Neuroprotective effects of a protein tyrosine phosphatase inhibitor against hippocampal excitotoxic injury

A Capsicum annuum L. seed extract exerts anti-neuroexcitotoxicity in HT22 hippocampal neurons

The hippocampal memory deficit stands out as a primary symptom in neurodegenerative diseases, including Alzheimer's disease. While numerous therapeutic candidates have been proposed, they primarily serve to delay disease progression. Given the irreversible brain atrophy or injury associated with these conditions, current research efforts are concentrated on preventive medicine strategies. Herein, we investigated whether the extracts of Capsicum annuum L. seeds (CSE) and Capsicum annuum L. pulp (CPE) have preventive properties against glutamate-induced neuroexcitotoxicity (one of the main causes of Alzheimer's disease) in HT22 hippocampal neuronal cells. Pretreatment with CSE demonstrated significant anti-neuroexcitotoxic activity, whereas CPE did not exhibit such effects. Specifically, CSE pretreatment dose-dependently inhibited the elevation of excitotoxic elements (intracellular calcium influx and reactive oxygen species; ROS) and apoptotic elements (p53 and cleaved caspase-3). In addition, the glutamate-induced alterations of neuronal activity indicators (brain-derived neurotrophic factor; BDNF and cAMP response element-binding protein phosphorylation; CREB) were significantly attenuated by CSE treatment. We also found that luteolin is the main bioactive compound corresponding to the anti-neuroexcitotoxic effects of CSE. Our results strongly suggest that Capsicum annuum L. seeds (but not its pulp) could be candidates for neuro-protective resources especially under conditions of neuroexcitotoxicity. Its underlying mechanisms may involve the amelioration of ROS-mediated cell death and BDNF-related neuronal inactivity and luteolin would be an active compound.

A highly sensitive colorimetric sensing platform based on silver nanocomposites for alkaline phosphatase

Alkaline phosphatase (ALP) plays significant roles in regulating intracellular processes and is an important biomarker connected to several diseases. In this work, one facile and sensitive sensing platform based on CQD-silver nanocomposites (CQD-silver NPs) for colorimetric detection of alkaline phosphatase (ALP) was introduced. ALP triggers the removal of the phosphate group of ascorbic acid 2-phosphate (AA2P), which is then transformed into ascorbic acid (AA). The as-obtained AA can easily cause significant aggregation of monodispersed NPs and cause the system color to turn from bright yellow to gray. Based on the color change of the ratio of 490 nm/630 nm, ALP was sensitively and selectively detected. Under the optimum, the established method showed linearity for ALP in the range of 0.1-50 U L^-1 and the detection limit was low at 0.035 U L^-1, and it was subjected to ALP inhibitor screening from goji berry extract. These results indicated that the colorimetric system can be used as a simple tool for visual and fast evaluation of ALP activity as well as providing an alternative to screen ALP inhibitors.

Impaired Oligodendrocyte Development Following Preterm Birth: Promoting GABAergic Action to Improve Outcomes

Preterm birth is associated with poor long-term neurodevelopmental and behavioral outcomes, even in the absence of obvious brain injury at the time of birth. In particular, behavioral disorders characterized by inattention, social difficulties and anxiety are common among children and adolescents who were born moderately to late preterm (32-37 weeks' gestation). Diffuse deficits in white matter microstructure are thought to play a role in these poor outcomes with evidence suggesting that a failure of oligodendrocytes to mature and myelinate axons is responsible. However, there remains a major knowledge gap over the mechanisms by which preterm birth interrupts normal oligodendrocyte development. In utero neurodevelopment occurs in an inhibitory-dominant environment due to the action of placentally derived neurosteroids on the GABA_A receptor, thus promoting GABAergic inhibitory activity and maintaining the fetal behavioral state. Following preterm birth, and the subsequent premature exposure to the ex utero environment, this action of neurosteroids on GABA_A receptors is greatly reduced. Coinciding with a reduction in GABAergic inhibition, the preterm neonatal brain is also exposed to ex utero environmental insults such as periods of hypoxia and excessive glucocorticoid concentrations. Together, these insults may increase levels of the excitatory neurotransmitter glutamate in the developing brain and result in a shift in the balance of inhibitory: excitatory activity toward excitatory. This review will outline the normal development of oligodendrocytes, how it is disrupted under excitation-dominated conditions and highlight how shifting the balance back toward an inhibitory-dominated environment may improve outcomes.

