Electrical signalling goes bacterial

Abstract

WAT and mediate leptin-stimulated lipolysis is not surprising. However, Zeng and colleagues' study fills a gap in our understanding of precisely how organisms respond to an abundance of leptin. Their work also specifically demonstrates that sympathetic neurons projecting to WAT are a central trigger for leptin-mediated lipolysis. Of course, questions arise from these findings. Leptin is thought to signal through several brain areas 11 , but it remains unclear which neuronal networks sense increased blood leptin concentrations and control sympathetic relay stations to ultimately regulate lipolysis and fat mass. Notably, only half of the nerve fibres found in WAT expressed tyrosine hydroxylase, and the authors did not analyse the other half, nor the characteristics of the fat cells that the neurons innervate. Although their identities remain elusive, these neurons and fat cells hold the potential for further exciting discoveries. Future experiments should define the key brain areas that control sympathetic traffic to WAT and the molecular circuitry that controls lipolysis downstream of these effectors. Zeng et al. estimated that tyrosinehydroxylase-expressing neurons envelop between 3 and 12% of fat cells, a relatively sparse coverage. Nonetheless, the fact that optogenetic activation markedly increased lipolysis indicates that catecholamine signalling through neuro-adipose junctions has an important role in the control of lipid homeostasis. Given that leptin resistance is a common feature of obesity, it is to be hoped that this study will fuel further dissections of the brain-fat axis. It might also open a door to assessing the therapeutic potential of controlling catecholamine signalling in fat. ■

Gut Microbiota and Neuroplasticity

“…Gut bacteria can influence the excitability and electrophysiological properties of enteric neurons through ion-channel-related actions [43,44]. Furthermore, it has been demonstrated that bacteria communicate with each other via some of the same mechanisms and algorithms used by neurons in the brain (ion-channel-mediated electrical and chemical signaling, which underlie computation) [40,[45][46][47][48][49][50][51][52], performing cognitive tasks both as individual bacterial cells and as colonial super-organisms [53,54]. The rich behavioral and ion-channel-or bioelectricity-related repertoire of these two systems suggests that they, and the communication interface between them (which is increasingly being recognized as a crucial part of human physiology [41,55,56]), can be exploited to tackle fundamental questions of the bidirectional communication between neurons and bacteria.…”

On Having No Head: Cognition throughout Biological Systems

“…Already simple cells of bacteria enjoy sensory systems feeding into cognitive-behavioral circuits and showing many other neural features ( Miller and Koshland, 1977 ; Koshland, 1980 ; Lyon, 2015 ). Electrical long-distance signaling and information exchange via spatially propagating waves of potassium is synchronizing bacterial biofilms ( Beagle and Lockless, 2015 ; Nunes-Alves, 2015 ; Prindle et al, 2015 ). Integrated bacteria within the biofilm community appear to act as some kind of ‘microbial brain’.…”

Bacterial communication

“…To coordinate their intense social acitivity, research carried out in the last twenty years strongly suggests that bacteria typically engage in cellto-cell communication (Kolter and Greenberg, 2006;Mukherjee and Bassler, 2019). Increasing evidence points at the existence of intra-species, interspecies (Ley et al, 2008) and inter-kingdom communication (Hughes and Sperandio, 2008;Ismail et al, 2016), as well as dierent kinds of signaling systems including a form of electrical signals (Prindle et al 2015;Beagle and Lockless, 2015).…”