What is the Difference Between Prostaglandin and Prostacyclin

The main difference between prostaglandin and prostacyclin is that prostaglandin is a physiologically active lipid compound of the family eicosanoids whereas prostacyclin (PGI2) is a type of prostaglandin that has functions in vasodilation, bronchodilation, and inhibit platelet aggregation.

Prostaglandin and prostacyclin are two types of physiologically important lipid compounds. They have diverse, hormone-like effects. Prostaglandins occur in almost all tissues of the human body. However, plants also produce jasmonate with a similar structure to prostaglandin. Moreover, these compounds regulate processes such as plant reproduction, fruit ripening, and flowering.

Key Areas Covered

1. What is Prostaglandin
   • Definition, Characteristics, Importance
2. What is Prostacyclin
   • Definition, Characteristics, Importance
3. Similarities Between Prostaglandin and Prostacyclin
   • Outline of Common Features
4. Difference Between Prostaglandin and Prostacyclin
   • Comparison of Key Differences

Key Terms

Prostacyclin, Prostaglandin

What is Prostaglandin

Prostaglandin (PG) is a group of physiologically active lipid compounds in the family of eicosanoids. It has a diverse hormone-like effect in animals. Prostaglandins are derived enzymatically from the fatty acid, arachidonic acid. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring. However, they are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives. In addition, different prostaglandins account for different biological activities. Moreover, the same prostaglandin may have different functions in different tissues. This occurs by the binding of prostaglandin with different receptors.

Figure 1: Eicosanoid Synthesis

Unlike enzymes that are endocrine, prostaglandins are autocrine or paracrine. They are not produced in specific sites but in many places of the human body. Furthermore, the main functions of prostaglandin include vasodilation, inhibiting the aggregation of platelets, involvement in inflammation, regulating the contraction of smooth muscle, etc.

What is a Prostacyclin

Prostacyclin or prostaglandin I2 or PGI2 is a type of prostaglandin. Its main function is to inhibit platelet activation and to be an effective vasodilator. Therefore, it prevents the formation of the platelet plug in primary hemostasis. Platelet plug formation is a part of blood clot formation. 

Figure 2: Prostacyclin

In addition, prostacyclin is an effective vasodilator in contrast to thromboxane, another eicosanoid. Both prostacyclin and thromboxane work together with the opposite of platelet aggregation.

When used as a drug, prostacyclin is also known as epoprostenol.

Similarities Between Prostaglandin and Prostacyclin

• Prostaglandin and prostacyclin are two types of physiologically active lipid compounds.
• They have diverse, hormone-like effects.
• They are derived enzymatically from the fatty acid arachidonic acid.
• Moreover, they are a subclass of eicosanoids.
• Structurally, they contain 20 carbon atoms, including a 5-carbon ring

Difference Between Prostaglandin and Prostacyclin

Definition

Prostaglandin refers to any of a group of compounds with varying hormone-like effects, notably the promotion of uterine contractions, while prostacyclin refers to a compound of the prostaglandin type produced in arterial walls, which functions as an anticoagulant and vasodilator.

Relationship

Usually, prostaglandin is a lipid compound that belongs to the family eicosanoid while prostacyclin is a type of prostaglandin.  

Type of Action

Prostaglandins may have different physiological roles in the body while prostacyclin undergoes vasodilation and inhibition of the platelet plug formation.  

Conclusion

In brief, prostaglandin is a type of physiologically active lipid compound. It belongs to the family of eicosanoids. Moreover, different prostaglandins have different physiological functions in different tissues including vasodilation, smooth muscle contraction, etc. Prostaglandins also have diverse effects in different tissues as hormones. But, they are not endocrine. Prostacyclin is a type of prostaglandin or PGI2. In addition, the main function of prostacyclin is to undergo vasodilation and inhibition of platelet plug formation. Therefore, the main difference between prostaglandin and prostacyclin is their function.

References:

1. Wikimedia Foundation. (2022, July 4). Prostaglandin. Wikipedia. Retrieved September 1, 2022.
2. Wikimedia Foundation. (2022, August 4). Prostacyclin. Wikipedia. Retrieved September 1, 2022.

Image Courtesy:

1. “Eicosanoid synthesis” By Jfdwolff – Own Work (CC BY-SA 3.0) via Commons Wikimedia
2. “Prostacyclin-2D-skeletal” By Benjah-bmm27 – Own Work (Public Domain) via Commons Wikimedia