Ghrelin exhibited antidepressant and anxiolytic effect via the p38-MAPK signaling pathway in hippocampus

Ghrelin/GHSR System in Depressive Disorder: Pathologic Roles and Therapeutic Implications

Depression is the most common chronic mental illness and is characterized by low mood, insomnia, and affective disorders. However, its pathologic mechanisms remain unclear. Numerous studies have suggested that the ghrelin/GHSR system may be involved in the pathophysiologic process of depression. Ghrelin plays a dual role in experimental animals, increasing depressed behavior and decreasing anxiety. By combining several neuropeptides and traditional neurotransmitter systems to construct neural networks, this hormone modifies signals connected to depression. The present review focuses on the role of ghrelin in neuritogenesis, astrocyte protection, inflammatory factor production, and endocrine disruption in depression. Furthermore, ghrelin/GHSR can activate multiple signaling pathways, including cAMP/CREB/BDNF, PI3K/Akt, Jak2/STAT3, and p38-MAPK, to produce antidepressant effects, given which it is expected to become a potential therapeutic target for the treatment of depression.

Nucleus accumbens ghrelin signaling controls anxiety-like behavioral response to acute stress

BACKGROUND

Anxiety disorders are one of the most common mental disorders. Ghrelin is a critical orexigenic brain-gut peptide that regulates food intake and metabolism. Recently, the ghrelin system has attracted more attention for its crucial roles in psychiatric disorders, including depression and anxiety. However, the underlying neural mechanisms involved have not been fully investigated.

METHODS

In the present study, the effect and underlying mechanism of ghrelin signaling in the nucleus accumbens (NAc) core on anxiety-like behaviors were examined in normal and acute stress rats, by using immunofluorescence, qRT-PCR, neuropharmacology, molecular manipulation and behavioral tests.

RESULTS

We reported that injection of ghrelin into the NAc core caused significant anxiolytic effects. Ghrelin receptor growth hormone secretagogue receptor (GHSR) is highly localized and expressed in the NAc core neurons. Antagonism of GHSR blocked the ghrelin-induced anxiolytic effects. Moreover, molecular knockdown of GHSR induced anxiogenic effects. Furthermore, injection of ghrelin or overexpression of GHSR in the NAc core reduced acute restraint stress-induced anxiogenic effects.

CONCLUSIONS

This study demonstrates that ghrelin and its receptor GHSR in the NAc core are actively involved in modulating anxiety induced by acute stress, and raises an opportunity to treat anxiety disorders by targeting ghrelin signaling system.

Complement C1q/C3-CR3 signaling pathway mediates abnormal microglial phagocytosis of synapses in a mouse model of depression

BACKGROUND

Both functional brain imaging studies and autopsy reports have indicated the presence of synaptic loss in the brains of depressed patients. The activated microglia may dysfunctionally engulf neuronal synapses, leading to synaptic loss and behavioral impairments in depression. However, the mechanisms of microglial-synaptic interaction under depressive conditions remain unclear.

METHODS

We utilized lipopolysaccharide (LPS) to induce a mouse model of depression, examining the effects of LPS on behaviors, synapses, microglia, microglial phagocytosis of synapses, and the C1q/C3-CR3 complement signaling pathway. Additionally, a C1q neutralizing antibody was employed to inhibit the C1q/C3-CR3 signaling pathway and assess its impact on microglial phagocytosis of synapses and behaviors in the mice.

RESULTS

LPS administration resulted in depressive and anxiety-like behaviors, synaptic loss, and abnormal microglial phagocytosis of synapses in the hippocampal dentate gyrus (DG) of mice. We found that the C1q/C3-CR3 signaling pathway plays a crucial role in this abnormal microglial activity. Treatment with the C1q neutralizing antibody moderated the C1q/C3-CR3 pathway, leading to a decrease in abnormal microglial phagocytosis, reduced synaptic loss, and improved behavioral impairments in the mice.

CONCLUSIONS

The study suggests that the C1q/C3-CR3 complement signaling pathway, which mediates abnormal microglial phagocytosis of synapses, presents a novel potential therapeutic target for depression treatment.

Exploring the impact of lifestyle and environmental exposures on appetite hormone levels in children and adolescents: An observational study

BACKGROUND

Appetite hormones are considered a promising target in fighting obesity as impaired appetite hormone levels have already been associated with obesity. However, further insights in the drivers of appetite hormone levels are needed.

OBJECTIVES

In this study, we investigated the associations of fasting appetite hormone levels with lifestyle and environmental exposures in children and adolescents.

METHODS

A total of 534 fasting blood samples were collected from children and adolescents (4-16y,50% boys) and appetite hormone levels (glucagon-like peptide-1 (GLP-1), peptide YY (PYY), pancreatic polypeptide (PP), leptin and ghrelin) were measured. Exposures included dietary quality (fiber-rich food intake, sugar propensity, fat propensity), psychosocial stress (happiness, negative emotions, negative life events and emotional problems), sleep duration, physical activity and environmental quality (long term black carbon (BC), particulate matter <2.5 μM (PM2.5), nitrogen dioxide (NO2) exposure, and green space in a 100 m and 2000 m radius around the residence). A multi-exposure score was calculated to combine all the exposures at study in one measure. Associations of individual exposures and multi-exposure score with appetite hormone levels were evaluated using linear mixed regression models adjusting for sex, age, socioeconomic status, waist-to-height ratio and multiple testing.

RESULTS

GLP-1 was associated with air pollution exposure (NO2 β* = -0.13, BC β* = -0.15, PM2.5 β* = -0.16, all p < 0.001). Leptin was associated with green space in a 100 m radius around the residence (β* = -0.11; p = 0.002). Ghrelin was associated with negative emotions (active ghrelin β* = -0.16; p = 0.04, total ghrelin β* = -0.23; p = 0.0051) and happiness (active ghrelin β* = 0.25; p < 0.001, total ghrelin β* = 0.26; p < 0.001). Furthermore, total ghrelin levels were associated with the multi-exposure score, reflecting unhealthy exposures and lifestyle (β* = -0.22; p = 0.036).

