Tanshinone IIA improves contextual fear- and anxiety-like behaviors in mice via the CREB/BDNF/TrkB signaling pathway

New Insights into Contradictory Changes in Brain-Derived Neurotrophic Factor (BDNF) in Rodent Models of Posttraumatic Stress Disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a neuropsychiatric disorder that may develop after experiencing traumatic events. Preclinical studies use various methods to induce PTSD-like models such as fear-conditioning, single-prolonged stress (SPS), restraint stress, and social defeat. Brain-derived neurotrophic factor (BDNF) is a crucial neurotrophin in mood regulation. Evidence shows BDNF changes in different neuropsychiatric disorders particularly PTSD. This review examined BDNF alterations in preclinical rodent models of PTSD where we demonstrated a wide range of paradoxical changes in BDNF. We found that the fear-conditioning model produced the most inconsistent alterations in BDNF, and suggest that conclusions drawn from these changes be approached with caution. We suggest that BDNF maladaptive changes in social defeat and restraint stress models may be related to the duration of stress, while the SPS model appears to have more consistent results. Ultimately, we propose that evaluating BDNF alterations in the process of treating PTSD symptoms may not be a reliable factor.

Ruscogenin Exerts Anxiolytic-Like Effect via Microglial NF-κB/MAPKs/NLRP3 Signaling Pathways in Mouse Model of Chronic Inflammatory Pain

Long-term inflammation can cause chronic pain and trigger patients' anxiety by sensitizing the central nervous system. However, effective drugs with few side effects for treating chronic pain-induced anxiety are still lacking. The anxiolytic and anti-inflammatory effects of ruscogenin (RUS), an important active compound in Ophiopogon japonicus, were evaluated in a mouse model of chronic inflammatory pain and N9 cells. RUS (5, 10, or 20 mg/kg/day, i.g.) was administered once daily for 7 days after CFA injection; pain- and anxiety-like behaviors were assessed in mice. Anti-inflammatory effect of RUS (0.1, 1, 10 μM) on N9 microglia after LPS treatment was evaluated. Inflammatory markers (TNF-α, IL-1β, IL-6, CD86, IL-4, ARG-1, and CD206) were measured using qPCR. The levels of IBA1, ROS, NF-κB, TLR4, P-IKK, P-IκBα, and P65, MAPKs (ERK, JNK, and P38), NLRP3 (caspase-1, ASC, and NLRP3) were detected by Western blotting or immunofluorescence staining. The potential target of RUS was validated by molecular docking and adeno-associated virus injection. Mice in CFA group exhibited allodynia and anxiety-like behaviors. LPS induced neuroinflammation in N9 cells. Both CFA and LPS increased the levels of IBA1, ROS, and inflammatory markers. RUS (10 mg/kg in vivo and 1 μM in vitro) alleviated these alterations through NF-κB/MAPKs/NLRP3 signaling pathways but had no effect on pain hypersensitivity. TLR4 strongly interacted with RUS, and TLR4 overexpression abolished the effects of RUS on anxiety and neuroinflammation. RUS exerts anti-inflammatory and anxiolytic effects via TLR4-mediated NF-κB/MAPKs/NLRP3 signaling pathways, which provides a basis for the treatment of chronic pain-induced anxiety.

Neuroprotective effects of salvianolic acids combined with Panax notoginseng saponins in cerebral ischemia/reperfusion rats concerning the neurovascular unit and trophic coupling

BACKGROUND

The neurovascular unit (NVU) and neurovascular trophic coupling (NVTC) play a key regulatory role in brain injury caused by ischemic stroke. Salvianolic acids (SAL) and Panax notoginseng saponins (PNS) are widely used in China to manage ischemic stroke. Neuroprotective effects of SAL and PNS, either taken alone or in combination, were examined in this research.

METHODS

Wistar rats were randomly divided into the following groups: Sham group (Sham), cerebral ischemia/reperfusion group (I/R), I/R with SAL group (SAL), I/R with PNS group (PNS), I/R with SAL combined with PNS (SAL + PNS), and I/R with edaravone group (EDA). Treatment was administered once daily for two days after modeling of middle cerebral artery occlusion/reperfusion (MCAO/R).

