Gastrodin ameliorates depression-like behaviors and up-regulates proliferation of hippocampal-derived neural stem cells in rats: involvement of its anti-inflammatory action.

Gastrodin (GAS), an active constituent of the Chinese herbal medicine tianma, has antidepressant-like activity in animals but no specific molecular mechanisms have been identified. In the present study, chronic unpredictable stress (CUS) was used to establish a rat depression model; The sucrose preference test, forced swim test and Morris water maze test were used to assess depression-like behaviors (anhedonia, behavioral despair, motor retardation, and poor spatial memory), and the proliferation of hippocampal stem cells was tested by BrdU immunohistochemistry. The stress and inflammatory responses were assayed by measuring IL-RA, NF-κB, and p-iκB expression by Western blot and IL-1β production by ELISA. Direct and indirect effects of GAS on NSC viable cell number were examined in vitro by WST-1 and BrdU assays. It was found that GAS (200 mg/kg daily) reversed all tested depression-like behaviors in CUS model rats and up-regulated NSCs proliferation in the hippocampus. Enhanced expression of p-iκB, NF-κB, and IL-1β by CUS was also reversed by GAS. Moreover, in vitro experiments revealed that GAS alone did not increase the viability of NSCs but protected them from IL-1β-induced damage. These results support the antidepressant and neuroprotective effects of GAS, and GAS may reduce depression-like behaviors by protecting hippocampal NSCs against the proinflammatory cytokine IL-1β.