Prostaglandins and Autocoids

Front

What are autocoids?

Back

Substances having intense biological activity but acting locally at the site of synthesis and release; they differ from hormones in that they are produced in a cell-specific manner.

Front

Name the classifications of autocoids.

Back

1. Amine autocoids: Histamine, 5-HT 2. Lipid-derived autocoids: Prostaglandins, leukotrienes, PAF 3. Peptide autocoids: Plasma kinins (Bradykinin, Kallidin), Angiotensin, Cytokines, Gastrin, VIP, Somatostatin.

Front

What is the role of cyclo-oxygenase (COX) enzymes in prostaglandin synthesis?

Back

COX enzymes are involved in the conversion of arachidonic acid into prostaglandins and are present in most cells, participating in physiological functions such as secretion of mucus and maintenance of renal functions.

Front

Differentiate between COX-1 and COX-2.

Back

COX-1 is constitutive and maintains normal physiological functions, while COX-2 is inducible and is expressed during inflammation.

Front

What are the actions of PGE2 and PGI2 in the cardiovascular system?

Back

PGE2 and PGI2 cause vasodilation in most vascular beds, leading to a decrease in blood pressure.

Front

What is the role of TXA2 in the cardiovascular system?

Back

TXA2 causes vasoconstriction and promotes platelet aggregation.

Front

How do prostaglandins affect the uterus?

Back

Prostaglandins (PGE2 and PGF2α) contract the uterus, with PGF2α being more potent, and play a role in the initiation and progression of labor.

Front

What are the gastrointestinal actions of PGE2?

Back

PGE2 increases mucus production, enhances mucosal blood flow, and decreases gastric acid secretion, contributing to secretory diarrheas.

Front

What is the effect of prostaglandins on the kidneys?

Back

Prostaglandins promote natriuresis and renal vasodilation, inhibiting ADH action and tubular reabsorption, thus facilitating water clearance.

Front

What are the central nervous system effects of prostaglandins?

Back

Prostaglandins can cause sedation, rigidity, behavioral changes, and a marked rise in body temperature.