Attenuation of Rotenone-Induced Mitochondrial Oxidative Damage and Neurotoxicty in Drosophila melanogaster Supplemented with Creatine

Mini-encyclopedia of mitochondria-relevant nutraceuticals protecting health in primary and secondary care-clinically relevant 3PM innovation

Despite their subordination in humans, to a great extent, mitochondria maintain their independent status but tightly cooperate with the "host" on protecting the joint life quality and minimizing health risks. Under oxidative stress conditions, healthy mitochondria promptly increase mitophagy level to remove damaged "fellows" rejuvenating the mitochondrial population and sending fragments of mtDNA as SOS signals to all systems in the human body. As long as metabolic pathways are under systemic control and well-concerted together, adaptive mechanisms become triggered increasing systemic protection, activating antioxidant defense and repair machinery. Contextually, all attributes of mitochondrial patho-/physiology are instrumental for predictive medical approach and cost-effective treatments tailored to individualized patient profiles in primary (to protect vulnerable individuals again the health-to-disease transition) and secondary (to protect affected individuals again disease progression) care. Nutraceuticals are naturally occurring bioactive compounds demonstrating health-promoting, illness-preventing, and other health-related benefits. Keeping in mind health-promoting properties of nutraceuticals along with their great therapeutic potential and safety profile, there is a permanently growing demand on the application of mitochondria-relevant nutraceuticals. Application of nutraceuticals is beneficial only if meeting needs at individual level. Therefore, health risk assessment and creation of individualized patient profiles are of pivotal importance followed by adapted nutraceutical sets meeting individual needs. Based on the scientific evidence available for mitochondria-relevant nutraceuticals, this article presents examples of frequent medical conditions, which require protective measures targeted on mitochondria as a holistic approach following advanced concepts of predictive, preventive, and personalized medicine (PPPM/3PM) in primary and secondary care.

Creatine supplementation with exercise reduces α-synuclein oligomerization and necroptosis in Parkinson's disease mouse model

Parkinson's disease (PD) is an incurable neurological disorder that causes typical motor deficits. In this study, we investigated the effects of creatine supplementation and exercise in the subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. We found that 2% creatine supplementation and/or exercise intervention for 4 weeks elicited neurobehavioral recovery and neuroprotective effects regarding dopaminergic cell loss in MPTP-treated mice; this effect implies functional preservation of dopaminergic cells in the substantia nigra, as reflected by tyrosine hydroxylase expression recovery. Creatine and exercise reduced necroptotic activity in dopaminergic cells by lowering mixed lineage kinase domain-like protein (MLKL) modification to active phenotypes (phosphorylation at Ser345 and oligomerization) and phosphorylated receptor-interacting protein kinase 1 (RIPK1) (Ser166-p) and RIPK3 (Ser232-p) levels. In addition, creatine and exercise reduced the MPTP-induced increase in pathogenic α-synuclein forms, such as Ser129 phosphorylation and oligomerization. Furthermore, creatine and exercise had anti-inflammatory and antioxidative effects in MPTP mice, as evidenced by a decrease in microglia activation, NF-κB-dependent pro-inflammatory molecule expression, and increase in antioxidant enzyme expression. These phenotypic changes were associated with the exercise/creatine-induced AMP-activated protein kinase (AMPK)/nuclear factor erythroid 2-related factor 2 (Nrf2) and sirtuin 3 (SIRT3)/forkhead box O3 (FoxO3a) signaling pathways. In all experiments, combining creatine with exercise resulted in considerable improvement over either treatment alone. Consequently, these findings suggest that creatine supplementation with exercise has anti-inflammatory, antioxidative, and anti-α-synucleinopathy effects, thereby reducing necroptotic cell death in a PD mouse model.

Drosophila tweety facilitates autophagy to regulate mitochondrial homeostasis and bioenergetics in Glia

Mitochondria support the energetic demands of the cells. Autophagic turnover of mitochondria serves as a critical pathway for mitochondrial homeostasis. It is unclear how bioenergetics and autophagy are functionally connected. Here, we identify an endolysosomal membrane protein that facilitates autophagy to regulate ATP production in glia. We determined that Drosophila tweety (tty) is highly expressed in glia and localized to endolysosomes. Diminished fusion between autophagosomes and endolysosomes in tty-deficient glia was rescued by expressing the human Tweety Homolog 1 (TTYH1). Loss of tty in glia attenuated mitochondrial turnover, elevated mitochondrial oxidative stress, and impaired locomotor functions. The cellular and organismal defects were partially reversed by antioxidant treatment. We performed live-cell imaging of genetically encoded metabolite sensors to determine the impact of tty and autophagy deficiencies on glial bioenergetics. We found that tty-deficient glia exhibited reduced mitochondrial pyruvate consumption accompanied by a shift toward glycolysis for ATP production. Likewise, genetic inhibition of autophagy in glia resulted in a similar glycolytic shift in bioenergetics. Furthermore, the survival of mutant flies became more sensitive to starvation, underlining the significance of tty in the crosstalk between autophagy and bioenergetics. Together, our findings uncover the role for tty in mitochondrial homeostasis via facilitating autophagy, which determines bioenergetic balance in glia.

Efficacy of creatine nitrate supplementation on redox status and mitochondrial function in pectoralis major muscle of preslaughter transported broilers

This study was purposed to investigate the efficacy of dietary creatine nitrate (CrN) supplementation on redox status and mitochondrial function in pectoralis major (PM) muscle of broilers that experienced preslaughter transport. A total of 288 Arbor Acres broilers (28-day-old) were randomly assigned into five dietary treatments, including a basal diet or the basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN for 14 days, respectively. On the transportation day, the basal diet group was divided into two groups on average, resulting in six groups. The control group was transported for 0.5 h and the other groups for 3 h (identified as Control, T3h, GAA600, CrN300, CrN600, and CrN900 group, respectively), and all crates were randomly placed on the truck travelling at an average speed of 80 km/h. Our results showed that GAA600 and CrN treatments decreased the muscle ROS level and MDA content (P < 0.05) and increased the mitochondrial membrane potential (P < 0.001), as well as a higher mRNA expression of avUCP (P < 0.001) and lower mRNA expressions of Nrf2 (P < 0.001), Nrf2 and PGC-1α (P < 0.05) compared with T3h group. Meanwhile, the mRNA and protein expressions of Nrf1, TFAM, and PGC-1α in CrN600 and CrN900 groups were lower than those in the T3h group (P < 0.05). Conclusively, dietary supplementation with GAA and CrN decreased muscle oxidative products and enhanced mitochondrial uncoupling mechanism and mtDNA copy number, which relieved muscle oxidative damage and maintained mitochondrial function.

Asymmetric Presynaptic Depletion of Dopamine Neurons in a Drosophila Model of Parkinson's Disease

Parkinson's disease (PD) often displays a strong unilateral predominance in arising symptoms. PD is correlated with dopamine neuron (DAN) degeneration in the substantia nigra pars compacta (SNPC), and in many patients, DANs appear to be affected more severely on one hemisphere than the other. The reason for this asymmetric onset is far from being understood. Drosophila melanogaster has proven its merit to model molecular and cellular aspects of the development of PD. However, the cellular hallmark of the asymmetric degeneration of DANs in PD has not yet been described in Drosophila. We ectopically express human α-synuclein (hα-syn) together with presynaptically targeted syt::HA in single DANs that innervate the Antler (ATL), a symmetric neuropil located in the dorsomedial protocerebrum. We find that expression of hα-syn in DANs innervating the ATL yields asymmetric depletion of synaptic connectivity. Our study represents the first example of unilateral predominance in an invertebrate model of PD and will pave the way to the investigation of unilateral predominance in the development of neurodegenerative diseases in the genetically versatile invertebrate model Drosophila.

