The Rapid and Long-Lasting Antidepressant Effects of Iridoid Fraction in Gardenia Jasminoides J.Ellis Are Dependent on Activating PKA-CREB Signaling Pathway

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response. Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region-specific, particularly involving the corticolimbic system, including the ventral tegmental area, nucleus accumbens, prefrontal cortex, amygdala, and hippocampus. Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology. In this review, we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression. We focused on associated molecular pathways and neural circuits, with special attention to the brain-derived neurotrophic factor-tropomyosin receptor kinase B signaling pathway and the ventral tegmental area-nucleus accumbens dopamine circuit. We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature, severity, and duration of stress, especially in the above-mentioned brain regions of the corticolimbic system. Therefore, BDNF might be a biological indicator regulating stress-related processes in various brain regions.

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

ETHNOPHARMACOLOGICAL RELEVANCE

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

AIM OF THE STUDY

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

PACAP/VIP in the prefrontal cortex mediates the rapid antidepressant effects of zhizichi decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Zhizichi decoction (ZZCD) is a traditional Chinese medicine formula that consists of Gardenia jasminoides J.Ellis (GJ) and Semen Sojae Praeparatum. It is used to treat insomnia and emotion-related disorders, such as irritability. Previous studies have found that GJ has a rapid antidepressant effect. The study found that ZZCD is safer than GJ at the same dosage. Consequently, ZZCD is a superior drug with quicker antidepressant effects than GJ. The rapid antidepressant effects of ZZCD were examined in this study, along with the components that make up this effect. It was determined that the activation of prefrontal Pituitary Adenylate Cyclase Activating Polypeptide (PACAP)/Vasoactive Intestinal Polypeptide (VIP) is essential for ZZCD's rapid antidepressant effects.

AIM

This study identified and discussed the rapid antidepressant effects and biological mechanisms of ZZCD.

MATERIALS AND METHODS

The tail suspension test (TST) and the forced swimming test (FST) were used to screen the effective dosage of ZZCD (0.67 g/kg, 1 g/kg, 4 g/kg). The effective dosage of ZZCD (1 g/kg) was tested in the TST conducted on Institute of Cancer Research (ICR) mice that were treated with lipopolysaccharide (LPS) at a concentration of 0.1 mg/mL. To confirm the expression of c-Fos, PACAP, and VIP in the prefrontal cortex (PFC), immunohistochemistry tests were conducted on mice following intragastric injection of ZZCD. Chemical characterization analysis and HPLC quality control analysis were conducted using UHPLC-Q-Obitrap-HRMS and chromatographic analysis.

RESULTS

The results showed that an acute administration of ZZCD (1 g/kg) decreased the immobility time of Kunming (KM) mice in TST and FST. Depressive behaviors in TST-induced ICR mice treated with LPS (0.1 mg/mL) were reversed by ZZCD (1 g/kg). The results of immunohistochemical experiments showed that ZZCD (1 g/kg) activated neurons in the PFC and PACAP/VIP in the PFC. In this study, 22 substances in ZZCD were identified. Five primary distinctive fingerprint peaks-geniposide, genistin, genipin-1-β-D-gentiobioside, glycitin, and daidzin-were found among the ten common peaks.

CONCLUSION

ZZCD (1 g/kg) had significant rapid antidepressant effects. PACAP/VIP in the PFC was found to mediate the rapid antidepressant effects of ZZCD.

Acupuncture alleviates CUMS-induced depression-like behaviors of rats by regulating oxidative stress, neuroinflammation and ferroptosis

BACKGROUND

The treatment of depression with acupuncture has been documented. The mechanism behind acupuncture's curative and preventative effects is still unknown.

