Autocoids are locally-acting substances that are produced in various tissues and organs of the body. These substances are involved in a wide range of physiological processes, including inflammation, pain, blood clotting, and regulation of blood pressure. Autocoids are important mediators of many biological responses and have both beneficial and detrimental effects on the body.
Autocoids can be classified into several groups based on their chemical structure and biological activity. Some of the major groups of autocoids include:
Prostaglandins: Prostaglandins are lipid molecules that are synthesized from arachidonic acid by the action of cyclooxygenase enzymes. Prostaglandins play important roles in inflammation, pain, and fever. They also regulate blood pressure and blood clotting.
Leukotrienes: Leukotrienes are also lipid molecules that are synthesized from arachidonic acid by the action of lipoxygenase enzymes. Leukotrienes are involved in inflammation, bronchoconstriction, and allergy.
Histamine: Histamine is a nitrogen-containing compound that is synthesized from the amino acid histidine by the action of the enzyme histidine decarboxylase. Histamine is involved in allergic reactions, inflammation, and gastric acid secretion.
Serotonin: Serotonin is a neurotransmitter that is synthesized from the amino acid tryptophan. Serotonin is involved in mood regulation, sleep, and pain perception. It is also a potent vasoconstrictor and can regulate blood pressure.
Bradykinin: Bradykinin is a peptide that is generated from a precursor protein called kininogen by the action of the enzyme kallikrein. Bradykinin is involved in pain, inflammation, and regulation of blood pressure.
Nitric oxide: Nitric oxide is a gas molecule that is synthesized from the amino acid arginine by the action of the enzyme nitric oxide synthase. Nitric oxide is involved in regulation of blood pressure, blood flow, and inflammation.
Adenosine: Adenosine is a nucleoside that is produced from the breakdown of ATP. Adenosine is involved in regulation of blood flow, inflammation, and sleep.
Autocoids play important roles in maintaining homeostasis in the body, but their dysregulation can lead to various pathological conditions. For example, excessive production of prostaglandins can lead to inflammation and pain, while excessive production of histamine can lead to allergic reactions. Understanding the roles of autocoids in different physiological processes is important for the development of novel therapeutics for various diseases.Lacture notes downloading, Hand written notes, Pharmacy notes, MBBS notes, Study material, Dental study material, study material PDF, study material PPT, study Lacture notes, Study science notes, Drugs name, free study material PPT, PDF download Free, paramedical study notes
Autocoids are a class of signaling molecules that are produced and released by cells in response to various stimuli. Unlike hormones, which are secreted into the bloodstream and travel long distances to reach their target cells, autocoids act locally and exert their effects near the site of their synthesis.
Autocoids include several types of molecules, such as prostaglandins, leukotrienes, histamine, serotonin, and bradykinin. These molecules are synthesized and released from various cells, including macrophages, endothelial cells, mast cells, platelets, and nerve cells. They can act on nearby cells of the same or different types, including smooth muscle cells, immune cells, nerve cells, and epithelial cells.
Autocoids play important roles in many physiological processes, including inflammation, pain, fever, blood clotting, vascular homeostasis, bronchial constriction, gastrointestinal motility, and nervous system functioning. They also have pathological implications in various diseases, such as asthma, arthritis, allergic reactions, cardiovascular disease, and cancer.
Prostaglandins, for example, are produced by the cyclooxygenase (COX) enzymes from arachidonic acid and have various functions depending on the subtype and location. For instance, they can induce inflammation by promoting vasodilation, increased vascular permeability, and immune cell recruitment. They also promote pain by sensitizing nerve endings and enhancing histamine release. Moreover, they have roles in blood clotting, ovulation, and labor.
Leukotrienes, on the other hand, are produced by the lipoxygenase enzymes from arachidonic acid and are mainly involved in allergic and inflammatory reactions. They can cause bronchoconstriction in asthma, increase vascular permeability, and induce smooth muscle contraction.
Histamine is mainly produced by mast cells and plays a key role in allergic reactions and inflammation by promoting vasodilation, increased vascular permeability, and smooth muscle contraction.
Serotonin, also known as 5-hydroxytryptamine (5-HT), is produced by enterochromaffin cells in the gut and neurons in the brain. It regulates various physiological functions, such as gastrointestinal motility, vasoconstriction, and mood.
Bradykinin is produced by the kallikrein enzymes and plays a role in inflammatory responses by promoting vasodilation, smooth muscle contraction, and increased vascular permeability.
Autocoids are well-known targets for many drugs that aim to modulate their effects or production. For instance, nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen inhibit COX enzymes and reduce prostaglandin production, thus providing pain relief and anti-inflammatory effects. Antihistamines block histamine receptors and reduce allergic symptoms, while leukotriene receptor antagonists inhibit the effects of leukotrienes in asthma. Overall, the modulation of autocoids remains an active area of research and therapeutic development