**Question:** Anti-inflammatory action of glucocorticoids is mainly due to

A. Suppression of cytokine synthesis
B. Inhibition of phospholipase A2
C. Activation of glucocorticoid receptors
D. Inhibition of nitric oxide production

**Core Concept:** Glucocorticoids are a class of corticosteroids that have potent anti-inflammatory, immunosuppressive, and anti-proliferative effects. Their anti-inflammatory action is primarily attributed to their actions on the immune system and inflammation-related molecules.

**Why the Correct Answer is Right:** The correct answer is A: Suppression of cytokine synthesis. Glucocorticoids exert their anti-inflammatory effects by modulating the production of various inflammatory mediators, such as cytokines, chemokines, and prostaglandins. Cytokines are small proteins that play a crucial role in the immune response, inflammation, and cell communication. By suppressing the synthesis of cytokines, glucocorticoids help reduce inflammation and immune system activation.

**Why Each Wrong Option is Incorrect:**

B. Inhibition of phospholipase A2 (PLA2) is not the primary mechanism of glucocorticoid anti-inflammatory action. PLA2 is an enzyme involved in the initiation of arachidonic acid cascade, which leads to the synthesis of prostaglandins and leukotrienes, but not cytokines.

C. Activation of glucocorticoid receptors is part of their overall mechanism but is not solely responsible for their anti-inflammatory effect. Glucocorticoid receptors are steroid hormone receptors that bind glucocorticoids and modulate gene expression, leading to anti-inflammatory and immunosuppressive actions.

D. Inhibition of nitric oxide (NO) production is not the primary mechanism of glucocorticoid anti-inflammatory action. Nitric oxide is a free radical involved in various physiological processes, including vasodilation, neurotransmission, and immune system regulation. Glucocorticoids can modulate NO production, but their primary mechanism is related to cytokine synthesis inhibition.

**Clinical Pearl:** Glucocorticoids are essential drugs in the management of various inflammatory and autoimmune disorders. Understanding their anti-inflammatory mechanisms, including the suppression of cytokine synthesis, is crucial for effective therapy. Adequate knowledge of these mechanisms allows physicians to prescribe glucocorticoids appropriately, minimizing side effects and achieving optimal therapeutic outcomes.