Pedicularis resupinata Extract Prevents Depressive-like Behavior in Repeated Corticosterone-Induced Depression in Mice: A Preliminary Study

Co-decoction of Lilii bulbus and Radix Rehmannia Recens and its key bioactive ingredient verbascoside inhibit neuroinflammation and intestinal permeability associated with chronic stress-induced depression via the gut microbiota-brain axis

BACKGROUND

Gut microbiota plays a critical role in the pathogenesis of depression and are a therapeutic target via maintaining the homeostasis of the host through the gut microbiota-brain axis (GMBA). A co-decoction of Lilii bulbus and Radix Rehmannia Recens (LBRD), in which verbascoside is the key active ingredient, improves brain and gastrointestinal function in patients with depression. However, in depression treatment using verbascoside or LBRD, mechanisms underlying the bidirectional communication between the intestine and brain via the GMBA are still unclear.

PURPOSE

This study aimed to examine the role of verbascoside in alleviating depression via gut-brain bidirectional communication and to study the possible pathways involved in the GMBA.

METHODS

Key molecules and compounds involved in antidepressant action were identified using HPLC and transcriptomic analyses. The antidepressant effects of LBRD and verbascoside were observed in chronic stress induced depression model by behavioural test, neuronal morphology, and synaptic dendrite ultrastructure, and their neuroprotective function was measured in corticosterone (CORT)-stimulated nerve cell injury model. The causal link between the gut microbiota and the LBRD and verbascoside antidepressant efficacy was evaluate via gut microbiota composition analysis and faecal microbiota transplantation (FMT).

RESULTS

LBRD and Verbascoside administration ameliorated depression-like behaviours and synaptic damage by reversing gut microbiota disturbance and inhibiting inflammatory responses as the result of impaired intestinal permeability or blood-brain barrier leakiness. Furthermore, verbascoside exerted neuroprotective effects against CORT-induced cytotoxicity in an in vitro depression model. FMT therapy indicated that verbascoside treatment attenuated gut inflammation and central nervous system inflammatory responses, as well as eliminated neurotransmitter and brain-gut peptide deficiencies in the prefrontal cortex by modulating the composition of gut microbiota. Lactobacillus, Parabacteroides, Bifidobacterium, and Ruminococcus might play key roles in the antidepressant effects of LBRD via the GMBA.

CONCLUSION

The current study elucidates the multi-component, multi-target, and multi-pathway therapeutic effects of LBRD on depression by remodeling GMBA homeostasis and further verifies the causality between gut microbiota and the antidepressant effects of verbascoside and LBRD.

Verbascoside: A neuroprotective phenylethanoid glycosides with anti-depressive properties

BACKGROUND

Verbascoside is a natural and water-soluble phenylethanoid glycoside found in several medicinal plants. It has extensive pharmacological effects, including antioxidative and antineoplastic actions, and a wide range of therapeutic effects against depression.

PURPOSE

In this review, we appraised preclinical and limited clinical evidence to fully discuss the anti-depression capacity of verbascoside and its holistic characteristics that can contribute to better management of depression in vivo and in vitro models, as well as, its toxicities and medicinal value.

METHODS

This review was prepared according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A systematic review of 32 preclinical trials published up to April 2023, combined with a comprehensive bioinformatics analysis of network pharmacology and molecular docking, was conducted to elucidate the antidepressant mechanism of action of verbascoside. Studies included in the systematic review were obtained from 7 electronic databases: PubMed, Scopus, Web of Science, Cochrane, ResearchGate, ScienceDirect, and Google Scholar.

RESULTS

Studies on the antidepressant effects of verbascoside showed that various pharmacological mechanisms and pathways, such as modulating the levels of monoamine neurotransmitters, inhibiting hypothalamic-pituitary-adrenal (HPA) axis hyperfunction and promoting neuroprotection may be involved in the process of its action against depression. Verbascoside promotes dopamine (DA) biosynthesis by promoting the expression of tyrosine hydroxylase mRNA and protein, upregulates the expression of 5-hydroxytryptamine receptor 1B (5-HT1B), prominence protein, microtubule-associated protein 2 (MAP2), hemeoxygenase-1 (HO-1), SQSTM1, Recombinant Autophagy Related Protein 5 (ATG5) and Beclin-1, and decreases the expression of caspase-3 and a-synuclein, thus exerting antidepressant effects. We identified seven targets (CCL2, FOS, GABARAPL1, CA9, TYR, CA12, and SQSTM1) and three signaling pathways (glutathione metabolism, metabolism of xenobiotics by cytochrome P450, fluid shear stress and atherosclerosis) as potential molecular biological sites for verbascoside.

CONCLUSIONS

These findings provide strong evidence that verbascoside exerts its antidepressant effects through various pharmacological mechanisms. However, further multicentre clinical case-control and molecularly targeted fishing studies are required to confirm the clinical efficacy of verbascoside and its underlying direct targets.

Sargassum horneri Extract Attenuates Depressive-like Behaviors in Mice Treated with Stress Hormone

Sargassum horneri, a brown seaweed, is known for its various health benefits; however, there are no reports on its effects on depression. This study aimed to investigate the antidepressant effects of S. horneri ethanol extract (SHE) in mice injected with corticosterone (CORT) and to elucidate the underlying molecular mechanisms. Behavioral tests were conducted, and corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and CORT levels were measured. A fluorometric monoamine oxidase (MAO) enzyme inhibition assay was performed. Neurotransmitters like serotonin, dopamine, and norepinephrine levels were determined. Moreover, the ERK-CREB-BDNF signaling pathway in the prefrontal cortex and hippocampus was evaluated. Behavioral tests revealed that SHE has antidepressant effects by reducing immobility time and increasing time spent in open arms. Serum CRH, ACTH, and CORT levels decreased in the mice treated with SHE, as did the glucocorticoid-receptor expression in their brain tissues. SHE inhibited MAO-A and MAO-B activities. In addition, SHE increased levels of neurotransmitters. Furthermore, SHE activated the ERK-CREB-BDNF pathway in the prefrontal cortex and hippocampus. These findings suggest that SHE has antidepressant effects in CORT-injected mice, via the regulation of the hypothalamic-pituitary-adrenal axis and monoaminergic pathway, and through activation of the ERK-CREB-BDNF signaling pathway. Thus, our study suggests that SHE may act as a natural antidepressant.

