L-tyrosine administration increases acetylcholinesterase activity in rats

Bioaccumulation and behavioral response patterns of crucian carp (Carassius carassius) after carbamazepine exposure and elimination

The antiepileptic drug carbamazepine (CBZ) has been widely detected in freshwater, yet its toxic actions in fish at multiple endpoints and the subsequent recovery patterns of the impacted are less discussed. This study investigated the bioaccumulation, physiological and behavioral changes of crucian carp (Carassius carassius) following CBZ exposure (G1 = 6.15 μg/L, G2 = 61.5 μg/L, G3 = 615 μg/L, G4 = 6150 μg/L) and subsequent recovery. Our results showed that CBZ was more likely to accumulate in the liver and brain than in the gills. A concentration-dependent phenomenon was observed; however, the residual CBZ decreased to similar levels after recovery. The behavioral indicators (i.e. feeding, social and spontaneous swimming) were significantly inhibited after 7-days of CBZ exposure, and only recovered at low concentration treatment (G1) after 7-days recovery in CBZ-free water. The acetylcholinesterase (AChE) activity in the brain and superoxide dismutase (SOD) activity in the liver and gills were induced after CBZ exposure and returned to normal levels after 7-days of recovery. In contrast, the inhibition of catalase (CAT) activity caused by CBZ exposure persisted in the high concentration treatment (G4) after recovery. Furthermore, correlation analysis indicated that changes in feeding behavior were closely related to the variation of CBZ concentrations in tissues, and the persistence of abnormal swimming and social behavior was closely related to gill CAT activity. These findings contribute to explore the toxic mechanisms of CBZ and highlight the recovery process and connections between various endpoints.

Biotoxicity of silver nanoparticles complicated by the co-existence of micro-/nano-plastics

Silver nanoparticles (AgNP) and polystyrene (PS) plastics have been broadly utilized in various field, e.g., food storage, packaging materials, and medical therapies. However, investigation on the potential biotoxicity induced by the co-exposure to AgNP and PS plastics remains understudied. Thus, we performed this study to examine the toxicological profile of the co-exposure to AgNP and PS in mice. Biochemical and microbial characterizations were performed in mice receiving 90-day oral gavage feeding to examine the hepatotoxicity, neurotoxicity, inflammatory responses, gut microbial alterations. It has been found that the presence of plastic particles aggravates the toxicity of silver nanoparticle materials. Regardless of the plastic type and size, energy and choline metabolisms will be altered by the co-exposures. Moreover, microplastics may induce cell damage by modulating fatty acid peroxidation in unison with stimulating inflammatory responses. Due to the smaller size of nanoplastics, they may pass through blood-brain barrier to induce neuronal damage and increase vascular risks. Changes in the microbial functional abundances are sensitive to the microplastics doses. These results support the necessity of reducing the co-exposure between AgNP and multiscale plastics, and advocate further developments of biodegradable package materials to improve food safety.

Toxicity of gold nanoparticles complicated by the co-existence multiscale plastics

Introduction

Gold nanoparticles (AuNPs) have been developed as treatment materials for various diseases and shown magnificent potential. By contrast to the broad toxicological studies on the single exposure (AuNPs), how the other health risks modulate the toxicological profile of AuNPs remains to be investigated. Plastics are among the most common health risks in daily life due to the broad utilization of plastic products. Therefore, in this study, we aimed to reveal the toxicological effects induced by co-exposure of gold nanorod (AuR) and polystyrene micro- and nano-plastics (hereinafter, referred to as AuRmPS and AuRnPS, respectively) in mice.

Methods

Systematic biochemical characterizations were performed to investigate the hepatotoxicity, nephrotoxicity, neurotoxicity, inflammatory responses, alterations in gut microbiota induced by co-exposure, and to analyze the toxicological phenomena from the roles of reactive oxygen species and gut-organ axis.

Results

It has been found that hepatotoxicity, nephrotoxicity, neurotoxicity, and inflammation were exacerbated in AuRnPS and AuRmPS, and gut microbiota composition was more severely altered in AuRnPS exposure. These results suggest the necessity of reducing plastics exposure in AuNPs-based therapies. Moreover, protection against the nano-sized plastic particles holds higher priority.

Conclusion

These findings will facilitate the explorations of methods to reduce therapeutic toxicity and improve biosafety for specific treatments by referring to the orders of importance in protecting different organs.

Molecular, behavioral, and growth responses of juvenile yellow catfish (Tachysurus fulvidraco) exposed to carbamazepine

Carbamazepine (CBZ) is an anticonvulsant medication used to treat epilepsy and bipolar disorder. Due to its persistence and low removal rate in wastewater treatment plants, it is frequently detected in the environment, raising concerns regarding its potential adverse effects on aquatic organisms and ecosystems. In this study, we aimed to assess the impact of CBZ on the behavior and growth of juvenile yellow catfish Tachysurus fulvidraco, a native and economically important species in China. Fish were exposed to CBZ at three concentrations of 1, 10, or 100 µg/L for 14 days. The fish exposed to 10 and 100 μg/L of CBZ exhibited decreased feeding, and a significant increase in cannibalistic tendencies was observed in fish exposed to 100 μg/L CBZ. Acetylcholinesterase activity was increased in the brain of fish exposed to 100 μg/L CBZ. CBZ also inhibited the growth of yellow catfish. To better elucidate mechanisms of toxicity, transcriptomics was conducted in both the brain and liver. In the brain, gene networks associated with neurotransmitter dysfunction were altered by CBZ, as well as networks associated with mitochondrial dysfunction and metabolism. In the liver, gene networks associated with the immune system were altered by CBZ. The current study improves comprehension of the sub-lethal effects of CBZ and reveals novel insight into molecular and biochemical pathways disrupted by CBZ, identifying putative key events associated with reduced growth and altered behavior. This study emphasizes the necessity for improved comprehension of the effects of pharmaceutical contaminants on fish at environmentally relevant levels.

