Effects of cysteamine on MPTP-induced dopaminergic neurodegeneration in mice

Cysteamine HCl Administration Impedes Motor and Olfactory Functions, Accompanied by a Reduced Number of Dopaminergic Neurons, in Experimental Mice: A Preclinical Mimetic Relevant to Parkinson's Disease

Cysteamine hydrochloride (Cys-HCl) has been established as a potent ulcerogenic agent of the gastrointestinal (GI) system. GI dysfunction and olfactory deficits are the most common clinical symptoms of many movement disorders, including Parkinson's disease (PD). Cys-HCl has been shown to interfere with dopamine, a neurotransmitter crucial for motor, olfactory, and cognitive functions. However, the reports on the effect of Cys-HCl treatment on the behavioral aspects and functions of the dopamine system appear to be inconsistent. Therefore, we revisited the impact of Cys-HCl on the motor function in experimental mice using a battery of behavioral tests, such as the pole test (PT), beam-walking test (BWT), and rotarod test (RDT), while the olfactory ability and cognitive functions were examined through the buried-food test (BFT) and Y-maze test. Furthermore, we investigated the effect of Cys-HCl on the number of dopaminergic tyrosine hydroxylase (TH)-positive cells in the substantia nigra (SN) and olfactory bulb (OB) of the experimental mice using immunohistochemistry. The results revealed that Cys-HCl administration in the mice induced significant impairments in their motor balance and coordination, as their movement-related performances were markedly reduced in terms of the behavioral tasks. Mice exposed to Cys-HCl showed pronounced reductions in their odor discrimination abilities as well as cognitive impairments. Strikingly, the number of TH-positive neurons was found to be reduced in the SN and OB of the Cys-HCl-treated group, which is a bonafide neuropathogenic hallmark of PD. This study highlights the potential neurotoxic effects of Cys-HCl in experimental brains and suggests further investigation into its role in the pathogenesis of Parkinsonism.

RETRACTED: Tangzhiqing-mediated NRF2 reduces autophagy-dependent ferroptosis to mitigate diabetes-related cognitive impairment neuronal damage

The publisher of Rejuvenation Research officially retracts the article entitled, "Tangzhiqing-mediated NRF2 reduces autophagy-dependent ferroptosis to mitigate diabetes-related cognitive impairment neuronal damage," by Lingyan Qiu, Mr. Kai Chen, Prof. Xu Wang, and Ms. Yun Zhao. (Rejuvenation Res 2023; epub 6 Jun; doi: 10.1089/rej.2023.0013). After the acceptance and Instant Online publication of the paper, the authors were contacted repeatedly regarding their page proofs, and for further clarification of unresolved issues within the paper. All attempts to reach the authors were unsuccessful. Concurrently, the publisher identified a problematic overlap with a paper published in 2023 in Endocrine, Metabolic & Immune Disorders - Drug Targets.1 This paper was subsequently withdrawn. These troubling details have led the editorial leadership of Rejuvenation Research to lose confidence in the validity of the submission and to retract the paper. All authors were notified of the decision to retract the paper via email. The lead author, Lingyan Qiu, and the corresponding author, Xu Wang, quickly responded and appealed the decision to retract. The appeal was denied. Reference 1. https://www.eurekaselect.com/article/132631. Withdrawn: Experimental study on NRF2 mediated by Chinese medicine tangzhiqing to reduce autophagy-dependent ferroptosis and alleviate neuron damage in HT22 mice with diabetes-related cognitive disorder. 22 June, 2023; DOI: 10.2174/1871530323666230622151649 Diabetes is a chronic condition defined by the body's inability to process glucose. The most common form, diabetes mellitus, reflects the body's insulin resistance, which leads to long-term raised glucose blood levels. These levels can cause oxidative damage, cell stress, and excessive autophagy throughout the body, including the nervous system. Diabetes-related cognitive impairment (DCI) results from chronic elevation of blood glucose, and as diabetes cases continue to rise, so too do comorbidities such as DCI. Although there are medications to address high blood glucose, there are few that can inhibit excessive autophagy and cell death. Therefore, we investigated if the Traditional Chinese Medicine, Tangzhiqing (TZQ), can reduce the impact of DCI in a high-glucose cell model. We used commercially available kits to evaluate cell viability, mitochondrial activity, and oxidative stress. We found that TZQ treatment increased cell viability, ensured continued mitochondrial activity, and reduced reactive oxygen species. We also found that TZQ functions by increasing NRF2 activity, which decreases the ferroptotic-associated pathways that involve p62, HO-1, and GPX4. Therefore, TZQ should be further investigated for its role in reducing DCI.

