Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.29.122432v1?rss=1 Authors: Lanz, A. J., Gordon, G. R., Bains, J. S. Abstract: Chloride (Cl-) dynamics shape inhibitory neurotransmission in the brain. In the hypothalamus, GABA signalling onto corticotropin-releasing hormone (CRHPVN) neurons can switch from inhibitory to excitatory during stress. Although Cl- fluctuations mediate this stress-dependent shift in GABA signalling, the underlying Cl- dynamics are poorly understood. Here, using a novel optogenetic strategy to load intracellular Cl- using halorhodopsin, we demonstrate that KCC2 rapidly restores Cl- setpoints in CRHPVN neurons from naive animals, but that this process is slowed following stress. Further, we report that somatic Cl- homeostasis remains intact after stress. Our results strongly support the idea that KCC2 functions primarily to maintain Cl- setpoints and that inhibitory synapses onto dendritic and somatic compartments of CRHPVN neurons are differentially regulated during stress. Copy rights belong to original authors. Visit the link for more info