Autacoid

Autacoids are biological factors that act like local hormones, have a brief duration, and act near their site of synthesis. They are involved in various physiological and pathological processes. Autacoids include histamine, serotonin, prostaglandins, and bradykinin. These substances play crucial roles in inflammation, pain, and other bodily functions.

Types of Autacoids

Autacoids can be classified into several categories based on their chemical nature and function:

• Amines: This group includes histamine and serotonin. Histamine is involved in allergic reactions and gastric acid secretion, while serotonin regulates mood, appetite, and sleep.
• Lipid-derived autacoids: These include prostaglandins, leukotrienes, and thromboxanes. Prostaglandins are involved in inflammation and pain, leukotrienes in allergic reactions, and thromboxanes in blood clotting.
• Peptides: This category includes bradykinin and angiotensin. Bradykinin causes blood vessels to dilate, leading to a drop in blood pressure, while angiotensin is involved in blood pressure regulation.
• Gasotransmitters: These include nitric oxide and carbon monoxide. Nitric oxide is a vasodilator, and carbon monoxide has various signaling roles in the body.

Functions

Autacoids have diverse functions in the body, including:

• Inflammation: Many autacoids, such as prostaglandins and leukotrienes, play a role in the inflammatory response.
• Pain: Autacoids like bradykinin and certain prostaglandins are involved in the sensation of pain.
• Allergic reactions: Histamine and leukotrienes are key mediators in allergic responses.
• Vasodilation and vasoconstriction: Autacoids such as nitric oxide and angiotensin regulate blood vessel diameter and blood pressure.
• Gastrointestinal function: Histamine stimulates gastric acid secretion.

Clinical Significance

Autacoids are targets for various drugs used to treat conditions like allergies, inflammation, pain, and hypertension. For example:

• Antihistamines block the action of histamine and are used to treat allergic reactions.
• NSAIDs inhibit the synthesis of prostaglandins and are used to reduce inflammation and pain.
• ACE inhibitors block the formation of angiotensin and are used to treat high blood pressure.

Related Pages

• Histamine
• Serotonin
• Prostaglandin
• Bradykinin
• Leukotriene
• Thromboxane
• Nitric oxide
• Angiotensin
• Antihistamine
• Nonsteroidal anti-inflammatory drug
• ACE inhibitor