Safer alternatives? Bisphenol F and Bisphenol S induce oxidative stress in Drosophila melanogaster larvae and trigger developmental damage

Bisphenol F (BPF) and Bisphenol S (BPS) are safe alternatives substances? Here Drosophila melanogaster were exposed during development (larval stage) to BPF and BPS (0.25, 0.5 and 1 mM). Upon reaching the last larval stage (3rd stage), markers of oxidative stress and metabolism of both substances were evaluated, along with investigation of mitochondrial and cell viability. This study is attributed to an unprecedented fact: BPF and BPS exposed larvae, both at concentrations of 0.5 and 1 mM, showed higher cytochrome P-450 (CYP450) activity. The GST activity increased in all BPF and BPS concentrations, and reactive species, lipid peroxidation, superoxide dismutase, and catalase activity increased in larvae (BPF and BPS; 0.5, and 1 mM); nonetheless, mitochondrial and cell viability decreased with 1 mM of BPF and BPS. In addition, the reduced number of pupae formed in the 1 mM BPF and BPS groups and melanotic mass formation may be attributed to oxidative stress. From the pupae formed, the hatching rate reduced in the 0.5 and 1 mM BPF and BPS groups. Thus, the possible presence of toxic metabolites may be related to the larval oxidative stress condition, which is detrimental to the complete development of Drosophila melanogaster.

Ackee (Blighia sapida K.D. Koenig) Leaves and Arils Methanolic Extracts Ameliorate CdCl2-Induced Oxidative Stress Biomarkers in Drosophila melanogaster

Different ethnomedical benefits have been documented on different parts of Ackee (Blighia sapida); however, their roles in ameliorating oxidative damages are not well established. CdCl2 inhibitory effects on some oxidative-stress biomarkers and ameliorative potentials of Ackee leaves (AL) and arils (AS) methanolic extracts were studied using Drosophila melanogaster as a model. One to 3-day-old D. melanogaster flies were orally exposed to different concentrations of CdCl2 in their diet for 7 days. The fly’s survival profile and negative geotaxis assays were subsequently analysed. Methanolic extracts of AL and AS treatments showed negative geotaxis behaviour, and extracts were able to ameliorate the effect of Cd2+ on catalase and GST activities and increase total thiol and GSH levels, while it reduced the H2O2 generation ( $p\le 0.05$ ) when compared to the control. Furthermore, Cd2+ exhibited noncompetitive and uncompetitive enzyme inhibition on catalase and GST activities, respectively, which may have resulted in the formation of Enzyme-substrate-Cd2+ transition complexes, thus inhibiting the conversion of substrate to product. This study, thus, suggests that the Cd2+ mechanism of toxicity was associated with oxidative damage, as evidenced by the alteration in the oxidative stress-antioxidant imbalance, and that the AL and AS extracts possess essential phytochemicals that could alleviate possibly deleterious oxidative damage effects of environmental pollutants such as CdCl2. Thus, Ackee plant parts possess essential phytonutrients which could serve as valuable resources in heavy metal toxicity management.

Sex-specific changes in oxidative stress parameters and longevity produced by Bisphenol F and S compared to Bisphenol A in Drosophila melanogaster

Female and male Drosophila melanogaster were exposed separately for seven days to Bisphenol A (BPA), Bisphenol F (BPF), and Bisphenol S (BPS) at concentrations of 0.25, 0.5, and 1 mM. We observed that males exposed to 0.5 and 1 mM BPS showed lower catalase (CAT) activity and higher superoxide dismutase (SOD) and reactive species (RS); CAT activity decreased for BPF 0.5 and 1 mM. Nevertheless, BPA 0.5 and 1 mM decreased CAT activity, increased RS and lipid peroxidation (LPO), and reduced mitochondrial viability. None of the bisphenols altered the cell viability of male flies, although BPA 0.5 and 1 mM reduced longevity. In female flies, BPA and BPS 0.5 and 1 mM increased RS and LPO levels and decreased CAT activity and glutathione-S-transferase (GST), which may have contributed to lower mitochondrial and cell viability. Furthermore, BPS decreased SOD activity at the 1 mM concentration, and BPA reduced the SOD activity at concentrations of 0.5 and 1 mM. In the BPF 1 mM group, there was a reduction in GST activity and an increase in RS and LPO levels. The toxicological effects were different between sexes, and BPA was more harmful than BPF and BPS in male flies. Thus, our findings showed that females were more susceptible to oxidative cell damage when exposed to BPA and BPS than to BPF, and daily exposure to BPA and BPS at all concentrations reduced female longevity, as well as in BPF 1 mM.

Chemically induced models of Parkinson's disease

Environmental toxins are harmful substances detrimental to humans. Constant exposure to these fatal neurotoxins can cause various neurodegenerative disorders. Although poisonous, specific neurotoxins at optimal concentrations mimic the clinical features of neurodegenerative diseases in several animal models. Such chemically-induced model systems are beneficial in deciphering the molecular mechanisms of neurodegeneration and drug screening for these disorders. One such neurotoxin is 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a widely used chemical that recapitulates Parkinsonian features in various animal models. Apart from MPTP, other neurotoxins like 6-hydroxydopamine (6-OHDA), paraquat, rotenone also induce specific clinical features of Parkinson's disease in animal models. These chemically-induced Parkinson's disease models are playing a crucial role in understanding Parkinson's disease onset, pathology, and novel therapeutics. In this review, we provide a concise overview of various neurotoxins that can recapitulate Parkinsonian features in different in vivo and in vitro model systems specifically focusing on the different treatment methodologies of neurotoxins.

Curcuma longa L. Prevents the Loss of β-Tubulin in the Brain and Maintains Healthy Aging in Drosophila melanogaster

Loss of tubulin is associated with neurodegeneration and brain aging. Turmeric (Curcuma longa L.) has frequently been employed as a spice in curry and traditional medications in the Indian subcontinent to attain longevity and better cognitive performance. We aimed to evaluate the unelucidated mechanism of how turmeric protects the brain to be an anti-aging agent. D. melanogaster was cultured on a regular diet and turmeric-supplemented diet. β-tubulin level and physiological traits including survivability, locomotor activity, fertility, tolerance to oxidative stress, and eye health were analyzed. Turmeric showed a hormetic effect, and 0.5% turmeric was the optimal dose in preventing aging. β-tubulin protein level was decreased in the brain of D. melanogaster upon aging, while a 0.5% turmeric-supplemented diet predominantly prevented this aging-induced loss of β-tubulin and degeneration of physiological traits as well as improved β-tubulin synthesis in the brain of D. melanogaster early to mid-age. The higher concentration (≥ 1%) of turmeric-supplemented diet decreased the β-tubulin level and degenerated many of the physiological traits of D. melanogaster. The turmeric concentration-dependent increase and decrease of β-tubulin level were consistent with the increment and decrement data obtained from the evaluated physiological traits. This correlation demonstrated that turmeric targets β-tubulin and has both beneficial and detrimental effects that depend on the concentration of turmeric. The findings of this study concluded that an optimal dosage of turmeric could maintain a healthy neuron and thus healthy aging, by preventing the loss and increasing the level of β-tubulin in the brain.

