Involvement of normalized NMDA receptor and mTOR-related signaling in rapid antidepressant effects of Yueju and ketamine on chronically stressed mice

The relationship of methylation and mRNA expression profile of AUTS2 with suicidal ideation in adolescents with bipolar depression

OBJECTIVE

This study aims to explore the correlation between the methylation levels of the AUTS2 gene and suicidal ideation in adolescents with bipolar depression, and investigate the mediating effect of AUTS2 mRNA expression levels.

METHODS

A total of 73 adolescents diagnosed with bipolar depression were recruited for the evaluation of suicidal ideation using the Suicidal Ideation Attributes Scale (SIOSS) and were categorized into two groups (with or without suicidal ideation). The methylation and mRNA expression levels of the AUTS2 gene were detected through pyrophosphate sequencing and quantitative reverse transcription polymerase chain reaction (qRT-PCR) respectively, and were analyzed for the association with suicidal ideation by group comparison, correlation analyses and mediation analyses.

RESULTS

Among 17 methylation sites identified, the methylation levels at the CpG14.15.16 loci were elevated in the group with suicidal ideation compared to those without such thoughts. The mRNA expression level of AUTS2 was also found be higher in the group with suicidal ideation. Quantitative analyses indicated significant correlation between the methylation level and suicidal ideation, between the methylation level of CpG14.15.16 loci and AUTS2 expression, and between its expression level and suicidal ideation. Further mediation analyses indicated that the AUTS2 mRNA expression levels mediated the relationship between the methylation levels at CpG14.15.16 and suicidal ideation, accounting for 30% of the observed effect.

CONCLUSION

The elevated methylation level of CpG14.15.16 of the AUTS2 gene might be involved in the pathophysiology of suicide ideation in adolescents with bipolar depression, which might be mediated by the mRNA expression of AUTS2.

MiR-129-5p alleviates depression and anxiety by increasing astrocyte ATP production partly through targeting deubiquitinase Mysm1

Major depressive disorder (MDD) is a major global mental concern that severely affects quality of life, yet current pharmacological treatments remain limited in their effectiveness. Long-term chronic stress has been shown to increase the incidence of depression and anxiety. Micro RNAs (miRNAs) have been revealed to participate in the pathological process of depression and represent promising therapeutic targets. In this study, we found that microRNA-129-5p (miR-129-5p) was significantly decreased in the brains of depressive mice. Overexpression of miR-129-5p in the hippocampus effectively alleviated depressive-like behaviors and reduced the activation of microglial cells and astrocytes. In addition, ATP levels in depressive mice were significantly increased following miR-129-5p overexpression. The antidepressant effects of miR-129-5p were reversed when ATP function was blocked with the non-specific P2 receptor antagonist suramin. In vitro experiments revealed that miR-129-5p overexpression enhanced ATP production in astrocytes. Furthermore, using a dual-luciferase reporter assay, we found that miR-129-5p directly targeted Mysm1. When overexpressed in astrocytes, miR-129-5p significantly suppressed Mysm1 expression, promoted phosphorylation of p53 and AMPK, and enhanced the expression of PGC1α, factors previously associated with ATP production. Our findings highlight the crucial role of miR-129-5p in regulating depression, suggesting that miR-129-5p overexpression may serve as an effective strategy for antidepressant treatment.

A refined formula derived from Jiawei-Xiaoyao pill exerts rapid antidepressant-like effects in LPS-induced depression by reducing neuroinflammation and restoring neuroplasticity signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Jiawei-Xiaoyao Pill (JWX), a classic formula in traditional Chinese medicine, is derived from Xiaoyao Pill by adding significant amounts of Gardeniae Fructus (GF) and Moutan Cortex (MC). It is frequently used for the treatment of depression. JWX has been demonstrated to uniquely elicit rapid antidepressant-like effects within the prescribed dosage range. To date, GF has been shown to have rapid antidepressant-like effects, but a much higher dose is required than its proportion in JWX. It is assumed that the synergism of GF with a minimum number of other herbs in JWX serves as a refined formula that exerts these rapid antidepressant-like effects. Identification of a refined formula is important for prioritizing the herbs and ingredients to optimize the quality control of JWX. However, such a refined formula for JWX has not been identified yet.

AIM OF THE STUDY

Here we aimed to identify a refined formula derived from JWX for optimized rapid antidepressant-like effects. Since the neuroinflammation mechanism involving in depression treatment has not been previously investigated for JWX, we tested the mechanism for both JWX and the refined formula.

MATERIALS AND METHODS

Individual herbs (MC; ASR, Angelica Sinensis Radix; Bupleuri Radix; Paeonia Radix Alba) that show antidepressant-like responses were mixed with GF at the proportional dosage in JWX to identify the refined formula. Rapid antidepressant-like effects were assessed by using NSF (Novelty Suppressed Feeding Test) and other behavioral tests following a single administration. The identified formula was further tested in a lipopolysaccharide (LPS)-induced depressive model, and the molecular signaling mechanisms were investigated using Western blot analysis, immunofluorescence, and pharmacological inhibition of mTOR signaling. Scopolamine (Scop) was used as a positive control for induction of rapid antidepressant effects.

RESULTS

A combination of GF, MC and ASR (GMA) at their dosages proportional to JWX induced behavioral signs of rapid antidepressant-like responses in both normal and LPS-treated mice, with the antidepressant-like effects sustained for 5 d. Similar to JWX or Scop, GMA rapidly reduced the neuroinflammation signaling of Iba-1-NF-кB, enhanced neuroplasticity signaling of CaMKII-mTOR-BDNF, and attenuated the upregulated expressions of the NMDAR sub-units GluN1 and GluN2B in the hippocampus of LPS-treated mice. GMA, JWX and Scop rapidly restored the number of BDNF-positive cells reduced by LPS treatment in the CA3 region of the hippocampus. Furthermore, rapamycin, a selective inhibitor of mTOR, blunted the rapid antidepressant-like effects and hippocampal BDNF signaling upregulation by GMA.

CONCLUSION

GMA may serve as a refined formula from JWX, capable of inducing rapid antidepressant-like effects. In the LPS-induced depression model, the effects of GMA were mediated via rapidly alleviating neuroinflammation and enhancing neuroplasticity.

Genipin 1-O-β-D-gentiobioside ameliorates CUMS-induced prefrontal cortex neuron neuronal apoptosis by modulating HIPK2 SUMOylation

BACKGROUND

Depression is a common mental illness with more than 280 million sufferers worldwide. Inflammation, particularly the c-Jun amino-terminal kinase (JNK) pathway, contributes to depression development and neuronal apoptosis. Gardenia is a herb with therapeutic effects on depression that has been shown to inhibit neuronal apoptosis. However, one of the components in gardenia, Genipin 1-O-β-D-gentiobioside(GG), has been less studied for its mechanism on depression. Thus, in the current study, we investigate how Genipin 1-O-β-D-gentiobioside improves depression and elucidate its possible mechanism of action.

METHODS

In this investigation, we utilize a chronic unpredictable mild stress (CUMS) mouse model and corticosterone-induced primary cortical neurons to examine the role of GG in ameliorating depressive symptoms and neuronal apoptosis. TUNEL staining and flow cytometry assessed the effects of GG on neuronal apoptosis. Western Blot analyses and immunofluorescence assays apoptosis-related proteins in the prefrontal cortex and primary neurons. The site of action of GG in regulating homeodomain interacting protein kinase 2 (HIPK2) SUMOylation was further explored in primary neurons. We constructed siRNA-SUMO1 vectors to transfect primary neuronal cells with intracellular SUMO1 knockdown. Proximity ligation assay (PLA) experiments were performed on primary neurons according to the instructions of the assay kit to observe the physical relationship between HIPK2 and SUMO1. We predicted the HIPK2 SUMOylation modification site by an online database and constructed vectors to target and site-directed mutagenesis, then to transfected primary neuronal cells.

RESULTS

The results showed that GG effectively alleviated depressive-like behaviours, down-regulated apoptosis-related proteins (p-JNK, Bax, Cleaved-Caspase-3), and inhibited neuronal apoptosis in CUMS-induced depressed mice and corticosterone-induced primary cortical neurons. We reveal a complex mechanism underlying the link between GG, SUMOylation of HIPK2, and complex pathways of neuronal apoptosis regulation. K326 and K1189 are the key SUMOylation sites regulated by GG in intricate interactions of apoptosis-related proteins.

CONCLUSION

Our study demonstrated that GG exerts antidepressant-like actions through neuroprotective effects by inhibiting the apoptosis of prefrontal cortex neurons, revealing the mechanism of GG inhibition of JNK phosphorylation by enhancing HIPK2 SUMOylation.

Hypoxanthine Produces Rapid Antidepressant Effects by Suppressing Inflammation in Serum and Hippocampus

The occurrence and development of depression are closely related to disorders of the brain and peripheral substances. Abnormal metabolites in the blood affect the signal regulation function of the nerve center, which is one of the key factors for depression episodes. This study was focused on metabolites in serum and the mechanism of its antidepressant in the hippocampus. In the present study, serum metabolites in patients with depression were screened by metabolomic techniques. Various depressive mouse models and behavioral tests were used to assess its antidepressant effects. The expressions of inflammatory signaling were detected by using Western blot, ELISA, and immunofluorescence. We found that the metabolite hypoxanthine in the serum of patients with depression was significantly reduced, and the same result was also found in two mouse models of depression such as chronic unpredictable mild stress (CUMS) and social defeat stress (SD). By administering different doses of hypoxanthine (5, 10, 15 mg/kg), we found that only 15 mg/kg was able to significantly reduce the latency and increase food consumption in the novelty suppressed-feeding test (NSF), which was also able to reverse the depressive phenotypes of mice in the CUMS model after a single administration at 2 h later. Hypoxanthine obviously reduced the expressions of inflammation in serum and downregulated the expressions of MAPK and NLRP3-related pathways in the hippocampus in CUMS mice. Moreover, hypoxanthine also suppressed the activations of glial cells including GFAP and IBA-1 in hippocampal CA1, CA3, and dentate gyrus (DG). To sum up, hypoxanthine exerted antidepressant effect relying on the inhibition of peripheral and hippocampal inflammations by regulating MAPK, NLRP3-related pathways, and glial cells. This was the first time that we have found a disordered metabolite in patients with depression and further systematically demonstrated its efficacy and potential mechanism of antidepressants, providing new ideas for antidepressant drug development.

