Prostaglandin

Any of a group of physiologically active substances having diverse hormonelike effects in animals are called prostaglandin. It was very first discovered in human semen in 1935 by the Swedish physiologist Ulf von Euler. He named it prostate because he thought that they were secreted by the prostate gland. 

Further, a detailed study on the prostate gland was done in the 1960s to 1970 by Swedish biochemists Sune K. Bergström and Bengt Ingemar Samuelsson and British biochemist Sir John Robert Vane. All three of them were awarded the Nobel prize for their study. 

Prostaglandin Synthesis

Prostaglandins are made up of unsaturated fatty acids that contain a cyclopentane ring i.e. 5-Carbon ring and they are derived from 20-carbon, straight-chain, polyunsaturated fatty acid precursor arachidonic acid. Here arachidonic acid is a key component of phospholipids, which itself is an integral component of the cell membrane. 

There are so many activities that cause the formation and release of prostaglandin like different stimuli, including various hormonal, chemical, or physical agents, a chain of events is set in motion. All these stimuli lead to the activation of an enzyme called phospholipase A2 either in a direct or indirect way. Further, this enzyme helps in catalysing the release of arachidonic acid from phospholipid molecules. 

Based on the stimulus type and presence of different enzymes, there is a divergence of the pathway of arachidonic acid.

Functions of Prostaglandins

Some of the major function of prostaglandins are listed below:

A. In plants also, they synthesize molecules similar in structure to prostaglandins, including jasmonic acid which help in processing functions like plant reproduction, fruit ripening, and flowering. 

B. Level or concentration of prostaglandins affect the level of blood pressure. 

C. Due to structural differences present in prostaglandin affect different biological activities of the body. 

D. Some prostaglandin work in autocrine fashion, stimulating reactions in the same tissue in which they are synthesized, and others act in a paracrine fashion. 

E. Prostaglandin also mediates functions like inflammatory or anti-inflammatory processes and therefore that can be harmful or not harmful.

F. They also participate in functions like contraction and relaxation of smooth muscle, the dilation and constriction of blood vessels.

G. Prostaglandin also shows effect on influencing the release of adrenergic neurotransmitters from nerve endings, possibly by a direct mechanism. 

Prostaglandins Examples

There are different types of prostaglandins, they are: including prostaglandin I2 (prostacyclin; PGI2), prostaglandin D2 (PGD2), prostaglandin E2 (PGE2), and prostaglandin F2α (PGF2α). Each of these have their specific function. 

Function of different Prostaglandins are:

A. Prostaglandin I2:

They perform functions like vasodilation, also inhibit platelet aggregation, bronchodilation. 

B. Prostaglandin D2: 

They are majorly  produced by mast cells; recruits Th2 cells, eosinophils, and basophils and they majorly critical to development of allergic diseases such as asthma. 

C. Prostaglandin E2: 

They perform smooth muscle contraction of the gastrointestinal tract.  

D. Prostaglandin F2α:

Their secretion helps in uterus contraction and urinary bladder contraction.