Current Landscape on Development of Phenylalanine and Toxicity of its Metabolites - A Review

Phenylalanine, an essential amino acid, is the "building block" of protein. It has a tremendous role in different aspects of metabolic events. The tyrosine pathway is the prime one and is typically used to degrade dietary phenylalanine. Phenylalanine exceeds its limit in bodily fluids and the brain when the enzyme, phenylalanine decarboxylase, phenylalanine transaminase, phenylalanine hydroxylase (PAH) or its cofactor tetrahydrobiopterin (BH4) is deficient causes phenylketonuria, schizophrenia, attentiondeficit/ hyperactivity disorder and another neuronal effect. Tyrosine, an amino acid necessary for synthesizing the pigments in melanin, is produced by its primary metabolic pathway. Deficiency/abnormality in metabolic enzymes responsible for the catabolism pathway of Phenylalanine causes an accumulation of the active intermediate metabolite, resulting in several abnormalities, such as developmental delay, tyrosinemias, alkaptonuria, albinism, hypotension and several other undesirable conditions. Dietary restriction of the amino acid(s) can be a therapeutic approach to avoid such undesirable conditions when the level of metabolic enzyme is unpredictable. After properly identifying the enzymatic level, specific pathophysiological conditions can be managed more efficiently.

The potential impacts of micro-and-nano plastics on various organ systems in humans

Humans are exposed to micro-and-nano plastics (MNPs) through various routes, but the adverse health effects of MNPs on different organ systems are not yet fully understood. This review aims to provide an overview of the potential impacts of MNPs on various organ systems and identify knowledge gaps in current research. The summarized results suggest that exposure to MNPs can lead to health effects through oxidative stress, inflammation, immune dysfunction, altered biochemical and energy metabolism, impaired cell proliferation, disrupted microbial metabolic pathways, abnormal organ development, and carcinogenicity. There is limited human data on the health effects of MNPs, despite evidence from animal and cellular studies. Most of the published research has focused on specific types of MNPs to assess their toxicity, while other types of plastic particles commonly found in the environment remain unstudied. Future studies should investigate MNPs exposure by considering realistic concentrations, dose-dependent effects, individual susceptibility, and confounding factors.

Glyphosate is Harmful to Early Life Stages of the Viviparous Fish Jenynsia Multidentata: Biochemical and Locomotor Effects

Glyphosate is the most widely used herbicide worldwide due to its efficacy in weed control in agriculture. This herbicide has been consistently detected in the aquatic environment, causing harmful consequences to nontarget organisms residing in agricultural regions. In this study, we assessed the effects of environmentally relevant concentrations of glyphosate (30-100 µg/L) on the early life stages of the viviparous fish Jenynsia multidentata through biochemical and locomotor endpoints. At 96 h of exposure, 30 and 65 µg/L glyphosate caused an increase in acetylcholinesterase (AChE) activity, and 65 µg/L glyphosate also augmented the levels of lipid peroxidation. Glyphosate at 100 µg/L did not alter the activity of acetylcholinesterase or the levels of lipid peroxidation, but it stimulated the activity of the cellular detoxification enzyme glutathione S-transferase. In addition, all concentrations affected the swimming of the fish. Under light conditions, glyphosate caused hypolocomotion at all concentrations tested, whereas under dark conditions, this was observed at 30 and 100 µg/L. Hyperlocomotion was observed at 65 µg/L glyphosate. These findings are alarming for the health of fish, such as J. multidentata that inhabit streams that pass through agricultural areas, especially for the early life stages of these fish. Research studying the effects of pollutants on native species is relevant to improve regulation that protects aquatic ecosystems.

Metabolic profiles and fingerprints for the investigation of the influence of nitisinone on the metabolism of the yeast Saccharomyces cerevisiae

Nitisinone (2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione, NTBC) is considered a potentially effective drug for the treatment of various metabolic diseases associated with disorders of L-tyrosine metabolism however, side-effects impede its widespread use. This work aimed to broaden the knowledge of the influence of NTBC and its metabolites 2-amino-4-(trifluoromethyl)benzoic acid (ATFA), 2-nitro-4-(trifluoromethyl)benzoic acid (NTFA), and cyclohexane-1,3-dione (CHD) on the catabolism of L-tyrosine and other endogenous compounds in Saccharomyces cerevisiae. Based on a targeted analysis performed by LC-ESI-MS/MS, based on multiple reaction monitoring, it was found that the dissipation kinetics of the parent compound and its metabolites are compatible with a first-order reaction mechanism. Moreover, it has been proven that formed NTBC metabolites, such as CHD, cause a decrease in L-tyrosine, L-tryptophan, and L-phenylalanine concentrations by about 34%, 59% and 51%, respectively, compared to the untreated model organism. The overall changes in the metabolism of yeast exposed to NTBC or its derivatives were evaluated by non-targeted analysis via LC-ESI-MS/MS in the ion trap scanning mode. Based on principal components analysis, a statistically significant similarity between metabolic responses of yeast treated with ATFA or NTFA was observed. These findings facilitate further studies investigating the influence of NTBC on the human body and the mechanism of its action.