DISCUSSION

Our findings provide new insights into the associations of exposures with appetite hormone levels, which are of high interest for preventive obesity research. Further research is crucial to reveal the underlying mechanisms of the observed associations.

Ghrelin/GHSR signaling in the lateral septum ameliorates chronic stress-induced depressive-like behaviors

Ghrelin is a gastrointestinal hormone on feeding and metabolism regulation, and acts through its receptor-growth hormone secretagogue receptor (GHSR), which is widely distributed throughout the central nervous system. Recent studies have suggested that ghrelin plays an important role in the regulation of depression, but the underlying mechanisms remain uncertain. Lateral septum (LS) is a critical brain region in modulating depression. Therefore, we investigated the role of ghrelin/GHSR signaling in the LS on the depressive-like behaviors of mice under conditions of chronic stress by using behavioral tests, neuropharmacology, and molecular biology techniques. We found that infusion of ghrelin into the LS produced antidepressant-like responses in mice. Activation of LS GABAergic neurons was involved in the antidepressant effect of ghrelin. Importantly, GHSR was highly expressed and distributed in the LS neurons. Blockade of GHSR in the LS reversed the ghrelin-induced antidepressant-like effects. Molecular knockdown of GHSR in the LS induced depressive-like symptoms in mice. Furthermore, administration of ghrelin into the LS alleviated depressive-like behaviors induced by chronic social defeat stress (CSDS). Consistent with the neuropharmacological results, overexpression of GHSR in the LS reversed CSDS-induced depressive-like behaviors. Our findings clarify a key role for ghrelin/GHSR signaling in the regulation of chronic stress-induced depressive-like behaviors, which could provide new strategies for the treatment of depression.

Cannabinoid type 2 receptors play a crucial role in social defeat-induced depression

BACKGROUND

The endocannabinoid system plays a crucial role in regulating mood, but the specific involvement of cannabinoid receptor type 2 (CB2R) in depression remains poorly understood. Similarly, the mechanisms by which electroacupuncture (EA) provides therapeutic benefits for depression are not clearly defined. This research aims to explore the function of CB2R in depression and examine if the therapeutic effects of EA are associated with the hippocampal CB2R system.

METHODS

Mice experiencing social defeat stress (SDS) were used to model depression and anxiety behaviors. We quantified hippocampal CB2R and N-arachidonoylethanolamide (AEA) levels. The efficacy of a CB2R agonist, JWH133, in mitigating SDS-induced behaviors was evaluated. Additionally, EA's impact on CB2R and AEA was assessed, along with the influence of CB2R antagonist AM630 on EA's antidepressant effects.

RESULTS

SDS led to depressive and anxiety-like behaviors, with corresponding decreases in hippocampal CB2R and AEA. Treatment with JWH133 ameliorated these behaviors. EA treatment resulted in increased CB2R and AEA levels, while AM630 blocked these antidepressant effects.

LIMITATIONS

The study mainly focused on the SDS model, which may not entirely reflect other depression models. Besides, further investigation is needed to understand the precise mechanisms by which CB2R and AEA contribute to EA's effects.

CONCLUSIONS

The study suggests hippocampal downregulation of CB2R and AEA contributes to depression. Upregulation of CB2R and AEA in response to EA suggests their involvement in EA's antidepressant effects. These findings provide insights into the role of the hippocampal CB2R system in depression and the potential mechanisms underlying EA's therapeutic effects.

Antioxioxidant and antiapoptotic effects of Thymosin β4 in Aβ-induced SH-SY5Y cells via the 5-HTR1A/ERK axis

Alzheimer's disease (AD) is a common amnestic cognitive impairment characterised by β-amyloid (Aβ) plaques deposit in the brain of the elderly. AD is a yet incurable disease due to its unknown exact pathogenesis and unavailability of effective remedies in clinical application. Thymosin β4 (Tβ4) is a housekeeping protein that plays important role in cell proliferation, migration and differentiation. It has the ability to protect and repair neurons however it is still unclear involvement in AD. Therefore, the aim of this study is to elucidate the role and mechanism of Tβ4 in mediating the improvement of AD. AD-like cell model was constructed in neuroblastoma cell line SH-SY5Y treated with Aβ. Overexpression of Tβ4 were done using lentivirus infection and downregulation through siRNA transfection. We performed western blot and flow cytometry to study the apoptosis and standard kits to measure the oxidative stress-associated biomarkers. There is significant increased in viability and decreased apoptosis in Tβ4 overexpression group compared to control. Furthermore, overexpression of Tβ4 suppressed the expression of pro-apoptotic markers such as Caspase-3, Caspase-8, and Bax meanwhile upregulated the expression of anti-apoptotic gene Bcl-2. Tβ4 alleviated oxidative damage by reducing MDA, LDH and ROS and increasing SOD and GSH-PX in Aβ-treated SH-SY5Y cells. We found that Tβ4 inhibit ERK/p38 MAPK pathway and intensify the expression of 5-HTR1A. Additionally, we showed that upregulation of 5-HTR1A dampened the Tβ4 to activate ERK signalling. In conclusion, our study revealed the neuroprotective role of Tβ4 in AD which may open up new therapeutic applications in AD treatment.

