Meihui Chen

Fasudil and its analogs: a new powerful weapon in the long war against central nervous system disorders?

Introduction: Rho kinase (ROCK) plays a critical role in actin cytoskeleton organization and is involved in diverse fundamental cellular functions such as contraction and gene expression. Fasudil, a ROCK inhibitor, has been clinically applied since 1995 for the treatment of subarachnoid hemorrhage (SAH) in Japan. Increasing evidences indicate that fasudil could exhibit markedly therapeutic effect on central nervous system (CNS) disorders, such as Alzheimers disease. Areas covered: This article summarizes results from supporting evidence for the potential therapy for fasudil against a variety of CNS diseases. And the properties of its analogs are also summarized. Expert opinion: Current therapies against CNS disorders are only able to attenuate the symptoms and fail in delaying or preventing disease progression and new approaches with disease-modifying activity are desperately needed. The dramatic effects of fasudil in animal models and/or clinical applications of CNS disorders make it a promising strategy to overcome CNS disorders in human beings. Given the complex pathology of CNS disorders, further efforts are necessary to develop multifunctional fasudil derivatives or combination strategies with other drugs in order to exert more powerful effects with minimized adverse effects in the combat of CNS disorders.

Advances in the studies of roles of Rho/Rho-kinase in diseases and the development of its inhibitors.

RhoA/Rho-kinase pathway plays a pivotal role in numerous fundamental cellular functions including contraction, motility, proliferation, differentiation and apoptosis. The pathway is also involved in the development of many diseases such as vasospasm, pulmonary hypertension, cancer and central nervous systems (CNS) disorders. The inhibitors of Rho kinase have been extensively studied since the Rho/Rho-kinase pathway was verified as a target for a number of diseases. Herein, we reviewed the advances in the studies of the roles of Rho/Rho-kinase in diseases and the development of Rho-kinase inhibitors in recent five years.

Protective effects of caffeic acid and caffeic acid phenethyl ester against acrolein-induced neurotoxicity in HT22 mouse hippocampal cells

Acrolein-induced oxidative stress is hypothesized to involve in the etiology of Alzheimers disease (AD). Caffeic acid (CA) and caffeic acid phenethyl ester (CAPE) have antioxidative and neuroprotective properties. The present study investigated the protective effects of CA/CAPE on acrolein-induced oxidative neuronal toxicity. HT22 mouse hippocampal cells were pretreated with CA/CAPE and then exposed to acrolein. Cell viability, intracellular reactive oxygen species (ROS), and glutathione (GSH) level were measured. MAPKs and Akt/GSK3β signaling proteins as well as α/β-secretase of amyloid protein precursor were assayed by Western blotting. Pretreatment with CA/CAPE significantly attenuated acrolein-induced neurotoxicity, ROS accumulation, and GSH depletion. Further study suggested that CA/CAPE showed protective effects against acrolein by modulating MAPKs and Akt/GSK3β signaling pathways. Moreover, CA/CAPE restored the changes of β-secretase (BACE-1) and/or activation of α-secretase (ADAM-10) induced by acrolein. These findings suggest that CA/CAPE may provide a promising approach for the treatment of acrolein-related neurodegenerative diseases, such as AD.

Discovery of novel N-substituted carbazoles as neuroprotective agents with potent anti-oxidative activity

Carbazole moiety is an important scaffold with a variety of biological applications, for example, anti-oxidative stress. Our previous synthesized carbazoles were screened for their neuroprotective properties against two individual oxidative stresses. Some of the new carbazole derivatives were observed with modest to good neuroprotective effects on neuronal cells HT22 against cell injury induced by glutamate or homocysteic acid (HCA). Substituents introduced to the carbazole ring system play crucial roles in their biological activities. In particular, a bulky group favors the neuroprotective activity of the compounds. One of the new compounds, 6, showed the best neuroprotective effects, which might result from its anti-oxidative activity with a GSH-independent mechanism. These findings might provide an alternative strategy for the development of novel carbazole derivatives for the treatment of CNS diseases such as Alzheimers disease.

Carvedilol, a third-generation β-blocker prevents oxidative stress-induced neuronal death and activates Nrf2/ARE pathway in HT22 cells

Carvedilol, a nonselective β-adrenoreceptor blocker with pleiotropic activities has been shown to exert neuroprotective effect due to its antioxidant property. However, the neuroprotective mechanism of carvedilol is still not fully uncovered. Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. Here we investigated the effect of carvedilol on oxidative stress-induced cell death (glutamate 2mM and H2O2 600 μM) and the activity of Nrf2/ARE pathway in HT22 hippocampal cells. Carvedilol significantly increased cell viability and decreased ROS in HT22 cells exposed to glutamate or H2O2. Furthermore, carvedilol activated the Nrf2/ARE pathway in a concentration-dependent manner, and increased the protein levels of heme oxygenase-1(HO-1) and NAD(P)H quinone oxidoreductase-1(NQO-1), two downstream factors of the Nrf2/ARE pathway. Collectively, our results indicate that carvedilol protects neuronal cell against glutamate- and H2O2-induced neurotoxicity possibly through activating the Nrf2/ARE signaling pathway.