Assessing the size-dependent effects of microplastics on zebrafish larvae through fish lateral line system and gut damage

This study evaluated the size-dependent effects of high-density polyethylene (HDPE) fragments in zebrafish. Larvae were exposed to HDPE microplastic (MP) in three sizes, small (14.12 μm), medium (80.32 μm), and large (120.97 μm), at 20 mg/L. Size-dependent effects in terms of MP intake, subsequent gut damage, and behavioral changes were observed. The results showed that HDPE exposure did not affect the survivability of zebrafish larvae but caused two significant changes. First, exposure to large MPs caused the most serious damage to hair cells and mechanosensory receptors in the fish's lateral line system. Second, exposure to MPs < 100 μm resulted in their ingestion by larvae, thereby causing morphological changes in the gastrointestinal tract. All larvae exposed to MPs showed behavioral pattern changes associated with size differences. This study improves our understanding of the effects of MPs on aquatic organisms and highlights the need to implement efficient strategies for plastic waste management.

Micro- and nanoplastic contamination in livestock production: Entry pathways, potential effects and analytical challenges

The abundant and widespread presence of particulate plastics in the environment is considered an area of increasing environmental, animal and human health concern. Despite the abundance and the potential to cause deleterious biological effects, studies related to the impact of micro and nanoplastics (MNPs) on livestock animals are limited. This review evaluates the sources and entry pathways of particulate plastics in all the types of livestock production systems. The potential health effects of MNPs on mouse models, ruminant animals and a few other livestock animals are discussed. Since evaluation of MNPs in almost all types of matrices in hindered by analytical challenges, this review also evaluates the commonly used methods, emerging techniques, and quality control/quality assurance (QC/QA) procedures. Plastic mulching, fragmentation of plastic wastes and stream water runoff have been identified as major routes of MNPs entry in grazing-based and mixed livestock production systems. Notwithstanding the controlled indoor environment and relatively efficient waste management, MNPs have been detected in industrial livestock systems. The bioaccumulation and biomagnification of chemical toxicants can exacerbate the adverse effects of MNPs on higher trophic level species. Although there are several methods for the analysis of MNPs, dearth of standardized methods, certified reference materials, MPs standards, and global database libraries are major impediments. The adverse effects of MNPs on the internal organs of different livestock animals have to be studied using large sample sizes and without raising ethical concerns. Importantly, investigations on the accurate quantification of MNPs and its adverse effects in various livestock animals using rapid, cost-effective and robust analytical methods are required.

Chronic Effects of Carbamazepine, Progesterone and Their Mixtures at Environmentally Relevant Concentrations on Biochemical Markers of Zebrafish (Danio rerio)

The impact of pharmaceuticals on non-target organisms in the environment is of increasing concern and study. Pharmaceuticals and other pollutants are often present as mixtures in an environmental compartment. Studies on the toxicological implications of these drugs on fish, particularly as mixtures at environmentally relevant concentrations, are very limited. Thus, this study aimed to evaluate the chronic effects of the anticonvulsant drug carbamazepine (CBZ) and progesterone (P4) at environmentally relevant concentrations, individually and in binary mixtures, applying a suite of biomarkers at the molecular level in zebrafish (Danio rerio). The effects on biotransformation enzymes 7-ethoxyresorufin O-deethylase (EROD) and glutathione-S-transferase (GST), antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidases (GPxSe and GPxTOT), and glutathione reductase (GR), and markers of damage, such as DNA strand breaks (DNAsb), lactate dehydrogenase (LDH), lipid peroxidation (LPO), and vitellogenin-like proteins (VTG), were evaluated. Analyses of the biochemical markers indicated that a synergistic dose-ratio-dependent effect of CBZ and P4 in zebrafish occurs after chronic exposure regarding VTG, biotransformation enzymes (EROD, GST), and oxidative stress marker (DNAsb). The results suggest a synergistic effect regarding VTG, thus indicating a high risk to the reproductive success of fish if these pharmaceuticals co-occur.