Chlorogenic Acid Ameliorates Post-Infectious Irritable Bowel Syndrome by Regulating Extracellular Vesicles of Gut Microbes

Post-infectious irritable bowel syndrome (PI-IBS) occurs after acute infectious diarrhea, and dysbiosis can be involved in its pathogenesis. Here, the role of chlorogenic acid (CGA) is investigated, a natural compound with several pharmacological properties, in alleviating PI-IBS in rats. It is elucidated that the gut microbiota plays a key role in PI-IBS pathogenesis and that rectal administration of CGA alleviated PI-IBS by modulating the gut microbiota and its metabolites. CGA supplementation significantly increased fecal Bacteroides acidifaciens abundance and glycine levels. Glycine structurally altered B. acidifaciens extracellular vesicles (EVs) and enriched functional proteins in the EVs; glycine-induced EVs alleviated PI-IBS by reducing inflammation and hypersensitivity of the intestinal viscera and maintaining mucosal barrier function. Moreover, B. acidifaciens EVs are enriched in the brain tissue. Thus, CGA mediates the mitigation of PI-IBS through the gut microbiota and its metabolites. This study proposes a novel mechanism of signal exchange between the gut microenvironment and the host.

Ghrelin receptor agonist MK0677 and overnight fasting do not rescue deficient fear extinction in 129S1/SvImJ mice

The hunger hormone ghrelin has been implicated in the modulation of anxiety- and fear-related behaviors in rodents and humans, while its dysregulation may be associated with psychiatric illness. Along these lines, the ghrelin system has been suggested as a potential target to facilitate fear extinction, which is the main mechanism underlying cognitive behavioral therapy. So far, this hypothesis has not been tested in individuals that have difficulties to extinguish fear. Thus, we investigated pharmacological (ghrelin receptor agonist MK0677) and non-pharmacological (overnight fasting) strategies to target the ghrelin system in the 129S1/SvImJ (S1) mouse strain, which models the endophenotype of impaired fear extinction that has been associated with treatment resistance in anxiety and PTSD patients. MK0677 induced food intake and overnight fasting increased plasma ghrelin levels in S1 mice, suggesting that the ghrelin system is responsive in the S1 strain. However, neither systemic administration of MK0677 nor overnight fasting had an effect on fear extinction in S1 mice. Similarly, our groups previously reported that both interventions did not attenuate fear in extinction-competent C57BL/6J mice. In summary, our findings are in contrast to several studies reporting beneficial effects of GHSR agonism and overnight fasting on fear- and anxiety-related behaviors in rodents. Rather, our data agree with accumulating evidence of divergent behavioral effects of ghrelin system activation and underscore the hypothesis that potential benefits of targeting the ghrelin system in fear extinction may be dependent on factors (e.g., previous stress exposure) that are not yet fully understood.

Molecular Mechanism of Cold Tolerance of Centipedegrass Based on the Transcriptome

Low temperature is an important limiting factor in the environment that affects the distribution, growth and development of warm-season grasses. Transcriptome sequencing has been widely used to mine candidate genes under low-temperature stress and other abiotic stresses. However, the molecular mechanism of centipedegrass in response to low-temperature stress was rarely reported. To understand the molecular mechanism of centipedegrass in response to low-temperature stress, we measured physiological indicators and sequenced the transcriptome of centipedegrass under different stress durations. Under cold stress, the SS content and APX activity of centipedegrass increased while the SOD activity decreased; the CAT activity, POD activity and flavonoid content first increased and then decreased; and the GSH-Px activity first decreased and then increased. Using full-length transcriptome and second-generation sequencing, we obtained 38.76 G subreads. These reads were integrated into 177,178 isoforms, and 885 differentially expressed transcripts were obtained. The expression of AUX_IAA and WRKY transcription factors and HSF transcription-influencing factors increased during cold stress. Through KEGG enrichment analysis, we determined that arginine and proline metabolism, plant circadian rhythm, plant hormone signal transduction and the flavonoid biosynthesis pathways played important roles in the cold stress resistance of centipedegrass. In addition, by using weighted gene coexpression network analysis (WGCNA), we determined that the turquoise module was significantly correlated with SS content and APX activity, while the blue module was significantly negatively correlated with POD and CAT activity. This paper is the first to report the response of centipedegrass to cold stress at the transcriptome level. Our results help to clarify the molecular mechanisms underlying the cold tolerance of warm-season grasses.

Ghrelin and Obestatin in Adolescent Patients with Anorexia Nervosa: Is There an Association with Disordered Eating, Depression, and Obsessive-Compulsive Symptoms?

Anorexia nervosa (AN) is an eating disorder characterized by restrictive eating and significant weight loss. In the course of AN, changes are observed in appetite regulation, including orexigenic ghrelin and potentially anorexigenic obestatin. The study aimed to determine if any changes in serum ghrelin and obestatin levels during treatment of AN are observed, while investigating the correlations between these peptides and the severity of disturbed eating attitudes, depression, and anxiety. Thirty adolescent inpatients with AN (examined twice: before hospitalization treatment AN-BT and after treatment AN-AT) and thirty healthy age- and height-matched girls (CG) participated in the study. Anthropometric, serum ghrelin and obestatin concentrations and psychometric evaluations (Eating Attitudes Test 26 Item-EAT-26, Beck Depression Inventory-BDI, Hamilton Depression Rating Scale-HDRS, and Yale Brown Obsessive-Compulsive Scale-Y-BOCS) were performed. The study revealed significantly higher ghrelin and obestatin levels in AN-BT than in AN-AT. A trend toward lower levels during treatment provided partial normalizations. Analyzing correlations in the AN-BT vs. CG group, correlations of peptides with EAT-26, BDI, and HDRS scores were detected. These results suggest a potential role for ghrelin and obestatin in the context of defense mechanisms regulating appetite and body weight in the course of AN and in terms of psychopathological changes co-occurring with this eating disorder.

Minocycline alleviates abnormal microglial phagocytosis of synapses in a mouse model of depression

BACKGROUND

As antidepressants commonly used in the clinic have proved to be problematic, it is urgent to gain an updated understanding of the pathogenesis of depression and find potential therapeutic targets. Since both functional brain imaging studies and autopsy reports indicated that there is indeed a loss of synapses in depressed patients, it is necessary to explore the mechanism of this process.

