The involvement of AMPA–ERK1/2–BDNF pathway in the mechanism of new antidepressant action of prokinetic meranzin hydrate

Neohesperidin exerts antidepressant-like effect via the mechanistic target of rapamycin complex 1 in the medial prefrontal cortex in male mice

Neohesperidin, a citrus flavonoid, shows potential for activating the mechanistic target of rapamycin complex 1 (mTORC1). Here, the antidepressant-like effect of neohesperidin was examined in male ICR mice (naïve mice and mice treated repeatedly with prednisolone, a synthetic glucocorticoid, which induces depression-like behavior). Oral neohesperidin administration exerted an antidepressant-like effect in the forced swim test 1 h post-treatment, in naïve mice; this effect was no longer observed at 24 h. Neohesperidin also reversed prednisolone-induced depression-like behavior. This effect was blocked by infusing rapamycin, an mTORC1 inhibitor, into the medial prefrontal cortex. Neohesperidin may rapidly produce an antidepressant-like effect.

Aniracetam: An Evidence-Based Model for Preventing the Accumulation of Amyloid-β Plaques in Alzheimer's Disease

 Alzheimer's disease is the leading cause of dementia in the world. It affects 6 million people in the United States and 50 million people worldwide. Alzheimer's disease is characterized by the accumulation of amyloid-β plaques (Aβ), an increase in tau protein neurofibrillary tangles, and a loss of synapses. Since the 1990s, removing and reducing Aβ has been the focus of Alzheimer's treatment and prevention research. The accumulation of Aβ can lead to oxidative stress, inflammation, neurotoxicity, and eventually apoptosis. These insults impair signaling systems in the brain, potentially leading to memory loss and cognitive decline. Aniracetam is a safe, effective, cognitive-enhancing drug that improves memory in both human and animal studies. Aniracetam may prevent the production and accumulation of Aβ by increasing α-secretase activity through two distinct pathways: 1) increasing brain derived neurotrophic factor expression and 2) positively modulating metabotropic glutamate receptors. This is the first paper to propose an evidence-based model for aniracetam reducing the accumulation and production of Aβ.

Microglial stimulation triggered by intranasal lipopolysaccharide administration produces antidepressant-like effect through ERK1/2-mediated BDNF synthesis in the hippocampus

We recently reported that reversing the chronic stress-induced decline of microglia in the dentate gyrus (DG) of the hippocampus by intraperitoneal injection of a low dose of lipopolysaccharide (LPS) ameliorated depression-like behavior in chronically stressed mice. In this study, we found that a single intranasal administration of LPS dose-dependently improved depression-like behavior in mice treated with chronic unpredictable stress (CUS), as evidenced by the reduction of immobility time in the tail suspension test (TST) and forced swimming test (FST) and by the increase of sucrose uptake in the sucrose preference test (SPT). The antidepressant effects of intranasal administration of LPS could be abolished by inhibition of brain-derived neurotrophic factor (BDNF) signaling by infusion of an anti-BDNF antibody, by knock-in of the mutant BDNF Val68Met allele, or by the BDNF receptor antagonist K252a. In addition, intranasal administration of LPS was found to exert antidepressant effects in a BDNF-dependent manner via promotion of BDNF synthesis mediated by extracellular signal-regulated kinase 1/2 (ERK1/2) signaling but not protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling in DG. Inhibition of microglia by minocycline or depletion of microglia by PLX3397 was able to abolish the reversal effect of intranasal LPS administration on CUS-induced depression-like behaviors as well as the CUS-induced decrease in phospho-ERK1/2 and BDNF protein levels in DG. These results demonstrate that stimulation of hippocampal microglia by intranasal LPS administration can induce antidepressant effects via ERK1/2-dependent synthesis of BDNF protein, providing hope for the development of new strategies for the treatment of depression.

ERK1/2-dependent BDNF synthesis and signaling is required for the antidepressant effect of microglia stimulation

Depressed mice have lower numbers of microglia in the dentate gyrus (DG). Reversal of this decline by a single low dose of lipopolysaccharide (LPS) may have antidepressant effects, but there is little information on the molecular mechanisms underlying this effect. It is known that impairment of brain-derived neurotrophic factor (BDNF) signaling is involved in the development of depression. Here, we used a combination of neutralizing antibodies, mutant mice, and pharmacological approaches to test the role of BDNF-tyrosine kinase receptor B (TrkB) signaling in the DG in the effect of microglial stimulation. Our results suggest that inhibition of BDNF signaling by infusion of an anti-BDNF antibody, the BDNF receptor antagonist K252a, or knock-in of the mutant BDNF Val68Met allele abolished the antidepressant effect of LPS in chronically stressed mice. Increased BDNF synthesis in DG, mediated by extracellular signal-regulated kinase1/2 (ERK1/2) signaling but not protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling, was essential for the antidepressant effect of microglial stimulation. These results suggest that increased BDNF synthesis through activation of ERK1/2 caused by a single LPS injection and subsequent TrkB signaling are required for the antidepressant effect of hippocampal microglial stimulation.

