Metformin Prevents Dopaminergic Neuron Death in MPTP/P-Induced Mouse Model of Parkinson's Disease via Autophagy and Mitochondrial ROS Clearance.

BACKGROUND: Our previous study demonstrated that metabolic inflammation exacerbates dopaminergic neuronal degeneration in type 2 diabetes mice. Metformin, a typical oral hypoglycemic agent for diabetes, has been regarded as an activator of AMP-activated protein kinase and a regulator of systemic energy metabolism. Although metformin plays potential protective effects in many disorders, it is unclear whether metformin has a therapeutic role in dopaminergic neuron degeneration in Parkinson's disease. METHODS: In the present study, a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine plus probenecid-induced mouse model of Parkinson's disease was established to explore the neuroprotective effect of metformin on dopaminergic neurons in substania nigra compacta. We next cultured SH-SY5Y cells to investigate the mechanisms for the neuroprotective effect of metformin. RESULTS: We showed that treatment with metformin (5mg/mL in drinking water) for 5 weeks significantly ameliorated the degeneration of substania nigra compacta dopaminergic neurons, increased striatal dopaminergic levels, and improved motor impairment induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine plus probenecid. We further found that metformin inhibited microglia overactivation-induced neuroinflammation in substania nigra compacta of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine plus probenecid Parkinson's disease mice, which might contribute to the protective effect of metformin on neurodegeneration. Furthermore, metformin (2mM) activated AMP-activated protein kinase in SH-SY5Y cells, in turn inducing microtubule-associated protein 1 light chain 3-II-mediated autophagy and eliminating mitochondrial reactive oxygen species. Consequently, metformin alleviated MPP+-induced cytotoxicity and attenuated neuronal apoptosis. CONCLUSIONS: Our findings demonstrate that metformin may be a pluripotent and promising drug for dopaminergic neuron degeneration, which will give us insight into the potential of metformin in terms of opening up novel therapeutic avenues for Parkinson's disease.

TRPV1 Modulator Ameliorates Alzheimer-Like Amyloid-ß Neuropathology via Akt/Gsk3ß-Mediated Nrf2 Activation in the Neuro-2a/APP Cell Model.

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder for which there is no effective therapeutic strategy. PcActx peptide from the transcriptome of zoantharian Palythoa caribaeorum has recently been identified and verified as a novel antagonist of transient receptor potential cation channel subfamily V member 1 (TRPV1). In the present study, we further investigated the neuroprotective potential of PcActx peptide and its underlying mechanism of action, in an N2a/APP cell model of AD. Both Western blot and RT-PCR analysis revealed that PcActx peptide markedly inhibited the production of amyloid-related proteins and the expression of BACE1, PSEN1, and PSEN2. Moreover, PcActx peptide notably attenuated the capsaicin-stimulated calcium response and prevented the phosphorylation of CaMKII and CaMKIV (calcium-mediated proteins) in N2a/APP cells. Further investigation indicated that PcActx peptide significantly suppressed ROS generation through Nrf2 activation, followed by enhanced NQO1 and HO-1 levels. In addition, PcActx peptide remarkably improved Akt phosphorylation at Ser 473 (active) and Gsk3ß phosphorylation at Ser 9 (inactive), while pharmacological inhibition of the Akt/Gsk3ß pathway significantly attenuated PcActx-induced Nrf2 activation and amyloid downregulation. In conclusion, PcActx peptide functions as a TRPV1 modulator of intercellular calcium homeostasis, prevents AD-like amyloid neuropathology via Akt/Gsk3ß-mediated Nrf2 activation, and shows promise as an alternative therapeutic agent for AD.

The development of behavioral sensitization induced by a single morphine exposure in adult zebrafish (Danio rerio).

BACKGROUND: Accumulating evidence suggest that behavioral sensitization is involved in the process of drug addiction. Zebrafish are sensitive to a variety of addictive drugs and are thus suitable for the study of behavioral sensitization. However, in contrast to mature rodent models of behavioral sensitization, how this phenomenon manifests in aquatic organisms, especially zebrafish, is largely unknown. In this study, we developed a morphine-induced behavioral sensitization adult zebrafish model and performed a preliminary investigation of the underlying mechanisms. METHODS: Behavioral sensitization was established in zebrafish by observing their behavior after treatment and challenge with morphine. The effect of morphine was evaluated by a behavioral locomotor test. Different doses of morphine and withdrawal times were used to evaluate the establishment of the behavioral sensitization model. RESULTS: Hyperlocomotion was induced after administration of morphine in adult zebrafish. After withdrawing the drug for a period, challenge with low-dose morphine evoked behavioral sensitization in zebrafish acutely pre-treated with morphine. Low-dose morphine failed to induce behavioral sensitization in zebrafish if the withdrawal time was less than 5 days or more than 7 days. Morphine induced behavioral sensitization in zebrafish may involve dopaminergic, glutamatergic and opioid systems. CONCLUSION: A single low-dose of morphine could induce behavioral sensitization in zebrafish acutely pre-treated with morphine, and this phenomenon was highly correlated with drug dose and withdrawal time. These findings suggest that zebrafish is a suitable model for the study of behavioral sensitization.