Succinate prodrugs as treatment for acute metabolic crisis during fluoroacetate intoxication in the rat

Sodium fluoroacetate (FA) is a metabolic poison that systemically inhibits the tricarboxylic acid (TCA) cycle, causing energy deficiency and ultimately multi-organ failure. It poses a significant threat to society because of its high toxicity, potential use as a chemical weapon and lack of effective antidotal therapy. In this study, we investigated cell-permeable succinate prodrugs as potential treatment for acute FA intoxication. We hypothesized that succinate prodrugs would bypass FA-induced mitochondrial dysfunction, provide metabolic support, and prevent metabolic crisis during acute FA intoxication. To test this hypothesis, rats were exposed to FA (0.75 mg/kg) and treated with the succinate prodrug candidate NV354. Treatment efficacy was evaluated based on cardiac and cerebral mitochondrial respiration, mitochondrial content, metabolic profiles and tissue pathology. In the heart, FA increased concentrations of the TCA metabolite citrate (+ 4.2-fold, p < 0.01) and lowered ATP levels (- 1.9-fold, p < 0.001), confirming the inhibition of the TCA cycle by FA. High-resolution respirometry of cardiac mitochondria further revealed an impairment of mitochondrial complex V (CV)-linked metabolism, as evident by a reduced phosphorylation system control ratio (- 41%, p < 0.05). The inhibition of CV-linked metabolism is a novel mechanism of FA cardiac toxicity, which has implications for drug development and which NV354 was unable to counteract at the given dose. In the brain, FA induced the accumulation of β-hydroxybutyrate (+ 1.4-fold, p < 0.05) and the reduction of mitochondrial complex I (CI)-linked oxidative phosphorylation (OXPHOSCI) (- 20%, p < 0.01), the latter of which was successfully alleviated by NV354. This promising effect of NV354 warrants further investigations to determine its potential neuroprotective effects.

Effect of cysteamine hydrochloride-loaded liposomes on skin depigmenting and penetration

Skin hyperpigmentation is caused by an excessive production of melanin. Cysteamine, an aminothiol compound physiologically synthetized in human body cells, is known as depigmenting agent. The aim of this study was to evaluate the depigmenting activity and skin penetration of liposome formulations encapsulating cysteamine hydrochloride. First, cysteamine hydrochloride-loaded liposomes were prepared and characterized for their size, polydispersity index, zeta potential and the encapsulation efficiency of the active molecule. The stability of cysteamine hydrochloride in the prepared liposome formulations in suspension and freeze-dried forms was then assessed. The in vitro cytotoxicity of cysteamine and cysteamine-loaded liposome suspensions (either original or freeze-dried) was evaluated in B16 murine melanoma cells. The measurement of melanin and tyrosinase activities was assessed after cells treatment with free and encapsulated cysteamine. The antioxidant activity of the free and encapsulated cysteamine was evaluated by the measurement of ROS formation in treated cells. The ex vivo human skin penetration study was also performed using Franz diffusion cell. The stability of cysteamine hydrochloride was improved after encapsulation in liposomal suspension. In addition, for the liposome re-suspended after freeze-drying, a significant increase of vesicle stability was observed. The free and the encapsulated cysteamine in suspension (either original or freeze-dried) did not show any cytotoxic effect, inhibited the melanin synthesis as well as the tyrosinase activity. An antioxidant activity was observed for the free and the encapsulated cysteamine hydrochloride. The encapsulation enhanced the skin penetration of cysteamine hydrochloride. The penetration of this molecule was better for the re-suspended freeze-dried form than the original liposomal suspension where the drug was found retained in the epidermis layer of the skin.

Therapeutics in the Pipeline Targeting α-Synuclein for Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder and the fastest growing neurologic disease in the world, yet no disease-modifying therapy is available for this disabling condition. Multiple lines of evidence implicate the protein α-synuclein (α-Syn) in the pathogenesis of PD, and as such, there is intense interest in targeting α-Syn for potential disease modification. α-Syn is also a key pathogenic protein in other synucleionpathies, most commonly dementia with Lewy bodies. Thus, therapeutics targeting this protein will have utility in these disorders as well. Here we discuss the various approaches that are being investigated to prevent and mitigate α-Syn toxicity in PD, including clearing its pathologic aggregates from the brain using immunization strategies, inhibiting its misfolding and aggregation, reducing its expression level, enhancing cellular clearance mechanisms, preventing its cell-to-cell transmission within the brain and perhaps from the periphery, and targeting other proteins associated with or implicated in PD that contribute to α-Syn toxicity. We also discuss the therapeutics in the pipeline that harness these strategies. Finally, we discuss the challenges and opportunities for the field in the discovery and development of therapeutics for disease modification in PD. SIGNIFICANCE STATEMENT: PD is the second most common neurodegenerative disorder, for which disease-modifying therapies remain a major unmet need. A large body of evidence points to α-synuclein as a key pathogenic protein in this disease as well as in dementia with Lewy bodies, making it of leading therapeutic interest. This review discusses the various approaches being investigated and progress made to date toward discovering and developing therapeutics that would slow and stop progression of these disabling diseases.