Creatine attenuates seizure severity, anxiety and depressive-like behaviors in pentylenetetrazole kindled mice

Epilepsy has been associated with several behavioral changes such as depression and anxiety while some antiepileptic drugs can precipitate psychiatric conditions in patients. This study evaluated the ameliorative effect of creatine on seizure severity and behavioral changes in pentylenetetrazole (PTZ) kindled mice. Mice were kindled by administering sub-convulsive doses of PTZ (35 mg/kg i.p.) at interval of 48 h. The naïve group (n = 7) constituted group 1, while successfully kindled mice were randomly assigned to five groups (n = 7). Group II served as vehicle treated group; groups III-V were treated with creatine 75, 150, and 300 mg/kg/day, p.o; Group V was given 25 mg/kg/day of phenytoin p.o. The treatment was for 15 consecutive days. The intensity of convulsion was scored according to a seven-point scale ranging from stage 0-7. Tail suspension test (TST) and Elevated plus maze (EPM) were utilized to assess depression and anxiety-like behavior respectively. After behavioral evaluation on day 15th, their brain was isolated and assayed for catalase, superoxide dismutase, reduced glutathione, and malondialdehyde. There was a significant (p < 0.05) reduction in the seizure scores, anxiety and depression-like behaviors in mice from the 5th day of treatment. The antioxidant assays revealed significant (p < 0.05) increase in catalase and reduced glutathione, and significant (p < 0.05) reduction in lipid peroxidation in treated mice. This study provides evidence for the seizure reducing property of creatine and its ameliorating potential on anxiety and depressive-like behaviors that follows seizure episodes.

Drosophila as an emerging model organism for studies of food-derived antioxidants

Dietary supplementation with antioxidants provides health benefits by preventing diseases caused by oxidative stress and damage. Consequently, there has been growing interest in the study of antioxidative foods and their active ingredients. Oxidative stress and antioxidative responses are mechanistically conserved from Drosophila to mammals. Therefore, as a well-established model organism with a short life cycle and advantages of genetic manipulation, the fruit fly has been increasingly employed to assess functions of antioxidants in vivo. In this review, the antioxidative defense mechanisms, methods used and assays developed in Drosophila to evaluate antioxidant supplementation, are highlighted. The main manifestations of antioxidation include reduction of reactive species, up-regulation of endogenous antioxidants, inhibition on oxidative damage to biomacromolecules, enhanced resistance against oxidative stress and extension of lifespan, which are related to the activations of nuclear factor erythroid 2-related factor 2-antioxidant response element pathway and other adaptive responses. Moreover, the key considerations and future perspectives for the application of Drosophila models in the studies of food-derived antioxidants are discussed.

Creatine Supplementation, Physical Exercise and Oxidative Stress Markers: A Review of the Mechanisms and Effectiveness

Oxidative stress is the result of an imbalance between the generation of reactive oxygen species (ROS) and their elimination by antioxidant mechanisms. ROS degrade biogenic substances such as deoxyribonucleic acid, lipids, and proteins, which in turn may lead to oxidative tissue damage. One of the physiological conditions currently associated with enhanced oxidative stress is exercise. Although a period of intense training may cause oxidative damage to muscle fibers, regular exercise helps increase the cells' ability to reduce the ROS over-accumulation. Regular moderate-intensity exercise has been shown to increase antioxidant defense. Endogenous antioxidants cannot completely prevent oxidative damage under the physiological and pathological conditions (intense exercise and exercise at altitude). These conditions may disturb the endogenous antioxidant balance and increase oxidative stress. In this case, the use of antioxidant supplements such as creatine can have positive effects on the antioxidant system. Creatine is made up of two essential amino acids, arginine and methionine, and one non-essential amino acid, glycine. The exact action mechanism of creatine as an antioxidant is not known. However, it has been shown to increase the activity of antioxidant enzymes and the capability to eliminate ROS and reactive nitrogen species (RNS). It seems that the antioxidant effects of creatine may be due to various mechanisms such as its indirect (i.e., increased or normalized cell energy status) and direct (i.e., maintaining mitochondrial integrity) mechanisms. Creatine supplement consumption may have a synergistic effect with training, but the intensity and duration of training can play an important role in the antioxidant activity. In this study, the researchers attempted to review the literature on the effects of creatine supplementation and physical exercise on oxidative stress.

The Potential Role of Creatine in Vascular Health

Creatine is an organic compound, consumed exogenously in the diet and synthesized endogenously via an intricate inter-organ process. Functioning in conjunction with creatine kinase, creatine has long been known for its pivotal role in cellular energy provision and energy shuttling. In addition to the abundance of evidence supporting the ergogenic benefits of creatine supplementation, recent evidence suggests a far broader application for creatine within various myopathies, neurodegenerative diseases, and other pathologies. Furthermore, creatine has been found to exhibit non-energy related properties, contributing as a possible direct and in-direct antioxidant and eliciting anti-inflammatory effects. In spite of the new clinical success of supplemental creatine, there is little scientific insight into the potential effects of creatine on cardiovascular disease (CVD), the leading cause of mortality. Taking into consideration the non-energy related actions of creatine, highlighted in this review, it can be speculated that creatine supplementation may serve as an adjuvant therapy for the management of vascular health in at-risk populations. This review, therefore, not only aims to summarize the current literature surrounding creatine and vascular health, but to also shed light onto the potential mechanisms in which creatine may be able to serve as a beneficial supplement capable of imparting vascular-protective properties and promoting vascular health.

Rotenone-induced necrosis in insect cells via the cytoplasmic membrane damage and mitochondrial dysfunction

Rotenone, a selective inhibitor of mitochondrial complex I, has been extensively studied on kinds of neuron and neuroblast in Parkinson's disease. However, little is known about the potential mechanism of this promising botanical insecticide upon insect cells. In the article, cell proliferation of two Lepidoptera cell lines, Spodoptera litura SL-1 cells and Spodoptera frugiperda Sf9 cells, were all inhibited by rotenone in a time- and dose-dependent manner. Typical necrotic characteristics of cell morphology and ultrastructure, such as plasma membrane collapses and organelle lyses, were all observed by transmission electron microscope and scanning electron microscope. Moreover, irregular DNA degradation was also detected by DNA gel electrophoresis and Hoechst 33258 staining, while the typical apoptotic feature, DNA ladder, hadn't been observed. Flow cytometric analysis showed that rotenone-induced cell death of Sf9 and SL-1 cells accompanied with the plasma membrane potential depolarization and mitochondrial membrane potential reduction. Furthermore, the activity of Na⁺-K⁺-ATPase was detected in our study. In conclusion, rotenone could cause necrosis but not apoptosis in insect cells through a mitochondrial- and plasmic membrane-dependent pattern, which shed a light on the rotenone-induced cytotoxicity on insects.