METHODS

We firstly investigated the effect of chronic social defeat stress (CSDS), a mouse model of depression, on behaviors, synapses, microglia, and microglial phagocytosis of synapses in mice. Then, as it is unclear whether microglial phagocytosis leads to synaptic loss, or synaptic loss induces the microglial clearance in CSDS mice, we used minocycline, a microglial activation inhibitor, to inhibit the microglial phagocytosis of synapses and study its effect on synapses and behaviors in CSDS mice.

RESULTS

Our results showed that the expression levels of PSD-95 in the hippocampal dentate gyrus (DG) of CSDS mice were significantly reduced, while the microglia were significantly activated and the Iba1+CD68⁺ cell (phagocytic microglia) density was increased. We co-labeled the synaptic protein PSD-95 with the microglia marker Iba1 and found that the microglia in the hippocampal DG of CSDS mice contained significantly more PSD-95 engulfed puncta, which revealed that microglia in CSDS mice abnormally phagocytized synapses. Moreover, our results indicated that minocycline treatment dampened microglial activation, decreased the phagocytic microglia density, reduced abnormal microglial phagocytosis of synapses, reversed synaptic loss, and alleviated behavioral impairment in CSDS mice.

CONCLUSIONS

Under depressive pathological conditions, the activated microglia may abnormally engulf neuronal synapses causing synaptic loss and behavioral impairments. Thus, microglial phagocytosis may be a novel therapeutic target for the treatment of depression.

Prevention and treatment of natural products from Traditional Chinese Medicine in depression: Potential targets and mechanisms of action

The molecular pathology involved in the development of depression is complex. Many signaling pathways and transcription factors have been demonstrated to display crucial roles in the process of depression occurrence and development. The multi-components and multi-targets of Traditional Chinese Medicine (TCM) are uniquely advantageous in the prevention and treatment of chronic diseases. This review summarizes the pharmacological regulations of natural products from TCM in the prevention and treatment of depression from the aspects of transcription factors (CREB, NF-κB, Nrf2) and molecular signaling pathways (BDNF-TrkB, MAPK, GSK-3β, TLR-4).

Serum ghrelin is positively associated with physiological anxiety but negatively associated with pathological anxiety in humans: Data from a large community-based study

The orexigenic hormone ghrelin is being increasingly recognized as a stress hormone being involved in anxiety regulation. In animals, ghrelin effects on, and responses to acute stress differed from those in chronic stress, an animal model for anxiety and depression. In humans, elevated ghrelin levels were reported in pathological anxiety (e.g. panic disorder). However, no reports exist on physiological anxiety in mentally healthy subjects. In addition, reports on generalized anxiety symptoms, both in mentally healthy subjects (e.g. worrying) or in adult patients, are lacking. Total serum ghrelin was determined in 1666 subjects of a population-based cross-sectional study ('LIFE'). The 7-item Generalized Anxiety Disorder Scale (GAD-7), detecting also other anxiety disorders, was administered. For multiple linear regression analyses, 1091 subjects were finally included. Serum ghrelin and GAD-7 scores were positively but not significantly associated in the total group (ß=0.00025, standardized β = 0.039, 95%CI: -0.00006;0.0006;p = 0.144), in subjects with no more than mild anxiety, there was a significant positive association (GAD-7 ≤9: n = 1061, 97.25%, β = 0.00032; standardized β = 0.060; 95%CI: 0.000023;0.00062;p = 0.036). In contrast, there was a negative association in subjects with anxiety symptoms above the GAD-7 cut-off (GAD-7 ≥10: n = 30, 2.75%, ß=-0.003, standardized β = -0.462; 95% CI:-0.006;0.0001;p = 0.045). Ghrelin levels were only numerically (p = 0.23) higher in subjects with clinically relevant anxiety symptoms (963.5 ± 399.6 pg/ml; mean±SD) than in those without (901.0 ± 416.4 pg/ml). In conclusion, the positive association between ghrelin and no more than mild anxiety is an initial indication for a role for ghrelin in the regulation of physiological anxiety in humans. This association and the opposed association in pathological anxiety resemble findings in animals showing diverging ghrelin effects in acute and chronic stress.

Effects of Meranzin Hydrate On the LncRNA-miRNA-mRNA Regulatory Network in the Hippocampus of a Rat Model of Depression

Meranzin hydrate (MH) is a frequently used antidepressant drug in China; however it underlying mechanism remains unknown. In this study, we aimed to explore whether MH could ameliorate depression-like behavior in rats by regulating the competitive endogenous RNA (ceRNA) network. We developed a depression-like rat model using an unpredictable chronic mild stress (UCMS) protocol, and the differentially expressed lncRNAs, miRNAs, and mRNAs were identified between the model group and MH group. Then, a ceRNA network responding to MH treatment was constructed by their corresponding relationships in the databases. Finally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted to explore molecular mechanisms associated with MH treatment. The study indicated that rats in the model group showed loss of weight and deteriorated behavior in behavior tests compared with rats in the normal group. A total of 826 lncRNAs, 121 miRNAs, and 954 mRNAs were differentially expressed in the hippocampus of UCMS rats after MH treatment. In addition, 13 miRNAs were selected, and 12 of them were validated in the hippocampus by qRT-PCR. Then, we predicted upstream lncRNAs and downstream mRNAs of the validated miRNAs and interacted with the results of microarrays. Eventually, a lncRNA-miRNA-mRNA regulatory network, responding to MH treatment, was constructed based on the 314 lncRNAs, 11 miRNAs, and 221 mRNAs. KEGG pathways suggested that these genes may be highly related to Wnt signaling, axon guidance, and MAPK signaling pathways. All these results suggest that MH may be a potential representative compound for the treatment of depression, and its mechanism of action is related to the ceRNA modification.