Lipid Emulsion Improves Functional Recovery in an Animal Model of Stroke

Stroke is a life-threatening condition that leads to the death of many people around the world. Reperfusion injury after ischemic stroke is a recurrent problem associated with various surgical procedures that involve the removal of blockages in the brain arteries. Lipid emulsion was recently shown to attenuate ischemic reperfusion injury in the heart and to protect the brain from excitotoxicity. However, investigations on the protective mechanisms of lipid emulsion against ischemia in the brain are still lacking. This study aimed to determine the neuroprotective effects of lipid emulsion in an in vivo rat model of ischemic reperfusion injury through middle cerebral artery occlusion (MCAO). Under sodium pentobarbital anesthesia, rats were subjected to MCAO surgery and were administered with lipid emulsion through intra-arterial injection during reperfusion. The experimental animals were assessed for neurological deficit wherein the brains were extracted at 24 h after reperfusion for triphenyltetrazolium chloride staining, immunoblotting and qPCR. Neuroprotection was found to be dosage-dependent and the rats treated with 20% lipid emulsion had significantly decreased infarction volumes and lower Bederson scores. Phosphorylation of Akt and glycogen synthase kinase 3-β (GSK3-β) were increased in the 20% lipid-emulsion treated group. The Wnt-associated signals showed a marked increase with a concomitant decrease in signals of inflammatory markers in the group treated with 20% lipid emulsion. The protective effects of lipid emulsion and survival-related expression of genes such as Akt, GSK-3β, Wnt1 and β-catenin were reversed by the intra-peritoneal administration of XAV939 through the inhibition of the Wnt/β-catenin signaling pathway. These results suggest that lipid emulsion has neuroprotective effects against ischemic reperfusion injury in the brain through the modulation of the Wnt signaling pathway and may provide potential insights for the development of therapeutic targets.

Neuroprotective Effect of Antioxidants in the Brain

The brain is vulnerable to excessive oxidative insults because of its abundant lipid content, high energy requirements, and weak antioxidant capacity. Reactive oxygen species (ROS) increase susceptibility to neuronal damage and functional deficits, via oxidative changes in the brain in neurodegenerative diseases. Overabundance and abnormal levels of ROS and/or overload of metals are regulated by cellular defense mechanisms, intracellular signaling, and physiological functions of antioxidants in the brain. Single and/or complex antioxidant compounds targeting oxidative stress, redox metals, and neuronal cell death have been evaluated in multiple preclinical and clinical trials as a complementary therapeutic strategy for combating oxidative stress associated with neurodegenerative diseases. Herein, we present a general analysis and overview of various antioxidants and suggest potential courses of antioxidant treatments for the neuroprotection of the brain from oxidative injury. This review focuses on enzymatic and non-enzymatic antioxidant mechanisms in the brain and examines the relative advantages and methodological concerns when assessing antioxidant compounds for the treatment of neurodegenerative disorders.

Neuroprotection from Excitotoxic Injury by Local Administration of Lipid Emulsion into the Brain of Rats

Lipid emulsion was recently shown to attenuate cell death caused by excitotoxic conditions in the heart. There are key similarities between neurons and cardiomyocytes, such as excitability and conductibility, which yield vulnerability to excitotoxic conditions. However, systematic investigations on the protective effects of lipid emulsion in the central nervous system are still lacking. This study aimed to determine the neuroprotective effects of lipid emulsion in an in vivo rat model of kainic acid-induced excitotoxicity through intrahippocampal microinjections. Kainic acid and/or lipid emulsion-injected rats were subjected to the passive avoidance test and elevated plus maze for behavioral assessment. Rats were sacrificed at 24 h and 72 h after kainic acid injections for molecular study, including immunoblotting and qPCR. Brains were also cryosectioned for morphological analysis through cresyl violet staining and Fluorojade-C staining. Anxiety and memory functions were significantly preserved in 1% lipid emulsion-treated rats. Lipid emulsion was dose-dependent on the protein expression of β-catenin and the phosphorylation of GSK3-β and Akt. Wnt1 mRNA expression was elevated in lipid emulsion-treated rats compared to the vehicle. Neurodegeneration was significantly reduced mainly in the CA1 region with increased cell survival. Our results suggest that lipid emulsion has neuroprotective effects against excitotoxic conditions in the brain and may provide new insight into its potential therapeutic utility.