Fig. 1: Peripheral administration of lactate reverses the reduction of adult hippocampal neural progenitor cells (NPCs) proliferation and survival in the corticosterone model of depression.

a Timeline showing the experimental design for measuring NPCs proliferation. Mice received a single subcutaneous injection of corticosterone (20 mg/kg) or vehicle (2% DMSO in sesame oil) on each of 21 consecutive days. Together with corticosterone treatment, mice received intraperitoneal injections of vehicle (0.9% NaCl) or lactate (1 g/kg) daily for 21 days. On the last day of treatment, mice also received BrdU injections. b Confocal maximal projection micrographs of hippocampal sections immunostained for BrdU. Inset: higher magnification confocal micrograph of a BrdU-immunolabeled group of cells. c Analysis of NPCs proliferation. Histogram of the number of BrdU⁺ cells in the granule cell layer of the dentate gyrus. d Timeline showing the experimental design for measuring NPCs survival. BrdU administration was performed the day before the start of the treatment. Then, mice received a single subcutaneous injection of corticosterone (20 mg/kg) or vehicle (2% DMSO in sesame oil) on each of 14 consecutive days. Together with corticosterone treatment, mice received intraperitoneal injections of vehicle (0.9% NaCl) or lactate (1 g/kg) daily for 14 days. e Analysis of NPCs survival. Histogram of the number of BrdU⁺ cells in the granule cell layer of the dentate gyrus. f Analysis of adult neurogenesis in the mouse dentate gyrus. Histogram showing the number of BrdU⁺ NeuN⁺ cells per mm³. g Confocal images of cells double-labeled for BrdU (red) and NeuN (green) and counterstained with DAPI (blue) in the dentate gyrus. The right panel corresponds to a higher magnification view of the boxed region shown in the merged image. Solid arrows point to BrdU⁺ NeuN⁺ cells and thin arrows to BrdU⁺ cells. Data are the mean ± SEM. One-way ANOVA followed by Tukey post-hoc test ((c): n = 7/condition; (e): n > 10/condition; (f): n > 4/condition). *p < 0.05. NS not significant.