Prostaglandins are part of a class of substances called eicosanoids. Eicosanoids are a group of substances derived from fatty acids and include prostaglandins, thromboxanes, and leukotrienes, all of which are formed from precursor fatty acids by the incorporation of oxygen atoms into the fatty acid chains. This reaction is called oxygenation and is carried out by cyclo-oxygenase enzymes. Prostaglandins and their metabolites have been found in virtually every tissue in the body.
After that brief introduction into prostaglandins, we can now begin to discuss more specifically the role of prostaglandins in muscle growth. In a nutshell, mechanical stimulation (i.e. intermittent stretch) results in the production and efflux of two prostaglandins, PGE2 and PGF2a. PGE2 increases protein degradation where as PGF2a increases protein synthesis. Muscle hypertrophy is usually achieved by an increase in protein synthesis as well as a proportionately smaller increase in degradation. The simultaneous release of both PGE2 and PGF2a creates this condition.
It is well known that mechanical stretch, without any electrical activity, is sufficient to induce muscle hypertrophy. Recent studies have shown that the mechanism by which mechanical stretch leads to prostaglandin production and ultimately muscle growth, involves G proteins embedded in the cell membrane. These G proteins increase the amount of cyclo-oxygenase, the enzyme responsible for making prostaglandins from arachidonic acid. Skeletal muscle cyclooxygenase generates PGE2 and PGF2 alpha at a ratio approximately equal to one.