Fig. 4: H2S activates the brain circuitry linked to danger integration.
From: Hydrogen sulfide as a potent predator-derived kairomone mediating fear-related responses in mice
a Localization of the three brain zones of interest in the mouse. Zone 1, the necklace glomeruli (NG) region of the Olfactory Bulb. Zone 2, Cerebrum with regions such as in the lateral amygdala (La; Bregma: −0.94 to −2.46 mm) and the ventromedial hypothalamus dorsal (VMHDM; Bregma: −1.34 to −1.94 mm) and zone 3, Cerebrum with the periaqueductal gray zone (PAG; Bregma: −2.7 to −3.16 mm). Brain regions by BioRender. b Neuronal activation in the NG region after stimulation with H2O (Control) and H2S (125 µM). Representative cFOS expression (yellow), axonal processes of olfactory neurons innervating glomeruli in the bulb (green), nuclei stained with DAPI (cyan) showing the neuronal stimulation induced by H2S; Zoom out to show the general view of cFOS/neuronal activation in zone 1 (a). Scale bars: 20 μm. c Representative cFOS (in red) immunostainings experiments performed in La, VMHDM (zone 2) and PAG (zone 3) regions after H2O (control) or H2S stimulation. Scale bars: 20 μm. d Quantification of the number of cFOS-positive cells (cFOS+) observed after H2O (white bars) and H2S (grey bars) stimulation for NG (n = 3 and n = 5 slices for H2O and H2S, respectively), La (n = 5 and n = 4 slices for H2O and H2S, respectively), VMHDM (n = 5 and n = 4 slices for H2O and H2S, respectively) and PAG regions (n = 10 and n = 8 for H2O and H2S, respectively). Data are represented as mean ± SEM with aligned dot plots and statistical analysis performed with an unpaired Student’s t test two-tailed, ***p < 0.001; **p < 0.01; ns for non-significant.