S-ketamine alleviates depression-like behavior and hippocampal neuroplasticity in the offspring of mice that experience prenatal stress

Prenatal stress exerts long-term impact on neurodevelopment in the offspring, with consequences such as increasing the offspring's risk of depression in adolescence and early adulthood. S-ketamine can produce rapid and robust antidepressant effects, but it is not clear yet whether and how S-ketamine alleviates depression in prenatally stressed offspring. The current study incestigated the preliminary anti-depression mechanism of S-ketamine in prenatally stressed offspring, particularly with regard to neuroplasticity. The pregnant females were given chronic unpredictable mild stress on the 7th-20th day of pregnancy and their male offspring were intraperitoneally injected with a single dose of S-ketamine (10 mg/kg) on postnatal day 42. Our findings showed that S-ketamine treatment counteracted the development of depression-like behaviors in prenatally stressed offspring. At the cellular level, S-ketamine markedly enhanced neuroplasticity in the CA1 hippocampus: Golgi-Cox staining showed that S-ketamine alleviated the reduction of neuronal complexity and dendritic spine density; Transmission electron microscopy indicated that S-ketamine reversed synaptic morphology alterations. At the molecular level, by western blot and RT-PCR we detected that S-ketamine significantly upregulated the expression of BDNF and PSD95 and activated AKT and mTOR in the hippocampus. In conclusion, prenatal stress induced by chronic unpredictable mild stress leads to depressive-like behaviors and hippocampal neuroplasticity impairments in male offspring. S-ketamine can produce antidepressant effects by enhancing hippocampal neuroplasticity via the BDNF/AKT/mTOR signaling pathway.

Extremely Low-Frequency Electromagnetic Field (ELF-EMF) Increases Mitochondrial Electron Transport Chain Activities and Ameliorates Depressive Behaviors in Mice

Compromised mitochondrial electron transport chain (ETC) activities are associated with depression in humans and rodents. However, the effects of the enhancement of mitochondrial ETC activities on depression remain elusive. We recently reported that an extremely low-frequency electromagnetic field (ELF-EMF) of as low as 10 μT induced hormetic activation of mitochondrial ETC complexes in human/mouse cultured cells and mouse livers. Chronic social defeat stress (CSDS) for 10 consecutive days caused behavioral defects mimicking depression in mice, and using an ELF-EMF for two to six weeks ameliorated them. CSDS variably decreased the mitochondrial ETC proteins in the prefrontal cortex (PFC) in 10 days, which were increased by an ELF-EMF in six weeks. CSDS had no effect on the mitochondrial oxygen consumption rate in the PFC in 10 days, but using an ELF-EMF for six weeks enhanced it. CSDS inactivated SOD2 by enhancing its acetylation and increased lipid peroxidation in the PFC. In contrast, the ELF-EMF activated the Sirt3-FoxO3a-SOD2 pathway and suppressed lipid peroxidation. Furthermore, CSDS increased markers for mitophagy, which was suppressed by the ELF-EMF in six weeks. The ELF-EMF exerted beneficial hormetic effects on mitochondrial energy production, mitochondrial antioxidation, and mitochondrial dynamics in a mouse model of depression. We envisage that an ELF-EMF is a promising therapeutic option for depression.

New antidepressant mechanism of Yueju Pill: Increasing ghrelin level by inhibiting gastric mTOR/S6K signaling pathway and sensitizing hippocampal GHS-R

Background and aim

Yueju Pill (YJ) not only has good antidepressant effect but also can effectively treat digestive system diseases. However,it remains unclear whether the mechanism of antidepressant action of YJ is related to the peripheral digestive system. The purpose of this study was to elucidate the antidepressant mechanism of YJ on ghrelin level based on gastric mTOR/S6K signal pathway and sensitized hippocampal Ghrelin/GHS-R system in CUMS mice.

Experimental procedure

The depression model was induced by chronic unpredictable mild stress (CUMS) and social isolation. The antidepressant effect of YJ was observed by behavioral experiment and hemodynamic experiments. Ghrelin levels in in hippocampus and blood were measured by Elisa kit, and the mRNA of ghrelin in mice stomach was measured by Real-time Quantitative PCR (RT-qPCR). The activation level of gastric mTOR/S6K signal pathway was detected by Western Blot (WB). Rapamycin (Rapa) and L-Leucine (L-Leu) were used to verify the effects of YJ on the synthesis and release of ghrelin. The activity of GHS-R in hippocampus was observed by immunofluorescence. Hippocampal neuronal damage was evaluated by HE staining and Nissl staining. The level of central neurotransmitter was measured by liquid chromatograph mass spectrometer (LC-MS).

Results and conclusion

YJ ameliorates CUMS-induced depressive-like behavior by inhibiting the gastric mTOR/S6K signaling pathway and increasing GHR expression in the mouse stomach. However, these effects of YJ could be resisted by L-Leu (a mTOR receptor agonist). Further studies have shown that YJ can sensitize the Ghrelin/GHS-R system in the hippocampus, with significant neuroprotective effects, and is also involved in regulating the levels of key neurotransmitters (5-hydroxytryptamine, Dopamine and γ-aminobutyric acid) in depressive-like states.

Hippocampal PACAP signaling activation triggers a rapid antidepressant response

BACKGROUND

The development of ketamine-like rapid antidepressants holds promise for enhancing the therapeutic efficacy of depression, but the underlying cellular and molecular mechanisms remain unclear. Implicated in depression regulation, the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is investigated here to examine its role in mediating the rapid antidepressant response.

METHODS

The onset of antidepressant response was assessed through depression-related behavioral paradigms. The signaling mechanism of PACAP in the hippocampal dentate gyrus (DG) was evaluated by utilizing site-directed gene knockdown, pharmacological interventions, or optogenetic manipulations. Overall, 446 mice were used for behavioral and molecular signaling testing. Mice were divided into control or experimental groups randomly in each experiment, and the experimental manipulations included: chronic paroxetine treatments (4, 9, 14 d) or a single treatment of ketamine; social defeat or lipopolysaccharides-injection induced depression models; different doses of PACAP (0.4, 2, 4 ng/site; microinjected into the hippocampal DG); pharmacological intra-DG interventions (CALM and PACAP6-38); intra-DG viral-mediated PACAP RNAi; and opotogenetics using channelrhodopsins 2 (ChR2) or endoplasmic natronomonas halorhodopsine 3.0 (eNpHR3.0). Behavioral paradigms included novelty suppressed feeding test, tail suspension test, forced swimming test, and sucrose preference test. Western blotting, ELISA, or quantitative real-time PCR (RT-PCR) analysis were used to detect the expressions of proteins/peptides or genes in the hippocampus.

RESULTS

Chronic administration of the slow-onset antidepressant paroxetine resulted in an increase in hippocampal PACAP expression, and intra-DG blockade of PACAP attenuated the onset of the antidepressant response. The levels of hippocampal PACAP expression were reduced in both two distinct depression animal models and intra-DG knockdown of PACAP induced depression-like behaviors. Conversely, a single infusion of PACAP into the DG region produced a rapid and sustained antidepressant response in both normal and chronically stressed mice. Optogenetic intra-DG excitation of PACAP-expressing neurons instantly elicited antidepressant responses, while optogenetic inhibition induced depression-like behaviors. The longer optogenetic excitation/inhibition elicited the more sustained antidepressant/depression-like responses. Intra-DG PACAP infusion immediately facilitated the signaling for rapid antidepressant response by inhibiting calcium/calmodulin-dependent protein kinase II (CaMKII)-eukaryotic elongation factor 2 (eEF2) and activating the mammalian target of rapamycin (mTOR). Pre-activation of CaMKII signaling within the DG blunted PACAP-induced rapid antidepressant response as well as eEF2-mTOR-brain-derived neurotrophic factor (BDNF) signaling. Finally, acute ketamine treatment upregulated hippocampal PACAP expression, whereas intra-DG blockade of PACAP signaling attenuated ketamine's rapid antidepressant response.

CONCLUSIONS

Activation of hippocampal PACAP signaling induces a rapid antidepressant response through the regulation of CaMKII inhibition-governed eEF2-mTOR-BDNF signaling.

Antidepressant effects of esketamine via the BDNF/AKT/mTOR pathway in mice with postpartum depression and their offspring

Postpartum depression (PPD) is a serious mental health problem that can negatively affect future generations. BDNF/AKT/mTOR signaling in the frontal lobe and hippocampus in mice is associated with depression, but its role in mice with PPD and their offspring is unknown. This study was aimed at investigating the effects of esketamine (ESK), a drug approved for treatment of refractory depression, on the BDNF/AKT/mTOR pathway in mice with PPD and their offspring. A model of chronic unpredictable mild stress with pregnancy was used. ESK was injected into postpartum mice, and behavioral tests were conducted to predict the severity of symptoms at the end of lactation and in the offspring after adulthood. Both mice with PPD and their offspring showed significant anxiety- and depression-like behaviors that were ameliorated with the ESK intervention. ESK enhanced exploratory behavior in unfamiliar environments, increased the preference for sucrose, and ameliorated the impaired BDNF/AKT/mTOR signaling in the frontal and hippocampal regions in mice. Thus, ESK may have great potential in treating PPD and decreasing the incidence of depression in offspring.

Exploring the multifaceted potential of (R)-ketamine beyond antidepressant applications

(R, S)- and (S)-ketamine have made significant progress in the treatment of treatment-resistant depression (TRD) and have become a research focus in recent years. However, they both have risks of psychomimetic effects, dissociative effects, and abuse liability, which limit their clinical use. Recent preclinical and clinical studies have shown that (R)-ketamine has a more efficient and lasting antidepressant effect with fewer side effects compared to (R, S)- and (S)-ketamine. However, a recent small-sample randomized controlled trial found that although (R)-ketamine has a lower incidence of adverse reactions in adult TRD treatment, its antidepressant efficacy is not superior to the placebo group, indicating its antidepressant advantage still needs further verification and clarification. Moreover, an increasing body of research suggests that (R)-ketamine might also have significant applications in the prevention and treatment of medical fields or diseases such as cognitive disorders, perioperative anesthesia, ischemic stroke, Parkinson's disease, multiple sclerosis, osteoporosis, substance use disorders, inflammatory diseases, COVID-19, and organophosphate poisoning. This article briefly reviews the mechanism of action and research on antidepressants related to (R)-ketamine, fully revealing its application potential and development prospects, and providing some references and assistance for subsequent expanded research.

