Research On The Improving Effect Of Oyster Meat Enzymatic Hydrolysate On Zebrafish Depression Model Of Chronic Unpredictable Mild Stress

Depression is a common neurological disease that occurs in all age groups.According to the World Health Organization,more than 322 million people worldwide suffer from depression.It is estimated that by 2030,depression will become an important factor causing the global burden of disease.The current drugs for the treatment of depression have problems such as single target and large side effects.Therefore,the development of natural active substances with multiple targets and low side effects has become a research hotspot.Hong Kong oyster(Crassostrea hongkongensis)is rich in various nutrients and has medicinal value.According to records in "Shen Nong’s Materia Medica" and "Sea Medicine Materia Medica",oysters have the functions of soothing the nerves and eliminating heat.In recent years,studies have proved that water extract of oyster meat can improve brain oxidative stress and brain aging,and has a protective effect on neural stem cells.However,there are few reports in the literature that oysters can improve brain health problems associated with depression.Based on the above research background,this topic is to verify whether oyster meat has antidepressant activity,explore its main active components and their mechanism of action,and improve the added value of oysters.On the basis of the research team’s preliminary research on oysters,Hong Kong oysters were used as raw materials and zebrafish were used as experimental animals to establish a zebrafish depression model of chronic unpredictable mild stress;after the intervention of oyster hydrolysates,through behavior and sugar The level of corticosteroids and the expression level of brain cytokines preliminarily verified the antidepressant activity of oyster hydrolysates;then the oyster hydrolysates were divided into different ultrafiltration components by ultrafiltration,again using the chronic unpredictable mild stress zebrafish depression model,Evaluate the antidepressant activity of different components through indicators such as behavior,glucocorticoid levels and brain cytokine expression levels,and screen the optimal components;finally,use the zebrafish chronic unpredictable mild stress depression model to pass the optimal components The drug administration intervention,explore its antidepressant mechanis from the perspective of gene expression.The experimental results are as follows:(1)Evaluate the effect of enzymatic hydrolysates of oyster meat on the depressive behavior of zebrafish under chronic unpredictable mild stress through animal experiments.The results showed that after chronic unpredictable mild stress, zebrafish depression-like behaviors were obvious,manifested as decreased exploratory behavior,increased darkening behavior,decreased body mass,and increased glucocorticoid levels.The dosage group of oyster meat enzymatic hydrolysate can significantly improve zebrafish’s exploration ability,which is characterized by increased residence time in the upper part(P<0.01),weakened darkening behavior,and significantly shortened incubation period in the dark area (P<0.05).The staying time in the bright area was significantly increased(P<0.01), the body mass index was significantly increased(P<0.01),the cortisol level in peripheral tissues was significantly reduced(P<0.05),and the levels of inflammatory factors such as TNF-α in the brain tissue were also Significantly reduced(P<0.01).(2)In order to further separate and purify,screen out the best antidepressant active components,separate the oyster enzymatic hydrolysis products by ultrafiltration, and collect three ultrafiltration components of <3k Da,3-5 k Da,and >5 k Da for basic chemistry Composition analysis.The results show that the molecular weight of ultrafiltration components <3k Da and 3-5k Da are mainly concentrated in <3k Da,and the content percentage is as high as 60%-80%.The content of crude protein and minerals in the <3k and 3-5k groups is higher than that in the >5k group,and the amino acid composition is relatively complete,and the essential amino acids and lysine content are higher.Among them,the content of 3-5k Da trace elements is rich,and the content of Cu,Mn,and Zn is higher than the other two groups.The 3-5k group has higher nutritional value and neurodevelopmental potential.(3)Animal experiments were conducted to evaluate the effects of ultrafiltration components of oyster hydrolysates on the depressive behavior of zebrafish under chronic unpredictable mild stress.The results show that compared with the chronic unpredictable mild stress model group zebrafish,the ultrafiltration component can effectively improve zebrafish depression-like behavior,significantly reduce the peripheral cortisol expression level,and significantly reduce the peripheral cortisol expression level and pro-inflammatory Factors(4)TNF-α and IL-1β content,and found that the zebrafish brain tissue antioxidant enzyme SOD activity in the oyster ultrafiltration fraction is higher,and the comprehensive effect of improving zebrafish behavior in the 3-5k Da group is compared with the <3k Da group and the >5k Da group is stronger.(5)In order to further explore the mechanism of 3-5 k Da component affecting neuro-cytokine,real-time fluorescent quantitative PCR was used to explore the antidepressant mechanism of 3-5 k Da component.The results show that compared with the chronic unpredictable mild stress model group zebrafish,3-5k Da ultrafiltration components can effectively regulate the balance of M1/M2 type cells, promote the M1-M2 transition of microglia activity,and inhibit nerves The production of inflammatory factors plays a role in neuro-immune regulation.At the same time,it reduces the expression of the apoptosis gene Caspase3,increases the expression of the glucocorticoid receptor gene,improves the GR sensitivity,and then regulates the function of the HPA axis and plays an antidepressant effect.