Heme oxygenase-1 in Alzheimer disease: a tribute to Moussa Youdim

Detrimental Roles of Hypoxia-Inducible Factor-1α in Severe Hypoxic Brain Diseases

Hypoxia stabilizes hypoxia-inducible factors (HIFs), facilitating adaptation to hypoxic conditions. Appropriate hypoxia is pivotal for neurovascular regeneration and immune cell mobilization. However, in central nervous system (CNS) injury, prolonged and severe hypoxia harms the brain by triggering neurovascular inflammation, oxidative stress, glial activation, vascular damage, mitochondrial dysfunction, and cell death. Diminished hypoxia in the brain improves cognitive function in individuals with CNS injuries. This review discusses the current evidence regarding the contribution of severe hypoxia to CNS injuries, with an emphasis on HIF-1α-mediated pathways. During severe hypoxia in the CNS, HIF-1α facilitates inflammasome formation, mitochondrial dysfunction, and cell death. This review presents the molecular mechanisms by which HIF-1α is involved in the pathogenesis of CNS injuries, such as stroke, traumatic brain injury, and Alzheimer's disease. Deciphering the molecular mechanisms of HIF-1α will contribute to the development of therapeutic strategies for severe hypoxic brain diseases.

Pericyte Control of Gene Expression in the Blood-Brain Barrier Endothelium: Implications for Alzheimer's Disease

Background

A strong body of evidence suggests that cerebrovascular pathologies augment the onset and progression of Alzheimer's disease (AD). One distinctive aspect of this cerebrovascular dysfunction is the degeneration of brain pericytes-often overlooked supporting cells of blood-brain barrier endothelium.

Objective

The current study investigates the influence of pericytes on gene and protein expressions in the blood-brain barrier endothelium, which is expected to facilitate the identification of pathophysiological pathways that are triggered by pericyte loss and lead to blood-brain barrier dysfunction in AD.

Methods

Bioinformatics analysis was conducted on the RNA-Seq expression counts matrix (GSE144474), which compared solo-cultured human blood-brain barrier endothelial cells against endothelial cells co-cultured with human brain pericytes in a non-contact model. We constructed a similar cell culture model to verify protein expression using western blots.

Results

The insulin resistance and ferroptosis pathways were found to be enriched. Western blots of the insulin receptor and heme oxygenase expressions were consistent with those observed in RNA-Seq data. Additionally, we observed more than 5-fold upregulation of several genes associated with neuroprotection, including insulin-like growth factor 2 and brain-derived neurotrophic factor.

Conclusions

Results suggest that pericyte influence on blood-brain barrier endothelial gene expression confers protection from insulin resistance, iron accumulation, oxidative stress, and amyloid deposition. Since these are conditions associated with AD pathophysiology, they imply mechanisms by which pericyte degeneration could contribute to disease progression.

Integrative metabolomics science in Alzheimer's disease: Relevance and future perspectives

Alzheimer's disease (AD) is determined by various pathophysiological mechanisms starting 10-25 years before the onset of clinical symptoms. As multiple functionally interconnected molecular/cellular pathways appear disrupted in AD, the exploitation of high-throughput unbiased omics sciences is critical to elucidating the precise pathogenesis of AD. Among different omics, metabolomics is a fast-growing discipline allowing for the simultaneous detection and quantification of hundreds/thousands of perturbed metabolites in tissues or biofluids, reproducing the fluctuations of multiple networks affected by a disease. Here, we seek to critically depict the main metabolomics methodologies with the aim of identifying new potential AD biomarkers and further elucidating AD pathophysiological mechanisms. From a systems biology perspective, as metabolic alterations can occur before the development of clinical signs, metabolomics - coupled with existing accessible biomarkers used for AD screening and diagnosis - can support early disease diagnosis and help develop individualized treatment plans. Presently, the majority of metabolomic analyses emphasized that lipid metabolism is the most consistently altered pathway in AD pathogenesis. The possibility that metabolomics may reveal crucial steps in AD pathogenesis is undermined by the difficulty in discriminating between the causal or epiphenomenal or compensatory nature of metabolic findings.

Neurodegenerative Proteinopathies Induced by Environmental Pollutants: Heat Shock Proteins and Proteasome as Promising Therapeutic Tools

Environmental pollutants' (EPs) amount and diversity have increased in recent years due to anthropogenic activity. Several neurodegenerative diseases (NDs) are theorized to be related to EPs, as their incidence has increased in a similar way to human EPs exposure and they reproduce the main ND hallmarks. EPs induce several neurotoxic effects, including accumulation and gradual deposition of misfolded toxic proteins, producing neuronal malfunction and cell death. Cells possess different mechanisms to eliminate these toxic proteins, including heat shock proteins (HSPs) and the proteasome system. The accumulation and deleterious effects of toxic proteins are induced through HSPs and disruption of proteasome proteins' homeostatic function by exposure to EPs. A therapeutic approach has been proposed to reduce accumulation of toxic proteins through treatment with recombinant HSPs/proteasome or the use of compounds that increase their expression or activity. Our aim is to review the current literature on NDs related to EP exposure and their relationship with the disruption of the proteasome system and HSPs, as well as to discuss the toxic effects of dysfunction of HSPs and proteasome and the contradictory effects described in the literature. Lastly, we cover the therapeutic use of developed drugs and recombinant proteasome/HSPs to eliminate toxic proteins and prevent/treat EP-induced neurodegeneration.

Dimethyl Fumarate as Potential Treatment for Alzheimer's Disease: Rationale and Clinical Trial Design

Alzheimer's Disease (AD) is a debilitating disease that leads to severe cognitive impairment and functional decline. The role of tau hyperphosphorylation and amyloid plaque deposition in the pathophysiology of AD has been well described; however, neuroinflammation and oxidative stress related to sustained microglial activation is thought to play a significant role in the disease process as well. NRF-2 has been identified in modulating the effects of inflammation and oxidative stress in AD. Activation of NRF-2 leads to an increased production of antioxidant enzymes, including heme oxygenase, which has been shown to have protective effects in neurodegenerative disorders such as AD. Dimethyl fumarate and diroximel fumarate (DMF) have been approved for the use in relapsing-remitting multiple sclerosis. Research indicates that they can modulate the effects of neuroinflammation and oxidative stress through the NRF-2 pathway, and as such, could serve as a potential therapeutic option in AD. We propose a clinical trial design that could be used to assess DMF as a treatment option for AD.

