σ₁ Receptor is important for microglial reaction toward injury.

(A) Percentage of microglia reacting to injury in DMSO compared to DTG and PB190 treated zebrafish larvae. (B) Speed of microglia branch extension and retraction in DMSO, DTG and PB190 treated embryos. (C) Time course of microglia (pU1::Gal4UAS::TagRFP) reaction toward injuries in DMSO treated embryos. (C1) before, (C2) 10 min after and (C3) 90 min after cut. (D) Time course of microglia (pU1::Gal4UAS::TagRFP) reaction toward injuries in PB190 treated embryos. (D1) before, (D2) 10 min after and (D3) 90 min after cut. (E) Dorsal views of a 3,5 dpf larval brain showing the time course of a Ca²⁺ wave (betaactin::GCaMP3.1) forming upon central brain injury in PB190 treated zebrafish larvae. (E1) before, (E2) 2 s after and (E3) 12 s after cut. Scalebar for all images 20 µm. Images (C) and (D) were obtained using an Andor Spinning Disk Confocal with a 40x/NA1.15 objective. Images (E) were produced using an Olympus FV 1000 with a 40x/NA1.15 objective. Statistical analysis was performed using a KruskalWallis test with a Dunn’s multiple comparison test.

Treatment with σ₁ agonist does not lead to a clearance phenotype.

(A) Acridine orange staining of 3,5 dpf zebrafish larvae treated with DMSO. (B) Acridine orange staining of 3,5 dpf zebrafish larvae treated with DTG. (C) Acridine orange staining of 3,5 dpf zebrafish larvae treated with PB190. (D) Quantification of uncollected acridine orange positive cells in a 3,5 dpf larvae treated with DMSO, DTG or PB190. Scalebar for all images 20 µm. All images were obtained using an Andor Spinning Disk Confocal with a 20x/NA0.7 objective. Statistical analysis was performed using a Kruskal-Wallis test with a Dunn’s multiple comparison test.

The σ₁ receptor allows for microglia to leave the site of damage.

(A) σ₁-Mo mediated knock-down on protein level. (B) Quantification of time until first microglia cell leaves the site of injury in DMSO compared to PB190 treated embryos with larvae lacking their σ₁ receptor. (C) Percentage of microglia reacting to an injury in DMSO and PB190 treated compared to larvae lacking their σ₁ receptor and PB190 treated σ₁ knock-down embryos. Statistical analysis was performed using a Kruskal-Wallis test with a Dunn’s multiple comparison test.