Ghrelin attenuates methylmercury-induced oxidative stress in neuronal cells

Methylmercury (MeHg) is a global pollutant, which can cause damage to the central nervous system at both high-acute and chronic-low exposures, especially in vulnerable populations, such as children and pregnant women. Nowadays, acute-high poisoning is rare. However, chronic exposure to low MeHg concentrations via fish consumption remains a health concern. Current therapeutic strategies for MeHg poisoning are based on the use of chelators. However, these therapies have limited efficacy. Ghrelin is a gut hormone with an important role in regulating physiologic processes. It has been reported that ghrelin plays a protective role against the toxicity of several xenobiotics. Here, we explored the role of ghrelin as a putative protector against MeHg-induced oxidative stress. Our data show that ghrelin was able to ameliorate MeHg-induced reactive oxygen species (ROS) production in primary neuronal hypothalamic and hippocampal cultures. An analogous effect was observed in mouse hypothalamic neuronal GT 1-7 cells. Using this model, our novel findings show that antioxidant protection of ghrelin against MeHg is mediated by glutathione upregulation and induction of the NRF2/NQO1 pathway.

The effect and mechanism of Jiao-tai-wan in the treatment of diabetes mellitus with depression based on network pharmacology and experimental analysis

BACKGROUND

The incidence of diabetes mellitus (DM) and depression is increasing year by year around the world, bringing a serious burden to patients and their families. Jiao-tai-wan (JTW), a well-known traditional Chinese medicine (TCM), has been approved to have hypoglycemic and antidepressant effects, respectively, but whether JTW has such dual effects and its potential mechanisms is still unknown. This study is to evaluate the dual therapeutic effects of JTW on chronic restraint stress (CRS)-induced DM combined with depression mice, and to explore the underlying mechanisms through network pharmacology.

METHODS

CRS was used on db/db mice for 21 days to induce depression-like behaviors, so as to obtain the DM combined with depression mouse model. Mice were treated with 0.9% saline (0.1 ml/10 g), JTW (3.2 mg/kg) and Fluoxetine (2.0 mg/kg), respectively. The effect of JTW was accessed by measuring fasting blood glucose (FBG) levels, conducting behavioral tests and observing histopathological change. The ELISA assay was used to evaluate the levels of inflammatory cytokines and the UHPLC-MS/MS method was used to determine the depression-related neurotransmitters levels in serum. The mechanism exploration of JTW against DM and depression were performed via a network pharmacological method.

RESULTS

The results of blood glucose measurement showed that JTW has a therapeutic effect on db/db mice. Behavioral tests and the levels of depression-related neurotransmitters proved that JTW can effectively ameliorate depression-like symptoms in mice induced by CRS. In addition, JTW can also improve the inflammatory state and reduce the number of apoptotic cells in the hippocampus. According to network pharmacology, 28 active compounds and 484 corresponding targets of JTW, 1407 DM targets and 1842 depression targets were collected by screening the databases, and a total of 117 targets were obtained after taking the intersection. JTW plays a role in reducing blood glucose level and antidepressant mainly through active compounds such as quercetin, styrene, cinnamic acid, ethyl cinnamate, (R)-Canadine, palmatine and berberine, etc., the key targets of its therapeutic effect include INS, AKT1, IL-6, VEGF-A, TNF and so on, mainly involved in HIF-1 signal pathway, pathways in cancer, Hepatitis B, TNF signal pathway, PI3K-Akt signal pathway and MAPK signaling pathway, etc. CONCLUSION: Our experimental study showed that JTW has hypoglycemic and antidepressant effects. The possible mechanism was explored by network pharmacology, reflecting the characteristics of multi-component, multi-target and multi-pathway, which provides a theoretical basis for the experimental research and clinical application of JTW in the future.

Tβ4 ameliorates oxidative damage and apoptosis through ERK/MAPK and 5-HT1A signaling pathway in Aβ insulted SH-SY5Y cells

AIMS

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder seriously endangering the physical and mental health of the elderly, while no effective treatments and drugs in clinical practice are available. Thymosin β4 (Tβ4) is a multifunctional polypeptide involved in many physiological and pathological processes including AD. This study aims to understand the function and molecular mechanism of Tβ4 in the development of AD.

MAIN METHODS

Neuroblastoma cell line SH-SY5Y was treated with β-amyloid (Aβ) to induce AD-like pathological changes, which serves as Alzheimer's disease model. Tβ4 was overexpressed in SH-SY5Y cells by lentivirus infection, and downregulated by siRNA transfection. Apoptosis of transfected SH-SY5Y cells after Aβ-treatment was examined by western blot and flow cytometry. Apoptotic proteins and Tβ4-related signaling pathways were also investigated by western blot.

KEY FINDINGS

We found that Tβ4 overexpression increased viability and suppressed apoptosis of Aβ-treated SH-SY5Y cells. Tβ4 ameliorated oxidative damage and suppressed reactive oxygen species production in Aβ-treated SH-SY5Y cells. Consistently, Tβ4 overexpression down-regulated the expression levels of pro-apoptotic markers such as Caspase-3, Caspase-8, and Bax, while up-regulated the expression level of anti-apoptotic gene Bcl-2 in Aβ-stimulated SH-SY5Y cells. Mechanistically, we demonstrated that Tβ4 dampened ERK/p38 MAPK signaling and enhanced 5-HTR1A expression in Aβ-treated SH-SY5Y cells. Moreover, we revealed that Tβ4 inhibited the activation of ERK pathway through up-regulating 5-HTR1A in Aβ-treated SH-SY5Y cells.

SIGNIFICANCE

Taken together, our findings provide evidences to support the neuroprotective role of Tβ4 and might open up new therapeutic applications of Tβ4 in AD treatment.