The Role of the Transcription Factor Nrf2 in Alzheimer’s Disease: Therapeutic Opportunities

Alzheimer’s disease (AD) is a common neurodegenerative disorder that affects the elderly. One of the key features of AD is the accumulation of reactive oxygen species (ROS), which leads to an overall increase in oxidative damage. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a master regulator of the antioxidant response in cells. Under low ROS levels, Nrf2 is kept in the cytoplasm. However, an increase in ROS production leads to a translocation of Nrf2 into the nucleus, where it activates the transcription of several genes involved in the cells’ antioxidant response. Additionally, Nrf2 activation increases autophagy function. However, in AD, the accumulation of Aβ and tau reduces Nrf2 levels, decreasing the antioxidant response. The reduced Nrf2 levels contribute to the further accumulation of Aβ and tau by impairing their autophagy-mediated turnover. In this review, we discuss the overwhelming evidence indicating that genetic or pharmacological activation of Nrf2 is as a potential approach to mitigate AD pathology.

Identification of repurposed drugs targeting significant long non-coding RNAs in the cross-talk between diabetes mellitus and Alzheimer's disease

The relationship between diabetes mellitus (DM) and Alzheimer's disease (AD) is so strong that scientists called it "brain diabetes". According to several studies, the critical factor in this relationship is brain insulin resistance. Due to the rapid global spread of both diseases, overcoming this cross-talk has a significant impact on societies. Long non-coding RNAs (lncRNAs), on the other hand, have a substantial impact on complex diseases due to their ability to influence gene expression via a variety of mechanisms. Consequently, the regulation of lncRNA expression in chronic diseases permits the development of innovative therapeutic techniques. However, developing a new drug requires considerable time and money. Recently repurposing existing drugs has gained popularity due to the use of low-risk compounds, which may result in cost and time savings. in this study, we identified drug repurposing candidates capable of controlling the expression of common lncRNAs in the cross-talk between DM and AD. We also utilized drugs that interfered with this cross-talk. To do this, high degree common lncRNAs were extracted from microRNA-lncRNA bipartite network. The drugs that interact with the specified lncRNAs were then collected from multiple data sources. These drugs, referred to as set D, were classified in to positive (D⁺) and negative (D^-) groups based on their effects on the expression of the interacting lncRNAs. A feature selection algorithm was used to select six important features for D. Using a random forest classifier, these features were capable of classifying D⁺ and D^- with an accuracy of 82.5%. Finally, the same six features were extracted for the most recently Food and Drug Administration (FDA) approved drugs in order to identify those with the highest likelihood of belonging to D⁺ or D^-. The most significant FDA-approved positive drugs, chromium nicotinate and tapentadol, were presented as repurposing candidates, while cefepime and dihydro-alpha-ergocryptine were recommended as significant adverse drugs. Moreover, two natural compounds, curcumin and quercetin, were recommended to prevent this cross-talk. According to the previous studies, less attention has been paid to the role of lncRNAs in this cross-talk. Our research not only did identify important lncRNAs, but it also suggested potential repurposed drugs to control them.

Protective Mechanisms of Nootropic Herb Shankhpushpi (Convolvulus pluricaulis) against Dementia: Network Pharmacology and Computational Approach

Convolvulus pluricaulis (CP), a Medhya Rasayana (nootropic) herb, is a major ingredient in Ayurvedic and Traditional Chinese formulae indicated for neurological conditions, namely, dementia, anxiety, depression, insanity, and epilepsy. Experimental evidence suggests various neuroactive potentials of CP such as memory-enhancing, neuroprotective, and antiepileptic. However, precise mechanisms underlying the neuropharmacological effects of CP remain unclear. The study, therefore, aimed at deciphering the molecular basis of neuroprotective effects of CP phytochemicals against the pathology of dementia disorders such as Alzheimer's (AD) and Parkinson's (PD) disease. The study exploited bioinformatics tools and resources, such as Cytoscape, DAVID (Database for annotation, visualization, and integrated discovery), NetworkAnalyst, and KEGG (Kyoto Encyclopedia of Genes and Genomes) database to investigate the interaction between CP compounds and molecular targets. An in silico analysis was also employed to screen druglike compounds and validate some selective interactions. ADME (absorption, distribution, metabolism, and excretion) analysis predicted a total of five druglike phytochemicals from CP constituents, namely, scopoletin, 4-hydroxycinnamic acid, kaempferol, quercetin, and ayapanin. In network analysis, these compounds were found to interact with some molecular targets such as prostaglandin G/H synthase 1 and 2 (PTGS1 and PTGS2), endothelial nitric oxide synthase (NOS3), insulin receptor (INSR), heme oxygenase 1 (HMOX1), acetylcholinesterase (ACHE), peroxisome proliferator-activated receptor-gamma (PPARG), and monoamine oxidase A and B (MAOA and MAOB) that are associated with neuronal growth, survival, and activity. Docking simulation further confirmed interaction patterns and binding affinity of selected CP compounds with those molecular targets. Notably, scopoletin showed the highest binding affinity with PTGS1, NOS3, PPARG, ACHE, MAOA, MAOB, and TRKB, quercetin with PTGS2, 4-hydroxycinnamic acid with INSR, and ayapanin with HMOX1. The findings indicate that scopoletin, kaempferol, quercetin, 4-hydroxycinnamic acid, and ayapanin are the main active constituents of CP which might account for its memory enhancement and neuroprotective effects and that target proteins such as PTGS1, PTGS2, NOS3, PPARG, ACHE, MAOA, MAOB, INSR, HMOX1, and TRKB could be druggable targets against dementia.

Histological alterations, oxidative stress, and inflammatory response in the liver of swamp eel (Monopterus albus) acutely exposed to copper

Copper (Cu) is widely used as an essential trace element in diets as well as a therapeutic chemical. However, excessive Cu has deleterious effects on organisms, including teleosts. Although numerous toxic effects of Cu have been reported, the effects of Cu exposure on the swamp eel (Monopterus albus) as well as the underlying mechanisms have not yet been elucidated. In this study, swamp eels were acutely exposed to 100, 200, and 400 μg/L of Cu for 96 h to evaluate liver histopathology, oxidative stress, and inflammation. Dissolution of hepatocyte membrane, vacuolar degeneration, and inflammatory cell infiltration were detected in the livers of the Cu-treated swamp eels, especially in the 400 μg Cu/L group. Cu-induced hepatic dysfunction was further verified by the elevated activities of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) and transcript levels of GOT and GPT genes. In addition, Cu exposure decreased the activities of total superoxide dismutase T-SOD and catalase (CAT) and the contents of glutathione (GSH) and total antioxidant capacity (T-AOC) and increased the levels of malondialdehyde (MDA). Cu exposure also significantly decreased the transcript levels of glutathione synthetase (GSS) and increased the transcript levels of SOD1, SOD2, CAT, and heme oxygenase-1 (HO-1) genes. Furthermore, pro-inflammatory genes such as interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), and IL-8 were significantly upregulated. These results indicate that Cu induces oxidative stress and inflammatory response and causes pathological changes in the liver of the swamp eel.

