Acteoside Attenuates Recognition Memory Impairment in CUMS Rats via Regulating Synaptic Plasticity and mTOR Signaling Pathway / El Acteoside Atenúa el Deterioro de la Memoria de Reconocimiento en Ratas ELCI Mediante la Regulación de la Plasticidad Sináptica y la Vía de Señalización mTOR

SUMMARY: We evaluated the role and mechanism of acteoside in the regulation of memory impairment induced by chronic unpredictable mild stress (CUMS). CUMS was used to induce depression in rats and the successful establishment of CUMS model were verified by forced swimming test and sucrose preference test. The Y-maze test and novel object recognition test assessed memory functions. The structural changes in the cortex and hippocampus were observed by hematoxylin and eosin (HE) staining. Immunofluorescence staining and western blotting determined the protein levels. Y-maze test and novel object recognition test showed that there was memory performance impairment in rats of CUMS group, which was improved by the acteoside treatment. HE staining showed that CUMS exposure damaged the structure in the cortex and hippocampus, while the acteoside treatment alleviated the structural changes. Compared with the control group, the levels of BNDF and CREB in the cortex and hippocampus of the CUMS group were significantly decreased. Acteoside significantly reversed the expressions of these proteins in CUMS rats. Meanwhile, compared with the control group, the levels of p-mTOR and p- P70S6K in the cortex and hippocampus of the CUMS group were significantly increased, and these changes were significantly reversed by acteoside. Nevertheless, the effect of acteoside on mTOR signaling was markedly blocked by rapamycin, a specific inhibitor of mTOR signaling. Acteoside can attenuate memory impairment and ameliorate neuronal damage and synaptic plasticity in depression rats probably via inhibiting the mTOR signaling pathway. Acteoside may serve as a novel reagent for the prevention of depression.

Evaluamos el papel y el mecanismo del acteoside en la regulación del deterioro de la memoria inducido por estrés leve crónico impredecible (ELCI). Se utilizó ELCI para inducir depresión en ratas y el establecimiento exitoso del modelo ELCI se verificó mediante una prueba de natación forzada y una prueba de preferencia de sacarosa. La prueba del laberinto en Y y la prueba de reconocimiento de objetos novedosos evaluaron las funciones de la memoria. Los cambios estructurales en la corteza y el hipocampo se observaron mediante tinción con hematoxilina y eosina (HE). La tinción por inmunofluorescencia y la transferencia Western determinaron los niveles de proteína. La prueba del laberinto en Y y la prueba de reconocimiento de objetos novedosos mostraron que había un deterioro del rendimiento de la memoria en ratas del grupo ELCI, que mejoró con el tratamiento con acteósidos. La tinción con HE mostró que la exposición a ELCI dañó la estructura de la corteza y el hipocampo, mientras que el tratamiento con actósidos alivió los cambios estructurales. En comparación con el grupo de control, los niveles de BNDF y CREB en la corteza y el hipocampo del grupo ELCI disminuyeron significativamente. Acteoside revirtió significativamente las expresiones de estas proteínas en ratas ELCI. Mientras tanto, en comparación con el grupo control, los niveles de p-mTOR y p-P70S6K en la corteza y el hipocampo del grupo ELCI aumentaron significativamente, y estos cambios fueron revertidos significativamente ELCI por el acteoside. Sin embargo, el efecto del acteoside sobre la señalización de mTOR fue notablemente bloqueado por la rapamicina, un inhibidor específico de la señalización de mTOR. El acteoside puede atenuar el deterioro de la memoria y mejorar el daño neuronal y la plasticidad sináptica en ratas con depresión, probablemente mediante la inhibición de la vía de señalización mTOR. Acteoside puede servir como un reactivo novedoso para la prevención de la depresión.