Therapeutic Applications of Cysteamine and Cystamine in Neurodegenerative and Neuropsychiatric Diseases

Current medications for neurodegenerative and neuropsychiatric diseases such as Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), and Schizophrenia mainly target disease symptoms. Thus, there is an urgent need to develop novel therapeutics that can delay, halt or reverse disease progression. AD, HD, PD, and schizophrenia are characterized by elevated oxidative and nitrosative stress, which play a central role in pathogenesis. Clinical trials utilizing antioxidants to counter disease progression have largely been unsuccessful. Most antioxidants are relatively non-specific and do not adequately target neuroprotective pathways. Accordingly, a search for agents that restore redox balance as well as halt or reverse neuronal loss is underway. The small molecules, cysteamine, the decarboxylated derivative of the amino acid cysteine, and cystamine, the oxidized form of cysteamine, respectively, mitigate oxidative stress and inflammation and upregulate neuroprotective pathways involving brain-derived neurotrophic factor (BDNF) and Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Cysteamine can traverse the blood brain barrier, a desirable characteristic of drugs targeting neurodegeneration. This review addresses recent developments in the use of these aminothiols to counter neurodegeneration and neuropsychiatric deficits.

Cystamine and cysteamine as inhibitors of transglutaminase activity in vivo

Cystamine is commonly used as a transglutaminase inhibitor. This disulphide undergoes reduction in vivo to the aminothiol compound, cysteamine. Thus, the mechanism by which cystamine inhibits transglutaminase activity in vivo could be due to either cystamine or cysteamine, which depends on the local redox environment. Cystamine inactivates transglutaminases by promoting the oxidation of two vicinal cysteine residues on the enzyme to an allosteric disulphide, whereas cysteamine acts as a competitive inhibitor for transamidation reactions catalyzed by this enzyme. The latter mechanism is likely to result in the formation of a unique biomarker, N-(γ-glutamyl)cysteamine that could serve to indicate how cyst(e)amine acts to inhibit transglutaminases inside cells and the body.

New insight into transglutaminase 2 and link to neurodegenerative diseases

Formation of toxic protein aggregates is a common feature and mainly contributes to the pathogenesis of neurodegenerative diseases (NDDs), which include amyotrophic lateral sclerosis (ALS), Alzheimer’s, Parkinson’s, Huntington’s, and prion diseases. The transglutaminase 2 (TG2) gene encodes a multifunctional enzyme, displaying four types of activity, such as transamidation, GTPase, protein disulfide isomerase, and protein kinase activities. Many studies demonstrated that the calcium-dependent transamidation activity of TG2 affects the formation of insoluble and toxic amyloid aggregates that mainly consisted of NDD-related proteins. So far, many important and NDD-related substrates of TG2 have been identified, including amlyoid-β, tau, α-synuclein, mutant huntingtin, and ALS-linked trans-activation response (TAR) DNA-binding protein 43. Recently, the formation of toxic inclusions mediated by several TG2 substrates were efficiently inhibited by TG2 inhibitors. Therefore, the development of highly specific TG2 inhibitors would be an important tool in alleviating the progression of TG2-related brain disorders. In this review, the authors discuss recent advances in TG2 biochemistry, several mechanisms of molecular regulation and pleotropic signaling functions, and the presumed role of TG2 in the progression of many NDDs.

Cysteamine, an Endogenous Aminothiol, and Cystamine, the Disulfide Product of Oxidation, Increase Pseudomonas aeruginosa Sensitivity to Reactive Oxygen and Nitrogen Species and Potentiate Therapeutic Antibiotics against Bacterial Infection

Cysteamine is an endogenous aminothiol produced in mammalian cells as a consequence of coenzyme A metabolism through the activity of the vanin family of pantetheinase ectoenzymes. It is known to have a biological role in oxidative stress, inflammation, and cell migration. There have been several reports demonstrating anti-infective properties targeting viruses, bacteria, and even the malarial parasite. We and others have previously described broad-spectrum antimicrobial and antibiofilm activities of cysteamine. Here, we go further to demonstrate redox-dependent mechanisms of action for the compound and how its antimicrobial effects are, at least in part, due to undermining bacterial defenses against oxidative and nitrosative challenges. We demonstrate the therapeutic potentiation of antibiotic therapy against Pseudomonas aeruginosa in mouse models of infection. We also demonstrate potentiation of many different classes of antibiotics against a selection of priority antibiotic-resistant pathogens, including colistin (often considered an antibiotic of last resort), and we discuss how this endogenous antimicrobial component of innate immunity has a role in infectious disease that is beginning to be explored and is not yet fully understood.