The Evolving Applications of Creatine Supplementation: Could Creatine Improve Vascular Health?

Creatine is a naturally occurring compound, functioning in conjunction with creatine kinase to play a quintessential role in both cellular energy provision and intracellular energy shuttling. An extensive body of literature solidifies the plethora of ergogenic benefits gained following dietary creatine supplementation; however, recent findings have further indicated a potential therapeutic role for creatine in several pathologies such as myopathies, neurodegenerative disorders, metabolic disturbances, chronic kidney disease and inflammatory diseases. Furthermore, creatine has been found to exhibit non-energy-related properties, such as serving as a potential antioxidant and anti-inflammatory. Despite the therapeutic success of creatine supplementation in varying clinical populations, there is scarce information regarding the potential application of creatine for combatting the current leading cause of mortality, cardiovascular disease (CVD). Taking into consideration the broad ergogenic and non-energy-related actions of creatine, we hypothesize that creatine supplementation may be a potential therapeutic strategy for improving vascular health in at-risk populations such as older adults or those with CVD. With an extensive literature search, we have found only four clinical studies that have investigated the direct effect of creatine on vascular health and function. In this review, we aim to give a short background on the pleiotropic applications of creatine, and to then summarize the current literature surrounding creatine and vascular health. Furthermore, we discuss the varying mechanisms by which creatine could benefit vascular health and function, such as the impact of creatine supplementation upon inflammation and oxidative stress.

Herbal medicine for psychiatric disorders: Psychopharmacology and neuroscience-based nomenclature

Objectives: Herbs are frequently and concurrently used with prescribed drugs by patients worldwide. While clinical trials have found some herbs to be as useful as standard psychiatric drugs, most clinicians are unaware of their pharmacological mechanisms.Methods: We searched English language and other language literature with English abstracts listed in PubMed website, supplemented by additional through Google Scholar's free academic paper abstract website for publications on herbs, focussing on their clinical use in mental disorders, their neurobiology and their pharmacology.Results: A major reason for herbs remaining outside of mainstream psychiatry is that the terminology and concepts in herbal medicine are not familiar to psychiatrists in general. Many publications regarding the use of herbal medicine for psychiatric disorders are deficient in details regarding diagnosis, criteria for response and the neurobiology details compared with publications on standard psychotropic drugs. Nomenclature for herbal medicine is usually confusing and is not conducive to an easy understanding of their mode of action in psychiatric disorders.Conclusions: The recent neuroscience-based nomenclature (NbN) for psychotropics methodology would be a logical application to herbal medicine in facilitating a better understanding of the use of herbal medicine in psychiatry.

Deletion of the Creatine Transporter (Slc6a8) in Dopaminergic Neurons Leads to Hyperactivity in Mice

The lack of cerebral creatine (Cr) causes intellectual disability and epilepsy. In addition, a significant portion of individuals with Cr transporter (Crt) deficiency (CTD), the leading cause of cerebral Cr deficiency syndromes (CCDS), are diagnosed with attention-deficit hyperactivity disorder. While the neurological effects of CTD are clear, the mechanisms that underlie these deficits are unknown. Part of this is due to the heterogenous nature of the brain and the unique metabolic demands of specific neuronal systems. Of particular interest related to Cr physiology are dopaminergic neurons, as many CCDS patients have ADHD and Cr has been implicated in dopamine-associated neurodegenerative disorders, such as Parkinson's and Huntington's diseases. The purpose of this study was to examine the effect of a loss of the Slc6a8 (Crt) gene in dopamine transporter (Slc6a3; DAT) expressing cells on locomotor activity and motor function as the mice age. Floxed Slc6a8 (Slc6a8^flox) mice were mated to DAT^IREScre expressing mice to generate DAT-specific Slc6a8 knockouts (dCrt^-/y). Locomotor activity, spontaneous activity, and performance in the challenging beam test were evaluated monthly in dCrt^-/y and control (Slc6a8^flox) mice from 3 to 12 months of age. dCrt^-/y mice were hyperactive compared with controls throughout testing. In addition, dCrt^-/y mice showed increased rearing and hindlimb steps in the spontaneous activity test. Latency to cross the narrow bridge was increased in dCrt^-/y mice while foot slips were unchanged. Taken together, these data suggest that the lack of Cr in dopaminergic neurons causes hyperactivity while sparing motor function.

7-chloro-4-(phenylselanyl) quinoline prevents dopamine depletion in a Drosophila melanogaster model of Parkinson's-like disease

Neurodegeneration in Parkinson's disease appears to be caused by multiple factors, including oxidative damage and an increase in acetylcholinesterase expression that can culminate in loss of dopaminergic neurons. A selenium-containing quinoline derivative, 7-chloro-4-(phenylselanyl) quinoline (4-PSQ), shows important pharmacological actions mainly attributed to its antioxidant and anticholinesterase properties. Thus, this study investigated the neuroprotective effect of 4-PSQ in a model of Parkinson's-like disease induced by rotenone (ROT) in Drosophila melanogaster and verified whether these effects are related to selenium levels. Adult flies were divided into: [1] control, [2] 4-PSQ (25 μM), [3] ROT (500 μM), and [4] 4-PSQ (25 μM) + ROT (500 μM) groups and exposed to a diet containing ROT and/or 4-PSQ for 7 days, according to their respective groups. Survival, behavioral, and ex vivo analyses were performed. Dopamine levels, reactive species levels (RS), lipid peroxidation (LPO), superoxide dismutase (SOD) and catalase (CAT) activity, and proteic thiol (PSH) and non-proteic thiol (NPSH) content in the head region were analyzed, while acetylcholinesterase (AChE) activity and selenium levels in the head and body regions were analyzed. 4-PSQ was able to reverse the ROT-induced deficits in flies, reestablish dopamine and selenium levels, reverse cholinergic deficits, improve motor function, and ameliorate mortality. Furthermore, 4-PSQ also reduced RS levels and LPO, and restored the activities of the antioxidant enzymes, SOD and CAT. Interestingly, a positive relationship between dopamine and selenium levels could be seen. Our results demonstrate the neuroprotective effect of 4-PSQ, and we suggest that the compound may act via different mechanisms, such as improving antioxidant defenses and consequently reducing oxidative damages, as well as having an anticholinesterase action, which together can prevent dopamine depletion, as these actions were correlated with the presence of selenium in the 4-PSQ molecule.

Creatine as a Neuroprotector: an Actor that Can Play Many Parts

Creatine is a nitrogenous organic acid that plays a central role as an energy buffer in high energy demanding systems, including the muscular and the central nervous system. It can be acquired from diet or synthesized endogenously, and its main destination is the system creatine/phosphocreatine that strengthens cellular energetics via a temporal and spatial energy buffer that can restore cellular ATP without a reliance on oxygen. This compound has been proposed to possess secondary roles, such as direct and indirect antioxidant, immunomodulatory agent, and possible neuromodulator. However, these effects may be associated with its bioenergetic role in the mitochondria. Given the fundamental roles that creatine plays in the CNS, several preclinical and clinical studies have tested the potential that creatine has to treat degenerative disorders. However, although in vitro and in vivo animal models are highly encouraging, most clinical trials fail to reproduce positive results suggesting that the prophylactic use for neuroprotection in at-risk populations or patients is the most promising field. Nonetheless, the only clearly positive data of the creatine supplementation in human beings are related to the (rare) creatine deficiency syndromes. It seems critical that future studies must establish the best dosage regime to increase brain creatine in a way that can relate to animal studies, provide new ways for creatine to reach the brain, and seek larger experimental groups with biomarkers for prediction of efficacy.