METHODS

The current study examined the effects of acupuncture on depression-like behaviors in a rat model of chronic unpredictable mild stress (CUMS), while also exploring its potential mechanisms. A total of six groups of rats were randomly assigned: control, CUMS, acupuncture, fluoxetine, acupoint catgut embedding and sham acupoint catgut embedding. Fluoxetine (2.1 mg/kg) and acupoint catgut embedding were used for comparative research to acupuncture. The modelling evaluation is measured by body weight and behavior tests. Western blotting and reverse transcription-polymerase chain reaction were used to detect the proteins and mRNA expression of Silent information regulator 1 (Sirt1)/ nuclear factor-erythroid 2-related factor 2 (Nrf2)/ heme oxygenase-1 (HO-1)/ Glutathione peroxidase 4 (GPX4) pathway in the hippocampus. The expression of oxidative stress (OS)-related proteins and inflammatory cytokines in the serum was detected with ELISA. Immunofluorescence showed microglia and astrocytes activity in the hippocampus.

RESULTS

Acupuncture and fluoxetine could alleviate CUMS-induced depression-like behaviors. Acupuncture was also found to effectively reverse the levels of MDA, SOD, GSH, GSH-PX and T-AOC, IL-1β, IL-6 and TNF-α in the serum of CUMS-induced rats. Rats with CUMS showed decreased levels of Sirt1, Nrf2, HO-1 and GPX4 in the hippocampus, while acupuncture treatment could partly reverse the diminished effects. In addition, acupuncture treatment significantly reduced the activation of hippocampal microglia and astrocytes in CUMS-induced rats.

CONCLUSION

The study's findings indicate that acupuncture has the potential to mitigate depression-like behaviors in rats induced with CUMS by mitigating OS and reducing neuroinflammation.

Electroacupuncture ameliorates chronic unpredictable mild stress-induced depression-like behavior and cognitive impairment through suppressing oxidative stress and neuroinflammation in rats

BACKGROUND

Depression is associated with lowered mood, anxiety, anhedonia, cognitive impairments, and even suicidal tendencies in severe cases. Yet few studies have directed acupuncture's mechanism toward enhancing axonal repair correlated with synaptic plasticity and anti-inflammatory effects related to oxidative stress in the hippocampus.

METHODS

Male Sprague-Dawley (SD) rats were randomly divided into control group (CON), chronic unpredictable mild stress (CUMS) group, CUMS + electroacupuncture group (EA), and CUMS + fluoxetine group (FLX) (n = 10/group). Rats were given a 28-day treatment at the Shangxing (GV23) and Fengfu (GV16) acupoints with electroacupuncture or fluoxetine (2.1 mg/kg).

RESULTS

Rats exposed to CUMS induced depression-like behaviors and spatial learning-memory impairment, changed the ionized calcium binding adaptor molecule 1 (IBA-1), Vglut1, myelin basic protein (MBP), and postsynaptic density protein 95 (PSD95) level of hippocampal, increased the Nod-like receptor protein 3 (NLRP3), atypical squamous cell (ASC), Caspase level and hippocampal reactive oxygen species (ROS), and prompted the activation of Epha4-mediated signaling and an inflammatory response. Conversely, electroacupuncture administration reduced these changes and prevented depression-like behaviors and cognitive impairment. Electroacupuncture also promoted hippocampal expression of Sirtuin1(SIRT1), Nuclear factor erythroid 2-like (Nrf2), Heme oxygenase-1 (HO-1); reduced the expression of interleukin-1β (IL-1β), interleukin-18 (IL-18), and tumor necrosis factor-alpha (TNF-α); and prevented neural damage, particularly the synaptic myelin sheath, and neuroinflammation by regulating Eph receptor A4 (EphA4) in the hippocampal.

CONCLUSION

These results indicate that electroacupuncture prevents depression-like behaviors with cognitive impairment and synaptic and neuronal damage, probably by reducing EphA4, which mediates ROS hyperfunction and the inflammatory response.

