Study on the mechanism of TMRK electroacupuncture in repairing synaptic plasticity in amygdala and hippocampus to relieve fear memory in PTSD rats

Novel mechanisms of Anshen Dingzhi prescription against PTSD: Inhibiting DCC to modulate synaptic function and inflammatory responses

ETHNOPHARMACOLOGICAL RELEVANCE

Anshen Dingzhi prescription (ADP), documented in "Yi Xue Xin Wu", is a famous prescription for treating panic-related mental disorders such as post-traumatic stress disorder (PTSD). However, the underlying mechanism remains unclear.

AIM OF THE STUDY

This study aimed to investigate the mechanisms by which ADP intervened in PTSD-like behaviors.

METHODS

A mouse model of single prolonged stress (SPS) was established to evaluate the ameliorative effects and mechanisms of ADP on PTSD. Behavioral tests were used to assess PTSD-like behaviors in mice; transmission electron microscopy was used to observe changes in the ultrastructure of hippocampal synapses, and western blot, immunofluorescence, and ELISA were used to detect the expression of hippocampal deleted in colorectal cancer (DCC) and downstream Ras-related C3 botulinum toxin substrate 1 (Rac1) - P21-activated kinase 1 (PAK1) signal, as well as levels of synaptic proteins and inflammatory factors. Molecular docking technology simulated the binding of potential brain-penetrating components of ADP to DCC.

RESULTS

SPS induced PTSD-like behaviors in mice and increased expression of hippocampal netrin-1 (NT-1) and DCC on the 14th day post-modeling, with concurrent elevation in serum NT-1 levels. Simultaneously, SPS also decreased p-Rac1 level and increased p-PAK1 level, the down-stream molecules of DCC. Lentiviral overexpression of DCC induced or exacerbated PTSD-like behaviors in control and SPS mice, respectively, whereas neutralization antibody against NT-1 reduced DCC activation and ameliorated PTSD-like behaviors in SPS mice. Interestingly, downstream Rac1-PAK1 signal was altered according to DCC expression. Moreover, DCC overexpression down-regulated N-methyl-d-aspartate (NMDA) receptor 2A (GluN2A) and postsynaptic density 95 (PSD95), up-regulated NMDA receptor 2B (GluN2B) and increased neuroinflammatory responses. Administration of ADP (36.8 mg/kg) improved PTSD-like behaviors in the SPS mice, suppressed hippocampal DCC, and downstream Rac1-PAK1 signal, upregulated GluN2A and PSD95, downregulated GluN2B, and reduced levels of inflammatory factors NOD-like receptor protein 3 (NLRP3), nuclear factor kappa-B (NF-κB) and interleukin-6 (IL-6). Importantly, DCC overexpression could also reduce the ameliorative effect of ADP on PTSD. Additionally, DCC demonstrated a favorable molecular docking pattern with the potential brain-penetrating components of ADP, further suggesting DCC as a potential target of ADP.

CONCLUSION

Our data indicate that DCC is a key target for the regulation of synaptic function and inflammatory response in the onset of PTSD, and ADP likely reduces DCC to prevent PTSD via modulating downstream Rac1-PAK1 pathway. This study provides a novel mechanism for the onset of PTSD and warrants the clinical application of ADP.

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.

Acupuncture improves learning and memory ability of posttraumatic stress disorder model rats through epigenetic regulation of microglial phosphatidylinositol 3-kinase pathway

BACKGROUND

Microglia express phosphatidylinositol 3-kinase (PI3K) has been implicated in the induction and maintenance of long-term potentiation (LTP) and in hippocampal synaptic plasticity. However, there are few studies on the interference of PI3K signal pathway in microglia.

OBJECTIVE

The study goal is to gain a better understanding of the mechanism by which EA affects synapses provides insights into how electroacupuncture (EA) modulates synaptic plasticity in learning and memory.

METHODS

Rat models of posttraumatic stress disorder (PTSD) were used to explore the effects of EA on microglial PI3K pathway, brain-derived neurotrophic factor (BDNF) and LTP, and the target and mechanism underlying the effects of EA on PI3K from the perspective of protein ubiquitination.

RESULTS

EA induced microglial BDNF expression by activating the PI3K-AKT pathway, thereby facilitating LTP and synaptic plasticity. EA inhibited lincRNA 02023 to rescue the binding of WWP2 to PTEN, thereby promoting PTEN ubiquitination and degradation.