RESULTS

Compared with the I/R group, SAL, PNS, or SAL + PNS treatment reduced infarct size, improved neurological deficit score, reduced Evans blue extravasation, increased expression of CD31 and tight junction proteins (TJs), including zonula occludens-1 (ZO-1), zonula occludens-2 (ZO-2), and junctional adhesion molecule-1 (JAM-1). Furthermore, SAL, PNS, or SAL + PNS suppressed the activations of microglia and astrocyte and led to the amelioration of neuron and pericyte injury. Treatment also inhibited NVU dissociation of GFAP/PDGFRβ and Collagen IV/GFAP while upregulated the expression level of BDNF/TrkB and BDNF/NeuN.

CONCLUSIONS

SAL and PNS have significantly remedied structural and functional disorders of NVU and NVTC in I/R injury. These effects were more pronounced when SAL and PNS were combined than when used separately.

Exposure estimation and neurotoxicity inhibition of dioxins in sensitive populations near domestic waste incineration plant through adverse outcome pathway

The neurotoxicity induced by dioxins has been recognized as a serious concern to sensitive population living near waste incineration plants. However, investigating the intracellular neurotoxicity of dioxin in humans and the corresponding mitigation strategies has been barely studied. Thus, a domestic waste incineration plant was selected in this study to characterize the neurotoxicity risks of sensitive populations by estimating the ratio of dioxin in human cells using membrane structure dynamics simulation; and constructing a complete dioxin neurotoxicity adverse outcome pathway considering the binding process of AhR/ARNT dimer protein and dioxin response element (DRE). Six dioxins with high neurotoxicity risk were identified. According to the composite neurotoxicity risk analysis, the highest composite neurotoxicity risk appeared when the six dioxins were jointly exposed. Dietary schemes were designed using 1/2 partial factor experimental design to mitigate the composite neurotoxicity risk of six dioxins and No. 16 was screened as the optimum combination which can effectively alleviate the composite neurotoxicity risk by 29.52%. Mechanism analysis shows that the interaction between AhR/ARNT dimer protein and DRE was inhibited under the optimal dietary scheme. This study provides theoretical feasibility and reference significance for assessing composite toxicity risks of pollutants and safety mitigation measures for toxic effects.

Multi-frequency electromagnetic radiation induces anxiety in mice via inflammation in the cerebral cortex

Modern life is filled with radiofrequency electromagnetic radiation (RF-EMR) in various frequency bands, while the health risks are not clear. In this study, mice were whole-body exposed to 0.9/1.5/2.65 GHz radiofrequency radiation at 4 W/kg for 2 h per day for 4 weeks to investigate the emotional effects. It was found that the mice showed anxiety but no severe depression. The ELISA results showed a significant decrease in amino acid neurotransmitters (GABA, DA, 5-HT), although acetylcholine (ACH) levels were not significantly altered. Furthermore, Western blot results showed that BDNF, TrkB, and CREB levels were increased in the cerebral cortex, while NF-κB levels were decreased. In addition, pro-inflammatory factors (IL-6, IL-1β, TNF-α) were significantly elevated, and anti-inflammatory factors (IL-4, IL-10) tended to decrease. In conclusion, multi-frequency electromagnetic radiation induces an inflammatory response through the CREB-BDNF-TrkB and NF-κB pathways in the cerebral cortex and causes a decrease in excitatory neurotransmitters, which ultimately causes anxiety in mice.