Toxicity induced via ingestion of naturally-aged polystyrene microplastics by a small-sized terrestrial bird and its potential role as vectors for the dispersion of these pollutants

In recent years, there has been a growing number of studies on the impact of microplastics (MPs) on biota. However, its effects on birds' health are poorly understood. Thus, we aimed to evaluate the possible effects of ingestion of naturally-aged MPs by Coturnix Coturnix japonica (11 and 22 MP particles/day/bird, once a day, for 9 days), from different toxicity biomarkers. At the end of the experiment, it was found that the ingested MPs in birds showed a significant reduction in body biomass. Also, an increase in malondialdehyde production in the liver, brain, intestine, and gizzard of the birds, as well as a suppressive effect on hepatic nitric oxide production and superoxide dismutase activity in the liver and intestine were observed. Cerebral catalase activity was reduced in birds exposed to MPs and the cholinesterasic effect (marked by increased acetylcholinesterase activity) was observed in the muscle and brain of these animals. Despite these differences, through the main component analysis, hierarchical clustering analysis, and integrated biomarker response assessment, we observed similar toxicological effects in birds exposed to different amounts of MPs. In addition, the size of MPs was reduced, and their shape was altered as they transited through the gastrointestinal system, which probably explains their accumulation in the liver of birds. An expressive number of MPs are released through the feces of the birds throughout the experiment. As far as we know, this is the first report that associates MPs ingestion by small-sized terrestrial birds with biochemical alterations viz., predictive of oxidative stress, redox imbalance, and cholinesterasic effect, in addition to shedding light on the potential role of these birds as vectors for dispersal of MPs in natural environments.

Biochemical Marker Assessment of Chronic Carbamazepine Exposure at Environmentally Relevant Concentrations in Juvenile Common Carp (Cyprinus carpio)

Worldwide, the anticonvulsant drug carbamazepine (CBZ) is the most frequently identified pharmaceutical residue detected in rivers. Reported chronic effects of CBZ in non-target freshwater organisms, particularly fish, include oxidative stress and damage to liver tissues. Studies on CBZ effects in fish are mostly limited to zebrafish and rainbow trout studies. Furthermore, there are only a few chronic CBZ studies using near environmental concentrations. In this study, we provide data on subacute effects of CBZ exposure (28 days) to common carp (Cyprinus carpio), employing a set of biochemical markers of damage and exposure. CBZ was found to induce a significant change in the hepatic antioxidant status of fish subjected to 5 µg/L. Moreover, with increasing concentrations, enzymatic and non-enzymatic biomarkers of oxidative defence (catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), DNA strand breaks)), toxicant biotransformation (ethoxyresorufin-o-demethylase (EROD), glutathione-S-transferase (GST)), and organ and tissue damage (lactate dehydrogenase (LDH), cetylcholinesterase (AChE)) were altered. The AChE, LDH, and lipid peroxidation (LPO) results indicate the occurrence of apoptotic process activation and tissue damage after 28 days of exposure to CBZ. These findings suggest significant adverse effects of CBZ exposure to common carp at concentrations often found in surface waters.

Preventive Effect of Limosilactobacillus fermentum SCHY34 on Lead Acetate-Induced Neurological Damage in SD Rats

Lead poisoning caused by lead pollution seriously affects people's health. Lactic acid bacteria has been shown to be useful for biological scavenging of lead. In this experiment, Sprague-Dawley (SD) rats were treated with 200 mg/L of lead acetate solution daily to induce chronic lead poisoning, and oral Limosilactobacillus fermentum (L. fermentum) SCHY34 to study its mitigation effects and mechanisms on rat neurotoxicity. The L. fermentum SCHY34 showed competent results on in vitro survival rate and the lead ion adsorption rate. Animal experiments showed that L. fermentum SCHY34 maintained the morphology of rat liver, kidney, and hippocampi, reduced the accumulation of lead in the blood, liver, kidney, and brain tissue. Further, L. fermentum SCHY34 alleviated the lead-induced decline in spatial memory and response capacity of SD rats, and also regulated the secretion of neurotransmitters and related enzyme activities in the brain tissue of rats, such as glutamate (Glu), monoamine oxidase (MAO), acetylcholinesterase (AchE), cyclic adenosine monophosphate (cAMP), and adenylate cyclase (AC). In addition, the expression of genes related to cognitive capacity, antioxidation, and anti-apoptotic in rat brain tissues were increased L. fermentum SCHY34 treatment, such as brain-derived neurotrophic factor (BDNF), c-fos, c-jun, superoxide dismutase (SOD)1/2, Nuclear factor erythroid 2-related factor 2 (Nrf2), and B-cell lymphoma 2 (Bcl-2), and so on. L. fermentum SCHY34 showed a great biological scavenging and potential effect on alleviating the toxicity of lead ions.

Non-permitted food colorants induced neurotoxicity in cerebellum of rat brain

Food colorants are important food additives that not only enhance the appearance of food but also appetite. These can be obtained from natural and synthetic sources, but synthetic sources are more popular, efficient, and potential. Non-permitted food colorants (NPFCs) are banned, but their injudicious use in developing countries associated with various adverse health effects. They have potentially toxic effects on the body organs like the brain, liver, kidney, spleen, gut, etc. In view of their toxicity pattern, the present study aims to investigate the effect of three NPFCs (MY: Metanil yellow; MG: Malachite green; SIII: Sudan III) on oxidative stress, mitochondrial complexes, neurochemicals, and histological changes in the cerebellum of rats. Rats treated with MY (430 mg/kg), MG (13.75 mg/kg), SIII (250 mg/kg), and their mixtures (YGR) (MY 143.33 + MG 4.52 + SIII 83.33 mg/kg) p.o. for 60 days showed a significant increase in lipid peroxidation and decreased level of reduced glutathione, superoxide dismutase, and catalase activity as compared to controls. An increase in the activity of acetylcholinesterase (AChE) and a significant decrease in the activity of monoamine oxidase-B (MAO-B) and mitochondrial complex I and II was also observed in NPFCs treated rats as compared to controls. Further, the histological study also revealed the loss of Purkinje neurons in the cerebellum of the rat brain. The results of the present study indicate that NPFCs exposure to rats enhances oxidative stress and alters the activity of neurochemicals and mitochondrial complexes which could further lead to neuronal loss and behavioral dysfunctions.