Relationship between Brain Tissue Changes and Blood Biomarkers of Cyclophilin A, Heme Oxygenase-1, and Inositol-Requiring Enzyme 1 in Patients with Alzheimer's Disease

Cyclophilin A (CypA), heme oxygenase-1 (HO-1), and inositol-requiring enzyme 1 (IRE1) are believed to be associated with Alzheimer's disease (AD). In this study, we investigated the association between gray matter volume (GMV) changes and blood levels of CypA, HO-1, and IRE1 in cognitively normal (CN) subjects and those with amnestic mild cognitive impairment (aMCI) and AD. Forty-five elderly CN, 34 aMCI, and 39 AD subjects were enrolled in this study. The results of voxel-based multiple regression analysis showed that blood levels of CypA, HO-1, and IRE1 were correlated with GMV on brain magnetic resonance imaging (MRI) in the entire population (p = 0.0005). The three serum protein levels were correlated with GMV of signature AD regions in the population as a whole. CypA values increased with increasing GMV in the occipital gyrus (r = 0.387, p < 0.0001) and posterior cingulate (r = 0.196, p = 0.034). HO-1 values increased with increasing GMV at the uncus (r = 0.307, p = 0.0008), lateral globus pallidus and putamen (r = 0.287, p = 0.002), and hippocampus (r = 0.197, p = 0.034). IRE1 values decreased with increasing GMV at the uncus (r = -0.239, p = 0.010) and lateral globus pallidus and putamen (r = -0.335, p = 0.0002). Associations between the three serum protein levels and regional GMV indicate that the blood levels of these biomarkers may reflect the pathological mechanism of AD in the brain.

An Analysis of the Neurological and Molecular Alterations Underlying the Pathogenesis of Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by amyloid beta (Aβ) plaques, neurofibrillary tangles, and neuronal loss. Unfortunately, despite decades of studies being performed on these histological alterations, there is no effective treatment or cure for AD. Identifying the molecular characteristics of the disease is imperative to understanding the pathogenesis of AD. Furthermore, uncovering the key causative alterations of AD can be valuable in developing models for AD treatment. Several alterations have been implicated in driving this disease, including blood–brain barrier dysfunction, hypoxia, mitochondrial dysfunction, oxidative stress, glucose hypometabolism, and altered heme homeostasis. Although these alterations have all been associated with the progression of AD, the root cause of AD has not been identified. Intriguingly, recent studies have pinpointed dysfunctional heme metabolism as a culprit of the development of AD. Heme has been shown to be central in neuronal function, mitochondrial respiration, and oxidative stress. Therefore, dysregulation of heme homeostasis may play a pivotal role in the manifestation of AD and its various alterations. This review will discuss the most common neurological and molecular alterations associated with AD and point out the critical role heme plays in the development of this disease.

The Neuroprotective and Neurodegeneration Effects of Heme Oxygenase-1 in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by complex pathological and biological features. Notably, extracellular amyloid-β deposits as senile plaques and intracellular aggregation of hyperphosphorylated tau as neurofibrillary tangles remain the primary premortem criterion for the diagnosis of AD. Currently, there exist no disease-modifying therapies for AD, and many clinical trials have failed to show its benefits for patients. Heme oxygenase 1 (HO-1) is a 32 kDa enzyme, which catalyzes the degradation of cellular heme to free ferrous iron, biliverdin, and carbon monoxide under stressful conditions. Several studies highlight the crucial pathological roles of HO-1 in the molecular processes of AD. The beneficial roles of HO-1 overexpression in AD brains are widely accepted due to its ability to convert pro-oxidant heme to biliverdin and bilirubin (antioxidants), which promote restoration of a suitable tissue redox microenvironment. However, the intracellular oxidative stress might be amplified by metabolites of HO-1 and exacerbate the progression of AD under certain circumstances. Several lines of evidence have demonstrated that upregulated HO-1 is linked to tauopathies, neuronal damage, and synapse aberrations in AD. Here, we review the aspects of the molecular mechanisms by which HO-1 regulates AD and the latest information on the pathobiology of AD. We further highlight the neuroprotective and neurodystrophic actions of HO-1 and the feasibility of HO-1 as a therapeutic target for AD.

Identification of heme oxygenase-1 from golden pompano (Trachinotus ovatus) and response of Nrf2/HO-1 signaling pathway to copper-induced oxidative stress

Heme oxygenase-1(HO-1) is a stress-inducible enzyme that mediates antioxidative and cytoprotective effects to maintain cellular redox homeostasis. In the present study, the full sequence of HO-1 was cloned from golden pompano(Trachinotus ovatus) by RT-PCR and RACE-PCR. The full cDNA sequence of HO-1 was 1349 bp in length which comprised of a 726 bp open reading frame (ORF) preceded by 262 bp 5'-untranslated region (UTR), and followed by a 360 bp 3'UTR, encoding 241 amino acid residues. Phylogenetic analysis revealed that HO-1 showed highest similarity to that of Takifugu rubripes. Tissue distribution analysis showed that the expression level of HO-1 was relatively high in heart, liver and spleen. A trial was conducted to investigate the response of Nrf2/HO-1 signaling pathway to oxidative stress induced by copper. The results showed that mRNA expression of NF-E2-related nuclear factor2 (Nrf2), Kelch-like-ECH-associated protein1 (keap1), superoxide dismutase (SOD), catalase (CAT), HO-1, NAD(P)H quinone oxidoreductase 1 (NQO1) and Glutathione peroxidase (GSH-PX) all significantly increased in copper treated group than that in the control group. This work provides new insight into the molecular mechanism underlying the Nrf2/HO-1 pathway in oxidative response in T. ovatus.