New iboga-type alkaloids from Ervatamia officinalis and their anti-inflammatory activity.

Four new iboga-type alkaloids, ervaoffines H-K (1-4), along with five known compounds were obtained from the aerial parts of Ervatamia officinalis. The absolute configurations of 1-4 were confirmed by X-ray diffraction and electronic circular dichroism (ECD) analyses. The isolates were tested for their anti-inflammatory activity. Compounds 1, 5, 6, and 9 showed potential inhibitory effect of NO production in LPS-stimulated BV2 and RAW264.7 cells.

Oxyphylla A ameliorates cognitive deficits and alleviates neuropathology via the Akt-GSK3ß and Nrf2-Keap1-HO-1 pathways in vitro and in vivo murine models of Alzheimer's disease.

Introduction: Alzheimer's disease (AD) is a progressive brain disorder, and one of the most common causes of dementia and amnesia. Due to the complex pathogenesis of AD, the underlying mechanisms remain unclear. Although scientists have made increasing efforts to develop drugs for AD, no effective therapeutic agents have been found. Objectives: Natural products and their constituents have shown promise for treating neurodegenerative diseases, including AD. Thus, in-depth study of medical plants, and the main active ingredients thereof against AD, is necessary to devise therapeutic agents. Methods: In this study, N2a/APP cells and SAMP8 mice were employed as in vitro and in vivo models of AD. Multiple molecular biological methods were used to investigate the potential therapeutic actions of oxyphylla A, and the underlying mechanisms. Results: Results showed that oxyphylla A, a novel compound extracted from Alpinia oxyphylla, could reduce the expression levels of amyloid precursor protein (APP) and amyloid beta (Aß) proteins, and attenuate cognitive decline in SAMP8 mice. Further investigation of the underlying mechanisms showed that oxyphylla A exerted an antioxidative effect through the Akt-GSK3ß and Nrf2-Keap1-HO-1 pathways.Conclusions.Taken together, our results suggest a new horizon for the discovery of therapeutic agents for AD.

Neuroprotective Potency of Saffron Against Neuropsychiatric Diseases, Neurodegenerative Diseases, and Other Brain Disorders: From Bench to Bedside.

The increasing morbidity rates of brain disorders and conditions such as anxiety, depression, Alzheimer's disease, and Parkinson's disease have become a severe problem in recent years. Although researchers have spent considerable time studying these diseases and reported many positive outcomes, there still are limited drugs available for their treatment. As a common traditional Chinese medicine (TCM), saffron was employed to treat depression and some other inflammatory diseases in ancient China due to its antioxidant, anti-inflammatory, and antidepressant properties. In modern times, saffron and its constituents have been utilized, alone and in TCM formulas, to treat neuropsychiatric and neurodegenerative diseases. In this review, we mainly focus on recent clinical and preclinical trials of brain disorders in which saffron was applied, and summarize the neuroprotective properties of saffron and its constituents from chemical, pharmacokinetic, and pharmacological perspectives. We discuss the properties of saffron and its constituents, as well as their applications for treating brain disorders; we hope that this review will serve as a comprehensive reference for studies aimed at developing therapeutic drugs based on saffron.

A new isoflavone with anti-inflammatory effect from the seeds of Millettia pachycarpa.

A new isoflavone, milletenol A (1), along with four known flavonoids (2-5) were isolated from the seeds of Millettia pachycarpa. The structure of 1 was established by extensive spectroscopic methods while known compounds were identified by comparisons with literature data. Compound 1 and 2 showed significant anti-inflammatory activities against nitric oxide production in LPS-induced RAW264.7 macrophages. The state of CuSO4-stimulated inflammation was effectively alleviated by compound 1 in zebrafish. However, no significant cytotoxicity against human breast cancer cells was observed among all isolates.

The effect of fluoxetine on astrocyte autophagy flux and injured mitochondria clearance in a mouse model of depression.