Impact of probiotics on development and behaviour in Drosophila melanogaster - a potential in vivo model to assess probiotics

In vitro models are frequently used in probiotic research. However, such models often fail to predict in vivo functionality and efficacy. This fact complicates the screening process for selecting the most suitable strains, prior to accomplish expensive animal studies and clinical intervention trials. Therefore, additional sensitive, discriminating and cost-effective models are needed to conduct preliminary assays before undertaking human intervention studies definitely proving efficacy. With this purpose in mind, we explored the potential of axenic Drosophila melanogaster populations as well as of these axenic flies treated with probiotic microbial strains as a model to test the effects of probiotics on a subset of developmental and behavioural traits. An axenic D. melanogaster progeny from the wild-type Canton S strain was obtained and its eggs were further developed until pupae eclosion occurred in growth medium containing either of two probiotic strains: Bifidobacterium animalis subsp. lactis Bb12 or Lactobacillus rhamnosus GG. Whereas B. animalis Bb12 colonised the flies, the capacity of L. rhamnosus LGG to colonise was considerably lower in our experimental conditions. Regarding the influence of microbial load on the flies' development, the axenic condition caused a decrease in egg survival, and lowered adults' average weight with respect to wild-type flies. Both probiotics were able to counteract these effects. An earlier emergence of adults was observed from eggs treated with L. rhamnosus GG in comparison to the other fly populations. The axenic condition did not influence negative geotaxis behaviour in Drosophila; however, flies mono-associated with B. animalis Bb12 moved faster than wild-type. Our results suggest that the use of axenic/probiotic-treated D. melanogaster populations may be an affordable model for preliminary testing of the effects of probiotics on developmental or behavioural aspects.

An ankyrin-binding motif regulates nuclear levels of L1-type neuroglian and expression of the oncogene Myc in Drosophila neurons

L1 cell adhesion molecule (L1CAM) is well-known for its importance in nervous system development and cancer progression. In addition to its role as a plasma membrane protein in cytoskeletal organization, recent in vitro studies have revealed that both transmembrane and cytosolic fragments of proteolytically cleaved vertebrate L1CAM translocate to the nucleus. In vitro studies indicate that nuclear L1CAM affects genes with functions in DNA post-replication repair, cell cycle control, and cell migration and differentiation, but its in vivo role and how its nuclear levels are regulated is less well-understood. Here, we report that mutations in the conserved ankyrin-binding domain affect nuclear levels of the sole Drosophila homolog neuroglian (Nrg) and that it also has a noncanonical role in regulating transcript levels of the oncogene Myc in the adult nervous system. We further show that altered nuclear levels of Nrg correlate with altered transcript levels of Myc in neurons, similar to what has been reported for human glioblastoma stem cells. However, whereas previous in vitro studies suggest that increased nuclear levels of L1CAM promote tumor cell survival, we found here that elevated levels of nuclear Nrg in neurons are associated with increased sensitivity to oxidative stress and reduced life span of adult animals. We therefore conclude that these findings are of potential relevance to the management of neurodegenerative diseases associated with oxidative stress and cancer.

Monitoring α-synuclein multimerization in vivo

The pathophysiology of Parkinson's disease is characterized by the abnormal accumulation of α-synuclein (α-Syn), eventually resulting in the formation of Lewy bodies and neurites in surviving neurons in the brain. Although α-Syn aggregation has been extensively studied in vitro, there is limited in vivo knowledge on α-Syn aggregation. Here, we used the powerful genetics of Drosophila melanogaster and developed an in vivo assay to monitor α-Syn accumulation by using a bimolecular fluorescence complementation assay. We found that both genetic and pharmacologic manipulations affected α-Syn accumulation. Interestingly, we also found that alterations in the cellular protein degradation mechanisms strongly influenced α-Syn accumulation. Administration of compounds identified as risk factors for Parkinson's disease, such as rotenone or heavy metal ions, had only mild or even no impact on α-Syn accumulation in vivo. Finally, we show that increasing phosphorylation of α-Syn at serine 129 enhances the accumulation and toxicity of α-Syn. Altogether, our study establishes a novel model to study α-Syn accumulation and illustrates the complexity of manipulating proteostasis in vivo.-Prasad, V., Wasser, Y., Hans, F., Goswami, A., Katona, I., Outeiro, T. F., Kahle, P. J., Schulz, J. B., Voigt, A. Monitoring α-synuclein multimerization in vivo.

Creatine Protects Against Cytosolic Calcium Dysregulation, Mitochondrial Depolarization and Increase of Reactive Oxygen Species Production in Rotenone-Induced Cell Death of Cerebellar Granule Neurons

Rotenone is a neurotoxin that is an active component of many pesticides which has been shown to induce Parkinsonism in animal models. We show that the cytotoxicity of exposure to nanomolar concentrations of rotenone in cultures of mature cerebellar granule neurons (CGN) in serum-free medium is not due to phagocytosis by glial contamination. A concentration as low as 5.65 ± 0.51 nM of rotenone was enough to trigger 50% cell death of mature CGN in culture after 12 h. The addition of serum proteins to the culture medium attenuated rotenone neurotoxicity, and this can account at least in part for the requirement of higher rotenone concentrations to elicit neuronal cytotoxicity reported in previous works. Creatine partial protection against CGN death promoted by 5 nM rotenone correlated with creatine protection against rotenone-induced mitochondrial depolarization and oxidative stress. Furthermore, creatine largely attenuated the early dysregulation of cytosolic Ca²⁺ concentration after acute rotenone treatment. Noteworthy, our results also revealed that the sustained alteration of Ca²⁺ homeostasis induced by rotenone takes place at the onset of the enhancement of intracellular oxidative stress and before mitochondrial depolarization, pointing out that cytosolic Ca²⁺ dysregulation is a very early event in the rotenone toxicity to CGN.

Protective effect of (−)-α-bisabolol on rotenone-induced toxicity in Drosophila melanogaster

(−)-α-Bisabolol (BISA) is a sesquiterpene alcohol, which has several recognized biological activities, including anti-inflammatory, anti-irritant, and antibacterial properties. In the present study, we investigated the influence of BISA (5, 25, and 250 μmol/L) on rotenone (500 μmol/L)-induced toxicity in Drosophila melanogaster for 7 days. BISA supplementation significantly decreased rotenone-induced mortality and locomotor deficits. The loss of motor function induced by rotenone correlated with a significant change in stress response factors; it decreased thiol levels, inhibited mitochondria complex I, and increased the mRNA expression of antioxidant marker proteins such as superoxide dismutase (SOD), catalase (CAT), and the keap1 gene product. Taken together, our findings indicate that the toxicity of rotenone is likely due to the direct inhibition of complex I activity, resulting in a high level of oxidative stress. Dietary supplementation with BISA affected the expression of SOD mRNA only at a concentration of 250 μmol/L, and did not affect any other parameter measured. Our results showed a protective effect of BISA on rotenone-induced mortality and locomotor deficits in Drosophila; this effect did not correlate with mitochondrial complex I activity, but may be related to the antioxidant protection afforded by eliminating superoxide generated as a result of rotenone-induced mitochondrial dysfunction.

