Validation Of Antidepressants And Mechanism Of Ahi1 Mediated Insensitivity To Antidepressants

Objective: Currently depression is the most common psychiatric syndrome affecting over 350 million people worldwide.By 2020,depression will become the second leading cause of death.In addition,Depression has brought a heavy economic burden to the whole society,accounting for 10.3% of the total burden of the disease,mainly due to the high cost and side effects of antidepressants.At present the main reason for the limited treatment of depression is that the mechanism of depression is unknown.Although the researchers found that depression was associated with monoamines(5-hydroxytryptam,norepinep Hrine and dopamine),glutamate receptors,epigenetic modifications,hypothalamic-pituitary-adrenal(HPA)axis,inflammatory cytokines,and neurotrop Hic factors.These factors participate in the occurrence of the mechanism but lack of convincing evidence.The current treatment of depression is based on the hypothesis of the monoamine neurotransmitter imbalance and developed a series of antidepressants.Therefore,a series of antidepressants such as tricyclic antidepressants and selective serotonin reuptake inhibitors(SSRIs)have been developed.However,these antidepressants have substantial side effects.Therefore,it is great social significance to develop new effective antidepressants.Methods: the model: spatial behavior restriction induced depressive mice model;behavior experiment: tail suspension test and forced swimming test;protein level detection: Western blot;hippocampal neurogenesis: immunofluorescence.Results: In order to find a new antidepressant,Fisetin was used to detect its antidepressant effect.Fisetin was found in fruits and vegetables and belongs to the class of flavonoids.It has been reported that it has antioxidative,anti-inflammatory and neuroprotective effects.Because of the above characteristics,Fisetin has been considered as an effective drug for treating neurological diseases such as stroke,Huntington’s disease and Alzheimer’s disease.In theory,the anti-inflammatory properties of Fisetin can inhibit chronic low-level inflammatory symptoms in depressive patients.Therefore,we are curious about the antidepressant effect of Fisetin and its mechanism of action.Therefore,we experimented with two different models of depression to study the antidepressant effect of Fisetin.In this article,we performed the model of spatial restraint stress in ICR mice and then treated them with Fisetin.In the classic depression behavior test(tail suspension test and forced swimming test),we found that the immobility time will be reduced,indicating that it has a certain degree of antidepressant effect.At the same time,we injected the Fisetin into a mouse model of depression in our laboratory(Ahi1 KO mice),which also slowed down its depressive behavior.Our groups has reported that Ahi1 KO mice have depressive behavior and can be considered as a very effective depressive model for exploring antidepressants.Since the TrkB signaling pathway is a classical and important signaling pathway in depression.Therefore,we examined the phosphorylation level of TrkB after administration and found that it increased and the total amount of TrkB remained unchanged.In our article,by administering an inhibitor of TrkB(K252a),we found that the depressive p Henotype was not alleviated and that the phosphorylation level of TrkB did not increase.These results suggest that Fisetin are antidepressant by activating the TrkB signaling pathway and have the potential to be effective drugs for the treatment of depression.Although Ahi1 KO mice were effective in the treatment of Fisetin and other drugs,the depression degree of control mice and Ahi1 KO mice increased under the condition of spatial behavior restriction stress.However,Ahi1 KO mice were not sensitive to antidepressants even if they were treated with fluoxetine.In order to find out the mechanism of drug insensitivity of Ahi1 KO mice under stress,Western blot was used to detect the protein level of Ahi1 in the control mice after fluoxetine treatment.It was found that spatial restriction stress can reduce the level of Ahi1 protein,while fluoxetine can increase the level of Ahi1 protein,suggesting that Ahi1 may be involved in the treatment of antidepressants.In addition,the number of hippocampal neurons in normal mice was reduced by spatial restriction stress,and fluoxetine treatment increased the number of hippocampal neurons in stressed mice;however,fluoxetine treatment did not increase the number of hippocampal neurons in stressed Ahi1 KO mice.In order to further study the regulation of Ahi1 on nerve regeneration,the expression of cend1 was detected in the hippocampus of mice.Cend1 plays an important role in nerve regeneration.The results showed that the level of cend1 in hippocampus of Ahi1 KO mice decreased.Further studies showed that Ahi1 delete reduced the distribution of cend1 in the nucleus.Therefore,Ahi1 may play a role in regulating nerve regeneration and antidepressant by regulating the intracellular distribution of cend1.Conclusions: These results suggest that Fisetin was an effective antidepressant through activating TrkB pathway in Ahi1 gene knockout animal model and spatial restriction stress model.At the same time,Ahi1 knockout mice were not sensitive to antidepressants.Further studies showed that Ahi1 knockout affected the intracellular distribution of cend1,a regulatory protein of neuronal regeneration,and affected the regeneration of hippocampal neurons.Ahi1 could server as a biomarker in evaluating the efficiency of antidepressants,and also provides a new idea for the development of antidepressants.