An insight into crosstalk among multiple signalling pathways contributing to the pathophysiology of PTSD and depressive disorders

Post-traumatic stress disorder (PTSD) and depressive disorders represent two significant mental health challenges with substantial global prevalence. These are debilitating conditions characterized by persistent, often comorbid, symptoms that severely impact an individual's quality of life. Both PTSD and depressive disorders are often precipitated by exposure to traumatic events or chronic stress. The profound impact of PTSD and depressive disorders on individuals and society necessitates a comprehensive exploration of their shared and distinct pathophysiological features. Although the activation of the stress system is essential for maintaining homeostasis, the ability to recover from it after diminishing the threat stimulus is also equally important. However, little is known about the main reasons for individuals' differential susceptibility to external stressful stimuli. The solution to this question can be found by delving into the interplay of stress with the cognitive and emotional processing of traumatic incidents at the molecular level. Evidence suggests that dysregulation in these signalling cascades may contribute to the persistence and severity of PTSD and depressive symptoms. The treatment strategies available for this disorder are antidepressants, which have shown good efficiency in normalizing symptom severity; however, their efficacy is limited in most individuals. This calls for the exploration and development of innovative medications to address the treatment of PTSD. This review delves into the intricate crosstalk among multiple signalling pathways implicated in the development and manifestation of these mental health conditions. By unravelling the complexities of crosstalk among multiple signalling pathways, this review aims to contribute to the broader knowledge base, providing insights that could inform the development of targeted interventions for individuals grappling with the challenges of PTSD and depressive disorders.

Dihydrotanshinone I-Induced CYP1 Enzyme Inhibition and Alteration of Estradiol Metabolism

Dihydrotanshinone I (DHTI) is a pharmacologically active component occurring in the roots of the herbal medicine Salvia miltiorrhiza Bunge. This study investigated DHTI-induced inhibition of CYP1A1, CYP1A2, and CYP1B1 with the aim to determine the potential effects of DHTI on the bioactivation of estradiol (E2), possibly related to preventive/therapeutic strategy for E2-associated breast cancer. Ethoxyresorufin as a specific substrate for CYP1s was incubated with human recombinant CYP1A1, CYP1A2, or CYP1B1 in the presence of DHTI at various concentrations. Enzymatic inhibition and kinetic behaviors were examined by monitoring the formation of the corresponding product. Molecular docking was further conducted to define the interactions between DHTI and the three CYP1s. The same method and procedure were employed to examine the DHTI-induced alteration of E2 metabolism. DHTI showed significant inhibition of ethoxyresorufin O-deethylation activity catalyzed by CYP1A1, CYP1A2 and CYP1B1 in a concentration-dependent manner (IC50 = 0.56, 0.44, and 0.11 μM, respectively). Kinetic analysis showed that DHTI acted as a competitive type of inhibitor of CYP1A1 and CYP1B1, whereas it noncompetitively inhibited CYP1A2. The observed enzyme inhibition was independent of NADPH and time. Molecular docking analysis revealed hydrogen bonding interactions between DHTI and Asp-326 of CYP1B1. Moreover, DHTI displayed preferential activity to inhibit 4-hydroxylation of E2 (a genotoxic pathway) mediated by CYP1B1. Exposure to DHTI could reduce the risk of genotoxicity induced by E2. SIGNIFICANCE STATEMENT: CYP1A1, CYP1A2, and CYP1B1 enzymes are involved in the conversion of estradiol (E2) into 2-hydroxyestradiol (2-OHE2) and 4-hydroxyestradiol (4-OHE2) through oxidation. 2-OHE2 is negatively correlated with breast cancer risk, and 4-OHE2 may be a significant initiator and promoter of breast cancer. The present study revealed that dihydrotanshinone I (DHTI) competitively inhibits CYP1A1/CYP1B1 and noncompetitively inhibits CYP1A2. DHTI exhibits a preference for inhibiting the genotoxicity associated with E2 4-hydroxylation pathway mediated by CYP1B1, potentially reducing the risk of 4-OHE2-induced genotoxicity.

