Toxic and signaling effects of the anaesthetic lidocaine on rice cultured cells.

Most studies on anesthesia focus on the nervous system of mammals due to their interest in medicine. The fact that any life form can be anaesthetised is often overlooked although anesthesia targets ion channel activities that exist in all living beings. This study examines the impact of lidocaine on rice (Oryza sativa). It reveals that the cellular responses observed in rice are analogous to those documented in animals, encompassing direct effects, the inhibition of cellular responses, and the long-distance transmission of electrical signals. We show that in rice cells, lidocaine has a cytotoxic effect at a concentration of 1%, since it induces programmed reactive oxygen species (ROS) and caspase-like-dependent cell death, as already demonstrated in animal cells. Additionally, lidocaine causes changes in membrane ion conductance and induces a sharp reduction in electrical long-distance signaling following seedlings leaves burning. Finally, lidocaine was shown to inhibit osmotic stress-induced cell death and the regulation of Ca2+ homeostasis. Thus, lidocaine treatment in rice and tobacco (Nicotiana benthamiana) seedlings induces not only cellular but also systemic effects similar to those induced in mammals.

[Anaesthesia, a process common to all living organisms]. / L'anesthésie, un processus commun à tout le vivant.

Because of their interest in medicine, most studies of anaesthesia focus on the nervous system of metazoans, and the fact that any life form can be anaesthetised is often underlooked. If electrical signalling is an essential phenomenon for the success of animals, it appears to be widespread beyond metazoans. Indeed, anaesthesia targets Na+/Ca2+ voltage-gated channels that exist in a wide variety of species and originate from ancestral channels that predate eukaryotes in the course of evolution. The fact that the anaesthetic capacity that leads to loss of sensitivity is common to all phyla may lead to two hypotheses: to be investigated is the evolutionary maintenance of the ability to be anaesthetised due to an adaptive advantage or to a simple intrinsic defect in ion channels? The study of anaesthesia in organisms phylogenetically distant from animals opens up promising prospects for the discovery of new anaesthetic treatments. Moreover, it should also lead to a better understanding of a still poorly understood phenomenon that yet unifies all living organisms. We hope that this new understanding of the unity of life will help humans to assume their responsibilities towards all species, at a time when we are threatening biodiversity with mass extinction.

Title: L'anesthésie, un processus commun à tout le vivant. Abstract: Du fait de leur intérêt en médecine, la majeure partie des études actuelles sur les anesthésiques se concentrent sur le système nerveux des animaux et négligent le fait que toute forme de vie peut être anesthésiée. En effet, l'anesthésie cible des canaux dépendants du voltage, canaux qui existent dans un grand nombre d'espèces diverses et qui proviennent de canaux ancestraux antérieurs à l'apparition même des eucaryotes. La question demeure : le maintien au cours de l'évolution de la capacité à être anesthésié est-il dû à un avantage adaptatif ou à un simple défaut intrinsèque des canaux ioniques ? Le regain d'intérêt actuel pour les modèles non animaux ouvre l'espoir non seulement de découvrir de nouvelles molécules anesthésiantes, mais aussi de progresser dans notre connaissance fondamentale de ce phénomène encore mal compris.