Meranzin Hydrate Improves Depression-Like Behaviors and Hypomotility via Ghrelin and Neurocircuitry

OBJECTIVE

To investigate whether meranzin hydrate (MH) can alleviate depression-like behavior and hypomotility similar to Chaihu Shugan Powder (CSP), and further explore the potential common mechanisms.

METHODS

Totally 120 Spraque-Dawley rats were randomly divided into 5-8 groups including sham, vehicle, fluoxetine (20 mg/kg), mosapride (10 mg/kg), CSP (30 g/kg), MH (9.18 mg/kg), [D-Lys3]-GHRP-6 (Dlys, 0.5 mg/kg), and MH+Dlys groups by a random number table, 8 rats in each group. And 32 mice were randomly divided into wild-type, MH (18 mg/kg), growth hormone secretagogue receptor-knockout (GHSR-KO), and GHSR+MH groups, 8 mice in each group. The forced swimming test (FST), open field test (OFT), tail suspension test (TST), gastric emptying (GE) test, and intestinal transit (IT) test were used to assess antidepressant and prokinetic (AP) effects after drug single administration for 30 min with absorbable identification in rats and mice, respectively. The protein expression levels of brain-derived neurotrophic factor (BDNF) and phosphorylated mammalian target of rapamycin (p-mTOR) in the hippocampus of rats were evaluated by Western blot. The differences in functional brain changes were determined via 7.0 T functional magnetic resonance imaging-blood oxygen level-dependent (fMRI-BOLD).

RESULTS

MH treatment improved depression-like behavior (FST, OFT) and hypomotility (GE, IT) in the acute forced swimming (FS) rats (all P<0.05), and the effects are similar to the parent formula CSP. The ghrelin antagonist [D-Lys3]-GHRP-6 inhibited the effect of MH on FST and GE (P<0.05). Similarly, MH treatment also alleviated depression-like behavior (FST, TST) in the wild-type mice, however, no effects were found in the GHSR KO mice. Additionally, administration of MH significantly stimulated BDNF and p-mTOR protein expressions in the hippocampus (both P<0.01), which were also prevented by [D-Lys3]-GHRP-6 (P<0.01). Besides, 3 main BOLD foci following acute FS rats implicated activity in hippocampus-thalamus-basal ganglia (HTB) circuits. The [D-Lys3]-GHRP-6 synchronously inhibited BOLD HTB foci. As expected, prokinetic mosapride only had effects on the thalamus and basal ganglia, but not on the hippocampus. Within the HTB, the hippocampus is implicated in depression and FD.

CONCLUSIONS

MH accounts for part of AP effects of parent formula CSP in acute FS rats, mainly via ghrelin-related shared regulation coupled to BOLD signals in brain areas. This novel functionally connection of HTB following acute stress, treatment, and regulation highlights anti-depression unified theory.

AMPAkine CX516 alleviated chronic ethanol exposure-induced neurodegeneration and depressive-like behavior in mice

Chronic ethanol exposure (CEE) is associated with greater neurodegenerative effects and an increased risk of depression disorder. The AMPAR is thought to be involved in depression and a reduction in its GluA1 subunit was observed in the mouse hippocampus after CEE. AMPAkines are positive allosteric modulators of the AMPA receptor and have improved depressive-like behavior. However, the role of AMPARs in CEE-induced depressive-like behavior is not clear. It is unclear whether AMPAkines, positive allosteric agonists of AMPARs, protect against ethanol-induced depression. We investigated the effects of CX516 on ethanol-induced depressive-like behavior in a mouse model. CX516 (5 mg/kg) administration alleviated 20% (m/V) ethanol-induced depressive-like behavior in mice. Furthermore, CX516 significantly diminished the inhibition of the ERK1/2-BDNF-TrkB pathway in the hippocampus of ethanol-exposed mice. In addition, CX516 attenuated the levels of pro-inflammatory (IL-6, IL-1β), apoptosis (BAX, BCL-2), and neurodegeneration (FJC) in the mouse hippocampus induced by CEE.

