Ibuprofen Inhibits Rat Brain Deamidation of Anandamide at Pharmacologically Relevant Concentrations. Mode of Inhibition and Structure-Activity Relationship

• Published in: The Journal of pharmacology and experimental therapeutics 1997-11, Vol.283 (2), p.729-734
• Main Authors: Fowler, Christopher J., Tiger, Gunnar, Stenström, Anders
• Format: Article
• Language: English
• Subjects: Animals; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Arachidonic Acids - metabolism; Brain - metabolism; Endocannabinoids; Ibuprofen - pharmacology; Polyunsaturated Alkamides; Rats; Structure-Activity Relationship
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1016/S0022-3565(24)37038-7

The ability of rat brain (minus cerebellum) homogenates to deamidate arachidonyl ethanolamide (anandamide) was determined with a custom-synthesized substrate, arachidonyl ethanolamide-[1- 3 H] ([ 3 H]anandamide). Conditions whereby initial velocities were measured were established. The homogenates deamidated anandamide with a K m value of 0.8 μM and a V max value of 1.73 nmol · (mg protein) −1 · min −1 . The deamidation of 2 μM [ 3 H]anandamide was inhibited by phenylmethylsulfonyl fluoride and arachidonyl trifluoromethyl ketone with IC 50 values of 3.7 and 0.23 μM, respectively. Ibuprofen inhibited anandamide deamidation in a mixed fashion, with K i and K′ i values of 82 and 1420 μM. At an anandamide concentration of 2 μM, the IC 50 values (in μM) of a series of compounds related in structure to ibuprofen were as follows: suprofen, 170; ibuprofen, 270; fenoprofen, 480; naproxen, 550; ketoprofen, 650; diclofenac, ∼1000. Sulindac produced 27% inhibition at a concentration of 1000 μM, whereas isobutyric acid, hydrocinnamic acid, acetylsalicylic acid and acetaminophen were essentially inactive at concentrations ≤ 1 mM. We conclude that ibuprofen inhibits anandamide deamidation at pharmacologically relevant concentrations and that there is some specificity to the inhibition produced by ibuprofen and suprofen.