Diclofenac, a nonsteroidal anti‐inflammatory drug, is an antagonist of human TRPM3 isoforms

Abstract

The effects of diclofenac (Dic), an acetic acid derivative‐type nonsteroidal anti‐inflammatory drug, were examined on the function of transient receptor potential (TRP) melastatin (TRPM) 3 (TRPM3) in human embryonic kidney 293 cell‐line (HEK293) cells with recombinant human TRPM3 isoforms (TRPM31325, TRPM3‐3, TRPM3‐9, and TRPM3‐S) and in a neuroblastoma cell line human neuroblastoma IMR‐32 cells (IMR‐32 cells) derived from human peripheral neurons. TRPM3 responses evoked by pregnenolone sulfate (PregS) were effectively inhibited by Dic in a concentration‐dependent manner in Ca2+ measurement and electrophysiological assays. The apparent IC 50 for PregS‐induced Ca2+ response of TRPM31325, TRPM3‐3, and TRPM3‐9 was calculated to be 18.8, 42.5, and 7.1 μmol/L, respectively. The TRPM3‐dependent Ca2+ responses evoked by nifedipine, another TRPM3 agonist, were also significantly inhibited by Dic. In contrast, aceclofenac, an acetoxymethyl analog of Dic, had no effects on PregS‐induced TRPM3 responses. Constitutive channel activity of TRPM3‐S without TRPM3 agonists was substantially inhibited by Dic, ruling out the possibility of interaction of Dic against TRPM3 agonists to the channel binding sites. Moreover, Dic reversibly inhibited TRPM3 single‐channel activity recorded in excised outside‐out patches without affecting the channel conductance. In differentiated neuronal IMR‐32 cells with endogenous TRPM3, Dic inhibited PregS‐evoked Ca2+ responses with an apparent IC 50 of 17.1 μmol/L. Taken together, our findings demonstrate that Dic inhibits human TRPM3 without interacting with the channel pore.

Primidone inhibits TRPM3 and attenuates thermal nociception in vivo

“…Of them, mefenamic acid, 11 progesterone and dihydrotestosterone, 15 voriconazole, 35 and diclofenac 29 are approved drugs, but inhibit TRPM3 only at concentrations that vastly exceed plasma concentrations that are reached in their cognate therapeutic fields. Other drug-like compounds, such as the flavonoids naringenin, hesperetin, eriodictyol, liquiritigenin, or isosakuranetin exhibited a higher potency and promising selectivity.…”

Antinociceptive Effects of Isosakuranetin in a Rat Model of Peripheral Neuropathy

“…As stated above, the natural-occurring TRPM3 blocker isosakuranetin is able to reduce acute heat nociception and inflammatory hyperalgesia [10]. Primidone and diclofenac have been shown to be TRPM3 blockers and are found to be effective in thermal and inflammatory pain [21,22]. It is of importance that recently a synthetic compound CIM0216 has been characterized as a TRPM3 activator, and the application of CIM0216 elicited the release of the peptides calcitonin gene-related peptide from sensory nerve terminals and induces a TRPM3-dependent nocifensive behavior [23], supporting the important role of TRPM3 in pain processing.…”

Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants—Possible Involvement in Pain Alleviation

“…Nonselective cation channels in the rat exocrine pancreas were suppressed by flufenamic acid and mefenamic acid but not indomethacin, aspirin and ibuprofen [119]. There was a distinction in depressing TRP melastatin-3 channels between diclofenac and aceclofenac [94]. Although NSAIDs not only suppress but also activate TRP ankyrin-1 channels, this activation also differed in magnitude among NSAIDs [120].…”