The effects of cysteamine in a mouse model of levodopa-induced dyskinesias

Levo-dopa (L-DOPA) has shown significant and long-lasting efficacy in the treatment of motor features characteristic of Parkinson's disease (PD). However, the effects tend to wear off at a time typically when side-effects, such as L-DOPA induced dyskinesias (LIDs), start to emerge and for which the treatment options are very limited. In recent years, we have reported on the neuroprotective and neurorestorative properties of the compounds cystamine/cysteamine in ameliorating several aspects of PD. Building on these observations, we set out to further evaluate the benefits of cysteamine on LIDs. We thus treated mice displaying LIDs with single cysteamine challenges at various doses (20, 50 and 30mg/kg) or chronically for 2 weeks using cysteamine at a dose of 30mg/kg. None of the regimens nor doses ameliorated any LID-related behavioral impairments. Mice displaying LIDs did, however, respond to a single treatment of 60mg/kg of amantadine, a drug used to clinically manage LIDs. Taken together, our results suggest that cysteamine does not induce benefits on LIDs, at least at the doses and regimen tested in our study. However, the disease-modifying effects depicted by cystamine/cysteamine, which we have shown in several reports, would strongly encourage its continued evaluation in the clinical setting.

Hierarchical Self-Assembly of Bile-Acid-Derived Dicationic Amphiphiles and Their Toxicity Assessment on Microbial and Mammalian Systems

A thiol-yne click chemistry approach was adopted for the first time to prepare highly water-soluble bile acid derived dicationic amphiphiles. The synthesized amphiphiles dicationic cysteamine conjugated cholic acid (DCaC), dicationic cysteamine conjugated deoxycholic acid (DCaDC), and dicationic cysteamine conjugated lithocholic acid (DCaLC) exhibited hierarchically self-assembled microstructures at various concentrations in an aqueous medium. Interestingly at below critical micellar concentration (CMC) the amphiphiles showed distinct fractal patterns such as fractal grass, microdendrites and fern leaf like fractals for DCaC, DCaDC and DCaLC respectively. The fractal dimension (Df) analysis indicated that the formation of fractal like aggregates is a diffusion limited aggregation (DLA) process. The preliminary aggregation studies such as determination of CMC, fluorescence quenching, wettability and contact angle measurements were elaborately investigated. The morphology of the aggregates were analyzed by SEM and OPM techniques. Further, we demonstrated the antimicrobial and hemolytic activity for the cationic amphiphiles. DCaC had potent antimicrobial activity and showed no toxicity on human RBCs indicating that DCaC could be used in biomedical applications, in addition to their industrial and laboratory applications such as detergency, surface cleaning, and disinfection agent.

A Pharmacogenetic Discovery: Cystamine Protects Against Haloperidol-Induced Toxicity and Ischemic Brain Injury

Haloperidol is an effective antipsychotic agent, but it causes Parkinsonian-like extrapyramidal symptoms in the majority of treated subjects. To address this treatment-limiting toxicity, we analyzed a murine genetic model of haloperidol-induced toxicity (HIT). Analysis of a panel of consomic strains indicated that a genetic factor on chromosome 10 had a significant effect on susceptibility to HIT. We analyzed a whole-genome SNP database to identify allelic variants that were uniquely present on chromosome 10 in the strain that was previously shown to exhibit the highest level of susceptibility to HIT. This analysis implicated allelic variation within pantetheinase genes (Vnn1 and Vnn3), which we propose impaired the biosynthesis of cysteamine, could affect susceptibility to HIT. We demonstrate that administration of cystamine, which is rapidly metabolized to cysteamine, could completely prevent HIT in the murine model. Many of the haloperidol-induced gene expression changes in the striatum of the susceptible strain were reversed by cystamine coadministration. Since cystamine administration has previously been shown to have other neuroprotective actions, we investigated whether cystamine administration could have a broader neuroprotective effect. Cystamine administration caused a 23% reduction in infarct volume after experimentally induced cerebral ischemia. Characterization of this novel pharmacogenetic factor for HIT has identified a new approach for preventing the treatment-limiting toxicity of an antipsychotic agent, which could also be used to reduce the extent of brain damage after stroke.

Knock-down of pantothenate kinase 2 severely affects the development of the nervous and vascular system in zebrafish, providing new insights into PKAN disease

Pantothenate Kinase Associated Neurodegeneration (PKAN) is an autosomal recessive disorder with mutations in the pantothenate kinase 2 gene (PANK2), encoding an essential enzyme for Coenzyme A (CoA) biosynthesis. The molecular connection between defects in this enzyme and the neurodegenerative phenotype observed in PKAN patients is still poorly understood. We exploited the zebrafish model to study the role played by the pank2 gene during embryonic development and get new insight into PKAN pathogenesis. The zebrafish orthologue of hPANK2 lies on chromosome 13, is a maternal gene expressed in all development stages and, in adult animals, is highly abundant in CNS, dorsal aorta and caudal vein. The injection of a splice-inhibiting morpholino induced a clear phenotype with perturbed brain morphology and hydrocephalus; edema was present in the heart region and caudal plexus, where hemorrhages with reduction of blood circulation velocity were detected. We characterized the CNS phenotype by studying the expression pattern of wnt1 and neurog1 neural markers and by use of the Tg(neurod:EGFP/sox10:dsRed) transgenic line. The results evidenced that downregulation of pank2 severely impairs neuronal development, particularly in the anterior part of CNS (telencephalon). Whole-mount in situ hybridization analysis of the endothelial markers cadherin-5 and fli1a, and use of Tg(fli1a:EGFP/gata1a:dsRed) transgenic line, confirmed the essential role of pank2 in the formation of the vascular system. The specificity of the morpholino-induced phenotype was proved by the restoration of a normal development in a high percentage of embryos co-injected with pank2 mRNA. Also, addition of pantethine or CoA, but not of vitamin B5, to pank2 morpholino-injected embryos rescued the phenotype with high efficiency. The zebrafish model indicates the relevance of pank2 activity and CoA homeostasis for normal neuronal development and functioning and provides evidence of an unsuspected role for this enzyme and its product in vascular development.

