Question

which is an example of an autocrine messenger?
leukotrienes
platelet - derived growth factor (pdgf)
prostaglandins
nitric oxide

Explanation:

To determine the autocrine messenger, we analyze each option:

• Leukotrienes: Involved in immune responses, often paracrine.
• Platelet - derived growth factor (PDGF): Acts on the same cell that secretes it (autocrine) and also on nearby cells (paracrine). It is a classic example of an autocrine messenger as cells like smooth muscle cells can secrete PDGF and respond to it themselves.
• Prostaglandins: Have paracrine and autocrine actions but are more associated with local (paracrine) signaling in inflammation.
• Nitric oxide: Primarily acts as a paracrine messenger (e.g., in blood vessel dilation).

Among these, PDGF is a well - known autocrine messenger as it can stimulate the cell that produces it.

Answer:

B. Platelet - derived growth factor (PDGF)