Involvement of PI3K/AKT Pathway in the Rapid Antidepressant Effects of Crocetin in Mice with Depression-Like Phenotypes

The current first-line antidepressants have the drawback of slow onset, which greatly affects the treatment of depression. Crocetin, one of the main active ingredients in saffron (Crocus sativus L.), has been demonstrated to have antidepressant activities, but whether it has a rapid antidepressant effect remains unclear. This study aimed to investigate the onset, duration, and mechanisms of the rapid antidepressant activity of crocetin (20, 40 and 80 mg/kg, intraperitoneal injection) in male mice subjected to chronic restraint stress (CRS). The results of behavioral tests showed that crocetin exerted rapid antidepressant-like effect in mice with depression-like phenotypes, including rapid normalization of depressive-like behaviors within 3 h, and the effects could be maintained for 2 days. Hematoxylin-eosin (HE) and Nissl staining showed that crocetin ameliorated hippocampal neuroinflammation and nerve injuries in mice with depression-like phenotypes. The levels of inflammatory factors, corticosterone and pro brain-derived neurotrophic factor in crocetin-administrated mice serum were significantly reduced compared with those in the CRS group, as well as the levels of inflammatory factors in hippocampus. What's more, Western blot analyses showed that, compared to CRS-induced mice, the relative levels of mitogen-activated kinase phosphatase 1 and toll-like receptor 4 were significantly reduced after the administration of crocetin, and the relative expressions of extracellular signal-regulated kinase 1/2 (ERK1/2), cAMP-response element binding protein, phosphorylated phosphoinositide 3 kinase (p-PI3K)/PI3K, phosphorylated protein kinase B (p-AKT)/AKT, phosphorylated glycogen synthase kinase 3β (p-GSK3β)/GSK3β, phosphorylated mammalian target of rapamycin (p-mTOR)/mTOR were markedly upregulated. In conclusion, crocetin exerted rapid antidepressant effects via suppressing the expression of inflammatory cytokines and the apoptosis of neuronal cells through PI3K/AKT signaling pathways. The rapid antidepressant effect of crocetin (40 mg/kg) could be maintained for at least 2 days after single treatment.

PI3K-AKT/mTOR Signaling in Psychiatric Disorders: A Valuable Target to Stimulate or Suppress?

Economic development and increased stress have considerably increased the prevalence of psychiatric disorders in recent years, which rank as some of the most prevalent diseases globally. Several factors, including chronic social stress, genetic inheritance, and autogenous diseases, lead to the development and progression of psychiatric disorders. Clinical treatments for psychiatric disorders include psychotherapy, chemotherapy, and electric shock therapy. Although various achievements have been made researching psychiatric disorders, the pathogenesis of these diseases has not been fully understood yet, and serious adverse effects and resistance to antipsychotics are major obstacles to treating patients with psychiatric disorders. Recent studies have shown that the mammalian target of rapamycin (mTOR) is a central signaling hub that functions in nerve growth, synapse formation, and plasticity. The PI3K-AKT/mTOR pathway is a critical target for mediating the rapid antidepressant effects of these pharmacological agents in clinical and preclinical research. Abnormal PI3K-AKT/mTOR signaling is closely associated with the pathogenesis of several neurodevelopmental disorders. In this review, we focused on the role of mTOR signaling and the related aberrant neurogenesis in psychiatric disorders. Elucidating the neurobiology of the PI3K-AKT/mTOR signaling pathway in psychiatric disorders and its actions in response to antidepressants will help us better understand brain development and quickly identify new therapeutic targets for the treatment of these mental illnesses.

Fecal metabolomics combined with metagenomics sequencing to analyze the antidepressant mechanism of Yueju Wan

BACKGROUND

Yueju Wan (YJW), defined in Danxi's Mastery of Medicine, has Qi-regulating and Qi-promoting effects. YJW has frequently been applied in the clinic for the treatment of depression. Substantial evidence has shown that depression is related to metabolic abnormalities of the gut microbiota, and traditional Chinese medicine (TCM) can treat depression by adjusting gut microbiota metabolism. The antidepressant effect of YJW is well established, but thus far, whether its mechanism of action is achieved by regulating the intestinal flora has not been elucidated.

METHODS

In this study, chronic unpredictable mild stress (CUMS) along with isolated feeding created a rat depression model, and YJW was administered for intervention. Rats were put through behavioral tests to determine their level of depression, and ELISA was utilized for measuring the level of monoamine neurotransmitters (MNTs) in the hippocampus. Metagenomic gene sequencing analysis was used to study the effect of depression on the intestinal flora in rats and the regulatory mechanism of YJW on the intestinal flora. Furthermore, ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MS) was utilized for fecal metabolomics studies to further reveal the antidepressant mechanism of YJW. The antidepressant mechanism of YJW was explored and further verified by Western blot analysis.

RESULTS

Different doses of YJW improved the depressive state of rats and raised the levels of MNTs in the hippocampus. The results of metagenomic sequencing indicated that the YJW recovered the structure and diversity of the intestinal flora in depressed rats. Metabolomics revealed sustained changes in 21 metabolites after the treatment of YJW, suggesting that YJW can play an antidepressant role by improving abnormal metabolic pathways. The results of correlation analysis suggested that YJW might mediate Eubacterium, Oscillibacter, Roseburia, Romboutsia and Bacterium to regulate purine metabolism, tryptophan metabolism, primary bile acid biosynthesis, and glutamate metabolism and exert antidepressant effects. Western blot analysis showed that YJW reduced the content of IL-1β in the hippocampus, inhibited the activation of the NLRP3 inflammasome in the hippocampus of rats, and increased the content of ZO-1 in the colon of rats.

CONCLUSION

YJW can alleviate depressive symptoms in depressed rats, and its mechanism is connected to improving intestinal flora and regulating body metabolism.

Jiawei-Xiaoyao pill elicits a rapid antidepressant effect, dependent on activating CaMKII/mTOR/BDNF signaling pathway in the hippocampus

ETHNOPHARMACOLOGICAL RELEVANCE

Jiawei-Xiaoyao pill (JWX), a traditional Chinese medicine, was recorded in ancient Chinese medicine pharmacopoeia using for treatment of various diseases, including mood disorders. Current mainstream antidepressants have a disadvantage in delayed onset of action. The rapid antidepressant potential of JWX and the underlying mechanisms remain unclear.

AIM OF THE STUDY

We aimed to assess the rapid antidepressant potential of JWX, within the prescription dose range, and the distinct underlying neuroplasticity signaling mechanism.

MATERIALS AND METHODS

The rapid antidepressant response of JWX were determined using various behavioral paradigms, and in a corticosterone (CORT)-induced depression model in mice. The molecular neuroplasticity signaling and the expression of BDNF in the hippocampus was evaluated using immunoblotting and immunostaining. The contribution of specific signaling was investigated using pharmacological interventions.

RESULTS

A single dose of JWX induced rapid and persistent antidepressant effects in both the normal and chronic CORT-exposed mice. The phosphorylation of CaMKII, mTOR, ERK and the expressions of BDNF, synapsin1 and PSD95 increased at 30 min post JWX. JWX restored the expression of BDNF in the hippocampal dentate gyrus reduced by CORT-exposure. The rapid antidepressant effect and upregulation of BDNF expression by JWX was blunted by a mTOR antagonist, rapamycin, or a CaMKII antagonist, KN-93. CaMKII signaling blockade blunted mTOR signaling activated by JWX, but not vice versa.

CONCLUSION

JWX elicits a rapid antidepressant effect, via quickly stimulating CaMKII signaling, subsequently activating mTOR-BDNF signaling pathway, and thus enhancing hippocampal neuroplasticity.

Machine learning models of plasma proteomic data predict mood in chronic stroke and tie it to aberrant peripheral immune responses

Post-stroke depression is common, long-lasting and associated with severe morbidity and death, but mechanisms are not well-understood. We used a broad proteomics panel and developed a machine learning algorithm to determine whether plasma protein data can predict mood in people with chronic stroke, and to identify proteins and pathways associated with mood. We used Olink to measure 1,196 plasma proteins in 85 participants aged 25 and older who were between 5 months and 9 years after ischemic stroke. Mood was assessed with the Stroke Impact Scale mood questionnaire (SIS3). Machine learning multivariable regression models were constructed to estimate SIS3 using proteomics data, age, and time since stroke. We also dichotomized participants into better mood (SIS3 > 63) or worse mood (SIS3 ≤ 63) and analyzed candidate proteins. Machine learning models verified that there is indeed a relationship between plasma proteomic data and mood in chronic stroke, with the most accurate prediction of mood occurring when we add age and time since stroke. At the individual protein level, no single protein or set of proteins predicts mood. But by using univariate analyses of the proteins most highly associated with mood we produced a model of chronic post-stroke depression. We utilized the fact that this list contained many proteins that are also implicated in major depression. Also, over 80% of immune proteins that correlate with mood were higher with worse mood, implicating a broadly overactive immune system in chronic post-stroke depression. Finally, we used a comprehensive literature review of major depression and acute post-stroke depression. We propose that in chronic post-stroke depression there is over-activation of the immune response that then triggers changes in serotonin activity and neuronal plasticity leading to depressed mood.

