Preventive Effects of Ginseng Total Saponins on Chronic Corticosterone-Induced Impairment in Astrocyte Structural Plasticity and Hippocampal Atrophy
To further explore the underlying antidepressant mechanism of ginseng total saponins (GTS), this study observed the effects on hippocampal astrocyte structural plasticity and hippocampal volume in the corticosterone-induced mouse depression model. Corticosterone (20 mg/kg/day) was administered subcutaneously for 5 weeks, and GTS (12.5, 25, and 50 mg/kg/day; namely GTSL, GTSM, and GTSH) or fluoxetine (10 mg/kg/day) were given intragastrically during the last 3 weeks. On day 33 and day 34, depression-like behavior was observed via a forced swimming test and a tail suspension test, respectively. At 6 h after the last dose of corticosterone (day 35), all mice were sacrificed followed by serum corticosterone assays, stereological analysis of hippocampal glial fibrillary acidic protein-positive (GFAP+) astroctyes and hippocampal volume, and hippocampal glycogen tests. Results showed that all doses of GTS ameliorated depression-like behavior and the decrease in hippocampal glycogen without normalizing hypercortisolism. Moreover, GTSH and GTSM reversed the corticosterone-induced reduction in the total number of hippocampal GFAP+ astrocytes and hippocampal volume. Additionally, GTSH alleviated the diminished protrusion length and somal volume of GFAP+ astrocytes induced by corticosterone. These findings imply that the effects of GTS on corticosterone-induced depression-like behavior may be mediated partly through the protection to hippocampal astrocyte structural plasticity.