Protective and Healing Effects of Ghrelin and Risk of Cancer in the Digestive System

Ghrelin is an endogenous ligand for the ghrelin receptor, previously known as the growth hormone secretagogue receptor. This hormone is mainly produced by endocrine cells present in the gastric mucosa. The ghrelin-producing cells are also present in other organs of the body, mainly in the digestive system, but in much smaller amount. Ghrelin exhibits a broad spectrum of physiological effects, such as stimulation of growth hormone secretion, gastric secretion, gastrointestinal motility, and food intake, as well as regulation of glucose homeostasis and bone formation, and inhibition of inflammatory processes. This review summarizes the recent findings concerning animal and human data showing protective and therapeutic effects of ghrelin in the gut, and also presents the role of growth hormone and insulin-like growth factor-1 in these effects. In addition, the current data on the possible influence of ghrelin on the carcinogenesis, its importance in predicting the risk of developing gastrointestinal malignances, as well as the potential usefulness of ghrelin in the treatment of cancer, have been presented.

Expression of ghrelin or growth hormone secretagogue receptor in the brain of postpartum stress mice

Postpartum depression is one of the most common mental diseases that occur in women after childbirth; this disorder is extremely painful for women and represents a major burden on the society. Therefore, we designed this study to explore the possible material basis of the disease, and provide potential novel antidepressants therapy using a mouse model. We established a postpartum immobilization stress model. Maternal body weight changes and food intake were recorded for half a month after delivery, and levels of ghrelin and its receptor, growth hormone secretagogue receptor (GHSR) were measured. The mice in the immobilization stress group showed stress activity as well as low body weight and low feeding status. Ghrelin expression was elevated in blood whereas ghrelin or GHSR expression decreased in the hippocampus and prefrontal cortex of the immobilization stress mice, and the number of ghrelin-active and GHSR cells reduced.

Ghrelin attenuates depressive-like behavior, heart failure, and neuroinflammation in postmyocardial infarction rat model

Depression after myocardial infarction (MI) and chronic heart failure (CHF) is a common condition that is resistant to anti-depressive drugs. Ghrelin (a peptide hormone) shows dual protective effects on heart and brain. Whether ghrelin treatment attenuated depression after MI was investigated. Coronary artery occlusion was performed to induce MI and subsequent CHF in rats. Ghrelin (100 μg/kg in 0.5 ml of saline) or vehicle (0.5 ml of saline) was injected subcutaneously twice a day for 4 weeks. At week 5, all the animals underwent behavioral assessments including sucrose preference test (SPT), elevated plus maze test (EPM), and open field test (OFT). After cardiac function analysis, brain tissues were processed to determine inflammatory cytokines and microglial activations in hippocampus. Results showed that ghrelin substantially improved cardiac dysfunction, infarction size, and cardiac remodeling and modulated the release of inflammatory cytokines and the increase of Iba-1 positive microglia and glial fibrillary acidic protein-positive astrocytes in the CA1 area of hippocampus. Behavioral tests revealed that this treatment remarkably increased sucrose preference and mobile times and numbers. These findings provided evidence that peripheral ghrelin administration inhibits depression-like behavior and neuroinflammation and thus could be a new approach for the treatment of CHF-associated depression.

Preliminary evidence of acylated ghrelin association with depression severity in postmenopausal women

We have previously shown increased depression and anxiety scores in postmenopausal overweight women, when compared to overweight premenopausal women. The mechanisms responsible for these alterations are not understood. Although ghrelin involvement in mood modulation has been suggested, its role is still ambiguous and has not been evaluated in postmenopause. Here we investigated the association of ghrelin with depression and anxiety symptoms in postmenopausal women. Fifty-five postmenopausal women with depression symptoms, who were not in use of hormones or antidepressants, were included in the study. Depression symptoms were evaluated by Beck's Depression Inventory (BDI) and Patient Health Questionnaire-9 (PHQ-9) and anxiety symptoms were evaluated by Beck's Anxiety Inventory (BAI). Women were allocated into three groups, according to BDI classification of mild, moderate, or severe depression symptoms. Anthropometric, biochemical and hormonal parameters were analyzed. Total and acylated ghrelin levels were higher in the severe depression than in the mild depression group. Multivariate regression analyses showed positive associations of BDI scores with acylated ghrelin and BMI, and of PHQ-9 scores with acylated ghrelin and homeostasis model assessment of insulin resistance (HOMA-IR). BAI scores associated positively with waist-to-hip ratio. To the best of our knowledge, this is the first demonstration of an association between acylated ghrelin and the severity of depression symptoms in postmenopausal women. This association may reflect either a physiological response aimed at fighting against depression symptoms or a causal factor of this mental disorder.

The Ghrelin/Growth Hormone Secretagogue Receptor System Is Involved in the Rapid and Sustained Antidepressant-Like Effect of Paeoniflorin

Major depressive disorder (MDD) is a debilitating mental illness affecting people worldwide. Although significant progress has been made in the development of therapeutic agents to treat this condition, fewer than half of all patients respond to currently available antidepressants, highlighting the urgent need for the development of new classes of antidepressant drugs. Here, we found that paeoniflorin (PF) produced rapid and sustained antidepressant-like effects in multiple mouse models of depression, including the forced swimming test and exposure to chronic mild stress (CMS). Moreover, PF decreased the bodyweight of mice without affecting food intake and glucose homeostasis, and also reduced the plasma levels of total ghrelin and the expression of ghrelin O-acyltransferase in the stomach; however, the plasma levels of ghrelin and the ghrelin/total ghrelin ratio were unaffected. Furthermore, PF significantly increased the expression of growth hormone secretagogue receptor 1 alpha (GHSR1α, encoded by the Ghsr gene) in the intestine, whereas the levels of GHSR1α in the brain were only marginally downregulated following subchronic PF treatment. Finally, the genetic deletion of Ghsr attenuated the antidepressant-like effects of PF in mice exposed to CMS. These results suggested that increased GHSR1α expression in the intestine mediates the antidepressant-like effects of PF. Understanding peripheral ghrelin/GHSR signaling may provide new insights for the screening of antidepressant drugs that produce fast-acting and sustained effects.