Parkinson's Disease Model

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. It is known that there are many factors, either genetic or environmental factors, involved in PD, but the mechanism of PD is still not fully understood. Several animal models have been established to study the mechanisms of PD. Among these models, Drosophila melanogaster has been utilized as a valuable model to get insight into important features of PD. Drosophila melanogaster possesses a well-developed dopaminergic (DA) neuron system which is known to play an important role in PD pathogenesis. The well understanding of DA neurons from early larval through adult stage makes Drosophila as a powerful model for investigating the progressive neurodegeneration in PD. Besides, the short life cycle of Drosophila melanogaster serves an advantage in studying epidemiological features of PD. Most of PD symptoms can be mimicked in Drosophila model such as progressive impairment in locomotion, DA neuron degeneration, and some other non-motor symptoms. The Drosophila models of PD, therefore, show a great potential in application for PD genetic and drug screening.

The Combination of Physical Exercise with Muscle-Directed Antioxidants to Counteract Sarcopenia: A Biomedical Rationale for Pleiotropic Treatment with Creatine and Coenzyme Q10

Sarcopenia represents an increasing public health risk due to the rapid aging of the world's population. It is characterized by both low muscle mass and function and is associated with mobility disorders, increased risk of falls and fractures, loss of independence, disabilities, and increased risk of death. Despite the urgency of the problem, the development of treatments for sarcopenia has lagged. Increased reactive oxygen species (ROS) production and decreased antioxidant (AO) defences seem to be important factors contributing to muscle impairment. Studies have been conducted to verify whether physical exercise and/or AOs could prevent and/or delay sarcopenia through a normalization of the etiologically relevant ROS imbalance. Despite the strong rationale, the results obtained were contradictory, particularly with regard to the effects of the tested AOs. A possible explanation might be that not all the agents included in the general heading of "AOs" could fulfill the requisites to counteract the complex series of events causing/accelerating sarcopenia: the combination of the muscle-directed antioxidants creatine and coenzyme Q10 with physical exercise as a biomedical rationale for pleiotropic prevention and/or treatment of sarcopenia is discussed.

NMR-based metabolomic analysis for the effects of creatine supplementation on mouse myoblast cell line C2C12

Creatine (Cr) supplementation has drawn much attention from researchers owing to its widespread efficacy in sports, and more recently, in therapeutic fields. However, the underlying molecular mechanisms remain elusive. Here, we performed nuclear magnetic resonance-based metabolomic analysis to address the metabolic profile of aqueous extracts from the mouse myoblast cell line C2C12 exposed to 2 mM Cr for 24 h (the Cr-treated group). Results showed that Cr supplementation facilitated the proliferation of C2C12 myoblasts. Both pattern recognition and hierarchical cluster analyses demonstrated that the metabolic profiles of the Cr-treated and control groups were distinctly different. We identified 13 characteristic metabolites significantly responsible for the discrimination of metabolic profiles between the two groups, through orthogonal projection to latent structures discriminant analysis and independent samples t-test. We further verified the discrimination performances of these metabolites by conducting univariate receiver operating characteristic curve analysis. Compared with the control group, the Cr-treated group exhibited increased levels of Cr, phosphocreatine (PCr), glutathione (GSH), and glucose, but decreased levels of leucine, valine, isoleucine, phenylalanine, methionine, choline, O-phosphocholine, sn-glycero-3-phosphocholine, and glycerol. Our results demonstrated that Cr supplementation upregulated PCr and glucose, promoted trichloroacetic acid cycle anaplerotic flux and GSH-mediated antioxidant capacity, and stabilized lipid membranes through suppressing glycerophospholipid metabolism. Our work provides new clues to the molecular mechanisms underlying the pleiotropic effects of Cr in muscle cells.

Creatine Enhances Mitochondrial-Mediated Oligodendrocyte Survival After Demyelinating Injury

Chronic oligodendrocyte loss, which occurs in the demyelinating disorder multiple sclerosis (MS), contributes to axonal dysfunction and neurodegeneration. Current therapies are able to reduce MS severity, but do not prevent transition into the progressive phase of the disease, which is characterized by chronic neurodegeneration. Therefore, pharmacological compounds that promote oligodendrocyte survival could be beneficial for neuroprotection in MS. Here, we investigated the role of creatine, an organic acid involved in adenosine triphosphate (ATP) buffering, in oligodendrocyte function. We found that creatine increased mitochondrial ATP production directly in oligodendrocyte lineage cell cultures and exerted robust protection on oligodendrocytes by preventing cell death in both naive and lipopolysaccharide-treated mixed glia. Moreover, lysolecithin-mediated demyelination in mice deficient in the creatine-synthesizing enzyme guanidinoacetate-methyltransferase (Gamt) did not affect oligodendrocyte precursor cell recruitment, but resulted in exacerbated apoptosis of regenerated oligodendrocytes in central nervous system (CNS) lesions. Remarkably, creatine administration into Gamt-deficient and wild-type mice with demyelinating injury reduced oligodendrocyte apoptosis, thereby increasing oligodendrocyte density and myelin basic protein staining in CNS lesions. We found that creatine did not affect the recruitment of macrophages/microglia into lesions, suggesting that creatine affects oligodendrocyte survival independently of inflammation. Together, our results demonstrate a novel function for creatine in promoting oligodendrocyte viability during CNS remyelination.SIGNIFICANCE STATEMENT We report that creatine enhances oligodendrocyte mitochondrial function and protects against caspase-dependent oligodendrocyte apoptosis during CNS remyelination. This work has important implications for the development of therapeutic targets for diseases characterized by oligodendrocyte death, including multiple sclerosis.

Biomolecular characterization of exosomes released from cancer stem cells: Possible implications for biomarker and treatment of cancer

Cancer recognized as one of the leading irrepressible health issues is contributing to increasing mortality-rate day-by-day. The tumor microenvironment is an important field of cancer to understand the detection, treatment and prevention of cancer. Recently, cancer stem cell (CSC) research has shown promising results aiming towards cancer diagnostics and treatment. Here, we found that prostate and breast cancer stem cells secreted vesicles of endosomal origin, called exosomes showed strong connection between autophagy and exosomes released from CSCs. Exosomes may serve as vesicles to communicate with neoplastic cells (autocrine and paracrine manner) and normal cells (paracrine and endocrine manner) and thereby suppress immune systems and regulate neoplastic growth, and metastasis. They can also be used as biomarkers for various cancers. We detected tetraspanin proteins (CD9, CD63, CD81), Alix and tumor susceptibility gene-101 (TSG101) of exosomal markers from rotenone treated CSCs. We have also detected the induction of autophagy genes, Atg7 and conversion of autophagy marker (LC3-I to LC3-II), and tetraspanin proteins (CD9, CD63, CD81) in rotenone treated CSCs by western blotting. The mRNA expression of CD9, CD63, CD81 and TSG101 analyzed by qRT-PCR showed that the rotenone induced the expression of CD9, CD63, CD81 and TSG101 in CSCs. Electron microscopy of rotenone treated CSCs showed the mitochondrial damage of CSCs as confirmed by the release of exosomes from CSCs. The constituents of exosomes may be useful to understand the mechanism of exosomes formation, release and function, and also serve as a useful biomarker and provide novel therapeutic strategies for the treatment and prevention of cancer.