Neuroprotective Effects of Taraxacum officinale Wigg. Extract on Glutamate-Induced Oxidative Stress in HT22 Cells via HO-1/Nrf2 Pathways

Oxidative stress-mediated neuron damage is considered an important contributor to the pathogenesis and development of neurodegenerative diseases. Taraxacum officinale has been reported to possess antioxidant activities. However, whether it can protect neurons against oxidative damage and the underlying molecular mechanisms have not been fully determined. In the present study, we examined the neuroprotective effects of ethanol extracts of this plant (ETOW) on glutamate-induced oxidative stress in HT22 cells. Both cell viability and reactive oxygen species (ROS) assays showed that ETOW effectively attenuated glutamate-induced cytotoxicity and ROS generation. Furthermore, our results revealed that ETOW increased the expression of heme oxygenase-1 (HO-1) and promoted the nuclear translocation of nuclear factor erythroid 2-related factor-2 (Nrf2). The inhibitory effects of ETOW on glutamate-stimulated cell toxicity and ROS production were partially reversed by tin protoporphyrin (SnPP), an HO activity inhibitor. Taken together, these results demonstrate that ETOW can protect HT22 cells against glutamate-induced oxidative damage by inducing the Nrf2/HO-1 pathways. Our study supports the idea that Taraxacum officinale Wigg. is a promising agent for preventing neurodegenerative diseases.

Biometal Dyshomeostasis and Toxic Metal Accumulations in the Development of Alzheimer's Disease

Biometal dyshomeostasis and toxic metal accumulation are common features in many neurodegenerative disorders, including Alzheimer’s disease (AD), Parkinson’s disease, and Huntington’s disease. The neurotoxic effects of metal imbalance are generally associated with reduced enzymatic activities, elevated protein aggregation and oxidative stress in the central nervous system, in which a cascade of events lead to cell death and neurodegeneration. Although the links between biometal imbalance and neurodegenerative disorders remain elusive, a major class of endogenous proteins involved in metal transport has been receiving increasing attention over recent decades. The abnormal expression of these proteins has been linked to biometal imbalance and to the pathogenesis of AD. Here, we present a brief overview of the physiological roles of biometals including iron, zinc, copper, manganese, magnesium and calcium, and provide a detailed description of their transporters and their synergistic involvement in the development of AD. In addition, we also review the published data relating to neurotoxic metals in AD, including aluminum, lead, cadmium, and mercury.

Role of Gasotransmitters in Oxidative Stresses, Neuroinflammation, and Neuronal Repair

To date, three main gasotransmitters, that is, hydrogen sulfide (H₂S), carbon monoxide (CO), and nitric oxide (NO), have been discovered to play major bodily physiological roles. These gasotransmitters have multiple functional roles in the body including physiologic and pathologic functions with respect to the cellular or tissue quantities of these gases. Gasotransmitters were originally known to have only detrimental and noxious effects in the body but that notion has much changed with years; vast studies demonstrated that these gasotransmitters are precisely involved in the normal physiological functioning of the body. From neuromodulation, oxidative stress subjugation, and cardiovascular tone regulation to immunomodulation, these gases perform critical roles, which, should they deviate from the norm, can trigger the genesis of a number of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). The purpose of this review is to discuss at great length physical and chemical properties and physiological actions of H₂S, NO, and CO as well as shedding light on recently researched molecular targets. We particularly put emphasis on the roles in neuronal inflammation and neurodegeneration and neuronal repair.

Epalrestat Upregulates Heme Oxygenase-1, Superoxide Dismutase, and Catalase in Cells of the Nervous System

Heme oxygenase (HO)-1 has potent antioxidant and anti-inflammatory functions. Recent studies have shown that the upregulation of HO-1 is beneficial to counteract neuroinflammation, making HO-1 a new therapeutic target for neurological diseases. We have reported that epalrestat (EPS), which is currently used for the treatment of diabetic neuropathy, increases HO-1 levels through the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) in bovine aortic endothelial cells. In this study, we tested the hypothesis that EPS upregulates HO-1 via Nrf2 activation in the component cells of the nervous system, by using rat Schwann cells and human SH-SY5Y cells. Treatment of Schwann cells with EPS at near-plasma concentration led to a dramatic increase in HO-1 levels. Nrf2 knockdown by small interfering RNA (siRNA) suppressed the EPS-induced HO-1 expression. EPS did not promote the intracellular accumulation of free ferrous ion and reactive oxygen species, by increasing ferritin via Nrf2 during HO-1 induction. Moreover, EPS stimulated the expression of superoxide dismutase 1 and catalase, which also are Nrf2 target gene products. It also markedly increased HO-1 levels in SH-SY5Y cells through the activation of Nrf2. We demonstrated for the first time that EPS upregulates HO-1, superoxide dismutase, and catalase by activating Nrf2. We suggest that EPS has the potential to prevent several neurological diseases.

Drug discovery of neurodegenerative disease through network pharmacology approach in herbs

Neurodegenerative diseases, referring to as the progressive loss of structure and function of neurons, constitute one of the major challenges of modern medicine. Traditional Chinese herbs have been used as a major preventive and therapeutic strategy against disease for thousands years. The numerous species of medicinal herbs and Traditional Chinese Medicine (TCM) compound formulas in nervous system disease therapy make it a large chemical resource library for drug discovery. In this work, we collected 7362 kinds of herbs and 58,147 Traditional Chinese medicinal compounds (Tcmcs). The predicted active compounds in herbs have good oral bioavailability and central nervous system (CNS) permeability. The molecular docking and network analysis were employed to analyze the effects of herbs on neurodegenerative diseases. In order to evaluate the predicted efficacy of herbs, automated text mining was utilized to exhaustively search in PubMed by some related keywords. After that, receiver operator characteristic (ROC) curves was used to estimate the accuracy of predictions. Our study suggested that most herbs were distributed in family of Asteraceae, Fabaceae, Lamiaceae and Apocynaceae. The predictive model yielded good sensitivity and specificity with the AUC values above 0.800. At last, 504 kinds of herbs were obtained by using the optimal cutoff values in ROC curves. These 504 herbs would be the most potential herb resources for neurodegenerative diseases treatment. This study would give us an opportunity to use these herbs as a chemical resource library for drug discovery of anti-neurodegenerative disease.

Hemin protects against hippocampal damage following orthotopic autologous liver transplantation in adult rats

AIMS

Induction of heme oxygenase-1 (HO-1) has been widely accepted to be neuro-protective. This study aimed to examine whether hemin (a HO-1 inducer) attenuates neuronal damage in the hippocampus induced by orthotopic autologous liver transplantation (OALT) in adult rats.