Human Drug Pollution in the Aquatic System: The Biochemical Responses of Danio rerio Adults

Simple Summary

The release of medicinal products for human use in the aquatic environment is now a serious problem, and can be fatal for the organisms that live there. Danio rerio is a freshwater fish that provides the possibility to study the effects of these pollutants on the health of aquatic organisms. The results of the various existing scientific studies are scarce and conflicting. Here, we review the scientific studies that have analyzed these effects, highlighting that the impacts of drugs are evident in the biochemical responses of these animals.

Abstract

To date, drug pollution in aquatic systems is an urgent issue, and Danio rerio is a model organism to study the toxicological effects of environmental pollutants. The scientific literature has analyzed the effect of human drug pollution on the biochemical responses in the tissues of D. rerio adults. However, the information is still scarce and conflicting, making it difficult to understand its real impact. The scientific studies are not consistent with each other and, until now, no one has grouped their results to create a baseline of knowledge of the possible impacts. In this review, the analysis of literature data highlights that the effects of drugs on adult zebrafishes depend on various factors, such as the tissue analyzed, the drug concentration and the sex of the individuals. Furthermore, the most influenced biochemical responses concern enzymes (e.g., antioxidants and hydrolase enzymes) and total protein and hormonal levels. Pinpointing the situation to date would improve the understanding of the chronic effects of human drug pollution, helping both to reduce it in the aquatic systems and then to draw up regulations to control this type of pollution.

Experimental evidence of tyrosine neurotoxicity: focus on mitochondrial dysfunction

Tissue exposure to high levels of tyrosine, which is characteristic of an inborn error of metabolism named Tyrosinemia, is related to severe symptoms, including neurological alterations. The clinical manifestations and pathogenesis of tyrosine neurotoxicity can be recapitulated in experimental models in vivo and in vitro. A widely used experimental model to study brain tyrosine damage is the chronic and acute administration of this amino acid in infant rats. Other research groups and we have extensively studied the pathogenic events in the brain structures of rats exposed to high tyrosine levels. Rats administered acutely and chronically with tyrosine presented decreased and inhibition of the essential metabolism enzymes, e.g., Krebs cycle enzymes and mitochondrial respiratory complexes in the brain structures. These alterations induced by tyrosine toxicity were associated with brain oxidative stress, astrocytes, and, ultimately, cognitive impairments. Notably, in vivo data were corroborated by in vitro studies using cerebral regions homogenates incubated with tyrosine excess. Considering metabolism's importance to brain functioning, we hypothesized that mitochondrial and metabolic dysfunctions are closely related to neurological alterations induced by tyrosine neurotoxicity. Herein, we reviewed the main mechanisms associated with tyrosine neurotoxicity in experimental models, emphasizing the role of mitochondrial dysfunction.

Effects of nickel oxide nanoparticles on survival, reproduction, and oxidative stress biomarkers in the marine calanoid copepod Centropages ponticus under short-term exposure

Excessive use of nickel oxide nanoparticles (NiO NPs) in various industrial and commercial products can lead to various negative effects in human and environmental health due to their possible discharge into the environment. Nerveless, information about their ecotoxicological effects on marine organisms are lacking. Copepods are good ecotoxicological models because of their high sensitivity to environmental stress and their key role in the marine food webs. In this study, 48 h acute tests were conducted on the marine planktonic copepod Centropages ponticus to assess lethal and sublethal toxicities of NiO NPs. The results revealed LC₅₀ (48 h) of 4 mg/L for adult females. Aggregation and settling of NiO NPs were observed at concentrations ≥ 2 mg/L. Exposure to sublethal concentrations (≥ 0.02 mg/L for 48 h) had significant negative effects on reproductive success in C. ponticus. Egg production after 24 h and 48 h decreased by 32% and 46%, respectively at 0.02 mg/L and 70% and 82%, respectively, at 2 mg/L. Hatching success was reduced by 70% and 79% at 2 mg/L for eggs produced after 24 h and 48 h respectively. Antioxidant enzymatic activity increased significantly with NiO NP concentration and time, indicating that NiO NPs can cause oxidative stress in C. ponticus even under short-term exposure, while significant inhibition of acetylcholinesterase activity at 2 mg/L after 48 h suggests neurotoxic effects of NiO NPs.