Creatine affords protection against glutamate-induced nitrosative and oxidative stress

Creatine has been reported to exert beneficial effects in several neurodegenerative diseases in which glutamatergic excitotoxicity and oxidative stress play an etiological role. The purpose of this study was to investigate the protective effects of creatine, as compared to the N-Methyl-d-Aspartate (NMDA) receptor antagonist dizocilpine (MK-801), against glutamate or hydrogen peroxide (H2O2)-induced injury in human neuroblastoma SH-SY5Y cells. Exposure of cells to glutamate (60-80 mM) or H2O2 (200-300 μM) for 24 h decreased cellular viability and increased dichlorofluorescein (DCF) fluorescence (indicative of increased reactive oxygen species, ROS) and nitric oxide (NO) production (assessed by mono-nitrogen oxides, NOx, levels). Creatine (1-10 mM) or MK-801 (0.1-10 μM) reduced glutamate- and H2O2-induced toxicity. The protective effect of creatine against glutamate-induced toxicity involves its antioxidant effect, since creatine, similar to MK-801, prevented the increase on DCF fluorescence induced by glutamate or H2O2. Furthermore, creatine or MK-801 blocked glutamate- and H2O2-induced increases in NOx levels. In another set of experiments, the repeated, but not acute, administration of creatine (300 mg/kg, po) in mice prevented the decreases on cellular viability and mitochondrial membrane potential (assessed by tetramethylrhodamine ethyl ester, TMRE, probe) of hippocampal slices incubated with glutamate (10 mM). Creatine concentration-dependent decreased the amount of nitrite formed in the reaction of oxygen with NO produced from sodium nitroprusside solution, suggesting that its protective effect against glutamate or H2O2-induced toxicity might be due to its scavenger activity. Overall, the results suggest that creatine may be useful as adjuvant therapy for neurodegenerative disease treatments.

An update on the rotenone models of Parkinson's disease: their ability to reproduce the features of clinical disease and model gene-environment interactions

Parkinson's disease (PD) is the second most common neurodegenerative disorder that is characterized by two major neuropathological hallmarks: the degeneration of dopaminergic neurons in the substantia nigra (SN) and the presence of Lewy bodies in the surviving SN neurons, as well as other regions of the central and peripheral nervous system. Animal models have been invaluable tools for investigating the underlying mechanisms of the pathogenesis of PD and testing new potential symptomatic, neuroprotective and neurorestorative therapies. However, the usefulness of these models is dependent on how precisely they replicate the features of clinical PD with some studies now employing combined gene-environment models to replicate more of the affected pathways. The rotenone model of PD has become of great interest following the seminal paper by the Greenamyre group in 2000 (Betarbet et al., 2000). This paper reported for the first time that systemic rotenone was able to reproduce the two pathological hallmarks of PD as well as certain parkinsonian motor deficits. Since 2000, many research groups have actively used the rotenone model worldwide. This paper will review rotenone models, focusing upon their ability to reproduce the two pathological hallmarks of PD, motor deficits, extranigral pathology and non-motor symptoms. We will also summarize the recent advances in neuroprotective therapies, focusing on those that investigated non-motor symptoms and review rotenone models used in combination with PD genetic models to investigate gene-environment interactions.

Phytochemical Constituents and Toxicity of Duguetia furfuracea Hydroalcoholic Extract in Drosophila melanogaster

Duguetia furfuracea is frequently used as a medicinal plant in Brazil. However, studies have evidenced its cytotoxic, bactericide, and antitumor activities. In the present study we aimed to evaluate the potential toxicity of hydroalcoholic leaves extracts of D. furfuracea (HEDF) in a Drosophila melanogaster model. Toxicity was assessed as changes in locomotor performance, mitochondrial activity, oxidative stress, MAPKs phosphorylation, and apoptosis induction after exposure to HEDF concentrations (1–50 mg/mL) for 7 days. The phytoconstituents of the plant were screened for the presence of alkaloids, tannins, xanthones, chalcones, flavonoids, aurones, and phenolic acids. Exposure of adult flies to HEDF caused mitochondrial dysfunction, overproduction of ROS, and alterations in the activity of detoxifying enzymes GST, SOD and CAT. Induction of ERK phosphorylation and PARP cleavage was also observed, indicating occurrence of HEDF-induced cell stress and apoptotic cell death. In parallel, alterations in cholinesterase activity and impairments in negative geotaxis behavior were observed. Our study draws attention to the indiscriminate use of this plant by population and suggests oxidative stress as a major mechanism underlying its toxicity.

Both creatine and its product phosphocreatine reduce oxidative stress and afford neuroprotection in an in vitro Parkinson's model

Creatine is the substrate for creatine kinase in the synthesis of phosphocreatine (PCr). This energetic system is endowed of antioxidant and neuroprotective properties and plays a pivotal role in brain energy homeostasis. The purpose of this study was to investigate the neuroprotective effect of creatine and PCr against 6-hydroxydopamine (6-OHDA)-induced mitochondrial dysfunction and cell death in rat striatal slices, used as an in vitro Parkinson's model. The possible involvement of the signaling pathway mediated by phosphatidylinositol-3 kinase (PI3K), protein kinase B (Akt), and glycogen synthase kinase-3β (GSK3β) was also evaluated. Exposure of striatal slices to 6-OHDA caused a significant disruption of the cellular homeostasis measured as 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide reduction, lactate dehydrogenase release, and tyrosine hydroxylase levels. 6-OHDA exposure increased the levels of reactive oxygen species and thiobarbituric acid reactive substances production and decreased mitochondrial membrane potential in rat striatal slices. Furthermore, 6-OHDA decreased the phosphorylation of Akt (Serine(473)) and GSK3β (Serine(9)). Coincubation with 6-OHDA and creatine or PCr reduced the effects of 6-OHDA toxicity. The protective effect afforded by creatine or PCr against 6-OHDA-induced toxicity was reversed by the PI3K inhibitor LY294002. In conclusion, creatine and PCr minimize oxidative stress in striatum to afford neuroprotection of dopaminergic neurons.

