Prostaglandin-endoperoxide synthase 1 variant (COX-3) (COX-3)

Cyclooxygenase-3 (COX-3) is a splice variant of the COX-1 (PTGS1) enzyme, characterized by the retention of intron 1 in its mRNA transcript (Chandrasekharan et al., 2002, PNAS). Originally identified in canine cerebral cortex, it was proposed as the primary therapeutic target for acetaminophen (paracetamol) and other antipyretic analgesics that lack significant peripheral anti-inflammatory activity (Simmons et al., 2002, PNAS). COX-3 is expressed predominantly in the central nervous system, where it facilitates the synthesis of prostaglandins involved in pain and fever induction. Its high sensitivity to acetaminophen explains the drug's clinical profile, distinguishing it from traditional nonsteroidal anti-inflammatory drugs (NSAIDs) that target COX-1 and COX-2. However, the functional relevance of COX-3 in humans is controversial, as the human PTGS1 splice variant contains a frame-shift mutation that likely results in a non-functional protein (Graham & Scott, 2005, American Journal of Therapeutics). Despite this, the COX-3 hypothesis remains a significant pharmacological model for understanding central prostaglandin modulation (Botting, 2006, Thrombosis Research).

Other names

Cyclooxygenase-3COX-3COX-1bCyclooxygenase-1 variantPTGS1 variantAcetaminophen-sensitive cyclooxygenase

Inhibition of the cyclooxygenase activity of the COX-1 splice variant (COX-3) within the central nervous system, leading to reduced synthesis of pro-pyretic and pro-nociceptive prostaglandins such as PGE2.