Antidepressant Effect of n-Butyl Alcohol Extracts from Xiaoyaosan via IGF-1Rβ/PI3K/Akt Pathway / 中国实验方剂学杂志

ABSTRACT

Objective:To investigate the intervention effect of <italic>n</italic>-butyl alcohol extracts from Xiaoyaosan against depression-like behavior induced by chronic unpredictable mild stress （CUMS） in model mice and the role of insulin-like growth factor-1 receptor <italic>β</italic> （IGF-1R<italic>β</italic>）/phosphatidylinositol-3 kinase （PI3K）/protein kinase B （Akt） signaling pathway in such intervention. Method:The effective dose of n-butyl alcohol extracts from Xiaoyaosan was preliminarily determined in model mice with behavioral despair. Then the male C57BL/6 mice were randomly divided into the blank group， model group， fluoxetine group， Xiaoyaosan group， and the low- （20 g·kg^-1） and high-dose （40 g·kg^-1） <italic>n</italic>-butyl alcohol extract groups. The mice in all groups except for the blank group were exposed to CUMS for inducing the depression-like behavior， which was judged by the sucrose preference test （SPT）. The successfully modeled mice in the medication groups were intragastrically administered with the corresponding drugs， whereas those in the blank and model groups were treated with an equal volume of solvent for five successive weeks. Following the SPT， tail suspension test （TST）， and novelty suppressed feeding test （NSFT） at the end of the fifth week， the insulin-like growth factor-1 （IGF-1） levels in mouse serum and hippocampus were measured by enzyme-linked immunosorbent assay （ELISA）. The average optical density （<italic>IA</italic>） of Nissl bodies in mouse hippocampal CA3 region was detected by toluidine blue staining. The 5-bromo-2-deoxyuridine （Brdu） and doublecortin （DCX） expression in the dentate gyrus （DG） was assayed using immunofluorescence method. The protein expression levels of IGF-1R<italic>β</italic>， PI3K， phosphorylated-PI3K （p-PI3K）， Akt， p-Akt， cysteine aspartic acid-specific protease 3 （Caspase-3）， and cleaved Caspase-3 in the hippocampus were determined by Western blot. Result:The results of forced swimming test and TST showed that n-butyl alcohol extracts from Xiaoyaosan at 9.1 and 40 g·kg^-1 both significantly shortened the immobility time of mice （<italic>P</italic><0.05， <italic>P</italic><0.01）， indicating that the effective dose ranged from 9.1-40 g·kg^-1. Compared with the model control， the n-butyl alcohol extracts from Xiaoyaosan at 20 and 40 g·kg^-1 significantly increased the sucrose preference percentage （<italic>P</italic><0.05， <italic>P</italic><0.01）， shortened the immobility time in TST （<italic>P</italic><0.01） and the feeding latency in NSFT （<italic>P</italic><0.01）， reversed the down-regulated IGF-1 content in mouse serum and hippocampus （<italic>P</italic><0.01）， increased the AOD of Nissl bodies in the hippocampal CA3 region （<italic>P</italic><0.01）， promoted the expression of Brdu and DCX in DG （<italic>P</italic><0.05， <italic>P</italic><0.01）， and down-regulated the protein expression levels of IGF-1R<italic>β</italic> （<italic>P</italic><0.05， <italic>P</italic><0.01）， p-PI3K/PI3K （<italic>P</italic><0.05， <italic>P</italic><0.01）， p-Akt/Akt （<italic>P</italic><0.05）， and cleaved Caspase-3/Caspase-3 in the hippocampus of CUMS mice. Conclusion:The n-butyl alcohol extracts from Xiaoyaosan are equivalent to Xiaoyaosan in inhibiting expression. They alleviate the depression-like behavior in CUMS mice， induce the production of Nissl bodies in hippocampal CA3 region， enhance neuronal proliferation and differentiation in DG， and facilitate neurogenesis. All these may be related to the inhibition of over-activated IGF-1R<italic>β</italic>/PI3K/Akt pathway and the reduction of neuronal apoptosis.