Soybean isoflavone ameliorates β‐amyloid 1‐42‐induced learning and memory deficit in rats by protecting synaptic structure and function

This research aims to investigate whether soybean isoflavone (SIF) could alleviate the learning and memory deficit induced by β‐amyloid peptides 1‐42 (Aβ1‐42) by protecting the synapses of rats. Adult male Wistar rats were randomly allocated to the following groups: (1) control group; (2) Aβ1‐42 group; (3) SIF group; (4) SIF + Aβ1‐42 group (SIF pretreatment group) according to body weight. The 80 mg/kg/day of SIF was administered orally by gavage to the rats in SIF and SIF+Aβ1‐42 groups. Aβ1‐42 was injected into the lateral cerebral ventricle of rats in Aβ1‐42 and SIF+Aβ1‐42 groups. The ability of learning and memory, ultramicrostructure of hippocampal synapses, and expression of synaptic related proteins were investigated. The Morris water maze results showed the escape latency and total distance were decreased in the rats of SIF pretreatment group compared to the rats in Aβ1‐42 group. Furthermore, SIF pretreatment could alleviate the synaptic structural damage and antagonize the down‐regulation expressions of below proteins induced by Aβ1‐42: (1) mRNA and protein of the synaptophysin and postsynaptic density protein 95 (PSD‐95); (2) protein of calmodulin (CaM), Ca²⁺/calmodulin‐dependent protein kinase II (CaMK II), and cAMP response element binding protein (CREB); (3) phosphorylation levels of CaMK II and CREB (pCAMK II, pCREB). These results suggested that SIF pretreatment could ameliorate the impairment of learning and memory ability in rats induced by Aβ1‐42, and its mechanism might be associated with the protection of synaptic plasticity by improving the synaptic structure and regulating the synaptic related proteins. Synapse 67:856–864, 2013 . © 2013 Wiley Periodicals, Inc.     

Effectiveness of Microcurrent Stimulation in Preserving Retinal Function of Blind Leading Retinal Degeneration and Optic Neuropathy: A Systematic Review

ObjectivesTo systematically identify and summarize the effectiveness and the parameters of electrical stimulation (ES) for the preservation of visual function in major retinal degeneration and optic neuropathy.Materials and MethodsA systematic review of clinical studies, using ES therapy in patients with blind leading retinal degenerations, including retinitis pigmentosa (RP), age-related macular degeneration (AMD), glaucoma, retinal vein occlusion (RVO), retinal artery occlusion (RAO), and optic neuropathy was conducted. PubMed, EMBASE, Cochrane Library, and Web of Science were searched for relevant interventional studies including randomized controlled trials (RCTs) and observational studies.ResultsA total of 10 RCTs and 15 observational studies were included. Transcorneal ES (TcES), transpalpebral ES (TpES), transdermal ES (TdES), and repetitive transorbital alternating current stimulation (rtACS) were used for the treatment of the patients. ES using 20 Hz biphasic pulses with current strength at 150%–200% of individual electrical phosphene threshold (EPT) for RP patients showed improved retinal function detected by visual acuity (VA), visual field (VF), or electrical retinal graphs (ERG). rtACS on patients with optic neuropathy showed significant preservation of VA and VF. Clinical studies on AMD, RAO, and glaucoma indicated promising protective effects of ES on the visual function, though the amount of evidence is limited.ConclusionsES treatment has promising therapeutic effects on RP and optic neuropathy. More large-scale RCT studies should be conducted to elucidate the potential of ES, especially on AMD, RAO, and glaucoma. A comparison of the effects by different ES methods in the same disease populations is still lacking. Parameters of the electric current and sensitive detection method should be optimized for the evaluation of ES treatment effects in future studies.     

Resolution, the grail for healthy ocular inflammation

Acute inflammation is a frequent, essential and beneficial response to maintain normal tissue function. PMN are the primary effector cells of acute inflammatory responses and their timely resolution by macrophages from an injured, stressed or infected tissues are required for the successful execution of this routine tissue response. Dysregulation of this fundamental program is a major factor in the global disease burden and contributes to many ocular diseases. Counter-regulatory signals are critical to the controlled activation of innate and adaptive immune responses in the eye and recent studies have identified two circuits in the cornea, uvea and/or retina, namely 15-lipoxygenase and heme-oxygenase, which control inflammation, promote resolution of PMN and afford neuroprotection. The role of these counter-regulator and pro-resolution circuits may provide insight into ocular inflammatory diseases and opportunities to restore stressed ocular tissue to a pre-inflammatory state, namely homeostasis, rather than limiting therapeutic options to palliative inhibition of pro-inflammatory circuits.     