Meranzin hydrate elicits antidepressant effects and restores reward circuitry

The burden of depression is enormous, and numerous studies have found that major depressive disorder (MDD) induces cardiovascular disorders (CVD) and functional dyspepsia (FD). Excitingly, meranzin hydrate (MH), an absorbed bioactive compound of Aurantii Fructus Immaturus, reverses psychosocial stress-induced mood disorders, gastrointestinal dysfunction and cardiac disease. Pharmacological methods have repeatedly failed in antidepressant development over the past few decades, but repairing aberrant neural circuits might be a reasonable strategy. This article aimed to explore antidepressant-like effects and potential mechanisms of MH in a rat model of unpredictable chronic mild stress (UCMS). Utilizing blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI), we sought to find reliable neurocircuits or a dominant brain region revealing the multiple effects of MH. The results show that compared with UCMS rats, MH (10 mg/kg/day for 1 week i.g.)-treated rats exhibited decreased depression-like behaviour; increased expression of brain-derived neurotrophic factor (BDNF) in the hippocampal dentate gyrus; and normalized levels of adrenocorticotropic hormone (ACTH), corticosterone (CORT), and acylated ghrelin (AG). Additionally, the UCMS-induced rise in BOLD activation in the reward system was attenuated after MH treatment. A literature search shown that nucleus accumbens (NAc) and hypothalamus of the reward system might reveal multiple effects of MH on MDD-FD-CVD comorbidity. Further research will focus on the role of these two brain regions in treating depression associated with comorbidities.

Modified constraint-induced movement therapy alters synaptic plasticity of rat contralateral hippocampus following middle cerebral artery occlusion

Modified constraint-induced movement therapy is an effective treatment for neurological and motor impairments in patients with stroke by increasing the use of their affected limb and limiting the contralateral limb. However, the molecular mechanism underlying its efficacy remains unclear. In this study, a middle cerebral artery occlusion (MCAO) rat model was produced by the suture method. Rats received modified constraint-induced movement therapy 1 hour a day for 14 consecutive days, starting from the 7^th day after middle cerebral artery occlusion. Day 1 of treatment lasted for 10 minutes at 2 r/min, day 2 for 20 minutes at 2 r/min, and from day 3 onward for 20 minutes at 4 r/min. CatWalk gait analysis, adhesive removal test, and Y-maze test were used to investigate motor function, sensory function as well as cognitive function in rodent animals from the 1^st day before MCAO to the 21^st day after MCAO. On the 21^st day after MCAO, the neurotransmitter receptor-related genes from both contralateral and ipsilateral hippocampi were tested by micro-array and then verified by western blot assay. The glutamate related receptor was shown by transmission electron microscopy and the glutamate content was determined by high-performance liquid chromatography. The results of behavior tests showed that modified constraint-induced movement therapy promoted motor and sensory functional recovery in the middle cerebral artery-occluded rats, but had no effect on cognitive function. The modified constraint-induced movement therapy upregulated the expression of glutamate ionotropic receptor AMPA type subunit 3 (Gria3) in the hippocampus and downregulated the expression of the beta3-adrenergic receptor gene Adrb3 and arginine vasopressin receptor 1A, Avpr1a in the middle cerebral artery-occluded rats. In the ipsilateral hippocampus, only Adra2a was downregulated, and there was no significant change in Gria3. Transmission electron microscopy revealed a denser distribution the more distribution of postsynaptic glutamate receptor 2/3, which is an α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor, within 240 nm of the postsynaptic density in the contralateral cornu ammonis 3 region. The size and distribution of the synaptic vesicles within 100 nm of the presynaptic active zone were unchanged. Western blot analysis showed that modified constraint-induced movement therapy also increased the expression of glutamate receptor 2/3 and brain-derived neurotrophic factor in the hippocampus of rats with middle cerebral artery occlusion, but had no effect on Synapsin I levels. Besides, we also found modified constraint-induced movement therapy effectively reduced glutamate content in the contralateral hippocampus. This study demonstrated that modified constraint-induced movement therapy is an effective rehabilitation therapy in middle cerebral artery-occluded rats, and suggests that these positive effects occur via the upregulation of the postsynaptic membrane α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor expression. This study was approved by the Institutional Animal Care and Use Committee of Fudan University, China (approval No. 201802173S) on March 3, 2018.