Toxic effects of naturally-aged microplastics on zebrafish juveniles: A more realistic approach to plastic pollution in freshwater ecosystems

We aim at evaluating the toxicity of naturally-aged polystyrene microplastics (MPs) in Danio rerio at intermediate development stage. Animal models were stactically exposed to 4 × 10⁴ and 4 × 10⁶ microparticles/m³ for five days - this concentration is environmentally relevant. We evaluated MP's impact on animals' nutritional status and REDOX balance, as well as its potential neuro- and cytotoxic action on them. Initially, MPs did not induce any change in total carbohydrates, triglycerides and total cholesterol levels. MP accumulation was associated with oxidative stress induction, which was inferred by the nitrite and thiobarbituric acid reactive substances levels. Furthermore, we observed that such stress was not counterbalanced by increase in the assessed enzymatic (total glutathione, catalase and superoxide dismutase) and non-enzymatic (total thiols, reduced glutathione and DPPH radical scavenging activity) antioxidants. The association between high acetylcholinesterase activity and numerical changes in neuroblasts distributed on animals' body surface confirmed MP's neurotoxic potential. MP's ability to induce apoptosis and necrosis processes in animals' erythrocytes suggested its cytotoxic action; therefore, the present study is pioneer in providing insight on how MPs can affect young freshwater fish at environmental concentrations. It is essential knowing the magnitude of these pollutants' impact on the ichthyofauna.

How Does Mytilus galloprovincialis Respond When Exposed to the Gametophyte Phase of the Invasive Red Macroalga Asparagopsis armata Exudate?

Asparagopsis armata is classified as an invasive species in Europe. Through the exudation of secondary metabolites, this macroalga holds a chemical defence against consumers, with potential toxic effects to native rocky shore communities. This study aims to evaluate the potential impact of A. armata (gametophyte) exudate in a native species, the mussel Mytilus galloprovincialis, in terms of biochemical and organismal effects. The 96 h-LC50 was 3.667% and based on it, exudate concentrations (0.25; 0.5; 1; 2%) were determined to further sublethal experiments. These sublethal concentrations caused no oxidative damage in the digestive gland since lipid peroxidation and protein carbonylation were not affected. Nevertheless, there was a significant rise in the electron transport system activity and total glutathione content in muscle, suggesting an increased non-enzymatic antioxidant capacity and consequent energy consumption to cope with potential pro-oxidant compounds. This might have contributed to the observed decline in cellular energy allocation of the exposed mussels. At the organismal level, clearance capacity declined along the concentration gradient. Moreover, the number of functional byssuses decreased with increasing concentrations and a significant reduction in their attachment strength was observed. These findings suggest that the presence of A. armata may compromise M. galloprovincialis integrity in the invaded coastal areas.

Raising the water temperature: consequences in behavior and biochemical biomarkers of the freshwater crab Aegla longirostri (Crustacea, Anomura)

Understanding how temperature alone affects biomarkers commonly used in ecotoxicology studies and biomonitoring programs is important to obtain a more real response in field studies, especially in freshwater. Thus, we analyzed the behavioral responses, the lethality, and the biochemical biomarkers in the freshwater crustacean Aegla longirostri at different water temperatures. Animals were exposed under laboratory conditions, to 18 °C, 21 °C, 24 °C, and 26 °C for 48 h. There were significant changes in biochemical parameters in different tissues (hepatopancreas, gills, and muscle) and in the behavioral tests in A. longirostri. Hepatopancreas was especially affected by the elevation of temperature, as showed by the high levels of carbonyl proteins. The activity of acetylcholinesterase increased in a temperature-dependent manner in muscle. Glutathione S-transferase activity decreased with the elevation of temperature in all tissues sampled. The results obtained in this study indicate that when assessing the health of polluted limnic ecosystems through the use of organisms in situ, the intrinsic effect of abiotic factors, such as temperature, on biomarkers must be considered.

Omega-3 fatty acid supplementation can prevent changes in mitochondrial energy metabolism and oxidative stress caused by chronic administration of L-tyrosine in the brain of rats

Deficiency of hepatic enzyme tyrosine aminotransferase characterizes the innate error of autosomal recessive disease Tyrosinemia Type II. Patients may develop neurological and developmental difficulties due to high levels of the amino acid tyrosine in the body. Mechanisms underlying the neurological dysfunction in patients are poorly known. Importantly, Tyrosinemia patients have deficient Omega-3 fatty acids (n-3 PUFA). Here, we investigated the possible neuroprotective effect of the treatment with n-3 PUFA in the alterations caused by chronic administration of L-tyrosine on important parameters of energetic metabolism and oxidative stress in the hippocampus, striatum and cerebral cortex of developing rats. Chronic administration of L-tyrosine causes a decrease in the citrate synthase (CS) activity in the hippocampus and cerebral cortex, as well as in the succinate dehydrogenase (SDH) and isocitrate dehydrogenase (IDH) activities, and an increase in the α-ketoglutarate dehydrogenase activity in the hippocampus. Moreover, in the striatum, L-tyrosine administration caused a decrease in the activities of CS, SDH, creatine kinase, and complexes I, II-III and IV of the mitochondrial respiratory chain. We also observed that the high levels of L-tyrosine are related to oxidative stress in the brain. Notably, supplementation of n-3 PUFA prevented the majority of the modifications caused by the chronic administration of L-tyrosine in the cerebral enzyme activities, as well as ameliorated the oxidative stress in the brain regions of rats. These results indicate a possible neuroprotective and antioxidant role for n-3 PUFA and may represent a new therapeutic approach and potential adjuvant therapy to Tyrosinemia Type II individuals.

