Autacoid General Consideration
The autacoids are formed in various tissues of the body and are believed to function as local hormones. The important autacoids include histamine, 5 hydroxy tryptamine (Serotonin), prostaglandins and the kinins. The effect of autacoids are mostly localized but large amounts can be produced and moved into circulation. Autacoids may thus have systemic effect by being transported via circulation. These regulating molecules are also metabolized locally. So the compounds are produced locally, they act locally and are metabolised locally. Autacoids can have many different biological actions including modulation of the activity of smooth muscles, glands, nerves, platelets and other tissues.
Some other autacoids are primarily characterized by the effect they have upon different tissues, such as smooth muscle. With respect to vascular smooth muscle, there are both vasoconstrictor and vasodilator autacoids.
Vasodilator autacoids can be released during periods of exercise. Their main effect is seen in the skin, allowing for heat loss.
These are local hormones and therefore have a paracrine effect. Some notable autacoids are: eicosanoids, angiotensin, neurotensin, NO (nitric oxide), kinins, histamine, serotonin, endothelins, palmitoylethanolamide, etc.