Tacrine-6-Ferulic Acid, a Novel Multifunctional Dimer Against Alzheimer's Disease, Prevents Oxidative Stress-Induced Neuronal Death Through Activating Nrf2/ARE/HO-1 Pathway in HT22 Cells

1 State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China 2 Laboratory of Neurodegenerative Diseases and Aging, Department of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China 3 Departments of Pediatrics, Nuerosury & Neurodegenerative Diseases and Aging, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China 4 Department of Traditional Chinese Medicine Chemistry, College of Chinese Materia Madica, Guangzhou University of Chinese Medicine, Guangzhou, China 5 School of Pharmaceutical Sciences, Peking University, Beijing, China 6 Dipartimento di Scienze Farmaceutiche, Università di Pisa, Pisa, Italy

Carvedilol attenuates 6-hydroxydopamine-induced cell death in PC12 cells: involvement of Akt and Nrf2/ARE pathways.

Oxidative stress is closely related to the pathogenesis of neurodegenerative disorders such as Parkinson’s disease. Carvedilol, a nonselective β-adrenergic receptor blocker with pleiotropic activity has been shown to exert neuroprotective effect due to its antioxidant property. However, the neuroprotective mechanism of carvedilol is still not fully uncovered. The phosphotidylinositol 3-kinase (PI3K)/Akt signaling pathway plays key role in cell survival and the nuclear factor erythroid 2–related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway is the major cellular defense mechanism against oxidative stress. Here we investigated the effects of carvedilol on 6-hydroxydopamine (6-OHDA)-induced cell death as well as the Akt and Nrf2/ARE pathways in PC12 cells. We found that carvedilol significantly increased cell viability and decreased reactive oxygen species in PC12 cells exposed to 6-OHDA. Furthermore, carvedilol activated the Akt and Nrf2/ARE pathways in a concentration-dependent manner, and increased the protein levels of heme oxygenase-1(HO-1) and NAD(P)H quinone oxidoreductase-1(NQO-1), two downstream factors of the Nrf2/ARE pathway. In summary, our results indicate that carvedilol protects PC12 cells against 6-OHDA-induced neurotoxicity possibly through activating the Akt and Nrf2/ARE signaling pathways.

Downregulation of Nrf2/HO-1 pathway and activation of JNK/c-Jun pathway are involved in homocysteic acid-induced cytotoxicity in HT-22 cells

Previous studies have suggested that elevated blood homocysteic acid (HCA) levels increased the risk of Alzheimers disease (AD), but the underlying mechanisms are unclear. Herein, we studied the neuronal toxicity of HCA and the underlying mechanisms in HT-22 cells. Results showed that HCA induced cell death in concentration- and time-dependent manners, but did not activate Caspase-3. Additionally, HCA increased ROS production, depleted GSH, inactivated the Nrf2/HO-1 pathway, decreased mitochondrial membrane potential and increased the ratio of Bax/Bcl-2, two apoptosis-related proteins. Furthermore, HCA significantly increased the levels of p-JNK and p-c-Jun and its toxicity dramatically attenuated by SP600125, a specific JNK pathway inhibitor. Taken together, our results provide evidence that HCA induced cytotoxicity in HT-22 cells through down-regulating of Nrf2/HO-1 pathway and activating JNK/c-Jun pathway, supporting that HCA might be a therapeutic target for AD.

Simply combining fasudil and lipoic acid in a novel multitargeted chemical entity potentially useful in central nervous system disorders

Current drugs against central nervous system (CNS) disorders have limited symptomatic activities, and new approaches with neuroprotective and neurorestorative properties are urgently needed. The complex pathology of CNS disorders requires the development of multitargeted or multifunctional drugs towards several CNS targets. In the present work, employing the pharmacophore of fasudil, a Rho-associated coil kinase (ROCK) inhibitor, and alpha-lipoic acid (LA), a potent anti-oxidant, we have developed a novel multitargeted and neuroprotective drug, L-F 001. L-F 001 displayed potent inhibition towards both ROCK 1 (IC50 = 1.59 μM) and ROCK 2 (IC50 = 2.10 μM) and reduced the actin stress formation. Rat thoracic aorta assay showed that L-F 001 exerted potent vasodilation. Furthermore, the compound was capable of scavenging free radicals, increasing the level of glutathione, and preventing HT 22 cell death caused by glutamate (Glu). Moreover, the new entity had higher brain permeation over fasudil according to in vitro and in vivo blood–brain barrier (BBB) permeability tests. These results indicate that L-F 001 is a promising multifunctional agent for the treatment of CNS disorders.

Berberine protects homocysteic acid-induced HT-22 cell death: involvement of Akt pathway

Berberine (BBR), one of the major constituents of Chinese herb Rhizoma coptidis, has been reported to exert beneficial effects to various diseases, including Alzheimer’s disease (AD). In the present work, we aimed to investigate the effects of BBR on neuronal cell death induced by homocysteic acid (HCA), which was considered as a risk of AD. BBR significantly reduced HCA-induced reactive oxygen species (ROS) generation, lactate dehydrogenase release and subsequent cell death. LY294002, the PI3K inhibitor, blocked the protection as well as the up-regulation of Akt phosphorylation of BBR. Taken together, our results indicate that BBR protects HCA-induced HT-22 cell death partly via modulating Akt pathway, suggesting BBR may be a promising therapeutic agent for the treatment of HCA-related diseases, including AD.