Impacts of in vivo and in vitro exposures to tamoxifen: Comparative effects on human cells and marine organisms

Tamoxifen (TAM) is a first generation-SERM administered for hormone receptor-positive (HER+) breast cancer in both pre- and post-menopausal patients and may undergo metabolic activation in organisms that share similar receptors and thus face comparable mechanisms of response. The present study aimed to assess whether environmental trace concentrations of TAM are bioavailable to the filter feeder M. galloprovincialis (100 ng L^-1) and to the deposit feeder N. diversicolor (0.5, 10, 25 and 100 ng L^-1) after 14 days of exposure. Behavioural impairment (burrowing kinetic), neurotoxicity (AChE activity), endocrine disruption by alkali-labile phosphate (ALP) content, oxidative stress (SOD, CAT, GPXs activities), biotransformation (GST activity), oxidative damage (LPO) and genotoxicity (DNA damage) were assessed. Moreover, this study also pertained to compare TAM cytotoxicity effects to mussels and targeted human (i.e. immortalized retinal pigment epithelium - RPE; and human transformed endothelial cells - HeLa) cell lines, in a range of concentrations from 0.5 ng L^-1 to 50 μg L^-1. In polychaetes N. diversicolor, TAM exerted remarkable oxidative stress and damage at the lowest concentration (0.5 ng L^-1), whereas significant genotoxicity was reported at the highest exposure level (100 ng L^-1). In mussels M. galloprovincialis, 100 ng L^-1 TAM caused endocrine disruption in males, neurotoxicity, and an induction in GST activity and LPO byproducts in gills, corroborating in genotoxicity over the exposure days. Although cytotoxicity assays conducted with mussel haemocytes following in vivo exposure was not effective, in vitro exposure showed to be a feasible alternative, with comparable sensitivity to human cell line (HeLa).

A novel understanding of postoperative complications: In vitro study of the impact of propofol on epigenetic modifications in cholinergic genes

Background

Propofol is a widely used anaesthetic drug with advantageous operating conditions and recovery profile. However, propofol could have long term effects on neuronal cells and is associated with post-operative delirium (POD). In this context, one of the contributing factors to the pathogenesis of POD is a reduction of cholinesterase activity. Accordingly, we investigated the effects of propofol on the methylation, expression and activity of cholinergic genes and proteins in an in-vitro model.

Results

We found that propofol indeed reduced the activity of AChE / BChE in our in-vitro model, without affecting the protein levels. Furthermore, we could show that propofol reduced the methylation of a repressor region of the CHRNA7 gene without changing the secretion of pro–or anti-inflammatory cytokines. Lastly, propofol changed the expression patterns of genes responsible for maintaining the epigenetic status of the cell and accordingly reduced the tri-methylation of H3 K27.

Conclusion

In conclusion we found a possible functional link between propofol treatment and POD, due to a reduced cholinergic activity. In addition to this, propofol changed the expression of different maintenance genes of the epigenome that also affected histone methylation. Thus, propofol treatment may also induce strong, long lasting changes in the brain by potentially altering the epigenetic landscape.

Transport and Recovery of Gilthead Sea Bream (Sparus aurata L.) Sedated With Clove Oil and MS222: Effects on Oxidative Stress Status

The use of anesthesia is a common practice in aquaculture to sedate fish and mitigate handling stress. Although the employ of anesthesia is considered beneficial for fish, as it reduces stress and improves welfare, at the same time it may induce hazardous side-effects. The aim of the present study was to investigate the effects of clove oil (CO) and tricaine methanesulfonate (MS222), two of the most used anesthetics, on several oxidative stress related parameters in gilthead sea bream (Sparus aurata), as these types of effects of anesthetics have been seldom investigated. To assess these effects, S. aurata juveniles were placed in a setup of mobile water tanks and were transported during 6 h with either 2.5 mg/L CO or 5 mg/L MS222. After transport, half of the fish were sampled, whereas the remaining fish were transferred to tanks without anesthetics where they were allowed to recover for 18 h before sampling. Changes in the expression levels of several target genes related with the antioxidant response and cell-tissue repair were evaluated in the gills, liver and brain. Those transcripts included glutathione peroxidase 1 (gpx1), catalase (cat), glutathione S-transferase 3 (gst3), glutathione reductase (gr), superoxide dismutase [Zn] (sod2), heat shock protein-70 (hsp70), and metallothionein (mt). Antioxidant enzymatic activities glutathione S-transferase, GST; catalase, CAT; and glutathione reductase, GR, levels of non-enzymatic antioxidants (non-protein thiols - NPT), and pro-oxidative damage, assessed as lipid peroxidation (LPO), were determined in gills, liver and brain. Acetylcholinesterase activity (AChE) was determined in plasma, gills, brain, muscle and heart as an indicator of neuro-muscular alterations. In plasma, the total antioxidant capacity (TAC) and total oxidative status (TOS) were also measured. Results showed that the use of both anesthetic agents, CO and MS222, interferes with fish antioxidant status. All tested biological matrices displayed alterations in antioxidant endpoints, confirming that these substances, although minimizing the effects of transport stress, may have long term effects on fish defenses. This result is of high relevance to aquaculture considering that the oxidative stress, may increase the susceptibility to different environmental or biotic stress and different types of pathologies.