Electroacupuncture may alleviate behavioral defects via modulation of gut microbiota in a mouse model of Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) is a chronic neurodegenerative disease involving non-motor symptoms, of which gastrointestinal disorders are the most common. In light of recent results, intestinal dysfunction may be involved in the pathogenesis of PD. Electroacupuncture (EA) has shown potential effects, although the underlying mechanism remains mostly unknown. We speculated that EA could relieve the behavioral defects of PD, and that this effect would be associated with modulation of the gut microbiota.

METHODS

Mice were randomly divided into three groups: control, PD + MA (manual acupuncture), and PD + EA. MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) was used to establish the mouse model of PD. Rotarod performance tests, open field tests, and pole tests were carried out to assess motor deficiencies. Immunohistochemistry was conducted to examine the survival of dopaminergic neurons. 16S ribosomal RNA (rRNA) gene sequencing was applied to investigate the alterations of the gut microbiome. Quantitative real-time polymerase chain reaction (PCR) was performed to characterize the messenger RNA (mRNA) levels of pro-inflammatory and anti-inflammatory cytokines.

RESULTS

We found that EA was able to alleviate the behavioral defects in the rotarod performance test and pole test, and partially rescue the significant loss of dopaminergic neurons in the substantia nigra (SN) chemically induced by MPTP in mice. Moreover, the PD + MA mice showed a tendency toward decreased intestinal microbial alpha diversity, while EA significantly reversed it. The abundance of Erysipelotrichaceae was significantly increased in PD + MA mice, and the alteration was also reversed by EA. In addition, the pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α were substantially increased in the SN of PD + MA mice, an effect that was reversed by EA.

CONCLUSION

These results suggest that EA may alleviate behavioral defects via modulation of gut microbiota and suppression of inflammation in the SN of mice with PD, which provides new insights into the pathogenesis of PD and its treatment.

Behavioral Characterizing of CD24 Knockout Mouse-Cognitive and Emotional Alternations

CD24 is a small, glycophosphatidylinositol-anchored cell surface protein, mostly investigated with respect to cancer, inflammation, and autoimmune diseases. CD24 knockdown or inhibition has been used to test various biochemical mechanisms and neurological conditions; however, the association between CD24 and behavioral phenotypes has not yet been examined. This study aims to characterize cognitive and emotional functions of CD24 knockout mice (CD24-/-) compared with CD24 wild-type mice at three time-points: adolescence, young adulthood, and adulthood. Our results show that CD24-/- mice exhibited better cognitive performance and less anxiety-like behavior compared with WT mice, with no effect on depression-like behavior. This phenotype was constant from childhood (2 months old) to adulthood (6 months old). The results from our study suggest that CD24 may influence important behavioral aspects at the whole-organism level, which should be taken into consideration when using CD24 knockout models.

Drug repositioning for treatment-resistant depression: Hypotheses from a pharmacogenomic study

About 20-30% of patients with major depressive disorder (MDD) develop treatment-resistant depression (TRD) and finding new effective treatments for TRD has been a challenge. This study aimed to identify new possible pharmacological options for TRD. Genes in pathways included in predictive models of TRD in a previous whole exome sequence study were compared with those coding for targets of drugs in any phase of development, nutraceuticals, proteins and peptides from Drug repurposing Hub, Drug-Gene Interaction database and DrugBank database. We tested if known gene targets were enriched in TRD-associated genes by a hypergeometric test. Compounds enriched in TRD-associated genes after false-discovery rate (FDR) correction were annotated and compared with those showing enrichment in genes associated with MDD in the last Psychiatric Genomics Consortium genome-wide association study. Among a total of 15,475 compounds, 542 were enriched in TRD-associated genes (FDR p < .05). Significant results included drugs which are currently used in TRD (e.g. lithium and ketamine), confirming the rationale of this approach. Interesting molecules included modulators of inflammation, renin-angiotensin system, proliferator-activated receptor agonists, glycogen synthase kinase 3 beta inhibitors and the rho associated kinase inhibitor fasudil. Nutraceuticals, mostly antioxidant polyphenols, were also identified. Drugs showing enrichment for TRD-associated genes had a higher probability of enrichment for MDD-associated genes compared to those having no TRD-genes enrichment (p = 6.21e-55). This study suggested new potential treatments for TRD using a in silico approach. These analyses are exploratory only but can contribute to the identification of drugs to study in future clinical trials.

Diagnostic Accuracy of Plasma Ghrelin Concentrations in Pediatric Sepsis-Associated Acute Respiratory Distress Syndrome: A Single-Center Cohort Study

Background: Ghrelin is the endogenous ligand of growth hormone secretagogue receptor 1a, which plays a role in regulating immunity and inflammation. The aim of this study is to assess the diagnostic value of plasma ghrelin in sepsis-associated pediatric acute respiratory distress syndrome (PARDS). Methods: We recruited patients who were admitted to the pediatric ICU (PICU) of the Children's Hospital of Chongqing Medical University between January 2019 and January 2020 and met the diagnostic criteria for sepsis. Data on clinical variables, laboratory indicators, plasma ghrelin concentrations, and inflammatory factors were collected and evaluated, and patients were followed up for 28 days. The area under the receiver-operating characteristic curves (AUROC) were determined using logistic regression to calculate and test cut-off values for ghrelin as a diagnostic indicator of sepsis-associated PARDS. The log-rank test was used to compare survival according to ghrelin levels. Main results: Sixty-six PICU patients (30 with ARDS and 36 without ARDS) who met the diagnostic criteria of sepsis were recruited. The ghrelin level was significantly higher in the ARDS group than in the non-ARDS group. The AUROC of ghrelin was 0.708 (95% confidence interval: 0.584-0.833) and the positivity cutoff value was 445 pg/mL. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of plasma ghrelin for the diagnosis of PARDS-associated sepsis were 86.7, 50.0, 59.1, 81.8, 1.734, and 0.266%, respectively. The survival rate of sepsis patients were significantly improved when the ghrelin level was >445 pg/mL. Conclusions: Ghrelin plasma levels were higher in sepsis-associated PARDS, and accompanied by increased levels of inflammatory factors. High ghrelin levels are a positive predictor of ICU survival in sepsis patients. Yet, there is no evidence to prove that elevated ghrelin is a promising diagnostic indicator of sepsis-associated PARDS. Trial registration: Clinicaltrials, ChiCTR1900023254. Registered 1 December 2018 - Retrospectively registered, http://www.clinicaltrials.gov/ChiCTR1900023254.