Although multiple hypotheses had been proposed to clarify the causes of depression, the accurate pathogenesis and effective treatment of depression still need to be solved. Pathological change of astrocytes has been recognized to play a pivotal role in depression. Fluoxetine is the first selective serotonin reuptake inhibitor, however, the underlying mechanisms of fluoxetine are incompletely excavated. Emerging evidence shows that fluoxetine promotes autophagic processes in tumor cells. However, whether astrocytic autophagy gets involved in the cytoprotection of fluoxetine on astrocytes in depression treatment remains unexplored. Here we prepared chronic mild stress (CMS)-induced mouse model and treated mice with fluoxetine (10 mg/kg) for 4 weeks to determine the correlation between proautophagic effect of fluoxetine and astrocyte protection in depression. Primary hippocampal astrocytes were cultured to investigate the potential mechanism of fluoxetine in regulating astrocyte autophagy. We found that fluoxetine (10 mg/kg) treatment promoted autophagosome formation and increased clearance of injured mitochondria, consequently protected astrocytes in CMS model mice. Fluoxetine (10 µM) could also promote the autophagic flux unblocked via enhancing fusion of autophagosomes with lysosomes in primary astrocytes. Moreover, fluoxetine promoted mitophagy by increased colocalization of autophagosomes and mitochondria, eliminating damaged mitochondria in corticosterone-treated astrocytes. Further in vitro study showed that p53 presence is required for fluoxetine activated autophagy flux and fluoxetine promotes astrocytic autophagy in a p53-dependent mechanism. Collectively, this work gives us insights into a novel approach to treat depression depending on astrocytes, and provides a promising molecular target for the development of antidepressant drugs besides regulating neurotransmitters.

Neuroprotective Effects of BHDPC, a Novel Neuroprotectant, on Experimental Stroke by Modulating Microglia Polarization.

This study mainly investigated the therapeutic effects of BHDPC on ischemic stroke and its underlying mechanisms. In vivo, the transient middle cerebral artery occlusion (MCAO) was used to induce ischemic model. In vitro, oxygen and glucose deprivation/reperfusion (OGD/R)-induced ischemic stroke in BV-2 microglia and primary neurons, and bEnd.3 mouse cerebral microvascular endothelial cells (ECs) were also used. First, we found that BHDPC exerts considerable neuroprotection against MCAO-induced ischemic injury to mice via alleviating neurological deficits and brain infarcts, inhibiting neuronal cell loss and apoptosis, and attenuating blood-brain barrier disruption and tight junction protein changes. Next, we observed that BHDPC significantly reduced microglial M1 activation but enhanced M2 polarization in MCAO-induced ischemic brain. Further experiments in vitro indicated that BHDPC suppressed microglial activation but promoted M2 microglial polarization in OGD/R-induced BV-2 microglia. In addition, conditioned medium (CM) experiments showed that CM from BHDPC-treated BV-2 microglia provided protections against OGD/R-induced ischemic damage in primary neurons and bEnd.3 ECs. Moreover, we found that BHDPC actions on microglial inflammation were associated with the inactivation of NF-κB signaling. Interestingly, we also found that BHDPC enhanced phosphorylation of protein kinase A (PKA) and cAMP-response element-binding protein (CREB). The pharmacological inhibition or gene knockdown of PKA/CREB signaling diminished BHDPC-promoted microglial M2 polarization. In summary, BHDPC conferred neuroprotection against ischemic injury in experimental stroke models. Modulating microglial activation and polarization contributes to BHDPC-mediated neuroprotective actions, which in part were mediated by nuclear factor kappa B and PKA/CREB signaling pathway.

Fluoxetine protects against IL-1ß-induced neuronal apoptosis via downregulation of p53.

Fluoxetine, a selective serotonin reuptake inhibitor, exerts neuroprotective effects in a variety of neurological diseases including stroke, but the underlying mechanism remains obscure. In the present study, we addressed the molecular events in fluoxetine against ischemia/reperfusion-induced acute neuronal injury and inflammation-induced neuronal apoptosis. We showed that treatment of fluoxetine (40 mg/kg, i.p.) with twice injections at 1 h and 12 h after transient middle cerebral artery occlusion (tMCAO) respectively alleviated neurological deficits and neuronal apoptosis in a mouse ischemic stroke model, accompanied by inhibiting interleukin-1ß (IL-1ß), Bax and p53 expression and upregulating anti-apoptotic protein Bcl-2 level. We next mimicked neuroinflammation in ischemic stroke with IL-1ß in primary cultured cortical neurons and found that pretreatment with fluoxetine (1 µM) prevented IL-1ß-induced neuronal apoptosis and upregulation of p53 expression. Furthermore, we demonstrated that p53 overexpression in N2a cell line abolished the anti-apoptotic effect of fluoxetine, indicating that p53 downregulation is required for the protective role of fluoxetine in IL-1ß-induced neuronal apoptosis. Fluoxetine downregulating p53 expression could be mimicked by SB203580, a specific inhibitor of p38, but blocked by anisomycin, a p38 activator. Collectively, our findings have revealed that fluoxetine protects against IL-1ß-induced neuronal apoptosis via p38-p53 dependent pathway, which give us an insight into the potential of fluoxetine in terms of opening up novel therapeutic avenues for neurological diseases including stroke.