CONCLUSION

The mechanism of EA improving the learning and memory ability of PTSD rats may be that it can promote the competitive combination of WWP2 and PTEN by inhibiting Linc RNA02023, and then lead to microglial PI3K and its pathway activation, BDNF up-regulation, and finally induce LTP and repair damaged synaptic plasticity.

Various BDNF administrations attenuate SPS-induced anxiety-like behaviors

Post-traumatic stress disorder (PTSD) has become epidemic following severely stressful incidents. Previous studies have shown that brain-derived neurotrophic factor (BDNF) has anxiolytic effects on various anxiety or depression disorders including PTSD. However, the detailed mechanisms of BDNF for treating PTSD were rarely investigated. In the current study, single-prolonged stress (SPS) was used as an animal model recapitulating specific aspects for a PTSD-like phenotype. The effects of BDNF on SPS-induced anxiety-like behaviors were investigated. We showed that the levels of BDNF in the cerebro-spinal fluid (CSF) were significantly reduced after the rats experienced SPS. The SPS-induced reductions of percentages of time spent in the central area to total time in the open field test, were dose-dependently mitigated after BDNF intracerebroventricular (i.c.v.) injections. BDNF i.c.v. administration also dose-dependently increased the preference of the light box in the light-dark box test. Both expressions of tyrosine kinase receptor B (TrkB) protein and mRNA in the prefrontal cortex (PFC) and amygdala were significantly increased after SPS challenges. BDNF i.c.v. administration attenuated these compensatory increases of TrkB. At last, the anxiolytic effects of BDNF on SPS model were also observed by using other two injection methods. These results inspired us to study that different administrations of BDNF were used in patients with PTSD in the future, in-depthly.

Electroacupuncture alleviates anxiety and modulates amygdala CRH/CRHR1 signaling in single prolonged stress mice

BACKGROUND

Post-traumatic stress disorder (PTSD) is an anxiety-related psychiatric disorder, manifesting high comorbidity with anxiety disorders. Its underlying neurobiological mechanisms have been associated with hypothalamic-pituitary-adrenal (HPA) axis dysfunction and stress hormones. Corticotropin-releasing hormone (CRH) is a primary stress hormone, expressed in the hypothalamus and amygdala. Electroacupuncture (EA) can improve mood disorders, but its mechanisms have not been fully elucidated. The aim of this study was to observe the effect of EA on PTSD and explore the related mechanisms.

METHODS

We used single prolonged stress (SPS) mice to establish a PTSD model, and EA was performed after SPS or 7 days later for a week. Then we observed their fear and anxiety-like behavior through cue-induced fear condition tests, open field test and the elevated zero maze. CRH and CRH receptor 1 (CRHR1) protein levels in the amygdala were measured in SPS mice after EA intervention.

RESULTS

We found that EA at ST36 and GV20 improved fear and anxiety behavior in SPS mice. The amygdala CRH and CRHR1 protein levels increased in the SPS mice, and this effect was reversed by the EA intervention. CRHR1 inhibition by the CRHR1 antagonist NBI 27914 alleviated anxiety behavior in SPS mice.

CONCLUSION

CRH/CRHR1 signaling in the amygdala may contribute to the anxiolytic effect of EA in SPS mice.

Electroacupuncture Attenuates Anxiety-Like Behaviors in a Rat Model of Post-traumatic Stress Disorder: The Role of the Ventromedial Prefrontal Cortex