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Zebrafish pank2 gene is highly expressed in the CNS and the main vascular structures.

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Pank2 down-regulation severely affects the development of the forebrain.

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Pank2 down-regulation affects the dorsal aorta, caudal vein and inter-somitic vessels.

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Pantethine and Coenzyme A restore the normal development in the absence of pank2 expression.

Comparison of two fluid solutions for resuscitation in a rabbit model of crush syndrome

BACKGROUND

Crush syndrome is a common injury, the main characteristics of which include acute kidney injury. However, there is still lack of reliable animal model of crush syndrome, and it also remains controversial as to which type of fluid should be chosen as a more appropriate treatment option for prevention and treatment of acute kidney injury.

METHODS

The rabbits were crushed at the lower limbs for 6 h with 36 times the body weight, which means the pressure of each leg was also 36 times the body weight. Fluid resuscitation was performed from 1 h prior to the end of the crush treatment until 24 h after the reperfusion. Tissue, blood and urine samples were collected at predetermined time points before and after reperfusion. Twelve rabbits in each group were taken for survival observation for 72 h.

RESULTS

The model group showed elevated serum creatine kinase, aspartate aminotransferase, alanine aminotransferase, and K(+) level, reduced serum Ca(2+) level and Na(+) level, and increased serum creatinine and blood urea nitrogen levels, neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 (p < 0.05). The 0.9 % normal saline (SAL) group and SAL plus 6 % hydroxyethyl starch 130/0.4 SAL/HES group showed reduced serum creatinine and blood urea nitrogen levels (p < 0.05). The SAL/HES group also showed reduced serum IL-6 and IL-10 levels (p < 0.05). The 72 h survival rate of the SAL/HES group was higher than that of the model group (p < 0.05).

CONCLUSION

The rabbit model of crush syndrome showed clinical features consistent with those of crush syndrome. There was no significant difference in the ability of preventing AKI after a crush injury between the two fluid solutions, while SAL/HES can improve the survival rate.

No quiet surrender: molecular guardians in multiple sclerosis brain

The brain under immunological attack does not surrender quietly. Investigation of brain lesions in multiple sclerosis (MS) reveals a coordinated molecular response involving various proteins and small molecules ranging from heat shock proteins to small lipids, neurotransmitters, and even gases, which provide protection and foster repair. Reduction of inflammation serves as a necessary prerequisite for effective recovery and regeneration. Remarkably, many lesion-resident molecules activate pathways leading to both suppression of inflammation and promotion of repair mechanisms. These guardian molecules and their corresponding physiologic pathways could potentially be exploited to silence inflammation and repair the injured and degenerating brain and spinal cord in both relapsing-remitting and progressive forms of MS and may be beneficial in other neurologic and psychiatric conditions.

Indoleamine 2,3-dioxygenase is upregulated in the brain of rats with acute pancreatitis

BACKGROUND

Acute pancreatitis (AP) has an effect on both inflammatory/autoimmune processes and psychological states, but the pathophysiological causes of pancreatic encephalopathy in the brain are unclear. We hypothesized that the peripheral immune/inflammatory response during AP can affect indolamine 2,3-dioxygenase (IDO) expression and serotonin content in the brain.

METHODS

About 210 male Sprague Dawley rats were randomly divided into five groups: control (0 h) and 6 h, 24 h, 48 h and 72 h experimental groups. Acute pancreatitis was induced by an injection of a sodium taurocholate solution via a cannulated bile-pancreatic duct. We measured the plasma TNF-α and IL-6 levels; serotonin, 5-HIAA and the protein concentration levels of IDO and monoamine oxidase A (MAO-A) were evaluated in the striatum, hippocampus and left prefrontal cortex.

RESULTS

The IL-6 and the TNF-α levels increased in the 24 h, 48 h and 72 h groups. The IDO concentrations of both the 72 h group in the hippocampus and 48 h, 72 h groups in the prefrontal cortex increased; in the corpus striatum, the IDO concentrations fluctuated without statistical significance. The MAO-A protein concentration of the 6 h and 24 h groups decreased in the striatum, hippocampus and prefrontal cortex. There were no statistically significant differences found in the serotonin and 5-HIAA concentrations.

