Genistein Inhibits the activation of Transient Receptor Potential Vanilloid-1 and Ankryn-1 ion channels in in vitro, in silico and in vivo pain mouse models

Transient Receptor Potential (TRP) ion channels are non-selective cation channels expressed on sensory nerve terminals and sensory neurons. The TRP Vanilloid1 (TRPV1) and TRP Ankyrin1 (TRPA1) receptors play a prominent role in pain sensation. TRPV1 is activated by high temperature (>43°C), capsaicin and resiniferatoxin (RTX), TRPA1 by low temperature (<17°C), mechanical stimuli, allyl isothiocyanate and formaldehyde. Our research group previously described that 17β-estradiol (E2) sensitizes the TRPV1 ion channel via TrkA receptors. Because of the broad spectrum of side effects of estrogen replacement, it is important to investigate another replacement therapy options. The phytoestrogen genistein (GEN) is a soybean isoflavone with positive effects in prostate and breast cancer protection, regulation of ROS and cytokine overproduction, diabetic neuropathy. Our aim was to investigate whether GEN could exert similar effects on the activation of TRPV1 ion channel as E2 treatment. In vitro fluorescence Ca2+ influx was measured in TRPA1 and TRPV1 receptor-expressing CHO cells, and changes in receptor expression were examined in sensory neuron cultures after GEN treatment. In vivo RTX-induced hyperalgesia and formalin-induced allodynia models were used to investigate the effects of GEN. Weproved the mechanism of action of GEN on TRPA1 and TRPV1 receptors by in silico docking. In contrast to our previous results obtained with E2, GEN significantly reduced Ca2+-influx in TRPA1- and TRPV1-expressing CHO cells in a concentration-dependent manner, and overnight GEN treatment significantly increased the TRPV1 receptor expression. In an RTX-induced hyperalgesia model, we demonstrated that GEN decreased the mechanical and thermal hyperalgesia. In a formalin-induced allodynia model GEN reduced the time spent with nocifensive behavior. In silico docking experiments could prove that GEN could bind into the channel pores of TRPV1 and TRPA1 ion channel. GEN significantly inhibited the activation of TRPA1 and TRPV1 ion channels in contrast to previously described sensitizing effect of E2. In mouse models, it has analgesic and anti-inflammatory effects. In menopause, In menopause, GEN can potentially be used as hormone replacement therapy, as it does not have the hormonal effects of E2. Support: TKP2021-EGA-16, TKP2021-EGA-13, NKFIH-138936, RRF-2.3.1-21-2022-00015, KTIA_NAP_20017-1.2.1- NKP-2017-00002