Storm on predictive brain: A neurocomputational account of ketamine antidepressant effect

For the past decade, ketamine, an N-methyl-D-aspartate receptor (NMDAr) antagonist, has been considered a promising treatment for major depressive disorder (MDD). Unlike the delayed effect of monoaminergic treatment, ketamine may produce fast-acting antidepressant effects hours after a single administration at subanesthetic dose. Along with these antidepressant effects, it may also induce transient dissociative (disturbing of the sense of self and reality) symptoms during acute administration which resolve within hours. To understand ketamine's rapid-acting antidepressant effect, several biological hypotheses have been explored, but despite these promising avenues, there is a lack of model to understand the timeframe of antidepressant and dissociative effects of ketamine. In this article, we propose a neurocomputational account of ketamine's antidepressant and dissociative effects based on the Predictive Processing (PP) theory, a framework for cognitive and sensory processing. PP theory suggests that the brain produces top-down predictions to process incoming sensory signals, and generates bottom-up prediction errors (PEs) which are then used to update predictions. This iterative dynamic neural process would relies on N-methyl-D-aspartate (NMDAr) and α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic receptors (AMPAr), two major component of the glutamatergic signaling. Furthermore, it has been suggested that MDD is characterized by over-rigid predictions which cannot be updated by the PEs, leading to miscalibration of hierarchical inference and self-reinforcing negative feedback loops. Based on former empirical studies using behavioral paradigms, neurophysiological recordings, and computational modeling, we suggest that ketamine impairs top-down predictions by blocking NMDA receptors, and enhances presynaptic glutamate release and PEs, producing transient dissociative symptoms and fast-acting antidepressant effect in hours following acute administration. Moreover, we present data showing that ketamine may enhance a delayed neural plasticity pathways through AMPAr potentiation, triggering a prolonged antidepressant effect up to seven days for unique administration. Taken together, the two sides of antidepressant effects with distinct timeframe could constitute the keystone of antidepressant properties of ketamine. These PP disturbances may also participate to a ketamine-induced time window of mental flexibility, which can be used to improve the psychotherapeutic process. Finally, these proposals could be used as a theoretical framework for future research into fast-acting antidepressants, and combination with existing antidepressant and psychotherapy.

mGlu2/3 receptor antagonists for depression: overview of underlying mechanisms and clinical development

Triggered by the ground-breaking finding that ketamine exerts robust and rapid-acting antidepressant effects in patients with treatment-resistant depression, glutamatergic systems have attracted attention as targets for the development of novel antidepressants. Among glutamatergic systems, group II metabotropic glutamate (mGlu) receptors, consisting of mGlu2 and mGlu3 receptors, are of interest because of their modulatory roles in glutamatergic transmission. Accumulating evidence has indicated that mGlu2/3 receptor antagonists have antidepressant-like effects in rodent models that mirror those of ketamine and that mGlu2/3 receptor antagonists also share underlying mechanisms with ketamine that are responsible for these antidepressant-like actions. Importantly, contrary to their antidepressant-like profile, preclinical studies have revealed that mGlu2/3 receptor antagonists are devoid of ketamine-like adverse effects, such as psychotomimetic-like behavior, abuse potential and neurotoxicity. Despite some discouraging results for an mGlu2/3 receptor antagonist decoglurant (classified as a negative allosteric modulator [NAM]) in patients with major depressive disorder, clinical trials of two mGlu2/3 receptor antagonists, a phase 2 trial of TS-161 (an orthosteric antagonist) and a phase 1 trial of DSP-3456 (a NAM), are presently on-going. mGlu2/3 receptors still hold promise for the development of safer and more efficacious antidepressants.

Yueju volatile oil plays an integral role in the antidepressant effect by up-regulating ERK/AKT-mediated GLT-1 expression to clear glutamate

Phytochemical investigation of the volatile oil of Yueju (YJVO) and its constituent herbs induced the detection of 52 compounds in YJVO, mainly monoterpenes and sesquiterpenes as well as a small amount of aromatic and aliphatic compounds. 5 of these compounds were found only in the YJVO instead of the volatile oil of its constituent herbs. The anti-depressant effect of YJVO was proved by behavioral tests in chronic unpredictable mild stress (CUMS) mice. An acute oral toxicity evaluation determined the LD50 of YJVO was 5.780 mL/kg. Doppler ultrasound and laser speckle imaging have detected that the YJVO could improve depression-related cerebral blood flow. In addition, related neurotransmitters and proteins were analyzed through targeted metabolomics and immunofluorescence. The potential antidepressant mechanisms of YJVO related to significantly decreasing Glu in CUMS mice by up-regulating the ERK/AKT-mediated expression of GLT-1.

Different synaptic mechanisms of intermittent and continuous theta-burst stimulations in a severe foot-shock induced and treatment-resistant depression in a rat model

Treatment-resistant depression (TRD) is a condition wherein patients with depression fail to respond to antidepressant trials. A new form of repetitive transcranial magnetic stimulation (rTMS), called theta-burst stimulation (TBS), which includes intermittent theta-burst stimulation (iTBS) and continuous theta-burst stimulation (cTBS), is non-inferior to rTMS in TRD treatment. However, the mechanism of iTBS and cTBS underlying the treatment of TRD in the prefrontal cortex (PFC) remains unclear. Hence, we applied foot-shock stress as a traumatic event to develop a TRD rat model and investigated the different mechanisms of iTBS and cTBS. The iTBS and cTBS treatment were effective in depressive-like behavior and active coping behavior. The iTBS treatments improved impaired long-term potentiation and long-term depression (LTD), whereas the cTBS treatment only improved aberrant LTD. Moreover, the decrease in mature brain-derived neurotrophic factor (BDNF)-related protein levels were reversed by iTBS treatment. The decrease in proBDNF-related protein expression was improved by iTBS and cTBS treatment. Both iTBS and cTBS improved the decreased α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and downregulation of mammalian target of the rapamycin (mTOR) signaling pathway. The iTBS produces both excitatory and inhibitory synaptic effects, and the cTBS only produces inhibitory synaptic effects in the PFC.

The Missing Piece? A Case for Microglia's Prominent Role in the Therapeutic Action of Anesthetics, Ketamine, and Psychedelics

There is much excitement surrounding recent research of promising, mechanistically novel psychotherapeutics - psychedelic, anesthetic, and dissociative agents - as they have demonstrated surprising efficacy in treating central nervous system (CNS) disorders, such as mood disorders and addiction. However, the mechanisms by which these drugs provide such profound psychological benefits are still to be fully elucidated. Microglia, the CNS's resident innate immune cells, are emerging as a cellular target for psychiatric disorders because of their critical role in regulating neuroplasticity and the inflammatory environment of the brain. The following paper is a review of recent literature surrounding these neuropharmacological therapies and their demonstrated or hypothesized interactions with microglia. Through investigating the mechanism of action of psychedelics, such as psilocybin and lysergic acid diethylamide, ketamine, and propofol, we demonstrate a largely under-investigated role for microglia in much of the emerging research surrounding these pharmacological agents. Among others, we detail sigma-1 receptors, serotonergic and γ-aminobutyric acid signalling, and tryptophan metabolism as pathways through which these agents modulate microglial phagocytic activity and inflammatory mediator release, inducing their therapeutic effects. The current review includes a discussion on future directions in the field of microglial pharmacology and covers bidirectional implications of microglia and these novel pharmacological agents in aging and age-related disease, glial cell heterogeneity, and state-of-the-art methodologies in microglial research.

Antidepressant-like effect of acute dose of Naringin involves suppression of NR1 and activation of protein kinase A/cyclic adenosine monophosphate response element-binding protein/brain-derived neurotrophic factor signaling in hippocampus

Naringin (Nr) has been identified to have antidepressant-like effects through repeated treatment. However, the underlying mechanism of the rapid antidepressant-like effects of Nr was still unclear. The present study used behavioral tests, classic depressive model and pharmacological methods to reveal the rapid antidepressant-like potential of Nr. We found that a single dose of Nr (20 mg/kg) produced antidepressant-like action after 2 h in the tail suspension test (TST) and forced swimming test (FST). Moreover, ketamine-like effects were also demonstrated by using the chronic mild stress model (CMS) and learned helplessness (LH), and the results showed that Nr reversed all behavioral defects, TST, FST, source preference test (SPT) in CMS, and LH testing, TST, FST in LH model, at 2 h after a single administration. In addition, Nr (20 mg/kg) could improve the abnormal expressions of NMDA receptor NR1 and PKA/CREB/BDNF pathway in hippocampus 2 h after a single administration in CMS mice. Further investigation revealed that activation of NMDA receptors by NMDA (750 mg/kg) could block the antidepressant effects of acute administration of Nr (20 mg/kg). However, the inhibition of NMDA receptors by MK-801 (0.05 mg/kg) promoted the subdose of Nr (10 mg/kg) to have antidepressant effect, which was similar to the effective dose Nr (20 mg/kg). Taken together, acute dose of Nr produces rapid antidepressant-like action, and the underlying mechanism could be through inhibiting NMDA receptors in the hippocampus.

Fast antidepressant action of ketamine in mouse models requires normal VGLUT1 levels from prefrontal cortex neurons

The NMDA antagonist ketamine demonstrated a fast antidepressant activity in treatment-resistant depression. Pre-clinical studies suggest that de novo synthesis of the brain-derived neurotrophic factor (BDNF) in the PFC might be involved in the rapid antidepressant action of ketamine. Applying a genetic model of impaired glutamate release, this study aims to further identify the molecular mechanisms that could modulate antidepressant action and resistance to treatment. To that end, mice knocked-down for the vesicular glutamate transporter 1 (VGLUT1+/-) were used. We analyzed anhedonia and helpless behavior as well as the expression of the proteins linked to glutamate transmission in the PFC of mice treated with ketamine or the reference antidepressant reboxetine. Moreover, we analyzed the acute effects of ketamine in VGLUT1+/- mice pretreated with chronic reboxetine or those that received a PFC rescue expression of VGLUT1. Chronic reboxetine rescued the depressive-like phenotype of the VGLUT1+/- mice. In addition, it enhanced the expression of the proteins linked to the AMPA signaling pathway as well as the immature form of BDNF (pro-BDNF). Unlike WT mice, ketamine had no effect on anhedonia or pro-BDNF expression in VGLUT1+/- mice; it also failed to decrease phosphorylated eukaryote elongation factor 2 (p-eEF2). Nevertheless, we found that reboxetine administered as pretreatment or PFC overexpression of VGLUT1 did rescue the antidepressant-like activity of acute ketamine in the mice. Our results strongly suggest that not only do PFC VGLUT1 levels modulate the rapid-antidepressant action of ketamine, but also highlight a possible mechanism for antidepressant resistance in some patients.