Modified Xiaoyaosan Alleviates Depression-like Behaviors by Regulating Activation of Hippocampal Microglia Cells in Rat Model of Juvenile Depression / 中国实验方剂学杂志

ObjectiveTo investigate the mechanism of Baihuan Xiaoyao Decoction （Xiaoyaosan added with Lilii Bulbus and Albiziae Cortex） in alleviating depression-like behaviors of juvenile rats by regulating the polarization of microglia. MethodSixty juvenile SD rats were randomized into normal control， model， fluoxetine， and low-， medium-， and high-dose （5.36， 10.71， 21.42 g·kg-1， respectively） Baihuan Xiaoyao decoction groups. The rat model of juvenile depression was established by chronic unpredictable mild stress （CUMS）. The sucrose preference test （SPT） was carried out to examine the sucrose preference of rats. Forced swimming test （FST） was carried out to measure the immobility time of rats. The open field test （OFT） was conducted to measure the total distance， the central distance， the number of horizontal crossings， and the frequency of rearing. Morris water maze （MWM） was used to measure the escape latency and the number of crossing the platform. The immunofluorescence assay was employed to detect the expression of inducible nitric oxide synthase （iNOS， the polarization marker of M1 microglia） and CD206 （the polarization marker of M2 microglia）. Real-time polymerase chain reaction was employed to determine the mRNA levels of iNOS， CD206， pro-inflammatory cytokines ［tumor necrosis factor （TNF）-α， interleukin （IL）-1β， and IL-6］ and anti-inflammatory cytokines （IL-4 and IL-10） in the hippocampus. Western blotting was employed to determine the protein levels of iNOS and CD206 in the hippocampus. The levels of IL-4 and IL-6 in the hippocampus were detected by enzyme-linked immunosorbent assay. ResultCompared with the normal control group， the model rats showed a reduction in sucrose preference （P<0.05）， an increase in immobility time （P<0.05）， decreased motor and exploratory behaviors （P<0.05）， and weakened learning and spatial memory （P<0.05）. In addition， the model rats showed up-regulated mRNA and protein levels of iNOS and mRNA levels of IL-1β， IL-6， and TNF-α （P<0.05）. Compared with the model group， Baihuan Xiaoyao decoction increased the sucrose preference value （P<0.05）， shortened the immobility time （P<0.01）， increased the motor and exploratory behaviors （P<0.05）， and improved the learning and spatial memory （P<0.01）. Furthermore， the decoction down-regulated the positive expression and protein level of iNOS， lowered the levels of TNF-α， IL-1β， and IL-6 （P<0.01）， promoted the positive expression of CD206， and elevated the levels of IL-4 and IL-10 （P<0.01） in the hippocampus of the high dose group. Moreover， the high-dose Baihuan Xiaoyao decoction group had higher sucrose preference value （P<0.01）， shorter immobility time （P<0.01）， longer central distance （P<0.01）， stronger learning and spatial memory （P<0.01）， higher positive expression and protein level of iNOS （P<0.01）， lower levels of TNF-α， IL-1β， and IL-6 （P<0.05， P<0.01）， lower positive expression and mRNA level of iNOS （P<0.05）， and higher levels of IL-4 and IL-10 （P<0.05， P<0.01） than the fluoxetine group. ConclusionBaihuan Xiaoyao decoction can improve the depression-like behavior of juvenile rats by inhibiting the M1 polarization and promoting the M2 polarization of microglia in the hippocampus.

Antidepressant mechanism of Shenling Kaixin Granules based on BDNF/TrkB/CREB pathway / 中国中药杂志