Artemisinin reduces PTSD-like symptoms, improves synaptic plasticity, and inhibits apoptosis in rats subjected to single prolonged stress

Post-Traumatic Stress Disorder (PTSD) is a chronic mental disorder characterized by symptoms of panic and anxiety, depression, impaired cognitive functioning, and difficulty in social interactions. While the effect of the traditional Chinese medicine artemisinin (AR) on PTSD is unknown, its therapeutic benefits have been demonstrated by studies on models of multiple neurological disorders. This study aimed to extend such findings by investigating the effects of AR administration on a rat model of PTSD induced by a regimen of single prolonged stress (SPS). After rats were subjected to the SPS protocol, AR was administered and its impact on PTSD-like behaviors was evaluated. In the present study, rats were subjected to a multitude of behavioral tests to evaluate behaviors related to anxiety, memory function, and social interactions. The expression of hippocampal synaptic plasticity-related proteins was detected using Western blot and immunofluorescence. The ultrastructure of synapses was observed under transmission electron microscopy. The apoptosis of hippocampal neurons was examined with Western blot, TUNEL staining, and HE staining. The results showed that AR administration alleviated the PTSD-like phenotypes in SPS rats, including behavior indicative of anxiety, cognitive deficits, and diminished sociability. AR administration was further observed to improve synaptic plasticity and inhibit neuronal apoptosis in SPS rats. These findings suggest that administering AR after the onset of severe traumatic events may alleviate anxiety, cognitive deficits, and impaired social interaction, improve synaptic plasticity, and diminish neuronal apoptosis. Hence, the present study provides evidence for AR's potential as a multi-target agent in the treatment of PTSD.

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Bile acid signalling and its role in anxiety disorders

Anxiety disorder is a prevalent neuropsychiatric disorder that afflicts 7.3%~28.0% of the world's population. Bile acids are synthesized by hepatocytes and modulate metabolism via farnesoid X receptor (FXR), G protein-coupled receptor (TGR5), etc. These effects are not limited to the gastrointestinal tract but also extend to tissues and organs such as the brain, where they regulate emotional centers and nerves. A rise in serum bile acid levels can promote the interaction between central FXR and TGR5 across the blood-brain barrier or activate intestinal FXR and TGR5 to release fibroblast growth factor 19 (FGF19) and glucagon-like peptide-1 (GLP-1), respectively, which in turn, transmit signals to the brain via these indirect pathways. This review aimed to summarize advancements in the metabolism of bile acids and the physiological functions of their receptors in various tissues, with a specific focus on their regulatory roles in brain function. The contribution of bile acids to anxiety via sending signals to the brain via direct or indirect pathways was also discussed. Different bile acid ligands trigger distinct bile acid signaling cascades, producing diverse downstream effects, and these pathways may be involved in anxiety regulation. Future investigations from the perspective of bile acids are anticipated to lead to novel mechanistic insights and potential therapeutic targets for anxiety disorders.

Effects and mechanisms of tanshinone IIA on PTSD-like symptoms

BACKGROUND

In recent years, Salvia miltiorrhiza and its active substances have remarkably progressed in treating central neurological disorders. Tanshinone IIA (TSA) is an active ingredient derived from the rhizome of Salvia miltiorrhiza that has been found to alleviate the symptoms of several psychiatric illnesses. Post-traumatic stress disorder (PTSD) is a mental disorder that results after experiencing a serious physical or psychological injury. The currently used drugs are not satisfactory for the treatment of PTSD. However, it has been reported that TSA can improve PTSD-like symptoms like learning and memory, cognitive disorder, and depression through multi-target regulation.

PURPOSE

This paper discusses the ameliorative effects of TSA on PTSD-like symptoms and the possible mechanisms of action in terms of inhibition of neuronal apoptosis, anti-neuroinflammation, and anti-oxidative stress. Based on the pathological changes and clinical observations of PTSD, we hope to provide some reference for the clinical transformation of Chinese medicine in treating PTSD.

METHODS

A large number of literatures on tanshinone in the treatment of neurological diseases and PTSD were retrieved from online electronic PubMed and Web of Science databases.

CONCLUSION

TSA is a widely studied natural active ingredient against mental illness. This review will contribute to the future development of TSA as a new clinical candidate drug for improving PTSD-like symptoms.