Role of the mesolimbic dopamine pathway in the antidepressant effects of ketamine

Depression is a complex and highly heterogeneous disorder which diagnosis is based on an exceedingly variable set of clinical symptoms. Current treatments focus almost exclusively on the manipulation of monoamine neurotransmitter systems, but despite considerable efforts, these remain inadequate for a significant proportion of those afflicted by the disorder. The emergence of racemic (R, S)-ketamine as a fast-acting antidepressant has provided an exciting new path for the study of major depressive disorder (MDD) and the search for better therapeutics for its treatment. Previous work suggested that ketamine's mechanism of action is primarily mediated via blockaded of N-methyl-d-aspartate (NMDA) receptors, however, this is an area of active research and clinical and preclinical evidence now indicate that ketamine acts on multiple systems. The last couple of decades have cemented the mesolimbic dopamine reward pathway's involvement in the pathogenesis of MDD and related mood disorders. Exposure to negative stress dysregulates dopamine neuronal activity disrupting reward and motivational processes resulting in anhedonia (lack of pleasure), a hallmark symptom of depression. Although the mechanism(s) underlying ketamine's antidepressant activity continue to be elucidated, current evidence indicate that its therapeutic effects are mediated, at least in part, via long-lasting synaptic changes and subsequent molecular adaptations in brain regions within the mesolimbic dopamine system. Notwithstanding, ketamine is a drug of abuse, and this liability may pose limitations for long term use as an antidepressant. This review outlines the current knowledge of ketamine's actions within the mesolimbic dopamine system and its abuse potential. This article is part of the Special Issue on 'Ketamine and its Metabolites'.

Depression-related phenotypes at early stages of Aβ and tau accumulation in inducible Alzheimer's disease mouse model: Task-oriented and concept-driven interpretations

Depression is highly prevalent in Alzheimer Disease (AD); however, there is paucity of studies that focus specifically on the assessment of depression-relevant phenotypes in AD mouse models. Conditional doxycycline-dependent transgenic mouse models reproducing amyloidosis (TetOffAPPsi) and/or tau (TetOffTauP301L) pathology starting at middle age (6 months) were used in this study. As AD patients can experience depressive symptoms relatively early in disease, testing was conducted at early, pre-pathology stages of Aβ and/or tau accumulation (starting from 45 days of transgenes expression). Tau-related differences were detected in the Novelty Suppressed Feeding task (NSF), whereas APP-related differences were observed predominantly in measures of the Open Field (OF) and Forced Swim tasks (FST). Effects of combined production of Aβ and tau were detected in immobility during the 1st half of the Tail Suspension task (TST). These data demonstrate that results from different tasks are difficult to reconcile using task/variable-centered interpretations in which a single task/variable is assigned an ad-hoc meaning relevant to depression. An alternative, concept-oriented, approach is based on multiple variables/tests, with an understanding of their possible inter-dependence and utilization of statistical approaches that handle correlated data sets. The existence of strong correlations within and between some of the tasks supported utilization of factor analyses (FA). FA explained a similar amount of variability across the genotypes (∼80%) and identified two factors stable across genotypes and representing motor activity and anxiety measures in OF. In contrast, variables related to FST, TST, and NSFT did not demonstrate a structure of factor loadings that would support the existence of a single integral factor of "depressive state" measured by these tasks. In addition, factor loadings varied between genotypes, indicating that genotype-specific between-task correlations need to be considered for interpretations of findings in any single task. In general, this study demonstrates that utilization of multiple tasks to characterize behavioral phenotypes, an approach that is finally gaining more widespread adoption, requires a step of data integration across different behavioral tests for appropriate interpretations.

p85S6K sustains synaptic GluA1 to ameliorate cognitive deficits in Alzheimer's disease

BACKGROUND

Ribosomal protein S6 kinase 1 (S6K1) is a serine-threonine kinase that has two main isoforms: p70S6K (70-kDa isoform) and p85S6K (85-kDa isoform). p70S6K, with its upstream mammalian target of rapamycin (mTOR), has been shown to be involved in learning and memory and participate in the pathophysiology of Alzheimer's disease (AD). However, the function of p85S6K has long been neglected due to its high similarity to p70S6k. The role of p85S6K in learning and memory is still largely unknown.

METHODS

We fractionated the postsynaptic densities to illustrate the differential distribution of p85S6K and p70S6K. Coimmunoprecipitation was performed to unveil interactions between p85S6K and the GluA1 subunit of AMPA receptor. The roles of p85S6K in synaptic targeting of GluA1 and learning and memory were evaluated by specific knockdown or overexpression of p85S6K followed by a broad range of methodologies including immunofluorescence, Western blot, in situ proximity ligation assay, morphological staining and behavioral examination. Further, the expression level of p85S6K was measured in brains from AD patients and AD model mice.

RESULTS

p85S6K, but not p70S6K, was enriched in the postsynaptic densities. Moreover, knockdown of p85S6K resulted in defective spatial and recognition memory. In addition, p85S6K could interact with the GluA1 subunit of AMPA receptor through synapse-associated protein 97 and A-kinase anchoring protein 79/150. Mechanistic studies demonstrated that p85S6K could directly phosphorylate GluA1 at Ser845 and increase the amount of GluA1 in synapses, thus sustaining synaptic function and spine densities. Moreover, p85S6K was found to be specifically decreased in the synaptosomal compartment in the brains of AD patients and AD mice. Overexpression of p85S6K ameliorated the synaptic deficits and cognitive impairment in transgenic AD model mice.

CONCLUSIONS

These results strongly imply a significant role for p85S6K in maintaining synaptic and cognitive function by interacting with GluA1. The findings provide an insight into the rational targeting of p85S6K as a therapeutic potential for AD.

Resistance Training Modulates Hippocampal Neuroinflammation and Protects Anxiety-Depression-like Dyad Induced by an Emotional Single Prolonged Stress Model

Stress is a triggering factor for anxious and depressive phenotypes. Exercise is known for its action on the central nervous system. This study aimed to evaluate the role of resistance exercise in an anxiety-depression-like dyad in a model of stress. Male Swiss mice (35-day-old) were exercised, three times a week for 4 weeks on nonconsecutive days. The resistance exercise consisted of climbing a 1-m-high ladder 15 times. After mice were subjected to an emotional single prolonged stress (Esps) protocol. Seven days later, they were subjected to anxiety and depression predictive behavioral tests. The results showed that exercised mice gain less weight than sedentary from weeks 3 to 5. Resistance exercise was effective against an increase in immobility time in the forced swim test and tail suspension test and a decrease in grooming time of mice subjected to Esps. Resistance exercise protected against the decrease in the percentage of open arms time and open arm entries, and the increase in the anxiety index in Esps mice. Four-week resistance exercise did not elicit an antidepressant/anxiolytic phenotype in non-stressed mice. Esps did not alter plasma corticosterone levels but increased the hippocampal glucocorticoid receptor content in mice. Resistance exercise protected against the decrease in hippocampal levels of tropomyosin kinase B (TRκB), the p-Akt/Akt, and the p-mTOR/mTOR ratios of Esps mice. Resistance exercise proved to be effective in decreasing hippocampal neuroinflammation in Esps mice. Resistance exercise protected against the increase in the hippocampal Akt/mTOR pathway and neuroinflammation, and anxiety/depression-like dyad in Esps exposed mice.

ERK/mTOR signaling may underlying the antidepressant actions of rapastinel in mice

Rapastinel as the allosteric modulator of N-methyl-D-aspartate receptor (NMDAR) produces rapid antidepressant-like effects dependent on brain-derived neurotrophic factor (BDNF) and VGF (nonacryonimic) release. Herein, we further explore the molecular mechanisms of the antidepressant effects of repeated administration with rapastinel in mice. Our results showed that continuous 3-day rapastinel (5 and 10 mg/kg, i.v.) produced antidepressant-like actions dependent on the increase in extracellular regulated protein kinase (ERK)/mammalian target of rapamycin (mTOR) signaling and downstream substrates p70S6 kinase (p70S6k) and the eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), which may induce the expression of VGF and BDNF in the hippocampus and prefrontal cortex of mice. Furthermore, compared with a single treatment, our data indicated that 3-day repeated rapastinel treatment produced antidepressant-like actions accompanied by potentiation of ERK/mTOR/VGF/BDNF/tropomyosin-related kinase receptor B (TrkB) signaling. Based on previous and our supplementary data that showed the pivotal role of on α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) in the rapid release of VGF and BDNF and activation of TrkB by a single dose of rapastinel, we postulate that the antidepressant-like effects of single or repeated administration of rapastinel may result in the rapid release of VGF and BDNF or ERK/mTOR signaling pathway-mediated VGF/BDNF/TrkB autoregulatory feedback loop respectively. Our current work adds new knowledge to the molecular mechanisms that underlie the antidepressant-like actions of rapastinel in mice.

An Investigation of the Anti-Depressive Properties of Phenylpropanoids and Flavonoids in Hemerocallis citrina Baroni

The World Health Organization predicts that over the next several years, depression will become the most important mental health issue globally. Growing evidence shows that the flower buds of Hemerocallis citrina Baroni (H. citrina) possess antidepressant properties. In the search for new anti-depression drugs, a total of 15 phenylpropanoids and 22 flavonoids were isolated and identified based on spectral data (1D and 2D NMR, HR-ESI-MS, UV) from H. citrina. Among them, compound 8 was a novel compound, while compounds 1-4, 6, 9, 10, 15, 17, 24-26, 28, and 37 were isolated for the first time from Hemerocallis genus. To study the antidepressant activity of phenylpropanoids and flavonoids fractions from H. citrina, macroporous resin was used to enrich them under the guidance of UV characteristics. UHPLC-MS/MS was applied to identify the constituents of the enriched fractions. According to behavioral tests and biochemical analyses, it showed that phenylpropanoid and flavonoid fractions from H. citrina can improve the depressive-like mental state of chronic unpredictable mild stress (CUMS) rats. This might be accomplished by controlling the amounts of the inflammatory proteins IL-6, IL-1β, and TNF-α in the hippocampus as well as corticosterone in the serum. Thus, the monomer compounds were tested for their anti-neuroinflammatory activity and their structure-activity relationship was discussed in further detail.