To investigate the antidepressant mechanism of Shenling Kaixin Granules(SLKX) in treating chronic unpredictable mild stress(CUMS) model rats. Ninety male SD rats were randomly divided into control group, model group, Shugan Jieyu Capsules(110 mg·kg~(-1)) group and SLKX low-(90 mg·kg~(-1)), medium-(180 mg·kg~(-1)), and high-dose(360 mg·kg~(-1)) groups. Depression rat model was replicated by CUMS method. After treatment, the behavioral changes of rats were evaluated by sugar preference, open field, elevated cross maze and forced swimming experiments. The contents of interleukin 1 beta(IL-1β), tumor necrosis factor α(TNF-α), brain-derived neurotrophic factor(BDNF) and 5-hydroxytryptamine(5-HT) in serum were determined by enzyme linked immunosorbent assay(ELISA), and the activities of superoxide dismutase(SOD) and catalase(CAT) in hippocampal CA1 region were also detected. Pathological changes in hippocampal CA1 region were detected by hematoxylin-eosin(HE) staining, and Western blot was used to determine the expression of nerve growth factor(NGF), BDNF, phospho-tyrosine kinase receptor(p-TrkB)/TrkB, phospho-cAMP-response element binding protein(p-CREB)/CREB, nuclear factor E2 related factor 2(Nrf2), heme oxygenase 1(HO-1), B-cell lymphoma-2(Bcl-2)/Bcl-2 associated X protein(Bax) and caspase-3 in hippocampal CA1 region. RESULTS:: showed that compared with the control group, the model group had decreased sugar preference, reduced number of entries and time spent in the center of open field and shortened total distance of movement, reduced number of entries and proportion of time spent in open arm, and increased number and time of immobility in forced swimming experiment. Additionally, the serum contents of IL-1β and TNF-α and the expression of caspase-3 were higher, while the contents of BDNF and 5-HT, the activities of SOD and CAT in hippocampal CA1 region, the expressions of NGF, BDNF, p-TrkB/TrkB, p-CREB/CREB, HO-1 and Bcl-2/Bax, and the Nrf2 nuclear translocation were lower in model group than in control group. Compared with the conditions in model group, the sugar preference, the number of entries and time spent in the center of open, total distance of movement, and the number of entries and proportion of time spent in open arm in treatment groups were increased while the number and time of immobility in forced swimming experiment were decreased; the serum contents of IL-1β and TNF-α and the expression of caspase-3 were down regulated, while the contents of BDNF and 5-HT, the activities of SOD and CAT in hippocampal CA1 region, the expressions of NGF, BDNF, p-TrkB/TrkB, p-CREB/CREB, HO-1, Bcl-2/Bax, and Nrf2 nuclear translocation were enhanced. In conclusion, SLKX might regulate the Nrf2 nucleus translocation by activating BDNF/TrkB/CREB pathway, lower oxidative stress damage in hippocampus, inhibit caspase-3 activity, and reduce apoptosis of hippocampal nerve cells, thereby playing an antidepressant role.

Effect of Sinisan on NLRP3 Inflammasomes and Depression-like Behaviors in Depressed Rats / 中国实验方剂学杂志

ObjectiveTo observe the effects of Sinisan on behaviors and NOD-like receptor protein 3 （NLRP3） inflammasomes of depressed rats induced by chronic unpredictable mild stress （CUMS） and further explore the anti-depressant mechanism of Sinisan. MethodFifty male rats were randomly divided into a normal group， a model group， an NLRP3 inhibitor （MCC950） group （10 mg·kg-1）， and low- （2.5 g·kg-1） and high-dose （5 g·kg-1） Sinisan groups， with 10 rats in each group. The depression model was induced by 42 d CUMS in rats except for those in the normal group. Drug intervention was performed on the 22nd day of modeling by gavage in the Sinisan groups and by intraperitoneal injection in the MCC950 group. Except for the MCC950 group， the remaining four groups received 10 mg·kg-1 physiological saline by intraperitoneal injection， while the rats in the model group， the normal group， and the MCC950 group were administered with 3 mL of physiological saline by gavage. Twenty-one days later， the sucrose preference test and open field test were performed. Western blot was used to detect the protein expression of NLRP3， apoptosis-associated speck-like protein containing a CARD （ASC）， cysteinyl aspartate-specific protease-1 （Caspase-1）， B-cell lymphoma-2 （Bcl-2）， Bcl-2 associated X protein （Bax）， ionized calcium-binding adapter molecule 1 （Iba1）， and CD68 in the hippocampus of rats in each group. Enzyme-linked immunosorbent assay （ELISA） was used to detect the levels of interleukin-1β （IL-1β） and interleukin-18 （IL-18） in the hippocampus of rats. Nissl staining and TUNEL were used to assess the pathological changes and apoptosis level in the hippocampal CA1 region of rats， respectively. ResultThe sucrose preference rate and consumption volume in the sucrose preference test， the total distance， the percentage of central movement distance， and the percentage of residence time in the open field test of rats in the model group were lower than those in the normal group （P<0.01）. Compared with the model group， the Sinisan groups and the MCC950 group showed improved depression-like behaviors， apoptosis level in the hippocampal CA1 region， and neuron loss to varying degrees. Sinisan could reduce the levels of IL-1β， IL-18， Bax， Iba1， and CD68 in the hippocampus （P<0.05， P<0.01）， increase the level of Bcl-2 （P<0.05， P<0.01）， and inhibit the protein expression of NLRP3， ASC， and Caspase-1 related to NLRP3 inflammasomes （P<0.05， P<0.01）. ConclusionSinisan can improve the depression-like behaviors and pathological damage of hippocampal neurons in CUMS-induced rats， and the mechanism may be related to the inflammatory response mediated by the NLRP3 inflammasome signaling pathway.