Chaihu-Shugan-San Reinforces CYP3A4 Expression via Pregnane X Receptor in Depressive Treatment of Liver-Qi Stagnation Syndrome

Backgrounds. Chaihu-Shugan-San (CSS) is a classic traditional Chinese herbal prescription for treating depression. However, the underlying mechanism of the Chinese syndrome-specific efficacy of CSS is poorly understood. Aim of the Study. From traditional Chinese medicine and pharmacogenetics perspectives, the present study aimed to investigate the antidepressant effects of CSS on a mouse model of Liver-Qi Stagnation (LQS) syndrome and its underlying mechanisms. Methods and Materials. We used two main mouse models of depressive syndromes in the study, including LQS and liver stagnation and spleen deficiency (LSSD) syndrome. Tail suspension and forced swimming tests were used to evaluate the effects of CSS on animal behaviour. The expression level of the CYP450 enzyme from liver microsomes was analysed by western blot (WB) analysis and quantitative real-time polymerase chain reaction (qRT-PCR). More specifically, we analysed the key compounds of CSS that are responsible for CYP450 regulation via bioinformatics. Ultimately, luciferase assays were employed to confirm the prediction in vitro. Results. CSS remarkably reduced the immobile time in LQS rather than in LSSD mice. Although CSS significantly upregulated CYP2C9 in mice with both syndromes, activated translation of CYP3A4 induced by CSS was only observed in the LQS group. Bioinformatics analysis revealed that the unique regulation of CYP3A4 was responsible for the effects of glycyrrhetinic acid (GA) from CSS. Further luciferase assays confirmed the enhancement of CYP3A4 expression via the pregnane X receptor (PXR) pathway in vitro. Conclusions. CSS specifically upregulates the translation of CYP3A4 via the PXR pathway in depressed LQS mice. GA, a bioactive compound that originates from CSS, contributes to this activation. This work provides novel insight into Chinese syndrome-based therapy for depression.

Elevation of synaptic protein is associated with the antidepressant-like effects of ferulic acid in a chronic model of depression

Ferulic acid is a hydroxycinnamic acid that widely presents in plant cell wall components. It has been demonstrated that ferulic acid can reverse depressive-like behaviors in both forced swimming test and tail suspension test. However, it is unclear whether chronic ferulic acid treatment can ameliorate the depressive-like behaviors in chronic unpredictable mild stress (CUMS). Because of the putative relationship between neurotrophic system and antidepressant-like activity, we also investigated the effects of chronic ferulic acid on the brain-derived neurotrophic factor (BDNF), postsynaptic protein PSD95, presynaptic protein synapsin I in both prefrontal cortex and hippocampus. The results showed that ferulic acid significantly alleviated CUMS-induced depressive-like behaviors in sucrose preference test and forced swimming test. In addition, ferulic acid significantly up-regulated the levels of BDNF, PSD95 and synapsin I in the prefrontal cortex and hippocampus. The present data indicated that ferulic acid exerted the antidepressant-like effects on behaviors by increasing neurotrophin-related synaptic protein levels in CUMS mice.

N,N-dimethylglycine differentially modulates psychotomimetic and antidepressant-like effects of ketamine in mice

Ketamine, a dissociative anesthetic, produces rapid and sustained antidepressant effects at subanesthtic doses. However, it still inevitably induces psychotomimetic side effects. N,N-dimethylglycine (DMG) is a derivative of the amino acid glycine and is used as a dietary supplement. Recently, DMG has been found acting at glycine binding site of the N-methyl-d-aspartate receptor (NMDAR). As blockade of NMDARs is one of the main mechanisms responsible for the action of ketamine on central nervous system, DMG might modulate the behavioral responses to ketamine. The present study determined the effects of DMG on the ketamine-induced psychotomimetic, anesthetic and antidepressant-like effects in mice. DMG pretreatment reversed the ketamine-induced locomotor hyperactivity and impairment in the rotarod performance, novel location and novel object recognition tests, and prepulse inhibition. In addition, DMG alone exhibited antidepressant-like effects in the forced swim test and produced additive effects when combined with ketamine. However, DMG did not affect ketamine-induced anesthesia. These results reveal that DMG could antagonize ketamine's psychotomimetic effects, yet produce additive antidepressant-like effects with ketamine, suggesting that DMG might have antipsychotic potential and be suitable as an add-on therapy to ketamine for patients with treatment-resistant depression.