A rat study model of depression-driven chronic prostatitis by modulating the PI3K/Akt/mTOR network

Depression and chronic prostatitis (CP) are two common diseases that affect the human population worldwide. Clinically, it has been demonstrated that andrological patients often simultaneously suffer from depression and CP. Prior investigations have established that depression acts as an independent risk factor for CP. Herein, we explored the correlation between depression and CP using bioinformatics tools and through animal experiments. The potential targets and signalling pathways involved in depression and CP were predicted using bioinformatics tool, while depression in the rat model was established through chronic restraint stress. The expression of the related proteins and mRNA was assessed by Western blotting and real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Relative to those in the control rats, the protein contents of PI3K, p-Akt, and p-mTOR were lower in the model rats (p < 0.05). Similarly, the transcript levels of PI3K, Akt, and mTOR was also relatively lower in the model rats (p < 0.05). And PI3K/Akt agonists reduced inflammation in rat prostate tissue, accompanied by significant increases in the transcript and protein expression levels of PI3K, Akt, and mTOR. Thus, we proposed that depression model rats may induce CP as a result of mediation by the negative regulation of the PI3K/Akt/mTOR signalling network.

Translational control by ketamine and its implications for comorbid cognitive deficits in depressive disorders

Ketamine has shown antidepressant effects in patients with major depressive disorder (MDD) resistant to first-line treatments and approved for use in this patient population. Ketamine induces several forms of synaptic plasticity, which are proposed to underlie its antidepressant effects. However, the molecular mechanism of action directly responsible for ketamine's antidepressant effects remains under active investigation. It was recently demonstrated that the effectors of the mammalian target of rapamycin complex 1 (mTORC1) signalling pathway, namely, eukaryotic initiation factor 4E (eIF4E) binding proteins 1 and 2 (4E-BP1 and 4E-BP2), are central in mediating ketamine-induced synaptic plasticity and behavioural antidepressant-like effect. 4E-BPs are a family of messenger ribonucleic acid (mRNA) translation repressors inactivated by mTORC1. We observed that their expression in inhibitory interneurons mediates ketamine's effects in the forced swim and novelty suppressed feeding tests and the long-lasting inhibition of GABAergic neurotransmission in the hippocampus. In addition, another effector pathway that regulates translation elongation downstream of mTORC1, the eukaryotic elongation factor 2 kinase (eEF2K), has been implicated in ketamine's behavioural effects. We will discuss how ketamine's rapid antidepressant effect depends on the activation of neuronal mRNA translation through 4E-BP1/2 and eEF2K. Furthermore, given that these pathways also regulate cognitive functions, we will discuss the evidence of ketamine's effect on cognitive function in MDD. Overall, the data accrued from pre-clinical research have implicated the mRNA translation pathways in treating mood symptoms of MDD. However, it is yet unclear whether the pro-cognitive potential of subanesthetic ketamine in rodents also engages these pathways and whether such an effect is consistently observed in the treatment-resistant MDD population.

Synergistic effects of two natural compounds of iridoids on rapid antidepressant action by up-regulating hippocampal PACAP signaling

BACKGROUND AND PURPOSE

Current mainstream antidepressants have limited efficacy and a delayed onset of action. Yueju is a traditional herbal medicine conferring rapid antidepressant activity. Here we attempted to identify the effective compounds from Yueju and the underlying mechanisms.

EXPERIMENTAL APPROACH

A transcriptomic analysis was employed to discover key candidate molecules for rapid antidepressant response. The enriched compounds in Yueju were identified with HPLC. Antidepressant effects were evaluated periodically using various behavioral paradigms. The mechanistic signaling was assessed using site-directed pharmacological intervention or optogenetic manipulation.

KEY RESULTS

A transcriptomic analysis revealed that Yueju up-regulated pituitary adenylate cyclase activating polypeptide (PACAP) expression in the hippocampus. Two iridoids geniposide (GP) and shanzhiside methyl-ester (SM) were enriched in Yueju. Co-treatment of GP and SM each at an equivalent dose in Yueju synergistically increased PACAP expression and elicited rapid antidepressant effects, which were prevented by intra-hippocampal dentate gyrus (DG) infusions of a PACAP antagonist or optogenetic inactivation of PACAP-expressing neurons. GP-SM co-treatment rapidly reduced CaMKII phosphorylation and enhanced mTOR/4EBP1/P70S6k/BDNF signaling, while intra-DG infusions of a CaMKII activator blunted rapid antidepressant effects and BDNF expression up-regulation induced by GP-SM co-treatment. A single administration of GP-SM rapidly improved depression-like behaviors and up-regulated hippocampal PACAP signaling in the repeated corticosterone-induced depression model, further confirming its rapid antidepressant action and the involvement of PACAP.

CONCLUSION AND IMPLICATIONS

GP-SM co-treatment elicited a synergistic effect on rapid antidepressant effects via triggering hippocampal PACAP activity and associated CaMKII-BDNF signaling, shedding lights on the development of novel targeted antidepressants.

Ligand-Gated Ion Channels as Targets for Treatment and Management of Cancers

Ligand-gated ion channels are an ionotropic receptor subtype characterized by the binding of an extracellular ligand, followed by the transient passage of ions through a transmembrane pore. Ligand-gated ion channels are commonly subcategorized into three superfamilies: purinoreceptors, glutamate receptors, and Cys-loop receptors. This classification is based on the differing topographical morphology of the receptors, which in turn confers functional differences. Ligand-gated ion channels have a diverse spatial and temporal expression which implicate them in key cellular processes. Given that the transcellular electrochemical gradient is finely tuned in eukaryotic cells, any disruption in this homeostasis can contribute to aberrancies, including altering the activity of pro-tumorigenic molecular pathways, such as the MAPK/ERK, RAS, and mTOR pathways. Ligand-gated ion channels therefore serve as a potential targetable system for cancer therapeutics. In this review, we analyze the role that each of the three ligand-gated ion channel superfamilies has concerning tumor proliferation and as a target for the treatment of cancer symptomatology.

Repeated Yueju, But Not Fluoxetine, Induced Sustained Antidepressant Activity in a Mouse Model of Chronic Learned Helplessness: Involvement of CaMKII Signaling in the Hippocampus

OBJECTIVE

Depression is characterized with long disease length, whereas one major disadvantage of current mainstream treatment of depression is a high rate of relapse and recurrence. A sustained antidepressant activity is proposed to facilitate the prevention of relapse/recurrence. Here we compared the long-term antidepressant effect of Yueju, a traditional Chinese medicine formula, and a conventional antidepressant, fluoxetine, as well as revealing the underlying mechanism of long-term antidepressant effect of Yueju.

METHODS

Clinical long-term depression condition was modelled by using chronic learned helplessness (cLH) protocol in ICR strain mice. The short-term and long-term antidepressant effects of drugs were assessed with learned helplessness (LH), tail suspension test (TST), forced swim test (FST), and novelty-suppressed feeding (NSF) test. The expression of PKA, CaMKII signaling, and NR1, the NMDA receptor subunit, in hippocampus was determined. A CaMKII inhibitor (KN-62) was used to assess the role of CaMKII signaling in antidepressant effects of Yueju or fluoxetine.

RESULTS

In the mice exposed to chronic learned helplessness (cLH) procedure, administration of Yueju or fluoxetine for 3 weeks elicited comparable antidepressant effects, indicated by learned helplessness test, as well as TST and NSF. However, 5 days after termination of the 3-week-long drug administration, only mice previously treated with Yueju still showed the alleviation of depressive-like behaviors. At this time, the downregulation of PKA and p-CaMKII/CaMKII and upregulation of NMDA receptor subunit NR1 in the hippocampus were normalized in animals previously treated with Yueju. In contrast, none of the expressions of these proteins were changed in mice previously treated with fluoxetine. Interestingly, an administration of KN-62 blunted the antidepressant effect of Yueju.

CONCLUSION

These findings showed the sustained antidepressant efficacy of chronic treatment with routine dose of Yueju and the CaMKII signaling activation may play a critical role in the sustained antidepressant response.

mTORC1 Signaling Pathway Mediates Chronic Stress-Induced Synapse Loss in the Hippocampus

Background: The mechanistic target of rapamycin complex 1 (mTORC1) signaling has served as a promising target for therapeutic intervention of major depressive disorder (MDD), but the mTORC1 signaling underlying MDD has not been well elucidated. In the present study, we investigated whether mTORC1 signaling pathway mediates synapse loss induced by chronic stress in the hippocampus. Methods: Chronic restraint stress-induced depression-like behaviors were tested by behavior tests (sucrose preference test, forced swim test and tail suspension test). Synaptic proteins and alternations of phosphorylation levels of mTORC1 signaling-associated molecules were measured using Western blotting. In addition, mRNA changes of immediate early genes (IEGs) and glutamate receptors were measured by RT-PCR. Rapamycin was used to explore the role of mTORC1 signaling in the antidepressant effects of fluoxetine. Results: After successfully establishing the chronic restraint stress paradigm, we observed that the mRNA levels of some IEGs were significantly changed, indicating the activation of neurons and protein synthesis alterations. Then, there was a significant downregulation of glutamate receptors and postsynaptic density protein 95 at protein and mRNA levels. Additionally, synaptic fractionation assay revealed that chronic stress induced synapse loss in the dorsal and ventral hippocampus. Furthermore, these effects were associated with the mTORC1 signaling pathway-mediated protein synthesis, and subsequently the phosphorylation of associated downstream signaling targets was reduced after chronic stress. Finally, we found that intracerebroventricular infusion of rapamycin simulated depression-like behavior and also blocked the antidepressant effects of fluoxetine. Conclusion: Overall, our study suggests that mTORC1 signaling pathway plays a critical role in mediating synapse loss induced by chronic stress, and has part in the behavioral effects of antidepressant treatment.

