PGE is a bronchodilator, whereas PGF acts as a constrictor of bronchial smooth muscles. Thus, PGE and PGF oppose the actions of each other in the lungs. PGE1and PGE2 are used in the treatment of asthma.
Macrophages secrete PGE, which decreases the immunological functions of B and T-lympocytes.
PGE inhibits gastric secretion. PGS are used for the treatment of gastric ulcers. However, PGS stimulates pancreatic secretion and increases the motility of intestine which often causes diarrhoea.
PGE2 and PGF2 are used for medical termination of pregnancy and induction of labour. Pain and fever Pyrogens (fever-producing agents) promote prostaglandin biosynthesis, leading to formation of PGE2 in the hypothalamus, the site of regulation of body temperature. PGE2, along with histamine and bradykinin, causes pain.
PGE2 induces symptoms of inflammation (redness, swelling, edema, and so on)due to arteriolar vasodilation.
PGE, PGA, and PGI2 are vasodilators in function. This results in increased blood flow and decreased peripheral resistance to lower the blood pressure. PGS serve as agents in the treatment of hypertension.
Prostaglandins have many biochemical functions, which are different in different tissues. PGs also bring about opposing actions in the same tissue.
Prostaglandins are classified mainly into two groups shown in Table 4.5: Prostanoids are further subdivided into three groups: Structure of prostaglandins: Figure 4.8 Structure and Biosynthetic Pathway of Prostaglandins Table 4.5 Structure of Prostaglandin Prostaglandin Substituent Group Structure PGA Double bond C10—C11keto group C9 PGB Double bond C8—C12keto group C9 PGC Double bond C11—C12keto group C9 PGD —OH…
Prostaglandins are derivatives of a hypothetical 20 carbon fatty acid, namely prostanoic acid and hence known as prostaglandins or eicosanoids. The structure and biosynthetic pathway of prostaglandins are shown in Figure 4.8.
INTRODUCTION Prostaglandins (PG) are a group of biologically active lipids. They are widely present in mammalian tissues and body fluids. Though they were initially found in the seminal fluid, it is now known that they are present in all tissues. PGs are considered as hormones since their action appears to be confined to the cells…