Hippocampal pituitary adenylate cyclase-activating polypeptide mediates rapid antidepressant-like effects of Yueju pill

Yueju pill, a classic Chinese Medicine formulated, was recently found to produce rapid antidepressant-like effects in a PKA-CREB signaling-dependent manner. In our study, we found that the Yueju pill induced a remarkable increase in PACAP. The intracerebroventricular injection of PACAP agonist induced a rapid antidepressant-like effect; conversely, the intrahippocampal infusion of a PACAP antagonist reversed the antidepressant response of the Yueju pill. Mice with hippocampal PACAP knockdown via viral-mediated RNAi displayed depression-like behavior. PACAP knockdown also blunted the antidepressant effect of the Yueju pill. PACAP knockdown resulted in down-regulated CREB and expression of the synaptic protein PSD95 at both baselines and after administration of the Yueju pill. However, administration of the Yueju pill in the knockdown mice promoted PACAP and PKA levels. Chronically stressed mice showed deficient hippocampal PACAP-PKA-CREB signaling and depression-like behavior, which were reversed by a single dose of the Yueju pill. In this study, we demonstrated that the up-regulation of PACAP induced activating of PKA-CREB signaling would play a part in the rapid antidepressant-like effects of the Yueju pill. We also identified iridoids fraction of Gardenia jasminoides Ellis (GJ-IF), a vital component of the Yueju pill, was identified to recapitulate rapid antidepressant-like behavior through increased hippocampal PACAP expression of the Yueju pill. The promotion of hippocampal PACAP may collectively represent a novel mechanism of rapid antidepressant-like effect.

Fabrication of a bioconjugated dual-functional SERS probe for facile compound screening and detection

Surface-enhanced Raman spectroscopy (SERS) is an ultrasensitive technique for both detection and structural characterizations. To further exploit these advantages, we designed and fabricated a dual-functional SERS probe for specific capture and fast detection of small molecule ligands binding to target protein from a mixture of compounds such as extracts of natural products. As a proof of concept, we synthesized SiO₂@Ag nanoclusters that are coated with 6-chlorohexanoic acid for covalent immobilization of serotonin transporter (5-HTT) fused with a Halo-tag through enzyme-substrate recognition. As such, we fabricated a bioconjugated SERS probe, and the synthesis, coating, protein immobilization, and affinity-based ligand binding have been characterized and verified by transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and elemental mapping. By applying this probe to analyze Gardenia jasminoides extract, we have successfully identified crocin I as a compound binding to 5-HTT, which was further proved by using mass spectrometry (MS) and nuclear magnetic resonance (NMR). Taken together, we have developed a novel SERS probe by integrating the inherent strength of SERS in molecular analysis with an extended functionality of affinity-guided molecular capture, which has demonstrated the potential in drug screening of challenging systems.

Pexidartinib (PLX3397) through restoring hippocampal synaptic plasticity ameliorates social isolation-induced mood disorders

Social behavior is essential for the well-being and survival of individuals. However, social isolation is a serious public health issue, especially during the COVID-19 pandemic, affecting a significant number of people worldwide, and can lead to serious psychological crises. Microglia, innate immune cells in the brain, are strongly implicated in the development of psychiatry. Although many microglial inhibitors have been used to treat depression, there is no literature report on pexidartinib (PLX3397) and social isolation. Herein, we adopted PLX3397 to investigate the role of microglia in the modulation of social isolation. Our results found that social isolation during adolescence caused depressive-like, but not anxiety-like behavior in mice in adulthood, with enhanced expression of the microglial marker Iba1 in the hippocampus. In addition, treatment with PLX3397 reduced the expression of the microglial marker Iba1, decreased the mRNA expression of IL-1β, increased the mRNA expression of Arg1, elevated the protein levels of DCX and GluR1 and restored the dendritic spine branches and density, ultimately mitigating depressive-like behavior in mice. These findings suggest that inhibition of microglia in the hippocampus could ameliorate mood disorders in mice, providing a new perspective for the treatment of psychiatric disorders such as depression.