Study On The Biological Mechanism Of Gardenia's Effective Components In Treating Depression

Objective:In order to reduce the occurrence of side effects similar to antidepressants as much as possible,effective components are sought from natural products and the therapeutic mechanism is studied to serve the clinical practice.Gardenia fruit is considered to be one of the effective antidepressant traditional Chinese medicines,and is also a component of many traditional prescriptions,and iridoid glycosides and crocin are the main active ingredients in gardenia This study aims to explore the antidepressant effect of iridoid constituents in gardenia and the protective effect of crocin on cerebral ischemia and its mechanism.Method:Firstly,HPLC method was used to determine the content of the active ingredients.Secondly,male BALB/c mice were randomly divided into control group,model group,fluoxetine group and IGF group with 9 mice in each group.The antidepressant effect of IGF on SRS model mice was studied through sugar water preference,opening experiment,tail suspension and forced swimming experiments.The cell viability was detected by HT22 cells,the expression of proteins related to synaptic plasticity regulated by IGF in vivo was detected by Western Blot,and the level of cerebral corticosterone was determined by ELISA.Next,in this study,male SD rats were selected to establish cerebral ischemia model through conducting the MCAO experiment,and the rats were randomly divided into control group,model group and high and low dose group of safranin group.Neurological function of MCAO rats was evaluated through neurological score,2,3,5-triphenyltetrazolium ammonium chloride was stained and infarct ratio was calculated.Western Blot experiment was used to observe the effect of expression of autophagy marker in MCAO brain tissue.Results:Firstly,the main active contents of iridoid(IGF)(shanzhiside methyl ester,geniposide),crocin ?,crocin ?,neochlorogenic acid and chlorogenic acid are 5.28,37.17,2.95,0.49,0.10 and 0.67 mg/g respectively.Secondly,IGF has antidepressant effect on SRS model mice(P<0.05,P<0.01).At the same time,IGF can significantly inhibit NR1 expression and increase GluR1 expression(P<0.05,P<0.001).IGF can also up-regulate Akt-mTOR level in hippocampus of SRS mice(P<0.05,P<0.01,P<0.001).IGF significantly up-regulates activation of 4EBP1(P<0.05)and P70S6K(P<0.05,P<0.01).ELISA results showed that IGF could significantly reduce the level of corticosterone in SRS brain(P<0.0001)and up-regulate the level of p-mTOR/mTOR(P<0.01).Finally,saffron can significantly reduce infarct size and neurological function score of MCAO rats(P<0.001).Saffron can significantly reduce LC-ii/I of MCAO rats(P<0.001,P<0.01),significantly inhibit the expression of p62/SQSTM 1,and reduce the levels of p-AMPK/AMPK(P<0.05)and ULK 1 of MACO rats.Conclusion:IGF antidepressant mechanism may be related to mTOR pathway,and crocin can down-regulate autophagy through mTOR-AMPK-ULK 1 pathway.These research results provide basis for clinical and drug development of gardenia.