Autacoids refer to a class of biologically active substances that are produced within the body and have diverse physiological functions. These substances act locally at their site of synthesis and exert their effects through specific receptors present in the target tissues. Autacoids are often referred to as local hormones, as they function similar to classical hormones but have a restricted scope of action.
Autacoids can be categorized into three main groups: histamine, prostaglandins, and vasoactive peptides. Histamine is a small molecule derived from the amino acid histidine and is involved in various allergic and inflammatory responses. It acts on histamine receptors located in multiple tissues, including blood vessels, smooth muscles, and the gastrointestinal tract.
Prostaglandins are lipid compounds synthesized from arachidonic acid and play a crucial role in inflammation, pain signaling, and regulating the body's response to injury or infection. They act on specific receptors distributed throughout the body and affect target tissues differently, causing diverse effects such as vasodilation, bronchoconstriction, and uterine contraction.
Vasoactive peptides include substances like bradykinin, serotonin, and substance P, which control blood vessel dilation, contraction, and permeability. These peptides are involved in processes such as inflammation, pain transmission, and modulation of blood pressure.
Overall, autacoids play a vital role in regulating various physiological processes and maintaining homeostasis within the body. Their local actions and specific receptor binding allow for targeted effects, making them crucial signaling molecules in both health and disease conditions.