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

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.

Antidepressant effect of acidic polysaccharides from Poria and their regulation of neurotransmitters and NLRP3 pathway / 中国中药杂志

The rats were exposed to chronic unpredictable mild stress(CUMS) and kept in separate cages for inducing depressive disorder, which was judged by behavioral indicators. The number and morphology of neurons in hippocampal CA3 area and prefrontal cortex were observed by hematoxylin-eosin(HE) staining. The levels of brain-derived neurotrophic factor(BDNF), 5-hydroxytryptamine(5-HT), 5-hydroxyindoleacetic acid(5-HIAA), dopamine(DA), norepinephrine(NE), glutamic acid(GLU), interleukin-1β(IL-1β), interleukin-18(IL-18), and tumor necrosis factor-α(TNF-α) were detected by enzyme-linked immunosorbent assay(ELISA). Real-time polymerase chain reaction(RT-PCR) and Western blot were conducted to determine the mRNA and protein expression levels of related molecules in NLRP3 pathway. The results showed that compared with the model group, acidic polysaccharides from Poria at the low-, medium-, and high-doses(0.1, 0.3 and 0.5 g·kg~(-1)·d~(-1)) all improved the depression-like behavior of rats, increased the number of neurons and the levels of BDNF, 5-HT, 5-HIAA, DA, and NE in the hippocampus, and reduced GLU and serum IL-1β, IL-18, and TNF-α levels. The mRNA expression levels of ASC, caspase-1, IL-1β, and IL-18 and the protein expression levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in each medication group were down-regulated, whereas the protein expression levels of pro-caspase-1, pro-IL-1β, and pro-IL-18 were up-regulated. All these have indicated that acidic polysaccharides from Poria exerted the antidepressant effect possibly by regulating neurotransmitters and NLRP3 inflammasome signaling pathway.

1H-NMR Metabolomic Analysis of Brain Tissue of CUMS-Induced Depressed Mice Intervened by Iridoid Part of Valerianae Jatamansi Rhizoma et Radix / 中国实验方剂学杂志

Objective:Metabolomics was used to analyze the brain tissue samples of model mice with chronic unpredictable mild stress (CUMS) depression, in order to find out the differential metabolites related to depression and to explore the possible antidepressant mechanism of iridoid part of Valerianae Jatamansi Rhizoma et Radix (IEFV). Method:Forty-two Kunming mice were randomly divided into 6 groups, including the normal group, the model group, the fluoxetine group (2.5 mg·kg-1) and the IEFV low, medium, and high dose groups (doses were 5.73, 11.47, 22.94 mg·kg-1, respectively). The behavioral and biochemical indicators of CUMS model mice were used for pharmacodynamic evaluation with IEFV and a positive drug (fluoxetine) as the intervention drugs. Then, the effect of IEFV on endogenous substances of the brain tissue in CUMS model mice were analyzed by nuclear magnetic resonance hydrogen spectrum (1H-NMR) metabolomics, and multivariate statistical analysis was used to identify the differential metabolites and to enrich the metabolic pathways involved in the differential metabolites. Result:After modeling, the immobility time of the model mice increased significantly, their sucrose preference rate and the excitatory neurotransmitters [5-hydroxytryptamine (5-HT) and norepinephrine (NE)] decreased significantly, indicating the success of modeling. The depression was relieved after IEFV administration, mainly manifested by the recovery of the immobility time, sucrose preference rate and the excitatory neurotransmitters (5-HT and NE). Principal component analysis (PCA) of endogenous metabolites in brain tissue showed that the model group could be significantly separated from the normal group, while the IEFV groups and fluoxetine group all showed a trend of deviating from the model group to the normal group, which was consistent with the behavioral results. The results of orthogonal partial least squares discriminant analysis (OPLS-DA) showed that there were 16 different metabolites between the model group and the normal group, including 12 water-soluble metabolites and 4 liposoluble metabolites. Seven potential metabolism pathways were obtained through MetPA analysis, including metabolism of phenylalanine, metabolism of phenylalanine, tyrosine and tryptophan, metabolism of taurine and hypotaurine acid, metabolism of alanine, aspartic acid and glutamic acid, biosynthesis of valine, leucine and isoleucine, metabolism of D-glutamine and D-glutamate and tricarboxylic acid cycle (TCA). IEFV-high dose group could significantly recall 11 differential metabolites. Conclusion:IEFV may play an antidepressant role mainly by affecting energy metabolism, amino acid metabolism and neurotransmitter levels, which provides a reference for further study on the antidepressant mechanism of IEFV.