MAIN METHODS

Rats were randomly allocated into four groups (n=8 each): (i) Sham control group; (ii) OALT model group; (iii) Hemin+OALT group, with intra-peritoneal (i.p.) injection of hemin (5 mg/kg) 24 hours (h) before the OALT; and (iv) ZnPP (a HO-1 inhibitor)+OALT group, with i.p. injection of ZnPP (32 mg/kg) 24h before the OALT. Twenty four hours after the surgery, the hippocampal tissues were collected for electron microscopic examination and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) analysis. The levels of hippocampal HO-1 protein and serum S-100β, the concentrations of regional tumor necrosis factor-α (TNF-α) and interleukins (IL-6, IL-10), as well as the status of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) in the hippocampus were assessed.

KEY FINDINGS

Rats suffered severe neuronal damage in the hippocampus after OALT, mainly in apoptosis. Pre-treatment with hemin obviously alleviated the damage; up-regulated the HO-1 protein level; inhibited the release of TNF-α, IL-6 and MDA; and promoted the activities of SOD, CAT and IL-10; however, pre-treatment with ZnPP did not exhibit the opposite effect, except that a marked increase in serum S-100β level was detected.

SIGNIFICANCE

Hemin up-regulated the expression of HO-1 and attenuated hippocampal neuronal damage induced by OALT.

Insulin resistance in Alzheimer disease: Is heme oxygenase-1 an Achille's heel?

Insulin resistance, clinically defined as the inability of insulin to increase glucose uptake and utilization, has been found to be associated with the progression of Alzheimer disease (AD). Indeed, postmortem AD brain shows all the signs of insulin resistance including: (i) reduced brain insulin receptor (IR) sensitivity, (ii) hypophosphorylation of the insulin receptor and downstream second messengers such as IRS-1, and (iii) attenuated insulin and insulin growth factor (IGF)-1 receptor expression. However, the exact mechanisms driving insulin resistance have not been completely elucidated. Quite recently, the levels of the peripheral inducible isoform of heme oxygenase (HO-1), a well-known protein up-regulated during cell stress response, were proposed to be among the strongest positive predictors of metabolic disease, including insulin resistance. Because our group previously reported on levels, activation state and oxidative stress-induced post-translational modifications of HO-1 in AD brain and our ongoing studies to better elucidate the role of HO-1 in insulin resistance-associated AD pathology, the aim of this review is to provide reader with a critical analysis on new aspects of the interplay between HO-1 and insulin resistance and on how the available lines of evidence could be useful for further comprehension of processes in AD brain.

Oxidative modulation of K+ channels in the central nervous system in neurodegenerative diseases and aging

SIGNIFICANCE

Oxidative stress and damage are well-established components of neurodegenerative diseases, contributing to neuronal death during disease progression. Here, we consider key K(+) channels as target proteins that can undergo oxidative modulation, describe what is understood about how this influences disease progression, and consider regulation of these channels by gasotransmitters as a means of cellular protection.

RECENT ADVANCES

Oxidative regulation of the delayed rectifier Kv2.1 and the Ca(2+)- and voltage-sensitive BK channel are established, but recent studies contest how their redox sensitivity contributes to altered excitability, progression of neurodegenerative diseases, and healthy aging.

CRITICAL ISSUES

Both Kv2.1 and BK channels have recently been established as target proteins for regulation by the gasotransmitters carbon monoxide and hydrogen sulfide. Establishing the molecular basis of such regulation, and exactly how this influences excitability and vulnerability to apoptotic cell death will determine whether such regulation can be exploited for therapeutic benefit.

FUTURE DIRECTIONS

Developing a more comprehensive picture of the oxidative modulation of K(+) channels (and, indeed, other ion channels) within the central nervous system in health and disease will enable us to better understand processes associated with healthy aging as well as distinct processes underlying progression of neurodegenerative diseases. Advances in the growing understanding of how gasotransmitters can regulate ion channels, including redox-sensitive K(+) channels, are a research priority for this field, and will establish their usefulness in design of future approaches for the treatment of such diseases.

Heat shock proteins in neurodegenerative disorders and aging

Many members of the heat shock protein family act in unison to refold or degrade misfolded proteins. Some heat shock proteins also directly interfere with apoptosis. These homeostatic functions are especially important in proteinopathic neurodegenerative diseases, in which specific proteins misfold, aggregate, and kill cells through proteotoxic stress. Heat shock protein levels may be increased or decreased in these disorders, with the direction of the response depending on the individual heat shock protein, the disease, cell type, and brain region. Aging is also associated with an accrual of proteotoxic stress and modulates expression of several heat shock proteins. We speculate that the increase in some heat shock proteins in neurodegenerative conditions may be partly responsible for the slow progression of these disorders, whereas the increase in some heat shock proteins with aging may help delay senescence. The protective nature of many heat shock proteins in experimental models of neurodegeneration supports these hypotheses. Furthermore, some heat shock proteins appear to be expressed at higher levels in longer-lived species. However, increases in heat shock proteins may be insufficient to override overwhelming proteotoxic stress or reverse the course of these conditions, because the expression of several other heat shock proteins and endogenous defense systems is lowered. In this review we describe a number of stress-induced changes in heat shock proteins as a function of age and neurodegenerative pathology, with an emphasis on the heat shock protein 70 (Hsp70) family and the two most common proteinopathic disorders of the brain, Alzheimer's and Parkinson's disease.

The balance mediated by miRNAs and the heme oxygenase 1 feedback loop contributes to biological effects

Heme oxygenase-1 (HMOX1) is a ubiquitously expressed inducible enzyme that degrades heme to carbon monoxide, biliverdin, and free iron ions. Since 1950, many studies have revealed the role of HMOX1 in reducing the impact of oxidative stress in many types of diseases, such as Alzheimer's disease, heart disease, and the development of tumors. These effects arise as a result of the removal of heme, the biological activities of the products of HMOX1 and the activity of HMOX1 itself. However, HMOX1 has some contradictory effects. The discovery of microRNAs (miRNAs) and their relationship with HMOX1 has provided a new direction for research in this field. Here, we discuss the role of a potential regulatory feedback loop between HMOX1 and miRNAs in pathological processes based on recently published data. We hope to describe a new mechanism for HMOX1 function based on miRNAs to address the contradictory results reported in the literature.