Inhibition of caspase-3-mediated apoptosis improves spinal cord repair in a regeneration-competent vertebrate system

Teleost fish exhibit an excellent potential for structural and functional recovery after CNS lesions. The function of apoptosis in the process of regeneration remains controversial. While some studies have identified this type of cell death as essential for successful regeneration, other investigations have suggested some degree of functional improvement after inhibition of apoptosis. In the present study, we examined whether inhibition of apoptosis immediately after injury can improve spinal cord regeneration. As a model system, we used Apteronotus leptorhynchus, a regeneration-competent weakly electric fish. To inhibit apoptosis, we employed 2,2′-methylenebis (1,3-cyclohexanedione) (M50054), a compound that prevents caspase-3 activation. Administration of this apoptosis inhibitor led to a significant reduction in the numbers of apoptotic cells at 24 h, 5 days, and 30 days after the lesion. Using triple immunolabeling, we identified a significant reduction in the level of apoptosis at 5 and 30 days after the lesion among the following cellular categories: cells generated shortly after the lesion, existing neurons, and newly differentiated neurons. This reduced rate of apoptosis led to an increase in the relative number of differentiating and surviving neurons at both 5 and 30 days post-injury, compared to the control groups. Functional regeneration, as indicated by the recovery rate of the amplitude of the electric organ discharge (EOD), was significantly improved within the first 20 days after the lesion in the fish treated with M50054. Our data provide the first evidence that modulation of caspase-3 activation can significantly improve neuroregeneration and functional recovery in a regeneration-competent organism.     

Protein kinase C stabilizes X‐linked inhibitor of apoptosis protein (XIAP) through phosphorylation at Ser87 to suppress apoptotic cell death

Background: Multiple protein kinases have been shown to be involved in the apoptotic neuronal loss of Alzheimer's disease (AD). Although some studies support the role of protein kinase C (PKC) in amyloid precursor protein processing as well as in tau phosphorylation, a direct role for PKC in apoptotic neuronal death remains to be clarified. In the present study, we report on the possible role of PKC in cell survival during conditions of stress through phosphorylation of the X‐linked inhibitor of apoptosis protein (XIAP). Methods: Phosphorylation of XIAP at Ser87 was confirmed by western blot analysis employing phosphorylation dependent anti‐XIAP antibody after incubation of recombinant XIAP with active PKC in vitro. And increased phosphorylation of XIAP at the site was also confirmed in SH‐SY5Y cells treated with PKC activator, phorbol 12‐myristate 13‐acetate (PMA). A mutant XIAP construct in which Ser87 was substituted by Ala, was prepared, and transfected to cells. After the transfection of wild or mutant XIAP, cells viability was evaluated by counting living and dead cells treated with PMA during etoposide‐induced apoptosis. Results: Recombinant XIAP was phosphorylated at Ser⁸⁷ by PKC in vitro and treatment of XIAP‐transfected SH‐SY5Y cells with a PKC activator, phorbol 12‐myristate 13‐acetate (PMA) induced phosphorylation of XIAP at Ser⁸⁷. Pulse chase experiments revealed that, when phosphorylated at Ser⁸⁷, wild‐type XIAP is more stable than XIAP with a Ser87Ala substitution, which is degraded faster. Importantly, the phosphorylation of XIAP at the site by PKC significantly increased cell survival up to approximately 2.5 times under the condition of apoptosis induced by 25 µg/ml etoposide. Conclusion: The findings of the present study indicate a role for PKC, through phosphorylation of XIAP at Ser⁸⁷ and its stabilization, in cell survival under conditions of stress and lend strength to the idea that PKC is crucial in regulating neuronal homeostasis, which may be impaired in AD.     

