Transient Receptor Potential Channels in Sensory Neurons Are Targets of the Antimycotic Agent Clotrimazole

Abstract

Clotrimazole (CLT) is a widely used drug for the topical treatment of yeast infections of skin, vagina, and mouth. Common side effects of topical CLT application include irritation and burning pain of the skin and mucous membranes. Here, we provide evidence that transient receptor potential (TRP) channels in primary sensory neurons underlie these unwanted effects of CLT. We found that clinically relevant CLT concentrations activate heterologously expressed TRPV1 and TRPA1, two TRP channels that act as receptors of irritant chemical and/or thermal stimuli in nociceptive neurons. In line herewith, CLT stimulated a subset of capsaicin-sensitive and mustard oil-sensitive trigeminal neurons, and evoked nocifensive behavior and thermal hypersensitivity with intraplantar injection in mice. Notably, CLTinduced pain behavior was suppressed by the TRPV1-antagonist BCTC [(N-(-4-tertiarybutylphenyl)-4-(3-cholorpyridin-2-yl)tetrahydropyrazine-1(2H)-carboxamide)]and absent in TRPV1-deficient mice. In addition, CLT inhibited the cold and menthol receptor TRPM8, and blocked menthol-induced responses in capsaicin-and mustard oil-insensitive trigeminal neurons. The concentration for 50% inhibition (IC 50 ) of inward TRPM8 current was ϳ200 nM, making CLT the most potent known TRPM8 antagonist and a useful tool to discriminate between TRPM8-and TRPA1-mediated responses. Together, our results identify TRP channels in sensory neurons as molecular targets of CLT, and offer means to develop novel CLT preparations with fewer unwanted sensory side effects.

Mechanisms of Transient Receptor Potential Vanilloid 1 Activation and Sensitization by Allyl Isothiocyanate

“…Human embryonic kidney (HEK)-293 cells were seeded on 18-mm glass coverslips coated with poly(L-lysine) (0.1 mg/ml) and grown in Dulbecco's modified Eagle's medium containing 10% (v/v) fetal calf serum, 2 mM L-glutamine, 2 U/ml penicillin, and 2 mg/ml streptomycin at 37°C in a humidity controlled incubator with 10% CO 2 . HEK-293 cells were transiently transfected with either human (ENSG00000196689) or mouse (ENSMUSG00000005952) TRPV1 cDNAs cloned into the pCAGGSM2-IRES-green fluorescent protein (GFP) vector (Meseguer et al, 2008), using Trans-IT-293 reagents (Mirus, Madison, MI). All TRPV1 mutants were obtained using the standard polymerase chain reaction overlap extension technique (Ho et al, 1989) and verified by sequencing.…”

Ion channels involved in cold detection in mammals: TRP and non-TRP mechanisms

“…Most of these reactive compounds activating TRPA1 act by covalent binding to cysteine residues located in the intracellular N-terminal domain of the channel (Hinman et al 2006;Macpherson et al 2007a). A variety of other chemical agents exert their proalgesic action via TRPA1 activation, including formalin (McNamara et al 2007), the antimycotic agent clotrimazole (Meseguer et al 2008), the L-type calcium channel blockers 1,4-dihydropyridines (Fajardo et al 2008a), the general volatile anesthetics desflurane and isoflurane, the i.v. anesthetics propofol and etomidate (Matta et al 2008), and even the local anesthetic lidocaine (Piao et al 2009).…”

Chemical synthesis, pharmacological characterization, and possible formation in unicellular fungi of 3-hydroxy-anandamide

“…However, anandamide was shown to activate TRPV1 receptors when CB 1 receptors are blocked and/or when TRPV1 channels are sensitized by stimuli, like those occurring during inflammatory reactions (17,18,(35)(36)(37)(38)(39). TRPV1 sensitization likely occurs during candidiasis, because increased expression of vulvar TRPV1 receptors is observed during vulvodynia, a condition similar to that caused by candidiasis (14), and clotrimazole, a widely used antimycotic agent, was suggested to owe its inflamma- tory and algogenic side effects to its capability to activate TRPV1 receptors (40). On the other hand, several peripheral inflammatory conditions causing pain and/or itch are known to be accompanied by elevated levels of anandamide as an adaptive reaction to counteract these symptoms, as suggested by the observation that compounds that prolong the life span of anandamide by inhibiting its inactivation exert anti-inflammatory effects (15,16,(41)(42)(43)(44)(45)(46)(47).…”