Involvement of brain-derived neurotrophic factor signaling in the pathogenesis of stress-related brain diseases

Neurotrophins including brain-derived neurotrophic factor, BDNF, have critical roles in neuronal differentiation, cell survival, and synaptic function in the peripheral and central nervous system. It is well known that a variety of intracellular signaling stimulated by TrkB, a high-affinity receptor for BDNF, is involved in the physiological and pathological neuronal aspects via affecting cell viability, synaptic function, neurogenesis, and cognitive function. As expected, an alteration of the BDNF/TrkB system is suspected to be one of the molecular mechanisms underlying cognitive decline in cognitive diseases and mental disorders. Recent evidence has also highlighted a possible link between the alteration of TrkB signaling and chronic stress. Furthermore, it has been demonstrated that downregulation of the BDNF/TrkB system and chronic stress have a role in the pathogenesis of Alzheimer's disease (AD) and mental disorders. In this review, we introduce current evidence showing a close relationship between the BDNF/TrkB system and the development of cognition impairment in stress-related disorders, and the possible contribution of the upregulation of the BDNF/TrkB system in a therapeutic approach against these brain diseases.

Dried Loquat Fruit Extract Containing Chlorogenic Acid Prevents Depressive-like Behaviors Induced by Repeated Corticosteroid Injections in Mice

Eriobotrya japonica (loquat tree) has been used in traditional medicine to treat respiratory ailments, inflammation, and skin diseases; however, its potential antidepressant-like effects have not been extensively investigated. In this study, we evaluated the antidepressant-like effects of E. japonica fruit extract (EJFE) in a mouse model of corticosterone (CORT)-induced depression. An HPLC analysis revealed that chlorogenic acid (CGA) is the major compound in EJFE. Male ICR mice (5weeks-old) were injected with CORT (40 mg/kg, intraperitoneally) once daily for 21 days to induce depressive-like behaviors. Various behavioral tests, including the open field test, rotarod test, elevated plus maze (EPM), passive avoidance test (PAT), tail suspension test (TST), and forced swim test (FST), were conducted 1 h after the oral administration of EJFE at different doses (30, 100, and 300 mg/kg) and CGA (30 mg/kg). High-dose EJFE and CGA significantly alleviated CORT-induced depressive-like behaviors, as indicated by the reduced immobility times in the TST and FST. A decrease in the step-through latency time in the PAT, without an effect on locomotor activity, suggested an improvement in cognitive function. Moreover, EJFE- and CGA-treated mice exhibited significantly reduced anxiety-like behaviors in the EPM. Our results imply the promising potential of EJFE containing CGA as a therapeutic candidate for depression.

β-Arrestin2-biased Drd2 agonist UNC9995 alleviates astrocyte inflammatory injury via interaction between β-arrestin2 and STAT3 in mouse model of depression

Background

Major depressive disorder (MDD) is a prevalent and devastating psychiatric illness. Unfortunately, the current therapeutic practice, generally depending on the serotonergic system for drug treatment is unsatisfactory and shows intractable side effects. Multiple evidence suggests that dopamine (DA) and dopaminergic signals associated with neuroinflammation are highly involved in the pathophysiology of depression as well as in the mechanism of antidepressant drugs, which is still in the early stage of study and well worthy of investigation.

Methods

We established two chronic stress models, including chronic unpredictable mild stress (CUMS), and chronic social defeat stress (CSDS), to complementarily recapitulate depression-like behaviors. Then, hippocampal tissues were used to detect inflammation-related molecules and signaling pathways. Pathological changes in depressive mouse hippocampal astrocytes were examined by RNA sequencing. After confirming the dopamine receptor 2 (Drd2)/β-arrestin2 signaling changes in the depressive mice brain, we then established the depressive mouse model using the β-arrestin2 knockout mice or administrating the β-arrestin2-biased Drd2 agonist to investigate the roles. Label-free mass spectrometry was used to identify the β-arrestin2-binding proteins as the underlying mechanisms. We modeled neuroinflammation with interleukin-6 (IL-6) and corticosterone treatment and characterized astrocytes using multiple methods including cell viability assay, flow cytometry, and confocal immunofluorescence.

Results

Drd2-biased β-arrestin2 pathway is significantly changed in the progression of depression, and genetic deletion of β-arrestin2 aggravates neuroinflammation and depressive-like phenotypes. Mechanistically, astrocytic β-arrestin2 retains STAT3 in the cytoplasm by structural combination with STAT3, therefore, inhibiting the JAK–STAT3 pathway-mediated inflammatory activation. Furtherly, pharmacological activation of Drd2/β-arrestin2 pathway by UNC9995 abolishes the inflammation-induced loss of astrocytes and ameliorates depressive-like behaviors in mouse model for depression.

Conclusions

Drd2/β-arrestin2 pathway is a potential therapeutic target for depression and β-arrestin2-biased Drd2 agonist UNC9995 is identified as a potential anti-depressant strategy for preventing astrocytic dysfunctions and relieving neuropathological manifestations in mouse model for depression, which provides insights for the therapy of depression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02597-6.