CONCLUSIONS

During the process of AP, cytokines, such as IL-6 and TNF-α, may play a role in activation of neuronal pathways utilizing the metabolic enzyme IDO, which may play an important role in determining the mental symptomatology accompanying AP.

Acute pancreatitis affects the metabolism of catecholamine neurotransmitters in rats

Abnormalities of mental status represent a severe complication and an important cause of death in acute pancreatitis (AP), which is characterized by a pattern of neurological signs and symptoms. As some of the symptoms of AP are also affected by catecholamine neurotransmitters, they cannot be ruled out of the pathophysiology of AP; however, little research has been performed exploring this hypothesis. Our study aimed to elucidate whether AP affects the metabolism of catecholamine neurotransmitters in rats. A total of 300 male SD rats were randomly divided into five groups: control, 6H, 24H, 48H and 72H experimental groups. AP was induced in rats by an injection of a sodium taurocholate solution via a cannulated bile-pancreatic duct. In the striatum, hippocampus and cerebellum, catecholamine neurotransmitters were tested using high performance liquid chromatography equipped with a electrochemical detector, and the activities and protein concentration levels of monoamine oxidase A (MAO-A) and tyrosine hydroxylase (TH) were also evaluated using ELISA and Western blotting analyses. In the hippocampus, the dopamine (DA) concentrations increased in the 48-h and 72-h groups. The 3,4-dihydroxyphenylacetic acid (DOPAC) concentration of the 72-h group also increased. The MAO-A and TH activity of the 6-h and 24-h groups decreased, respectively. The TH activities of the 48-h groups also decreased. The MAO-A and TH protein concentration of the 6-h and 24-h groups decreased. In the corpus striatum, the homovanillic acid concentration of the 72-h group and norepinephrine concentrations of the 24-h and 48-h groups increased, respectively. The MAO-A and TH activities of the 6-h and 24-h groups decreased. The MAO-A and TH protein concentrations of the 6-h and 24-h groups decreased. In the prefrontal cortex (left prefrontal lobe), the DA and DOPAC concentrations of the 48-h group increased. The MAO-A and TH activities of the 6-h, 24-h and 48-h groups decreased. The MAO-A and TH protein concentrations of the 6-h and 24-h groups also decreased. The other catecholamine concentration and enzyme activities fluctuated, but there was no statistically significant difference compared with the control group. Catecholamine neurotransmitter metabolic systems are widely affected in AP, and these fluctuations may play an important role in determining the symptomatology of AP.

Pantethine treatment is effective in recovering the disease phenotype induced by ketogenic diet in a pantothenate kinase-associated neurodegeneration mouse model

Pantothenate kinase-associated neurodegeneration, caused by mutations in the PANK2 gene, is an autosomal recessive disorder characterized by dystonia, dysarthria, rigidity, pigmentary retinal degeneration and brain iron accumulation. PANK2 encodes the mitochondrial enzyme pantothenate kinase type 2, responsible for the phosphorylation of pantothenate or vitamin B5 in the biosynthesis of co-enzyme A. A Pank2 knockout (Pank2^−/−) mouse model did not recapitulate the human disease but showed azoospermia and mitochondrial dysfunctions. We challenged this mouse model with a low glucose and high lipid content diet (ketogenic diet) to stimulate lipid use by mitochondrial beta-oxidation. In the presence of a shortage of co-enzyme A, this diet could evoke a general impairment of bioenergetic metabolism. Only Pank2^−/− mice fed with a ketogenic diet developed a pantothenate kinase-associated neurodegeneration-like syndrome characterized by severe motor dysfunction, neurodegeneration and severely altered mitochondria in the central and peripheral nervous systems. These mice also showed structural alteration of muscle morphology, which was comparable with that observed in a patient with pantothenate kinase-associated neurodegeneration. We here demonstrate that pantethine administration can prevent the onset of the neuromuscular phenotype in mice suggesting the possibility of experimental treatment in patients with pantothenate kinase-associated neurodegeneration.

Protective effects of aliskiren on ischemia-reperfusion-induced renal injury in rats

The protective effect of aliskiren on ischemia-reperfusion (I/R) injury in the heart and brain has been reported. Whether or not this protective effect extends into the alleviation of renal I/R injury is not known. Therefore, we investigated the protective effect of aliskiren in the kidney in this study. Sprague-Dawley rats were randomly divided into four groups: sham control group; sham control with aliskiren pretreatment; I/R group and I/R with aliskiren pretreatment. Aliskiren (3mg/kg) or vehicle was administrated intravenously via vena cava. Blood samples and the left kidneys were then collected to check for renal function, angiotensin II (Ang II), apoptosis and oxidative stress levels. Compared with the sham rats, serum creatinine (SCR) and blood urea nitrogen (BUN) were significantly increased in the I/R rats, accompanied by histopathological damage to the kidney, which included tubular cell swelling, desquamation, and cast formation. There were also more apoptotic cells and leukocyte infiltration in the I/R rats than in the sham rats. Pretreatment with aliskiren ameliorated I/R induced renal injury, i.e. reduced SCR and BUN levels, ameliorated renal histopathological changes, and decreased the apoptosis of cells and leukocyte infiltration in kidney. I/R injury also decreased superoxide dismutase (SOD) and glutathione (GSH-reduced form) levels, which were blocked with the aliskiren pretreatment. Aliskiren pretreatment exerts a protective effect on ischemia/reperfusion injury in the kidney, via amelioration of oxidative stress, and reduction in leukocyte infiltration and cellular apoptosis.