The Good, the Bad and the Unknown Aspects of Ghrelin in Stress Coping and Stress-Related Psychiatric Disorders

Ghrelin is a peptide hormone released by specialized X/A cells in the stomach and activated by acylation. Following its secretion, it binds to ghrelin receptors in the periphery to regulate energy balance, but it also acts on the central nervous system where it induces a potent orexigenic effect. Several types of stressors have been shown to stimulate ghrelin release in rodents, including nutritional stressors like food deprivation, but also physical and psychological stressors such as foot shocks, social defeat, forced immobilization or chronic unpredictable mild stress. The mechanism through which these stressors drive ghrelin release from the stomach lining remains unknown and, to date, the resulting consequences of ghrelin release for stress coping remain poorly understood. Indeed, ghrelin has been proposed to act as a stress hormone that reduces fear, anxiety- and depression-like behaviors in rodents but some studies suggest that ghrelin may - in contrast - promote such behaviors. In this review, we aim to provide a comprehensive overview of the literature on the role of the ghrelin system in stress coping. We discuss whether ghrelin release is more than a byproduct of disrupted energy homeostasis following stress exposure. Furthermore, we explore the notion that ghrelin receptor signaling in the brain may have effects independent of circulating ghrelin and in what way this might influence stress coping in rodents. Finally, we examine how the ghrelin system could be utilized as a therapeutic avenue in stress-related psychiatric disorders (with a focus on anxiety- and trauma-related disorders), for example to develop novel biomarkers for a better diagnosis or new interventions to tackle relapse or treatment resistance in patients.

Functions of p38 MAP Kinases in the Central Nervous System

Mitogen-activated protein (MAP) kinases are a central component in signaling networks in a multitude of mammalian cell types. This review covers recent advances on specific functions of p38 MAP kinases in cells of the central nervous system. Unique and specific functions of the four mammalian p38 kinases are found in all major cell types in the brain. Mechanisms of p38 activation and downstream phosphorylation substrates in these different contexts are outlined and how they contribute to functions of p38 in physiological and under disease conditions. Results in different model organisms demonstrated that p38 kinases are involved in cognitive functions, including functions related to anxiety, addiction behavior, neurotoxicity, neurodegeneration, and decision making. Finally, the role of p38 kinases in psychiatric and neurological conditions and the current progress on therapeutic inhibitors targeting p38 kinases are covered and implicate p38 kinases in a multitude of CNS-related physiological and disease states.

Rapid and Prolonged Antidepressant-like Effect of Crocin Is Associated with GHSR-Mediated Hippocampal Plasticity-related Proteins in Mice Exposed to Prenatal Stress

Prenatal stress (PNS) has a prolonged and adverse effect on offspring, leading to a significantly increased vulnerability to developing depression in their later life. Traditional therapies have delayed onset and limited efficacy; thus, it remains an urgent need to find novel medications with fast-onset and high-efficacy potentials. Crocin, with its structure clearly examined, has shown antidepressant-like effects. However, few studies extensively investigated its effect especially in mice exposed to PNS. Using an established PNS model, we tested whether crocin could have a rapid and persistent antidepressant-like effect in PNS mice. Growth hormone secretagogue receptor (GHSR) and phosphoinositide 3-kinase (PI3K) inhibitors were used to test their effects in antidepressant-like effect of crocin. Hippocampal GHSR-PI3K signaling was examined both in PNS mice treated with a single dose of crocin and in combination of GHSR inhibitor. PNS mice showed depression-like behaviors at juvenile and adulthood, and crocin induced an instant and persistent antidepressant-like response in PNS mice in a dose-dependent manner. Moreover, crocin increased the expression of hippocampal synaptic plasticity-associated proteins through the restoration of GHSR-PI3K signaling. Inhibitions of both GHSR and PI3K abolished the effect of crocin in alleviating depressive-like behaviors. More importantly, GHSR inhibitor JMV2959 blocked the enhanced expression of hippocampal plasticity-related proteins induced by crocin. The present study demonstrated that crocin induced a fast-onset and prolonged antidepressant effect in PNS mice and suggested that GHSR-PI3K signaling may play a key role in crocin's effect at least partially by a restoration of hippocampal synaptic plasticity-associated proteins.

Forebrain excitatory neuron-specific SENP2 knockout mouse displays hyperactivity, impaired learning and memory, and anxiolytic-like behavior

Sentrin/SUMO-specific protease 2 (SENP2) is a member of SENPs family involved in maturation of SUMO precursors and deSUMOylation of specific target, and is highly expressed in the central nervous system (CNS). Although SENP2 has been shown to modulate embryonic development, fatty acid metabolism, atherosclerosis and epilepsy, the function of SENP2 in the CNS remains poorly understood. To address the role of SENP2 in the CNS and its potential involvement in neuropathology, we generated SENP2 conditional knockout mice by crossing floxed SENP2 mice with CaMKIIα-Cre transgenic mice. Behavioral tests revealed that SENP2 ablation induced hyper-locomotor activity, anxiolytic-like behaviors, spatial working memory impairment and fear-associated learning defect. In line with these observations, our RNA sequencing (RNA-seq) data identified a variety of differential expression genes that are particularly enriched in locomotion, learning and memory related biologic process. Taken together, our results indicated that SENP2 plays a critical role in emotional and cognitive regulation. This SENP2 conditional knockout mice model may help reveal novel mechanisms that underlie a variety of neuropsychiatric disorders associated with anxiety and cognition.