True statement about cyclooxygenase -2 is:
**Core Concept**
Cyclooxygenase-2 (COX-2) is an enzyme involved in the conversion of arachidonic acid to prostaglandin H2, playing a crucial role in inflammation and pain. It is primarily responsible for the production of pro-inflammatory prostaglandins in the body.
**Why the Correct Answer is Right**
COX-2 is induced in response to various stimuli, including cytokines, growth factors, and stress, leading to an increase in prostaglandin production. This results in the promotion of inflammation, pain, and fever. COX-2 inhibitors, such as celecoxib, have been developed to selectively block the activity of this enzyme, reducing the production of pro-inflammatory prostaglandins while minimizing the gastrointestinal side effects associated with traditional nonsteroidal anti-inflammatory drugs (NSAIDs).
**Why Each Wrong Option is Incorrect**
**Option A:** COX-2 is not involved in the production of thromboxane A2, which is actually produced by COX-1. COX-2 is primarily responsible for the production of prostaglandins.
**Option B:** COX-2 is not an inducible isoform of COX-1. While COX-1 is constitutively expressed in most tissues, COX-2 is induced in response to various stimuli.
**Option C:** COX-2 is not responsible for the production of leukotrienes. Leukotrienes are produced by the enzyme lipoxygenase, not cyclooxygenase.
**Clinical Pearl / High-Yield Fact**
COX-2 inhibitors have been associated with an increased risk of cardiovascular events, including myocardial infarction and stroke, due to their effects on prostaglandin production and vascular tone.
**Correct Answer: C. COX-2 is induced in response to various stimuli, including cytokines, growth factors, and stress, leading to an increase in prostaglandin production.**