Autocoids, short for “autonomous mediators,” refer to a diverse group of naturally occurring substances within the body that act locally to regulate physiological functions. These substances are produced in small quantities and exert their effects near the site of synthesis. Autocoids play essential roles in maintaining homeostasis and mediating various physiological processes.

Examples of autocoids include

1. Histamine: Histamine, released by mast cells, is involved in allergic responses, inflammation, and the regulation of gastric acid secretion.

2. Prostaglandins: These lipid compounds are crucial in inflammation, smooth muscle contraction, and various physiological processes. They are derived from arachidonic acid and act as local messengers.

3. Serotonin: Also known as 5-hydroxytryptamine (5-HT), serotonin regulates mood, appetite, and gastrointestinal function. It is produced in the gut and central nervous system.

4. Bradykinin: It causes vasodilation, increases vascular permeability, and is involved in pain perception and inflammation.

5. Leukotrienes: Involved in the immune response and inflammation, particularly in allergic reactions and asthma, these lipid mediators play a crucial role.

Autocoids act in an autocrine or paracrine fashion, affecting the same cell or nearby cells. Typically synthesized and released in response to specific stimuli, they play roles in physiological processes such as inflammation, immune response, blood clotting, and smooth muscle contraction. Autocoids contribute to the body’s ability to maintain balance and respond to various challenges in the internal and external environment.