Small Molecule c-jun-N-terminal Kinase (JNK) Inhibitors Protect Dopaminergic Neurons in a Model of Parkinson's Disease

There are currently no drugs to treat neurodegeneration in Parkinson's disease (PD) and all existing medications only treat symptoms, lose efficacy over time, and produce untoward side effects. In the current work, we report the first highly selective, orally bioavailable, c-jun-N-terminal kinase (JNK) inhibitor for protection of dopaminergic neurons in vitro and in vivo. At 300 nM this compound showed statistically significant protection of primary dopaminergic neurons exposed to 1-methyl-4-phenylpyridinium (MPP(+)), had pharmacokinetic properties in rodents consistent with twice daily (b.i.d.) dosing, and was orally efficacious at 30 mg/kg in a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease. Moreover, a dose-dependent target modulation of c-jun phosphorylation served as a biomarker for demonstrating on-target inhibition of JNK as the mechanism of action for this compound. Collectively these results suggest that this JNK inhibitor could be a promising therapeutic neuroprotective agent in the treatment of Parkinson's disease.     

Emerging technologies in the delivery of erythropoietin for therapeutics

Deciphering the function of proteins and their roles in signaling pathways is one of the main goals of biomedical research, especially from the perspective of uncovering pathways that may ultimately be exploited for therapeutic benefit. Over the last half century, a greatly expanded understanding of the biology of the glycoprotein hormone erythropoietin (Epo) has emerged from regulator of the circulating erythrocyte mass to a widely used therapeutic agent. Originally viewed as the renal hormone responsible for erythropoiesis, recent in vivo studies in animal models and clinical trials demonstrate that many other tissues locally produce Epo independent of its effects on red blood cell mass. Thus, not only its hematopoietic activity but also the recently discovered nonerythropoietic actions in addition to new drug delivery systems are being thoroughly investigated in order to fulfill the specific Epo release requirements for each therapeutic approach. The present review focuses on updating the information previously provided by similar reviews and recent experimental approaches are presented to describe the advances in Epo drug delivery achieved in the last few years and future perspectives. © 2009 Wiley Periodicals, Inc. Med Res Rev, 31, No. 2, 284–309, 2011     

Poly-arginine and arginine-rich peptides are neuroprotective in stroke models

Using cortical neuronal cultures and glutamic acid excitotoxicity and oxygen-glucose deprivation (OGD) stroke models, we demonstrated that poly-arginine and arginine-rich cell-penetrating peptides (CPPs), are highly neuroprotective, with efficacy increasing with increasing arginine content, have the capacity to reduce glutamic acid-induced neuronal calcium influx and require heparan sulfate preotoglycan-mediated endocytosis to induce a neuroprotective effect. Furthermore, neuroprotection could be induced with immediate peptide treatment or treatment up to 2 to 4 hours before glutamic acid excitotoxicity or OGD, and with poly-arginine-9 (R9) when administered intravenously after stroke onset in a rat model. In contrast, the JNKI-1 peptide when fused to the (non-arginine) kFGF CPP, which does not rely on endocytosis for uptake, was not neuroprotective in the glutamic acid model; the kFGF peptide was also ineffective. Similarly, positively charged poly-lysine-10 (K10) and R9 fused to the negatively charged poly-glutamic acid-9 (E9) peptide (R9/E9) displayed minimal neuroprotection after excitotoxicity. These results indicate that peptide positive charge and arginine residues are critical for neuroprotection, and have led us to hypothesize that peptide-induced endocytic internalization of ion channels is a potential mechanism of action. The findings also question the mode of action of different neuroprotective peptides fused to arginine-rich CPPs.     

银杏叶提取物对6-OHDA致PC12细胞损伤的保护作用及机制

目的探讨6-羟基多巴胺（6-OHDA）对PC12细胞的损伤作用，观测银杏叶提取物（Ginkgo biloba extract，GBE）对该损伤的保护作用并探讨其作用机制。方法采用细胞培养的方法，建立PC12细胞的6-OHDA损伤模型。MTT比色试验检测细胞活性，Hoechst33342荧光染色观察细胞形态变化，ELISA法检测胞质多巴胺（DA）的含量，免疫印迹法检测caspase～3观察细胞凋亡。结果40mg／LGBE对100umol／L6～OHDA作用于PC12细胞24h具有一定的保护作用，GBE可明显升高6-OHDA诱导的PC12细胞DA的含量（与损伤组比较，P〈0．05），GBE可减少6-OHDA诱导的PCI2细胞caspase-3过度表达。结论GBE可减轻6-OHDA诱导的PCI2细胞损伤和凋亡，其作用可能与抑制caspase-3蛋白酶的激活有关。