Electroacupuncture (EA) is a promising clinical approach to treating posttraumatic stress disorder (PTSD), yet the mechanisms whereby EA can alleviate anxiety and other PTSD symptoms have yet to be clarified. In the present report, rats underwent EA for 14 consecutive days following modified single prolonged stress (MSPS) exposure. These animals were then evaluated in open field and elevated plus maze tests (OFT and EPM), while Fos immunohistochemical staining was performed to assess ventromedial prefrontal cortex (vmPFC) functional activation. In addition, an extracellular recording and stimulation system was used to analyze vmPFC inputs into the ventral tegmental area (VTA) in these rats. Temporary vmPFC inactivation was further performed to assess whether this was sufficient to reverse the anxiolytic effects of EA. Overall, rats that underwent EA treatment spent more time in the central region (OFT) and the open arm (EPM) relative to MSPS model animals (P < 0.05). These MSPS model animals also exhibited significantly fewer activated Fos-positive nuclei in the vmPFC following behavioral testing, while EA was associated with a significant relative increase in c-Fos expression in this region. The transient inactivation of the vmPFC was sufficient to reverse the effects of EA treatment on anxiety-like behaviors in MSPS model rats. MSPS and SEA rats exhibiting no differences in bursting activity between baseline and vmPFC stimulation, whereas bursting activity rose relative to baseline upon ventral mPFC stimulation in EA treated and control rats. Together, these findings indicate that the vmPFC and its inputs into the VTA are functionally linked to the anxiolytic activity of EA, implicating this pathway in the EA-mediated treatment of PTSD.

Efficacy and Underlying Mechanism of Acupuncture in the Treatment of Posttraumatic Stress Disorder: A Systematic Review of Animal Studies

Acupuncture is a nonpharmacological intervention that can be useful in the clinical management of posttraumatic stress disorder (PTSD), especially in situations with a lack of medical resources, including large-scale PTSD events such as disasters. Some clinical studies have reported the clinical effect of acupuncture in improving PTSD symptoms, but the underlying therapeutic mechanism has yet to be explored. Therefore, this review summarized the underlying therapeutic mechanisms of acupuncture in animal PTSD models. A comprehensive search was conducted in 14 electronic databases, and two independent researchers performed study selection, data extraction, and the methodological quality assessment. Twenty-four relevant studies were included in this review and summarized according to the proposed main mechanisms. In behavioral evaluation, acupuncture, including manual acupuncture and electro-acupuncture, reduced anxiety and fear responses and weakened fear conditioning, improved sleep architecture, reduced depressive symptoms, and alleviated disturbance of spatial learning and memory of PTSD animal models. The therapeutic mechanisms of acupuncture proposed in the included studies could be classified into two categories: (1) regulation of stress responses in the neuroendocrine system and (2) promotion of neuroprotection, neurogenesis, and synaptic plasticity in several brain areas. However, the methodological quality of the included animal studies was not high enough to produce robust evidence. In addition, mechanistic studies on specific aspects of acupuncture that may affect PTSD, including expectancy effects, in human PTSD subjects are also needed.

Advances in Treatment of Post-Traumatic Stress Disorder with Chinese Medicine

"Timely, near, and expectation" is the main principle of battlefield rescue for military combat stress reaction (CSR). Post-traumatic stress disorder (PTSD) is the most common form of CSR and a long-term persistent mental disorder that is caused by unusual threatening or catastrophic psychological trauma. Chinese medicine (CM) has abundant resources, is simple, easy to master, with few side effects. This article summarizes the cellular and animal experimental mechanisms of CM treatment on PTSD, suggesting that traditional Chinese herbs and acupuncture can protect brain functional areas, and adjust hypothalamus-pituitary-adrenal axis. Traditional Chinese herbs and acupuncture have shown good anti-stress efficacy and fewer side effects in clinical application, which may improve the CSR in the battlefield.

Effects of Bisphenol A Exposure during Pregnancy and lactation on Hippocampal Function in Newborn Rats

Bisphenol A (BPA) is widely used in industrial production. It is closely related to the growth and development of the nervous system, and can enter the fetal circulation through the placental barrier, and can be secreted through breast milk. The development of nervous system is very important in fetus and neonatal period. The purpose of this study is to investigate the effects of different doses of BPA on learning and memory function of nervous system in rats. Pregnant rats were randomly divided into three treatment groups (control group, 5 mg/kg/d, 50 mg/kg/d). All animals received BPA from the discovery of pregnancy to 21 days after birth. Results had shown that after high concentration BPA exposure, the increase of PS amplitude and f-EPSP slope in hippocampal CA1 area of male offspring was lower than that of control group. High concentration of BPA could inhibit Nestin, Cyclin D1, bcl-2 and Rac1 in male offspring rats and the expression of bax and RhoA was promoted by BPA. In summary, our study indicated that BPA exposure during pregnancy and lactation could impair the hippocampal function of male offspring by affecting the growth and apoptosis of hippocampal neurons, which might be due to the abnormal regulation of RhoA and Rac1.