A dopamine receptor contributes to paraquat-induced neurotoxicity in Drosophila

Long-term exposure to environmental oxidative stressors, like the herbicide paraquat (PQ), has been linked to the development of Parkinson's disease (PD), the most frequent neurodegenerative movement disorder. Paraquat is thus frequently used in the fruit fly Drosophila melanogaster and other animal models to study PD and the degeneration of dopaminergic neurons (DNs) that characterizes this disease. Here, we show that a D1-like dopamine (DA) receptor, DAMB, actively contributes to the fast central nervous system (CNS) failure induced by PQ in the fly. First, we found that a long-term increase in neuronal DA synthesis reduced DAMB expression and protected against PQ neurotoxicity. Secondly, a striking age-related decrease in PQ resistance in young adult flies correlated with an augmentation of DAMB expression. This aging-associated increase in oxidative stress vulnerability was not observed in a DAMB-deficient mutant. Thirdly, targeted inactivation of this receptor in glutamatergic neurons (GNs) markedly enhanced the survival of Drosophila exposed to either PQ or neurotoxic levels of DA, whereas, conversely, DAMB overexpression in these cells made the flies more vulnerable to both compounds. Fourthly, a mutation in the Drosophila ryanodine receptor (RyR), which inhibits activity-induced increase in cytosolic Ca(2+), also strongly enhanced PQ resistance. Finally, we found that DAMB overexpression in specific neuronal populations arrested development of the fly and that in vivo stimulation of either DNs or GNs increased PQ susceptibility. This suggests a model for DA receptor-mediated potentiation of PQ-induced neurotoxicity. Further studies of DAMB signaling in Drosophila could have implications for better understanding DA-related neurodegenerative disorders in humans.

Standardized extract of Withania somnifera (Ashwagandha) markedly offsets rotenone-induced locomotor deficits, oxidative impairments and neurotoxicity in Drosophila melanogaster

Withania somnifera (Ashwagandha, WS) or Indian ginseng possesses multiple pharmacological properties which are mainly attributed to the active constituents, withanolides. Despite its extensive usage as a memory enhancer and a nerve tonic, few attempts have been made to ascertain its usage in the management of Parkinson's disease. In the present study, we investigated the neuroameliorative effects of WS in a rotenone (ROT) model of Drosophila melanogaster (Oregon-K). Initially, we ascertained the ability of WS-enriched diet (0-0.05 %) to protect against ROT induced lethality and locomotor phenotype in adult male flies. Further, employing a co-exposure paradigm, we investigated the propensity of WS to offset ROT-induced oxidative stress, mitochondrial dysfunctions and neurotoxicity. WS conferred significant protection against ROT-induced lethality, while the survivor flies exhibited improved locomotor phenotype. Biochemical investigations revealed that ROT-induced oxidative stress was significantly diminished by WS enrichment. WS caused significant elevation in the levels of reduced GSH/non-protein thiols. Furthermore, the altered activity levels of succinate dehydrogenase, MTT, membrane bound enzymes viz., NADH-cytochrome-c reductase and succinate-cytochrome-c reductase were markedly restored to normalcy. Interestingly, ROT-induced perturbations in cholinergic function and depletion in dopamine levels were normalized by WS. Taken together these data suggests that the neuromodulatory effect of WS against ROT- induced neurotoxicity is probably mediated via suppression of oxidative stress and its potential to attenuate mitochondrial dysfunctions. Our further studies aim to understand the underlying neuroprotective mechanisms of WS and withanolides employing neuronal cell models.

Neuroprotective effect of Decalepis hamiltonii in paraquat-induced neurotoxicity in Drosophila melanogaster: biochemical and behavioral evidences

In this paper, we have demonstrated for the first time, the antioxidant and neuroprotective effects of Decalepis hamiltonii (Dh) root extract against paraquat (PQ)-induced oxidative stress and neurotoxicity in Drosophila melanogaster. Exposure of adult D. melanogaster (Oregon K) to PQ induced oxidative stress as evidenced by glutathione depletion, lipid peroxidation and enhanced activities of antioxidant enzymes such as catalase, superoxide dismutase as well as elevated levels of acetylcholine esterase. Pretreatment of flies by feeding with Dh extract (0.1, 0.5 %) for 14 days boosted the activities of antioxidant enzymes and prevented the PQ-induced oxidative stress. Dietary feeding of Dh extract prior to PQ exposure showed a lower incidence of mortality and enhanced motor activities of flies in a negative geotaxis assay; both suggesting the neuroprotective potential of Dh. Based on the results, we contemplate that the roots of Dh might prevent and ameliorate the human diseases caused by oxidative stress. The neuroprotective action of Dh can be attributed to the antioxidant constituents while the precise mechanism of its action needs further investigations.

Acute exposure of Drosophila melanogaster to paraquat causes oxidative stress and mitochondrial dysfunction

Paraquat (PQ; 1, 1'-dimethyl-4-4'-bipyridinium), an herbicide and model neurotoxicant, is identified to be one of the prime risk factors in Parkinson's disease (PD). In the Drosophila system, PQ is commonly used to measure acquired resistance against oxidative stress (PQ resistance test). Despite this, under acute PQ exposure, data on the oxidative stress response and associated impact on mitochondria among flies is limited. Accordingly, in this study, we measured markers of oxidative stress and mitochondrial dysfunctions among adult male flies (8-10 days old) exposed to varying concentrations of PQ (10, 20, and 40 mM in 5% sucrose solution) employing a conventional filter disc method for 24 h. PQ exposure resulted in significant elevation in the levels of oxidative stress biomarkers (malondialdehyde: 43% increase: hydroperoxide: 32-39% increase), with concomitant enhancement in reduced glutathione and total thiol levels in cytosol. Higher activity of antioxidant enzymes were also evident along with increased free iron levels. Furthermore, PQ exposure caused a concentration-dependent increase in mitochondrial superoxide generation and activity of manganese-superoxide dismutase (Mn-SOD). The activity levels of complex I-III, complex II-III, and Mg+2 adinosine triphosphatase (ATPase) were also decreased significantly. A robust diminution in the activity of succinate dehydrogenase and moderate decline in the citrate synthase activity suggested a specific effect on citric acid cycle enzymes. Collectively, these data suggest that acute PQ exposure causes significant oxidative stress and mitochondrial dysfunction among flies in vivo. It is suggested that in various experimental settings, while conducting the "PQ resistance stress test" incorporation of selected biochemical end points is likely to enhance the quality of the data.

Sodium butyrate improves locomotor impairment and early mortality in a rotenone-induced Drosophila model of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder primarily affecting the dopaminergic neurons in the nigrastriatal pathway resulting in debilitating motor impairment in both familial and sporadic cases. Histone deacetylase (HDAC) inhibitors have been recently implicated as a therapeutic candidate because of their ability to correct the disrupted HDAC activity in PD and other neurodegenerative diseases. Sodium butyrate (SB), an HDAC inhibitor, reduces degeneration of dopaminergic neurons in a mutant alpha-synuclein Drosophila transgenic model of familial PD. Chronic exposure to the pesticide rotenone also causes selective degeneration of dopaminergic neurons and causes locomotor impairment and early mortality in a Drosophila model of chemically induced PD. This study investigated the effects of sodium butyrate on locomotor impairment and early mortality in a rotenone-induced PD model. We show that treatment with 10mM SB-supplemented food rescued the rotenone-induced locomotor impairment and early mortality in flies. Additionally, flies with the genetic knockdown of HDAC activity through Sin3A loss-of-function mutation (Sin3A(lof)) were resistant to rotenone-induced locomotor impairment and early mortality. Furthermore, SB-supplemented Sin3A(lof) flies had a modest additive effect for improving locomotor impairment. We also show SB-mediated improvement of rotenone-induced locomotor impairment was associated with elevated dopamine levels in the brain. However, the possibility of SB-mediated protective role through mechanisms independent from dopamine system is also discussed. These findings demonstrate that HDAC inhibitors like SB can ameliorate locomotor impairment in a rotenone-induced PD model.