Phencynonate hydrochloride exerts antidepressant effects by regulating the dendritic spine density and altering glutamate receptor expression

Phencynonate hydrochloride (PCH) is a drug that crosses the blood-brain barrier. Cellular experiments confirmed that PCH protects against glutamate toxicity and causes only weak central inhibition and limited side effects. As shown in our previous studies, PCH alleviates depression-like behaviours induced by chronic unpredictable mild stress (CUMS). Here we administered PCH at three different doses (4, 8 and 16 mg/kg) to male rats for two continuous days after CUMS and conducted behavioural tests to assess the dose-dependent antidepressant effects of PCH and its effects on the neuroplasticity in the hippocampus and medial prefrontal cortex (mPFC). Meanwhile, we measured the spine density and expression of related proteins to illustrate the mechanism of PCH. PCH treatment (8 mg/kg) significantly alleviated depression-like behaviours induced by CUMS. All doses of PCH treatment reversed the spine loss in prelimbic and CA3 regions induced by CUMS. Kalirin-7 expression was decreased in the hippocampus and mPFC of the CUMS group. The expression of the NR1 and NR2B subunits in the hippocampus, and NR2B in mPFC are increased by CUMS. PCH treatment (8 and 16 mg/kg) reversed all of these changes of Kalirin-7 in PFC and hippocampus, as well as NR1 and NR2B expression in the hippocampus. PCH is expected to be developed as a new type of rapid antidepressant. Its antidepressant effect may be closely related to the modulation of dendritic spine density in the prelimbic and CA3 regions and the regulation of Kalilin-7 and N-methyl-D-aspartic acid receptor levels in the hippocampus.

Early Enhancement of Neuroplasticity Index, the Ratio of Serum Brain-Derived Neurotrophic Factor Level to HAMD-24 Score, in Predicting the Long-Term Antidepressant Efficacy

Background: Current mainstream treatment of major depressive disorder (MDD) has a disadvantage in delayed onset of efficacy, making detection of early signatures predicative of the long-term treatment efficacy urgent.

Methods: MDD patients were scored with HAMD-24 and serum brain-derived neurotrophic factor (BDNF) levels were measured at different times in two independent trials: a single-arm observation of Yueju pill, a clinically approved traditional multiherbal medicine, and a two-arm random placebo-controlled trial for Yueju vs escitalopram. The ratio of the BDNF level to HAMD-24 score, or neuroplasticity index (NI), and its derived parameters were used for correlation analysis and receiver operating characteristic (ROC) analysis.

Results: On both the early (4th) and final (28th) days, Yueju and escitalopram significantly reduced HAMD-24 scores, compared to baselines, but only Yueju increased BDNF at both times. For either Yueju or escitalopram treatment, NI, but not BDNF, at baseline was correlated to NIs at the early or final treatment day. NI at early time was significantly correlated to early NI enhancement from the baseline for both Yueju and escitalopram, and to final NI enhancement from the baseline for Yueju in both trials. ROC analysis supported the predictability of Yueju’s final treatment efficacy from early NI enhancement.

Limitations: The small sample size and 28 days of treatment time may lead to the impossibility of ROC analysis of escitalopram.

Conclusion: Early NI enhancement is useful for prediction of long-term efficacy of Yueju and presumably some other antidepressants.

Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [ChiCTR1900021114].

Merazin Hydrate Produces Rapid Antidepressant Effects Depending on Activating mTOR Signaling by Upregulating Downstream Synaptic Proteins in the Hippocampus

Major depressive disorder has become an increasingly serious disease in the world. However, convenient antidepressants have low efficacy and slow onset defects, which is dangerous for suicidal tendency patients. Nowadays, rapid antidepressant research has become the focus. Merazin hydrate (MH), a component of the natural herb Fructus Aurantii, has been shown to produce rapid antidepressant-like effects in animal models. However, the mechanism of its rapid antidepressant-like effects was still elusive like that of ketamine. The study aimed to reveal the relationship between the rapid antidepressant-like effects of MH and mTOR signaling, which is closely related to rapid antidepressants. The results showed that a single administration of MH was capable of reversing the behavioral defects at 2 h in two classic depressive models including learned helplessness (LH) and chronic mild stress (CMS). Moreover, the phosphorylated expression of mTOR, reduced by LH or CMS, was upregulated after a single administration of MH, and the expressions of BDNF and synaptic proteins in the hippocampus were also reversed 2 h later, similar to ketamine. Moreover, LH increased the expressions of eNOS, IL-10, and TNF-α in serum, which were all reversed by a single dose of MH at 2 h, similar to ketamine. Furthermore, we used rapamycin, an antagonist of mTOR, to confirm whether the rapid antidepressant-like effects of MH depend on mTOR or not. We found that inhibiting the activation of mTOR blocked the rapid antidepressant-like effects of MH, which also inhibited the upregulation of expressions of BDNF and PSD95. To sum up, the rapid antidepressant effect of MH depended on the activation of mTOR to regulate downstream BNDF and synaptic protein expressions.

The effectiveness of (R)-ketamine and its mechanism of action differ from those of (S)-ketamine in a chronic unpredictable mild stress model of depression in C57BL/6J mice

(S)-ketamine has been approved as a rapid-acting antidepressant drug (RAAD). Although ketamine has an advantage over classic antidepressants (ADs) due to its rapid action, it remains a controversial drug due to its undesirable effects. Behavioral studies indicate that another enantiomer of ketamine, namely, (R)-ketamine, has been proposed as a safer but still effective RAAD. However, these conclusions have not been confirmed in any model of depression based on chronic environmental stress, which effectively reflects the core symptoms of this disease. Thus, we decided to compare the effects of (R)- and (S)-ketamine on chronic unpredictable mild stress (CUMS) in mice. Behavioral studies showed that (R)-ketamine induced anti-anhedonic and anti-apathetic efficacy up to seven days after administration, while the (S)-ketamine effect persisted up to 24 h or 3 days after injection. The behavioral effects of (R)-ketamine depended on the activation of TrkB receptors, while the (S)-ketamine effects did not. Western blot analyses showed that (S)-ketamine action might be related to both mTOR and ERK pathway activation and to the increased expression of GluA1 protein in the prefrontal cortex (PFC). In contrast, (R)-ketamine did not change ERK phosphorylation in the PFC, while it increased mTOR expression. (S)-Ketamine produced behavioral effects indicative of possible side effects in the dose range studied, while (R)-ketamine did not. This indicates that (R)-ketamine may be more effective, have a longer-lasting effect, and be safer to use than (S)-ketamine.

Translational control in neurovascular brain development

The human brain carries out complex tasks and higher functions and is crucial for organismal survival, as it senses both intrinsic and extrinsic environments. Proper brain development relies on the orchestrated development of different precursor cells, which will give rise to the plethora of mature brain cell-types. Within this process, neuronal cells develop closely to and in coordination with vascular cells (endothelial cells (ECs), pericytes) in a bilateral communication process that relies on neuronal activity, attractive or repulsive guidance cues for both cell types and on tight-regulation of gene expression. Translational control is a master regulator of the gene-expression pathway and in particular for neuronal and ECs, it can be localized in developmentally relevant (axon growth cone, endothelial tip cell) and mature compartments (synapses, axons). Herein, we will review mechanisms of translational control relevant to brain development in neurons and ECs in health and disease.

Oxidative Stress and the Pathophysiology and Symptom Profile of Schizophrenia Spectrum Disorders

Schizophrenia is associated with increased levels of oxidative stress, as reflected by an increase in the concentrations of damaging reactive species and a reduction in anti-oxidant defences to combat them. Evidence has suggested that whilst not the likely primary cause of schizophrenia, increased oxidative stress may contribute to declining course and poor outcomes associated with schizophrenia. Here we discuss how oxidative stress may be implicated in the aetiology of schizophrenia and examine how current understanding relates associations with symptoms, potentially via lipid peroxidation induced neuronal damage. We argue that oxidative stress may be a good target for future pharmacotherapy in schizophrenia and suggest a multi-step model of illness progression with oxidative stress involved at each stage.

Latent Sex Differences in CaMKII-nNOS Signaling That Underlie Antidepressant-Like Effects of Yueju-Ganmaidazao Decoction in the Hippocampus

Previous studies have demonstrated that Yueju-Ganmaidazao (YG) decoction induces rapid antidepressant-like effects, and the antidepressant response is mostly dependent on the suppression of nitric oxide-cyclic guanosine monophosphate signaling in male mice. This study aimed to investigate the sex difference mediated by calcium/calmodulin-dependent protein kinase II (CaMKII)-neuronal nitric oxide synthase (nNOS) signaling involved in the antidepressant-like effect of YG in mice. We found that the immobility times in the tail suspension test (TST) were found to be decreased after the single injection of YG in male and female mice with the same dosage. Additionally, chronic administration for 4 days of subthreshold dosage of YG and escitalopram (ES) also significantly decreased the immobility time in mice of both sexes. Chronic subthreshold dosage of YG and ES in LPS-treated mice and in chronic unpredictable stress (CUS) mice both decreased the immobility time, which was increased by stress. Meanwhile, in CUS-treated mice, sucrose preference test, forced swimming test, and open field test were applied to further confirm the antidepressant-like effects of YG and ES. Moreover, CUS significantly decreased the expression of nNOS and CaMKII, and both YG and ES could enhance the expression in the hippocampus of female mice, which was opposite to that in male mice, while endothelial nitric oxide synthase expression was not affected by stress or drug treatment neither in male mice nor in female mice. Finally, subthreshold dosage of YG combined with 7-nitroindazole (nNOS inhibitor) induced the antidepressant-like effects both in female and in male mice, while the single use of YG or 7-NI did not display any effect. However, pretreatment with KN-93 (CaMKII inhibitor) only blocked the antidepressant-like effect of high-dosage YG in female mice. Meanwhile, in CUS mice, chronic stress caused NR1 overexpression and inhibited cAMP response element binding protein action, which were both reversed by YG and ES in male and female mice, implying that YG and ES produced the same antidepressant-like effect in mice of both sexes. The study revealed that chronic treatment with a subthreshold dose of YG also produced antidepressant-like effects in female mice, and these effects depended on the regulation of the CaMKII-nNOS signaling pathway.