Electroacupuncture alleviates PTSD-like behaviors by modulating hippocampal synaptic plasticity via Wnt/β-catenin signaling pathway

Abnormalities in hippocampal synaptic plasticity contribute to the pathogenesis of post-traumatic stress disorder (PTSD). The Wnt/β-catenin signaling pathway is critical for the regulation of synaptic plasticity. PTSD symptoms can be alleviated by correcting impaired neural plasticity in the hippocampus (Hipp). Electroacupuncture (EA) has a therapeutic effect by relieving PTSD-like behaviors. However, little is known about whether the Wnt/β-catenin pathway is involved in EA-mediated improvements of PTSD symptoms. In this study, we found that enhanced single prolonged stress (ESPS)-induced PTSD led to abnormal neural plasticity, characterized by the decline of dendritic spines, the expression of postsynaptic density 95 (PSD95), and synaptophysin (Syn) in the stressed Hipp along with the reduction of Wnt3a and β-catenin, and increased GSK-3β. EA significantly alleviated PTSD-like behaviors, as assessed by the open field test, elevated platform maze test and conditioning fear test. This was paralleled by correcting abnormal neural plasticity by promoting the expression of PSD95 and Syn, as well as the number of dendritic spines in the Hipp. Importantly, EA exerted anti-PTSD effects by augmenting the expression levels of Wnt3a and β-catenin, and decreasing that of GSK-3β. The effects mediated by EA were abolished by XAV939, an inhibitor of the Wnt/β-catenin pathway. This suggests that EA relieved ESPS-induced PTSD-like behaviors, which can largely be ascribed to impaired neural plasticity in the Hipp. These findings provide new insights into possible mechanisms linking neural plasticity in the Hipp as potential novel targets for PTSD treatment in EA therapy.

Phytotherapy of abnormality of fear memory: A narrative review of mechanisms

It is generally believed that in post-traumatic stress disorder (PTSD), the high expression of fear memory is mainly determined by amygdala hyperactivity and hippocampus hypoactivity. In this review, we firstly updated the mechanisms of fear memory, and then searched the experimental evidence of phytotherapy for fear memory in the past five years. Based on the summary of those experimental studies, we further discussed the future research strategies of plant medicines, including the study of the mechanism of specific brain regions, the optimal time for the prevention and treatment of fear memory-related diseases such as PTSD, and the development of new drugs with active components of plant medicines. Accordingly, plant medicines play a clear role in improving fear memory abnormalities and have the drug development potential in the treatment of fear-related disorders.

Glucosyl hesperidin exhibits more potent anxiolytic activity than hesperidin accompanied by the attenuation of noradrenaline induction in a zebrafish model

Anxiety is a symptom of various mental disorders, including depression. Severe anxiety can significantly affect the quality of life. Hesperidin (Hes), a flavonoid found in the peel of citrus fruits, reportedly has various functional properties, one of which is its ability to relieve acute and chronic stress. However, Hes is insoluble in water, resulting in a low absorption rate in the body and low bioavailability. Glucosyl hesperidin (GHes) is produced by adding one glucose molecule to hesperidin. Its water solubility is significantly higher than that of Hes, which is expected to improve its absorption into the body and enhance its effects. However, its efficacy in alleviating anxiety has not yet been investigated. Therefore, in this study, the anxiolytic effects of GHes were examined in a zebrafish model of anxiety. Long-term administration of diets supplemented with GHes did not cause any toxicity in the zebrafish. In the novel tank test, zebrafish in the control condition exhibited an anxious behavior called freezing, which was significantly suppressed in GHes-fed zebrafish. In the black-white preference test, which also induces visual stress, GHes-fed zebrafish showed significantly increased swimming time in the white side area. Furthermore, in tactile (low water-level stress) and olfactory-mediated stress (alarm substance administration test) tests, GHes suppressed anxious behavior, and these effects were stronger than those of Hes. Increased noradrenaline levels in the brain generally cause freezing; however, in zebrafish treated with GHes, the amount of noradrenaline after stress was lower than that in the control group. Activation of c-fos/ERK/Th, which is upstream of the noradrenaline synthesis pathway, was also suppressed, while activation of the CREB/BDNF system, which is vital for neuroprotective effects, was significantly increased. These results indicate that GHes has a more potent anxiolytic effect than Hes in vivo, which may have potential applications in drug discovery and functional food development.