A photoswitchable inhibitor of TREK channels controls pain in wild-type intact freely moving animals

Abstract

By endowing light control of neuronal activity, optogenetics and photopharmacology are powerful methods notably used to probe the transmission of pain signals. However, costs, animal handling and ethical issues have reduced their dissemination and routine use. Here we report LAKI (Light Activated K+ channel Inhibitor), a specific photoswitchable inhibitor of the pain-related two-pore-domain potassium TREK and TRESK channels. In the dark or ambient light, LAKI is inactive. However, alternating transdermal illumination at 365 nm and 480 nm reversibly blocks and unblocks TREK/TRESK current in nociceptors, enabling rapid control of pain and nociception in intact and freely moving mice and nematode. These results demonstrate, in vivo, the subcellular localization of TREK/TRESK at the nociceptor free nerve endings in which their acute inhibition is sufficient to induce pain, showing LAKI potential as a valuable tool for TREK/TRESK channel studies. More importantly, LAKI gives the ability to reversibly remote-control pain in a non-invasive and physiological manner in naive animals, which has utility in basic and translational pain research but also in in vivo analgesic drug screening and validation, without the need of genetic manipulations or viral infection.

Microglial P2X4 receptors are essential for spinal neurons hyperexcitability and tactile allodynia in male and female neuropathic mice

“…This was demonstrated through in vivo recordings of the response of spinal WDR neurons to nociceptive electrical skin stimulation of their peripheral receptive field in the hind paw of anesthetized animals. 36 , 37 , 38 Associated with the mechanical hypersensitivity observed in male and female naive P2X4KI mice ( Figures 1 and S1 ), we demonstrate a significant decrease in the threshold to elicit a C-fiber response in WDR neurons of sham P2X4KI mice compared to sham WT mice in both males and females. This is in accordance with previous studies in both rats and mice showing increased WDR hyperexcitability in pathological model of persistent pain.…”

Spatiotemporally Precise Optical Manipulation of Intracellular Molecular Activities

“…Photoswitchable inhibitors of other cytoskeletal proteins or cellular enzymes can be paired with CW‐RPOC for precision manipulation of a wide range of biomolecules in cells. [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ] This approach would lead to new insights into cellular function through location‐specific manipulation of biomolecular activities, subcellular activation of drugs, and precisely controlled release.…”