Cysteamine: an old drug with new potential

Cysteamine is an amino thiol with the chemical formula HSCH2CH2NH2. Endogenously, cysteamine is derived from coenzyme A degradation, although its plasma concentrations are low. Most experience with cysteamine as a drug originates from the field of the orphan disease cystinosis, in which cysteamine is prescribed to decrease intralysosomal cystine accumulation. However, over the years, the drug has been used for several other applications both in vitro and in vivo. In this article, we review the different applications of cysteamine, ending with an overview of ongoing clinical trials for new indications, such as neurodegenerative disorders and nonalcoholic fatty liver disease (NAFLD). The recent development of an enteric-coated cysteamine formulation makes cysteamine more patient friendly and will extend its applicability for both old and new indications.

Exercise does not protect against MPTP-induced neurotoxicity in BDNF haploinsufficient mice

Exercise has been demonstrated to potently protect substantia nigra pars compacta (SN) dopaminergic neurons from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity. One mechanism proposed to account for this neuroprotection is the upregulation of neurotrophic factors. Several neurotrophic factors, including Brain Derived Neurotrophic Factor (BDNF), have been shown to upregulate in response to exercise. In order to determine if exercise-induced neuroprotection is dependent upon BDNF, we compared the neuroprotective effects of voluntary exercise in mice heterozygous for the BDNF gene (BDNF+/-) with strain-matched wild-type (WT) mice. Stereological estimates of SNpc DA neurons from WT mice allowed 90 days exercise via unrestricted running demonstrated complete protection against the MPTP-induced neurotoxicity. However, BDNF+/- mice allowed 90 days of unrestricted exercise were not protected from MPTP-induced SNpc DA neuron loss. Proteomic analysis comparing SN and striatum from 90 day exercised WT and BDNF+/- mice showed differential expression of proteins related to energy regulation, intracellular signaling and trafficking. These results suggest that a full genetic complement of BDNF is critical for the exercise-induced neuroprotection of SNpc DA neurons.

Defective autophagy in Parkinson's disease: role of oxidative stress

Parkinson's disease (PD) is a paradigmatic example of neurodegenerative disorder with a critical role of oxidative stress in its etiopathogenesis. Genetic susceptibility factors of PD, such as mutations in Parkin, PTEN-induced kinase 1, and DJ-1 as well as the exposure to pesticides and heavy metals, both contribute to altered redox balance and degeneration of dopaminergic neurons in the substantia nigra. Dysregulation of autophagy, a lysosomal-driven process of self degradation of cellular organelles and protein aggregates, is also implicated in PD and PD-related mutations, and environmental toxins deregulate autophagy. However, experimental evidence suggests a complex and ambiguous role of autophagy in PD since either impaired or abnormally upregulated autophagic flux has been shown to cause neuronal loss. Finally, it is generally believed that oxidative stress is a strong proautophagic stimulus. However, some evidence coming from neurobiology as well as from other fields indicate an inhibitory role of reactive oxygen species and reactive nitrogen species on the autophagic machinery. This review examines the scientific evidence supporting different concepts on how autophagy is dysregulated in PD and attempts to reconcile apparently contradictory views on the role of oxidative stress in autophagy regulation. The complex relationship between autophagy and oxidative stress is also considered in the context of the ongoing search for a novel PD therapy.

Transglutaminase 2: biology, relevance to neurodegenerative diseases and therapeutic implications

Neurodegenerative disorders are characterized by progressive neuronal loss and the aggregation of disease-specific pathogenic proteins in hallmark neuropathologic lesions. Many of these proteins, including amyloid Αβ, tau, α-synuclein and huntingtin, are cross-linked by the enzymatic activity of transglutaminase 2 (TG2). Additionally, the expression and activity of TG2 is increased in affected brain regions in these disorders. These observations along with experimental evidence in cellular and mouse models suggest that TG2 can contribute to the abnormal aggregation of disease causing proteins and consequently to neuronal damage. This accumulating evidence has provided the impetus to develop inhibitors of TG2 as possible neuroprotective agents. However, TG2 has other enzymatic activities in addition to its cross-linking function and can modulate multiple cellular processes including apoptosis, autophagy, energy production, synaptic function, signal transduction and transcription regulation. These diverse properties must be taken into consideration in designing TG2 inhibitors. In this review, we discuss the biochemistry of TG2, its various physiologic functions and our current understanding about its role in degenerative diseases of the brain. We also describe the different approaches to designing TG2 inhibitors that could be developed as potential disease-modifying therapies.

