatty acid that serves as the precursor for these eicosanoids .

3. The pathway begins with the release of arachidonic acid from the phospholipids of the cell membrane, usually in response to a stimulus such as inflammation or cellular activation. This release is mediated by the enzyme phospholipase A2 . Once arachidonic acid is released, it can be metabolized by two major enzymatic pathways: the cyclooxygenase (COX) pathway and the lipoxygenase (LOX) pathway.

4.  The arachidonic acid pathway describes the biosynthesis of eicosanoids from arachidonic acid (AA) including its formation from omega-6 polyunsaturated fatty acids (PUFAs) and the synthesis of eicosanoids from eicosapentaenoic acid (EPA) including its formation from omega-3 PUFAs.

5. Cyclooxygenase (COX) pathway: Arachidonic acid can be converted by the enzyme cyclooxygenase into various prostaglandins and thromboxanes . There are two isoforms of cyclooxygenase : COX-1 and COX-2. COX-1 is constitutively expressed in many tissues and involved in physiological functions, while COX-2 is induced during inflammation and plays a role in pain, fever, and inflammation. Prostaglandins and thromboxanes are involved in various biological processes, including regulation of inflammation, blood clotting, and gastrointestinal protection.

6. Lipoxygenase (LOX) pathway: Arachidonic acid can also be metabolized by the enzyme lipoxygenase into leukotrienes and lipoxins . Leukotrienes are involved in inflammatory and allergic reactions, while lipoxins are thought to have anti-inflammatory effects and play a role in resolving inflammation.

7. The products of the arachidonic acid pathway, including prostaglandins, thromboxanes , leukotrienes , and lipoxins , act as local hormones or signaling molecules, exerting a wide range of effects on various tissues and physiological processes. They can modulate inflammation, vascular tone, platelet aggregation, bronchoconstriction , and other important functions in the body.

8. The arachidonic acid pathway is tightly regulated, and its dysregulation can contribute to various diseases and conditions, such as inflammation, asthma, cardiovascular diseases, and cancer. Consequently, drugs that target specific enzymes in this pathway, such as COX inhibitors (e.g., nonsteroidal anti-inflammatory drugs or NSAIDs), are widely used to treat pain, inflammation, and other related conditions.

9. Arachidonic Acid Pathway