Impact of aging on heat shock protein expression in the substantia nigra and striatum of the female rat

Many heat shock proteins are chaperones that help refold or degrade misfolded proteins and battle apoptosis. Because of their capacity to protect against protein misfolding, they may help keep diseases of aging at bay. A few reports have examined heat shock proteins (eg. Hsp25, Hsp60, Hsp70, and heat shock cognate 70 or Hsc70) as a function of age in the striatum and nigra. In the present study, we examined the impact of aging on Hsp25, heme oxygenase 1 (HO1 or Hsp32), Hsp40, Hsp60, Hsc70, Hsc/Hsp70 interacting protein (Hip), 78 kDa glucose-regulated protein (GRP78), Hsp90, and ubiquitinated proteins in the nigra and striatum of the female rat by infrared immunoblotting. Female animals are not typically examined in aging studies, adding further to the novelty of our study. Striatal HO1 and Hsp40 were both higher in middle-aged females than in the oldest group. Hsp60 levels were also highest in middle age in the nigra, but were highest in the oldest animals in the striatum. Striatal levels of Hsc70 and the co-chaperone Hip were lower in the oldest group relative to the youngest animals. In contrast, Hsp25 rose with advancing age in both regions. Hsp25 was also colocalized with tyrosine hydroxylase in nigral neurons. Ubiquitinated proteins exhibited a trend to rise in the oldest animals in both regions, and K48 linkage-specific ubiquitin rose significantly from 4-6 to 16-19 months in the striatum. Our study reveals a complex array of age-related changes in heat shock proteins. Furthermore, the age-related rises in some proteins, such as Hsp25, may reflect endogenous adaptations to cellular stress.

Heme, an essential nutrient from dietary proteins, critically impacts diverse physiological and pathological processes

Heme constitutes 95% of functional iron in the human body, as well as two-thirds of the average person’s iron intake in developed countries. Hence, a wide range of epidemiological studies have focused on examining the association of dietary heme intake, mainly from red meat, with the risks of common diseases. High heme intake is associated with increased risk of several cancers, including colorectal cancer, pancreatic cancer and lung cancer. Likewise, the evidence for increased risks of type-2 diabetes and coronary heart disease associated with high heme intake is compelling. Furthermore, recent comparative metabolic and molecular studies of lung cancer cells showed that cancer cells require increased intracellular heme biosynthesis and uptake to meet the increased demand for oxygen-utilizing hemoproteins. Increased levels of hemoproteins in turn lead to intensified oxygen consumption and cellular energy generation, thereby fueling cancer cell progression. Together, both epidemiological and molecular studies support the idea that heme positively impacts cancer progression. However, it is also worth noting that heme deficiency can cause serious diseases in humans, such as anemia, porphyrias, and Alzheimer’s disease. This review attempts to summarize the latest literature in understanding the role of dietary heme intake and heme function in diverse diseases.

Statins more than cholesterol lowering agents in Alzheimer disease: their pleiotropic functions as potential therapeutic targets

Alzheimer disease (AD) is a progressive neurodegenerative disorder characterized by severe cognitive impairment, inability to perform activities of daily living and mood changes. Statins, long known to be beneficial in conditions where dyslipidemia occurs by lowering serum cholesterol levels, also have been proposed for use in neurodegenerative conditions, including AD. However, it is not clear that the purported effectiveness of statins in neurodegenerative disorders is directly related to cholesterol-lowering effects of these agents; rather, the pleiotropic functions of statins likely play critical roles. The aim of this review is to provide an overview on the new discoveries about the effects of statin therapy on the oxidative and nitrosative stress levels as well as on the modulation of the heme oxygenase/biliverdin reductase (HO/BVR) system in the brain. We propose a novel mechanism of action for atorvastatin which, through the activation of HO/BVR-A system, may contribute to the neuroprotective effects thus suggesting a potential therapeutic role in AD and potentially accounting for the observation of decreased AD incidence with persons on statin.

The Janus face of the heme oxygenase/biliverdin reductase system in Alzheimer disease: it's time for reconciliation

Alzheimer disease (AD) is the most common form of dementia among the elderly and is characterized by progressive loss of memory and cognition. These clinical features are due in part to the increase of reactive oxygen and nitrogen species that mediate neurotoxic effects. The up-regulation of the heme oxygenase-1/biliverdin reductase-A (HO-1/BVR-A) system is one of the earlier events in the adaptive response to stress. HO-1/BVR-A reduces the intracellular levels of pro-oxidant heme and generates equimolar amounts of the free radical scavengers biliverdin-IX alpha (BV)/bilirubin-IX alpha (BR) as well as the pleiotropic gaseous neuromodulator carbon monoxide (CO) and ferrous iron. Two main and opposite hypotheses for a role of the HO-1/BVR-A system in AD propose that this system mediates neurotoxic and neuroprotective effects, respectively. This apparent controversy was mainly due to the fact that for over about 20years HO-1 was the only player on which all the analyses were focused, excluding the other important and essential component of the entire system, BVR. Following studies from the Butterfield laboratory that reported alterations in BVR activity along with decreased phosphorylation and increased oxidative/nitrosative post-translational modifications in the brain of subjects with AD and amnestic mild cognitive impairment (MCI) subjects, a debate was opened on the real pathophysiological and clinical significance of BVR-A. In this paper we provide a review of the main discoveries about the HO/BVR system in AD and MCI, and propose a mechanism that reconciles these two hypotheses noted above of neurotoxic and the neuroprotective aspects of this important stress responsive system.

Protective effect of curcuminoids on age-related mitochondrial impairment in female Wistar rat brain

The present study demonstrated the neuroprotective effect of curcuminoids, the active polyphenols of Curcuma longa (L.) rhizomes on mitochondrial dysfunctioning in middle aged and aged female Wistar rat brain. Rats were orally treated with curcuminoids (100 mg/kg) for 3 months and their brain was collected for evaluation of mitochondrial enzymes and complexes activity, ultra structural changes in mitochondria, neuronal nitric oxide synthase (nNOS) protein expression, adenosine triphosphate (ATP) and lipofuscin content. Significant alterations were observed in all the tested parameters in highly aged rat brain when compared with young control. Long term curcuminoids administration prevented this age associated loss of mitochondrial enzymes and complexes activity in middle aged rat brain except for malate dehydrogenase, Complex II and IV activity when compared with young control. Among aged rats, curcuminoids treatment specifically elevated isocitrate and NADH dehydrogenase, cytochrome c oxidase, Complex I and total ATP content. A significant down-regulation of nNOS protein expression along with reduced lipofuscin content was also observed in curucminoids treated middle aged and aged rats. Thus, it was suggested that curcuminoids may act as a putative drug candidate for the prevention of deleterious effects of ageing and age associated neurodegenerative disorders through amelioration of aberrant mitochondrial functioning.