Endogenous neuroprotection in chronic neurodegenerative disorders: with particular regard to the kynurenines

Parkinson's disease (PD) and Huntington's disease (HD) are progressive chronic neurodegenerative disorders that are accompanied by a considerable impairment of the motor functions. PD may develop for familial or sporadic reasons, whereas HD is based on a definite genetic mutation. Nevertheless, the pathological processes involve oxidative stress and glutamate excitotoxicity in both cases. A number of metabolic routes are affected in these disorders. The decrease in antioxidant capacity and alterations in the kynurenine pathway, the main pathway of the tryptophan metabolism, are features that deserve particular interest, because the changes in levels of neuroactive kynurenine pathway compounds appear to be strongly related to the oxidative stress and glutamate excitotoxicity involved in the disease pathogenesis. Increase of the antioxidant capacity and pharmacological manipulation of the kynurenine pathway are therefore promising therapeutic targets in these devastating disorders.

Potential of cystamine and cysteamine in the treatment of neurodegenerative diseases

Neurodegenerative disorders are a subset of disabling pathologies characterized, in part, by a progressive and specific loss of certain brain cell populations. Current therapeutic approaches for the treatment of these disorders are mainly designed towards symptom management and do not manifestly block their typified neuronal loss. However, research conducted over the past decade has reflected the increasing interest and need to find disease-modifying molecules. Among the several neuroprotective agents emerging from experimental animal work, cystamine, as well as its reduced form cysteamine, have been identified as potential candidate drugs. Given the significant benefits observed in a Huntington's disease (HD) model, cysteamine has recently leaped to clinical trial. Here, we review the beneficial properties of these compounds as reported in animal studies, their mechanistic underpinnings, and their potential implications for the future treatment of patients suffering from neurodegenerative diseases, and more specifically for HD and Parkinson's disease (PD).

Transgenic conversion of omega-6 into omega-3 fatty acids in a mouse model of Parkinson's disease

We have recently identified a neuroprotective role for omega-3 polyunsaturated fatty acids (n-3 PUFAs) in a toxin-induced mouse model of Parkinson's disease (PD). Combined with epidemiological data, these observations suggest that low n-3 PUFA intake is a modifiable environmental risk factor for PD. In order to strengthen these preclinical findings as prerequisite to clinical trials, we further investigated the neuroprotective role of n-3 PUFAs in Fat-1 mice, a transgenic model expressing an n-3 fatty acid desaturase converting n-6 PUFAs into n-3 PUFAs. Here, we report that the expression of the fat-1 transgene increased cortical n-3:n-6 PUFA ratio (+28%), but to a lesser extent than dietary supplementation (92%). Such a limited endogenous production of n-3 PUFAs in the Fat-1 mouse was insufficient to confer neuroprotection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxicity as assessed by dopamine levels, tyrosine hydroxylase (TH)-positive neurons and fibers, as well as nigral Nurr1 and dopamine transporter (DAT) mRNA expression. Nevertheless, higher cortical docosahexaenoic acid (DHA) concentrations were positively correlated with markers of nigral dopaminergic neurons such as the number of TH-positive cells, in addition to Nurr1 and DAT mRNA levels. These associations are consistent with the protective role of DHA in a mouse model of PD. Taken together, these data suggest that dietary intake of a preformed DHA supplement is more effective in reaching the brain and achieving neuroprotection in an animal model of PD.

Cystamine metabolism and brain transport properties: clinical implications for neurodegenerative diseases

Cystamine has shown significant neuroprotective properties in preclinical studies of Parkinson's disease (PD) and Huntington's disease (HD). Cysteamine, its FDA-approved reduced form, is scheduled to be tested for clinical efficacy in HD patients. Here, we studied the key cystamine metabolites, namely cysteamine, hypotaurine and taurine, as well as cysteine, in order to identify which one is more distinctively responsible for the neuroprotective action of cystamine. After a single administration of cystamine (10, 50 or 200 mg/kg), naïve mice were perfused with phosphate-buffered saline (PBS) at 1, 3, 12, 24 or 48 h post-injection and brain and plasma samples were analyzed by two distinct HPLC methods. Although plasma levels remained under the detection threshold, significant increases in cysteamine brain levels were detected with the 50 and 200 mg/kg doses in mice perfused 1 and 3 h following cystamine injection. To further assess cysteamine as the candidate molecule for pre-clinical and clinical trials in PD, we evaluated its capacity to cross the blood brain barrier. Using an in situ cerebral perfusion technique, we determined that the brain transport coefficient (Clup) of cysteamine (259 μM) was 0.15 ± 0.02 μL/g/s and was increased up to 0.34 ± 0.07 μL/g/s when co-perfused in the presence of cysteine. Taken together, these results strongly suggest that cysteamine is the neuroactive metabolite of cystamine and may further support its therapeutic use in neurodegenerative diseases, particularly in HD and PD.