Anti-depressant Mechanism of Qing' ewan in CUMS Rats Based on Estrogen Receptor Pathway / 中国实验方剂学杂志

Objective::To study the anti-depressive effect of Qing' ewan in treating chronic unpredictable mild stress (CUMS) in rats, and the regulatory effect on estrogen receptor and estrogen receptor-related signaling pathways, in order to explore its anti-depressive mechanism. Method::The CUMS model was established. The experiment was divided into normal control group, model group, escitalopram oxalate group (positive control) and Qing' ewan groups (1.71, 5.13, 15.39 g·kg-1). After 4 weeks of modeling, rats were treated with corresponding drugs for 2 weeks. Behavioral evaluation [sucrose preference test (SPT), forced swimming test (FST), open field test (OFT)] was conducted to assess if the CUMS model was successful. Western blot was used to analyze the protein expression levels of estrogen receptor α (ERα), estrogen receptor β (ERβ), brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB). Result::Compared with the normal group, the sucrose consumption rate and the score of OFT in the model group decreased(P<0.05, P<0.01), the immobility time of FST prolonged significantly(P<0.01), and the protein expression levels of ERα, ERβ, BDNF and TrkB decreased(P<0.05, P<0.01). Compared with the model group, the behavioral performance of the treated group was improved, the sucrose consumption rate and the score of OFT increased(P<0.05, P<0.01), and the immobility time decreased(P<0.05). The protein expressions of ERα, ERβ, BDNF and TrkB in the treated group were significantly up-regulated(P<0.05, P<0.01), especially the middle-dose Qing' ewan group (5.13 g·kg-1). Conclusion::Qing' ewan can improve depression-like behavior in CUMS rats. Its mechanism may be related to the neuroprotective effect by up-regulating the expressions of ERα and ERβ and activating estrogen receptor-mediated ERβ/BDNF/TrkB pathways.

Changes in tau phosphorylation levels in the hippocampus and frontal cortex following chronic stress

Studies have indicated that early-life or early-onset depression is associated with a 2- to 4-fold increased risk of developing Alzheimers disease (AD). In AD, aggregation of an abnormally phosphorylated form of the tau protein may be a key pathological event. Tau is known to play a major role in promoting microtubule assembly and stabilization, and in maintaining the normal morphology of neurons. Several studies have reported that stress may induce tau phosphorylation. The main aim of the present study was to investigate possible alterations in the tau protein in the hippocampus and frontal cortex of 32 male Sprague-Dawley rats exposed to chronic unpredictable mild stress (CUMS) and then re-exposed to CUMS to mimic depression and the recurrence of depression, respectively, in humans. We evaluated the effects of CUMS, fluoxetine, and CUMS re-exposure on tau and phospho-tau. Our results showed that a single exposure to CUMS caused a significant reduction in sucrose preference, indicating a state of anhedonia. The change in behavior was accompanied by specific alterations in phospho-tau protein levels, but fluoxetine treatment reversed the CUMS-induced impairments. Moreover, changes in sucrose preference and phospho-tau were more pronounced in rats re-exposed to CUMS than in those subjected to a single exposure. Our results suggest that changes in tau phosphorylation may contribute to the link between depression and AD.