Mitochondria-targeted heme oxygenase-1 induces oxidative stress and mitochondrial dysfunction in macrophages, kidney fibroblasts and in chronic alcohol hepatotoxicity

The inducible form of Heme Oxygenase-1 (HO-1), a major endoplasmic reticulum (ER) associated heme protein, is known to play important roles in protection against oxidative and chemical stress by degrading free heme released from degradation of heme proteins. In this study we show that induced expression of HO-1 by subjecting macrophage RAW-264.7 cells to chemical or physiological hypoxia resulted in significant translocation of HO-1 protein to mitochondria. Transient transfection of COS-7 cells with cloned cDNA also resulted in mitochondrial translocation of HO-1. Deletion of N-terminal ER targeting domain increased mitochondrial translocation under the transient transfection conditions. Mitochondrial localization of both intact HO-1 and N-terminal truncated HO-1 caused loss of heme aa-3 and cytochrome c oxidase (CcO) activity in COS-7 cells. The truncated protein, which localizes to mitochondria at higher levels, induced substantially steeper loss of CcO activity and reduced heme aa3 content. Furthermore, cells expressing mitochondria targeted HO-1 also induced higher ROS production. Consistent with dysfunctional state of mitochondria induced by HO-1, the mitochondrial recruitment of autophagy markers LC-3 and Drp-1 was also increased in these cells. Chronic ethanol feeding in rats also caused an increase in mitochondrial HO-1 and decrease in CcO activity. These results show that as opposed to the protective effect of the ER associated HO-1, mitochondria targeted HO-1 under normoxic conditions induces mitochondrial dysfunction.

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Under hypoxia, the inducible Heme Oxygenase-1 (HO-1) is localized in mitochondria.

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N-terminal truncated HO-1 is more efficiently translocated to mitochondria.

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Mitochondria targeted HO-1 induces oxidative stress and CcO dysfunction.

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Mitochondrial HO-1 content is increased in alcohol treated rat livers.

Stress responses, vitagenes and hormesis as critical determinants in aging and longevity: Mitochondria as a "chi"

Understanding mechanisms of aging and determinants of life span will help to reduce age-related morbidity and facilitate healthy aging. Average lifespan has increased over the last centuries, as a consequence of medical and environmental factors, but maximal life span remains unchanged. Extension of maximal life span is currently possible in animal models with measures such as genetic manipulations and caloric restriction (CR). CR appears to prolong life by reducing reactive oxygen species (ROS)-mediated oxidative damage. But ROS formation, which is positively implicated in cellular stress response mechanisms, is a highly regulated process controlled by a complex network of intracellular signaling pathways. By sensing the intracellular nutrient and energy status, the functional state of mitochondria, and the concentration of ROS produced in mitochondria, the longevity network regulates life span across species by coordinating information flow along its convergent, divergent and multiply branched signaling pathways, including vitagenes which are genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. The hormetic dose-response, challenges long-standing beliefs about the nature of the dose-response in a lowdose zone, having the potential to affect significantly the design of pre-clinical studies and clinical trials as well as strategies for optimal patient dosing in the treatment of numerous diseases. Given the broad cytoprotective properties of the heat shock response there is now strong interest in discovering and developing pharmacological agents capable of inducing stress responses. Here we focus on possible signaling mechanisms involved in the activation of vitagenes resulting in enhanced defense against energy and stress resistance homeostasis dysiruption with consequent impact on longevity processes.

Oxidative stress is related to the deleterious effects of heme oxygenase-1 in an in vivo neuroinflammatory rat model

Heme oxygenase-1 (HO-1) induction is associated with beneficial or deleterious effects depending on the experimental conditions adopted and the neurodegenerative rodent models used. The present study aimed first to evaluate the effects of cerebral HO-1 induction in an in vivo rat model of neuroinflammation by intrastriatal injection of quinolinic acid (QA) and secondly to explore the role played by reactive oxygen species (ROS) and free iron (Fe²⁺) derived from heme catabolism promoted by HO-1. Chronic I.P. treatment with the HO-1 inductor and substrate hemin was responsible for a significant dose-related increase of cerebral HO-1 production. Brain tissue loss, microglial activation, and neuronal death were significantly higher in rats receiving QA plus hemin (H-QA) versus QA and controls. Significant increase of ROS production in H-QA rat brain was inhibited by the specific HO-1 inhibitor ZnPP which supports the idea that ROS level augmentation in hemin-treated animals is a direct consequence of HO-1 induction. The cerebral tissue loss and ROS level in hemin-treated rats receiving the iron chelator deferoxamine were significantly decreased, demonstrating the involvement of Fe²⁺in brain ROS production. Therefore, the deleterious effects of HO-1 expression in this in vivo neuroinflammatory model were linked to a hyperproduction of ROS, itself promoted by free iron liberation.

Hypoxia induces angiogenic factors in brain microvascular endothelial cells

Hypoxia is increasingly recognized as an important contributing factor to the development of brain diseases such as Alzheimer's disease (AD). In the periphery, hypoxia is a powerful regulator of angiogenesis. However, vascular endothelial cells are remarkably heterogeneous and little is known about how brain endothelial cells respond to hypoxic challenge. The objective of this study is to characterize the effect of hypoxic challenge on the angiogenic response of cultured brain-derived microvascular endothelial cells. Brain endothelial cell cultures were initiated from isolated rat brain microvessels and subjected to hypoxia (1% O(2)) for various time periods. The results showed that hypoxia induced rapid (≤ 0.5h) expression of hypoxia-inducible factor 1α (HIF-1α) and that cell viability, assessed by MTT assay, was unaffected within the first 8h. Examination of brain endothelial cell cultures for pro- and anti-angiogenic proteins by western blot, RT-PCR and ELISA revealed that within 0.5 to 2h of hypoxia levels of vascular endothelial growth factor and endothelin-1 mRNA and protein were elevated. The expression of heme oxygenase-1 also increased but only after 8h of hypoxia. In contrast, similar hypoxia exposure evoked a decrease in endothelial nitric oxide synthase and thrombospondin-2 levels. Exposure of brain endothelial cell cultures to hypoxia resulted in a significant (p<0.001) decrease (94%) in tube length, an in vitro index of angiogenesis, compared to control cultures. The data indicate that, despite a shift toward a pro-angiogenic phenotype, hypoxia inhibited vessel formation in brain endothelial cells. These results suggest that in brain endothelial cells expression of angiogenic factors is not sufficient for the development of new vessels. Further work is needed to determine what factors/conditions prevent hypoxia-induced angiogenic changes from culminating in the formation of new brain blood vessels and what role this may play in the pathologic changes observed in AD and other diseases characterized by cerebral hypoxia.

