Eicosanoid metabolism

Eicosanoid metabolism refers to the biochemical processes that produce eicosanoids, a group of signaling molecules derived from polyunsaturated fatty acids (PUFAs), specifically arachidonic acid. These processes are crucial for the regulation of various physiological functions, including inflammation, immune response, and platelet aggregation.

Overview

Eicosanoid metabolism begins with the release of arachidonic acid from the phospholipid bilayer of cell membranes by the action of phospholipase A2 (PLA2). This free arachidonic acid can then be metabolized by three main enzymatic pathways: the cyclooxygenase (COX) pathway, the lipoxygenase (LOX) pathway, and the cytochrome P450 pathway.

Cyclooxygenase pathway

The COX pathway leads to the production of prostaglandins, thromboxanes, and prostacyclins. These eicosanoids play key roles in inflammation, pain, fever, and the regulation of blood pressure.

Lipoxygenase pathway

The LOX pathway results in the formation of leukotrienes and lipoxins. Leukotrienes are involved in allergic and inflammatory responses, while lipoxins have anti-inflammatory effects.

Cytochrome P450 pathway

The cytochrome P450 pathway produces epoxyeicosatrienoic acids (EETs) and hydroxyeicosatetraenoic acids (HETEs). These eicosanoids are involved in the regulation of vascular tone and inflammation.

Regulation

The regulation of eicosanoid metabolism is complex and involves multiple factors, including the availability of arachidonic acid, the activity of the enzymes involved in eicosanoid synthesis, and the presence of specific receptors on target cells.

Clinical significance

Abnormalities in eicosanoid metabolism have been implicated in a variety of diseases, including asthma, rheumatoid arthritis, cancer, and cardiovascular disease. Therefore, drugs that target eicosanoid synthesis or action, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and leukotriene receptor antagonists, are widely used in the treatment of these conditions.