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

Cyclooxygenase-3 (COX-3) is a putative splice variant of the COX-1 enzyme, encoded by the PTGS1 gene, which retains intron 1 in its mRNA sequence (Chandrasekharan et al., 2002, PNAS). Originally identified in canine cerebral cortex, it was proposed as the primary central nervous system target for acetaminophen (paracetamol) and other antipyretic analgesics that lack significant peripheral anti-inflammatory activity (Botting, 2006, Journal of Thermal Biology). In humans, the existence of a functional COX-3 protein is controversial because the retention of intron 1 introduces a premature stop codon and a frame shift, leading to questions regarding the production of a full-length enzyme (Daba et al., 2014, Human & Experimental Toxicology). Despite this genomic discrepancy, the term 'central cyclooxygenase activity' is frequently used to describe the specific biochemical pathway through which acetaminophen modulates pain and fever without the gastrointestinal or anti-platelet side effects typical of traditional NSAIDs (Graham et al., 2013, British Journal of Clinical Pharmacology). Research continues to investigate whether this activity stems from a specific protein isoform or a unique biochemical environment within the brain that renders central COX enzymes more sensitive to certain inhibitors (Simmons et al., 2004, Pharmacology & Therapeutics).

Other names

COX-1bCOX-1vProstaglandin-endoperoxide synthase 1 splice variantCentral cyclooxygenase

Inhibition of prostaglandin synthesis within the central nervous system, likely through the reduction of the enzyme's active site or interference with the peroxidase catalytic cycle (Ayoub et al., 2004, PNAS).