Zhiqiaochuanxiong decoction for major depressive disorder complicated by functional dyspepsia: a case report with fast-acting efficacy

OBJECTIVE

To introduce a clinical case from Professor Huang Xi from Xiangya Hospital in traditional Chinese medical (TCM) treatment for a major depressive disorder (MDD) complicated by functional dyspepsia (FD).

METHODS

A 26-year old unemployed male migrant worker (Han nationality) presented himself at the TCM outpatient department of our hospital on May 13th 2013, with the chief complaint of persistent low mood and negative emotions lasting 2.5 years. He was diagnosed as having MDD complicated by FD. The TCM differentiation made was "Ganqi-Yujie" (Liver-Qi stagnation). Zhiqiaochuanxiong (ZQCX) decoction, composed of Zhiqiao (Fructus Aurantii Submaturus) 40 g and Chuanxiong (Rhizoma Chuanxiong) 40 g, was given to be taken twice daily. The patient's condition was evaluated with a 128-channel electroencephalogram (EEG) and high-resolution manometry (HRM). During follow-up the patient was monitored with the Patient Health Questionnaire and Leeds Dyspepsia Questionnaire.

RESULTS

After treatment, the symptoms of depression and the FD comorbidity disappeared. Furthermore, the main EEG and HRM were significantly improved after 1-7 weeks of ZQCX decoction administration.

CONCLUSION

ZQCX decoction showed rapid prokinetic and anti-depressive effects in a MDD patient complicated by FD. Most commonly used antidepressants target only the brain, whereas ZQCX decoction targets the brain-gut axis according to TCM theory.

Searching the cytochrome p450 enzymes for the metabolism of meranzin hydrate: a prospective antidepressant originating from Chaihu-Shugan-San

Meranzin hydrate (MH), an absorbed bioactive compound from the Traditional Chinese Medicine (TCM) Chaihu-Shugan-San (CSS), was first isolated in our laboratory and was found to possess anti-depression activity. However, the role of cytochrome P450s (CYPs) in the metabolism of MH was unclear. In this study, we screened the CYPs for the metabolism of MH in vitro by human liver microsomes (HLMs) or human recombinant CYPs. MH inhibited the enzyme activities of CYP1A2 and CYP2C19 in a concentration-dependent manner in the HLMs. The Km and Vmax values of MH were 10.3±1.3 µM and 99.1±3.3 nmol/mg protein/min, respectively, for the HLMs; 8.0±1.6 µM and 112.4±5.7 nmol/nmol P450/min, respectively, for CYP1A2; and 25.9±6.6 µM and 134.3±12.4 nmol/nmol P450/min, respectively, for CYP2C19. Other human CYP isoforms including CYP2A6, CYP2C9, CYP2D6, CYP2E1 and CYP3A4 showed minimal or no effect on MH metabolism. The results suggested that MH was simultaneously a substrate and an inhibitor of CYP1A2 and CYP2C9, and MH had the potential to perpetrate drug-drug interactions with other CYP1A2 and CYP2C19 substrates.

Orcinol glucoside produces antidepressant effects by blocking the behavioural and neuronal deficits caused by chronic stress

This study focused on the antidepressant potential of orcinol glucoside (OG) and its possible mechanisms of action. We established a depressed rat model using 3 consecutive weeks of chronic unpredictable mild stress (CUMS). The antidepressant-like effect of OG was revealed using the sucrose preference test, the open field test, the forced swimming test (FST), and the tail suspension test (TST). The activity of the hypothalamic-pituitary-adrenal (HPA) axis was evaluated by detecting the serum corticosterone (CORT) concentrations and mRNA expression of corticotrophin-releasing hormone (CRH) in the hypothalamus. The protein expression levels of brain-derived neurotrophic factor (BDNF) and total phosphorylated-ERK1/2 were detected by western blot. The results showed that OG treatment (1.5, 3, or 6mg/kg) alleviated the depression-like behaviour of rats under CUMS, as indicated by the increased sucrose preference and the decreased immobility in both the FST and TST, although the rearing frequency in the open field test increased only in the group that received the lowest dose (1.5mg/kg OG). Rats that received OG treatment exhibited reduced serum CORT levels and CRH mRNA expression in the hypothalamus, suggesting that the hyperactivity of the HPA axis in CUMS rats was reversed by OG treatment. Moreover, OG treatment upregulated the protein levels of BDNF and phosphorylated-ERK1/2 in the hippocampus, even above control levels. Our findings suggest that OG improved depressive behaviour in CUMS rats by downregulating HPA axis hyperactivity and increasing BDNF expression and ERK1/2 phosphorylation in the hippocampus.