Resveratrol protects rats from Aβ-induced neurotoxicity by the reduction of iNOS expression and lipid peroxidation

Alzheimer disease (AD) is an age-dependent neurodegenerative disease characterized by the formation of β–amyloid (Aβ)-containing senile plaque. The disease could be induced by the administration of Aβ peptide, which was also known to upregulate inducible nitric oxide synthase (iNOS) and stimulate neuronal apoptosis. The present study is aimed to elucidate the cellular effect of resveratrol, a natural phytoestrogen with neuroprotective activities, on Aβ-induced hippocampal neuron loss and memory impairment. On adult Sprague-Dawley rats, we found the injection of Aβ could result in a significant impairment in spatial memory, a marked increase in the cellular level of iNOS and lipid peroxidation, and an apparent decrease in the expression of heme oxygenase-1 (HO-1). By combining the treatment with Aβ, resveratrol was able to confer a significant improvement in spatial memory, and protect animals from Aβ-induced neurotoxicity. These neurological protection effects of resveratrol were associated with a reduction in the cellular levels of iNOS and lipid peroxidation and an increase in the production of HO-1. Moreover, the similar neurological and cellular response were also observed when Aβ treatment was combined with the administration of a NOS inhibitor, N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME). These findings strongly implicate that iNOS is involved in the Aβ-induced lipid peroxidation and HO-1 downregulation, and resveratrol protects animals from Aβ-induced neurotoxicity by suppressing iNOS production.

A polymorphism located at an ATG transcription start site of the heme oxygenase-2 gene is associated with classical Parkinson's disease

AIM

Oxidative stress and iron deposition is related to Parkinson's disease (PD). Heme oxygenase 2 (HMOX2) catalyzes the cleavage of the heme ring to form biliverdin with release of iron and carbon monoxide. This study aims to analyze variations in the HMOX2 gene in patients with PD.

MATERIALS AND METHODS

We mapped four single nucleotide polymorphisms (SNPs) and copy number variations of the HMOX2 gene in 691 patients with PD and 747 healthy individuals.

RESULTS

We identified a highly homogeneous association of the HMOX2 SNP rs2270363 homozygous G/G genotype with patients with classical PD phenotype compared with healthy individuals. We identified three patients with PD and two control individuals with a single copy of the HMOX2 gene. No individuals with zero or more than two gene copies were identified.

CONCLUSION

We describe for the first time, copy number variations in the HMOX2 gene and an association of the SNP rs2270363 with PD risk.

Ferulic acid ethyl ester as a potential therapy in neurodegenerative disorders

Oxidative stress is involved in the onset, progression and pathogenesis of a number of diseases including neurodegenerative diseases. It is critical to develop a pharmacological approach to combat oxidative stress which may reduce the risk of diseases and help in promoting healthy life. In an attempt to reduce the side effects associated with allopathic medicines a number of studies are now focusing on developing treatment regimens from naturally occurring plant products. In this review, the protective role of ferulic acid (4-hydroxy-3-methoxycinnamic acid) (FA), a naturally occurring antioxidant compound found in fruit, some vegetables, and grains, and its ethyl ester derivative are discussed with respect to neurodegeneration. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Hormesis, cellular stress response and vitagenes as critical determinants in aging and longevity

Understanding mechanisms of aging and determinants of life span will help to reduce age-related morbidity and facilitate healthy aging. Average lifespan has increased over the last centuries, as a consequence of medical and environmental factors, but maximal life span remains unchanged. Extension of maximal life span is currently possible in animal models with measures such as genetic manipulations and caloric restriction (CR). CR appears to prolong life by reducing reactive oxygen species (ROS)-mediated oxidative damage. But ROS formation, which is positively implicated in cellular stress response mechanisms, is a highly regulated process controlled by a complex network of intracellular signaling pathways. By sensing the intracellular nutrient and energy status, the functional state of mitochondria, and the concentration of ROS produced in mitochondria, the longevity network regulates life span across species by co-ordinating information flow along its convergent, divergent and multiply branched signaling pathways, including vitagenes which are genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, such as carnosine, carnitines or polyphenols, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. The hormetic dose-response, challenges long-standing beliefs about the nature of the dose-response in a lowdose zone, having the potential to affect significantly the design of pre-clinical studies and clinical trials as well as strategies for optimal patient dosing in the treatment of numerous diseases. Given the broad cytoprotective properties of the heat shock response there is now strong interest in discovering and developing pharmacological agents capable of inducing stress responses. In this review we discuss the most current and up to date understanding of the possible signaling mechanisms by which caloric restriction, as well hormetic caloric restriction-mimetics compounds by activating vitagenes can enhance defensive systems involved in bioenergetic and stress resistance homeostasis with consequent impact on longevity processes.

Induction of apoptotic change in the rat hippocampus caused by ferric nitrilotriacetate

Iron, a source of oxidative stress, plays a major role in the pathology of neurodegenerative disease. In Alzheimer's disease, the hippocampus is vulnerable to oxidative stress, leading to impairment in memory formation. In our previous study, a brain oxidative reaction was induced after intraperitoneal injection of ferric nitrilotriacetate (Fe-NTA). However, since only a small amount of iron reached the brain in the previous study, Fe-NTA was administered into the hippocampus using an osmotic pump in this study. After continuous injection of Fe-NTA for 2 weeks, a high level of apoptotic change was induced in the hippocampus, in accordance with the iron localization. After injection for 4 weeks, the hippocampus was totally destroyed. A small amount of iron infiltrated into the cerebral cortex and the striatum, and deposition was observed at the choroid plexus and ependymal cells. However, no apoptotic reaction or clear tissue injury was observed in these areas. In addition, muscarinic acetylcholine receptors (M1, M2, and M4) were decreased in both the cortex and hippocampus while it increased in the striatum. Thus, the hippocampus is likely vulnerable to oxidative stress from Fe-NTA, and the oxidative stress is considered to bring the disturbance in the muscarinic acetylcholine receptors.