Catalpol ameliorates depressive-like behaviors in CUMS mice via oxidative stress-mediated NLRP3 inflammasome and neuroinflammation

The purpose of the present study was to investigate whether catalpol exhibited neuroprotective effects in chronic unpredictable mild stress (CUMS) mice through oxidative stress-mediated nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin-domain-containing 3 (NLRP3) inflammasome and neuroinflammation. Deficits in behavioral tests, including open field test (OFT), forced swim test (FST), and elevated plus-maze test (EPM), were ameliorated following catalpol administration. To study the potential mechanism, western blots, quantitative real-time PCR (qRT-PCR) analysis and immunofluorescence imaging were performed on the hippocampus samples. We found that the defects of behavioral tests induced by CUMS could be reversed by the absence of NLRP3 and NLRP3 inflammasome might be involved in the antidepressant effects of catalpol on CUMS mice. Similar to the NLRP3 inflammasome, the expression of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and inducible nitride oxide synthase (iNOS) were increased after CUMS. The current study demonstrated that catalpol possessed anti-inflammatory effect on CUMS mice and inhibited microglial polarization to the M1 phenotype. In addition, the activity of mitochondrial oxidative stress might be involved in the NLRP3 activation, which was proved by the downregulation of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and cleaved IL-1β, after the administration of mitochondrion-targeted antioxidant peptide SS31. Taken together, we provided evidence that catalpol exhibited antidepressive effects on CUMS mice possibly via the oxidative stress-mediated regulation of NLRP3 and neuroinflammation.

Neuroplasticity: A Key Player in the Antidepressant Action of Chinese Herbal Medicine

Traditional Chinese medicine (TCM) is a systematic medicine. It provides alternative strategies for the treatment of depression with its clinical experience, comprehensive diagnosis, and treatment theory. Chinese herbal medicine (CHM) is the major form of TCM prescription, and numerous CHMs have been demonstrated to possess remarkable antidepressant-like properties. A diversity of mechanisms have been implicated in CHM-associated antidepressant property. This paper reviewed the neuroplastic mechanisms underlying the antidepressant actions of CHM, finding that CHM repairs neuroplasticity by improving neurogenesis, neurotrophic factors, synaptic spine morphology, cell signaling, glutamatergic system, monoamine neurotransmitters, and neural apoptosis. CHM thereby exerts an antidepressant effect, attempting to offer a better understanding of the mechanisms implicated in TCM-related antidepressant-like efficacy and laying a foundation for the scientific evaluation and development of TCM in treating depression.

Fecal microbiota transplantation ameliorates stress-induced depression-like behaviors associated with the inhibition of glial and NLRP3 inflammasome in rat brain

BACKGROUND

Evidence from previous studies has demonstrated that the gut-microbiota-brain axis is vital in regulating of behavior and neuroinflammation in the central nervous system. Considering the putative connection among gut microbiota, neural function, and behavior, the present study investigated the potential signaling of gut microbiota to modulate depression-like behaviors and neuroinflammation.

METHODS

Rats showing depression-like behaviors induced by chronic unpredictable mild stress received fecal microbiota treatment or vehicle for 14 days, and alterations in behavior and neuroinflammation were assessed. ELISA, immunofluorescence staining and Western blot were used to analysis the activation of glial cells and NLRP3 inflammasome.

RESULTS

Treatment with fecal microbiota transplantation ameliorated depression-like behaviors. 5-Hydroxytryptamine decreased in the chronic unpredictable mild stress rat model but significantly increased after fecal microbiota transplantation. The treatment with fecal microbiota transplantation decreased the production of IL-1β and TNF-α. Moreover, fecal microbiota transplantation administration suppressed the activation of Iba1 positive microglia cells and GFAP positive astrocytes cells and reduced the expression of NLRP3, ASC, Caspase-1, and IL-1β pathway in the prefrontal cortex and hippocampus.

CONCLUSIONS

Fecal microbiota transplantation can improve depression-like behaviors induced by chronic unpredictable mild stress. The anti-depression effects of fecal microbiota transplantation were associated with the suppressed activation of glial cells and NLRP3 inflammasome in the brain.

Jianpi Jieyu Decoction, An Empirical Herbal Formula, Exerts Psychotropic Effects in Association With Modulation of Gut Microbial Diversity and GABA Activity

Background: Recent studies suggest that gut microbiota was associated with the bidirectional gut-brain axis which could modulate neuropsychological functions of the central nervous system. Gut microbiota could produce gamma aminobutyric acid (GABA) that could modulate the gut-brain axis response. Jianpi Jieyu (JPJY) decoction, a traditional Chinese formula, is mainly composed of Astragalus membranaxeus and Radix Pseudostellariae. Although the JPJY decoction has been used to treat the depression in China, the potential action of its antidepressant has not been well understood. Thus this study was aim to investigate the role of JPJY improve gut microbiota homeostasis in the chronic stress induced depressive mice. Methods: The antidepressant effect of JPJY on chronic unpredictable mild stress (CUMS) mice was evaluated by using sucrose preference test, tail suspension test and forced swim test. Fatigue-like behaviors were evaluated using degree of redness, grip strength test, and exhaustive swimming test. The new object recognition test was used to evaluate cognition performance. Fecal samples were collected and taxonomical analysis of intestinal microbial distribution was conducted with 16S rDNA. Serum level of GABA was measured using high performance liquid chromatography (HPLC). The expression of GluR1 and p-Tau protein in the hippocampus was determined using Western blotting. Results: The dose of 9.2 g/kg JPJY produced antidepressant-like effects. JPJY and its major components also modulated gut microbiota diversity in the CUMS mice. Serum level of GABA and the expressions of hippocampal GluR1 and p-Tau were reversed after the administration of JPJY in CUMS mice. Conclusion: JPJY regulates gut microbiota to produce antidepressant-like effect and improve cognition deficit in depressive mice while its molecular mechanism possibly be enhanced NR1 and Tau expression in hippocampus and increased GABA in serum.

Anti-depressant effect of Zhi-zi-chi decoction on CUMS mice and elucidation of its signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zhi-zi-chi decoction (ZZCD) is used for treating depression as an effectively traditional Chinese medicine. Until now, studies on pharmacological research of ZZCD have mostly been centered in pharmacokinetic level. Little was known about its pharmacological mechanism of relieving depression.

AIM OF THE STUDY

This study was to evaluate the effect of ZZCD on relieving depression via behavioral tests, serum metabolomics and signaling target expression analysis on chronic unpredictable mild stress (CUMS) model mice.

MATERIALS AND METHODS

The CUMS exposure lasted 7 consecutive weeks. The mice were administrated with ZZCD for the last 3 weeks. Behavioral tests were applied and a serum metabolomics method based on UFLC/Q-TOF-MS with multivariate statistical and global metabolic network analysis was performed to identify relevant metabolites and pathways. Finally, the protein expressions in mouse hippocampi were determined by western blot to verify the metabolomics deduction.

RESULTS

Behavioral parameters were visibly changed after modeling, while high and medium dosage groups showed status improvement compared to the model group. Seventy six metabolites were identified as potential biomarkers from the metabolomics profiles in C₁₈ and HILIC systems. In addition, 9 significant pathways related to changed biomarkers were conducted. The pathways were closely connected by some key targets, which were significantly reduced in the model group compared with those in control group, while ZZCD treated groups showed corrections after 3-week administration. The results revealed that the anti-depression efficacy of ZZCD might be associated with PKA-CREB-BDNF-TrkB-PSD-95 pathway influenced by metabolic changes, verifying the pathway annotation speculation.

CONCLUSION

This study demonstrated that ZZCD had a positive treatment effect on CUMS depression model mice. Metabolomics results revealed the holistic and interconnected metabolic changes of ZZCD in CUMS mice. The metabolic pathway annotation suggested that the anti-depression mechanism of ZZCD might be related to signaling pathway in brain. PKA-CREB-BDNF-TrkB-PSD-95 signaling expression was a verification and complement to the metabolomics results.

Isoliquiritin ameliorates depression by suppressing NLRP3-mediated pyroptosis via miRNA-27a/SYK/NF-κB axis

Background

The NLRP3-mediated pyroptosis, which could be regulated by miRNA-27a, is a key player in the development of depression. Isoliquiritin is a phenolic flavonoid compound that has been demonstrated to suppress NLRP3-mediated pyroptosis. However, it is still unknown whether isoliquiritin could confer antidepressant activity via decreasing NLRP3-mediated pyroptosis by stimulating miRNA-27a. Thus, in the current study, we explored the antidepressant activity of isoliquiritin and its underlying mechanism.

Methods

Expression of miRNA-27a in depressed patients or mice was measured using qRT-PCR. Luciferase reporter assay was performed to illustrate the link between miRNA-27a and SYK. Lipopolysaccharide (LPS) and chronic social defeat stress (CSDS) depression models were established to investigate the antidepressant actions of isoliquiritin. Changes in miRNA-27a/SYK/NF-κB axis and NLRP3-mediated pyroptosis were also examined. The role of miRNA-27a in isoliquiritin-related antidepressant effect was further investigated by using miRNA-27a inhibitors and mimics of miRNA-27a.

Results

Our results showed the miRNA-27a expression was downregulated in the serum of depressed patients, and decreased serum and hippocampus expression of miRNA-27a were observed in rodent models of depression. SYK gene expression was significantly reduced by miRNA-27a mimic incubation. Isoliquiritin profoundly attenuated LPS or CSDS-induced depressive symptoms, as well as CSDS-induced anxiety behavior. In the hippocampus, LPS and CSDS decreased miRNA-27a mRNA expression; increased the protein levels of SYK, p-NF-κB, and NLRP3: cleaved Caspase-1, IL-1β, and GSDMD-N: and elevated the concentration of IL-1β, IL-6, and TNF-α, which were all restored by isoliquiritin administration. Meanwhile, isoliquiritin upregulated the hippocampal NeuN protein level, improved the survival and morphology of neurons, and decreased pyroptosis-related neuronal cell death. Moreover, isoliquiritin protected primary microglia against LPS and adenosine triphosphate (ATP) elicited NLRP3 inflammasome activation in vitro, evidenced by declined protein levels of p-NF-κB, NLRP3; cleaved Caspase-1, IL-1β, and GSDMD-N; upregulated miRNA-27a mRNA expression; and decreased the mRNA and protein levels of SYK. Nevertheless, miRNA-27a inhibitors significantly reversed isoliquiritin-generated therapeutic efficacy in CSDS mice and in vitro. Furthermore, the cytoprotective effect of isoliquiritin was similar to that of miRNA-27a mimics in LPS and ATP-treated primary microglia.

Taken together, these findings suggest that isoliquiritin possesses potent antidepressant property, which requires miRNA-27a/SYK/NF-κB axis controlled decrease of pyroptosis via NLRP3 cascade.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-020-02040-8.