Ecotoxicological Effect of Single and Combined Exposure of Carbamazepine and Cadmium on Female Danio rerio: A Multibiomarker Study

In aquatic environments, organisms are exposed to mixtures of pollutants which may change the toxicity profile of each contaminant, compared to its toxicity alone. Carbamazepine (CBZ) and cadmium (Cd) are among the pollutants that co-occur in aquatic environments. To date, most research about their toxicity towards aquatic vertebrates is based on single exposure experiments. The present study aims to evaluate single and combined effects of CBZ and Cd on biomarkers in female Danio rerio (zebrafish) by exposing them to environmentally relevant concentrations of these two pollutants for ten days. Four kinds of biomarkers involved in antioxidant systems, energy metabolism, nervous system, and endocrine disruption, respectively, were studied. Our research results coincided with those of former studies in single exposure experiments. However, the combined exposure of CBZ and Cd exerted different responses from other studies in which these two contaminants were examined alone in zebrafish. The present study evidenced the need to conduct more coexposure studies to enhance the environmental relevance of these experimental results.

Chronic effects of carbamazepine on zebrafish: Behavioral, reproductive and biochemical endpoints

Carbamazepine (Cbz), one of the most prescribed pharmaceuticals in the world is often detected in surface waters and sediments. However, few studies addressed its chronic effects in fish. In the present study, Danio rerio adults were exposed for 63 days to Cbz (0 - control, 10 μg L^-1 - concentration found in effluents, and 10,000 μg L^-1 - 5% of LC₅₀ at 72 h). Assessed endpoints were: feeding behavior, growth rate, number of eggs produced and their viability, histological alterations in female gonads, and biochemical biomarkers associated with antioxidant defenses (catalase - CAT, and glutathione S-transferase - GST activities), neurotransmission (acetylcholinesterase activity - AChE) and metabolism (lactate dehydrogenase - LDH). Cbz exposure increased the total time for food intake but did not affect D. rerio growth. Although the total number of eggs was not affected by Cbz exposure, the eggs viability was significantly impaired. Exposure to Cbz caused alterations in the female gonads follicular stages. In terms of biochemical endpoints, CAT activity in liver and gills, was sensitive to the pharmaceutical exposure presenting a decreased activity. AChE activity was induced in the head (both concentrations) and muscle (10,000 μg L^-1). GST activity was increased in gills (both concentrations) but inhibited in the intestine. Concerning LDH, enzymatic activity was increased in the liver and decreased in muscle and gills. Several of the above-mentioned effects can be directly linked with effects at population level (e.g. feeding behavior) and occurred at environmental concentrations (the lowest concentration tested), thus serious concerns regarding risks posed by Cbz residues to fish populations arise with this study.

Involvement of the Cholinergic Parameters and Glial Cells in Learning Delay Induced by Glutaric Acid: Protection by N-Acetylcysteine

Dysfunction of basal ganglia neurons is a characteristic of glutaric acidemia type I (GA-I), an autosomal recessive inherited neurometabolic disease characterized by deficiency of glutaryl-CoA dehydrogenase (GCDH) and accumulation of glutaric acid (GA). The affected patients present clinical manifestations such as motor dysfunction and memory impairment followed by extensive striatal neurodegeneration. Knowing that there is relevant striatal dysfunction in GA-I, the purpose of the present study was to verify the performance of young rats chronically injected with GA in working and procedural memory test, and whether N-acetylcysteine (NAC) would protect against impairment induced by GA. Rat pups were injected with GA (5 μmol g body weight^-1, subcutaneously; twice per day; from the 5th to the 28th day of life) and were supplemented with NAC (150 mg/kg/day; intragastric gavage; for the same period). We found that GA injection caused delay procedural learning; increase of cytokine concentration, oxidative markers, and caspase levels; decrease of antioxidant defenses; and alteration of acetylcholinesterase (AChE) activity. Interestingly, we found an increase in glial cell immunoreactivity and decrease in the immunoreactivity of nuclear factor-erythroid 2-related factor 2 (Nrf2), nicotinic acetylcholine receptor subunit alpha 7 (α7nAChR), and neuronal nuclei (NeuN) in the striatum. Indeed, NAC administration improved the cognitive performance, ROS production, neuroinflammation, and caspase activation induced by GA. NAC did not prevent neuronal death, however protected against alterations induced by GA on Iba-1 and GFAP immunoreactivities and AChE activity. Then, this study suggests possible therapeutic strategies that could help in GA-I treatment and the importance of the striatum in the learning tasks.

Antioxidants Reverse the Changes in the Cholinergic System Caused by L-Tyrosine Administration in Rats

Tyrosinemia type II is an inborn error of metabolism caused by a deficiency in the activity of the enzyme tyrosine aminotransferase, leading to tyrosine accumulation in the body. Although the mechanisms involved are still poorly understood, several studies have showed that higher levels of tyrosine are related to oxidative stress and therefore may affect the cholinergic system. Thus, the aim of this study was to investigate the effects of chronic administration of L-tyrosine on choline acetyltransferase activity (ChAT) and acetylcholinesterase (AChE) in the brain of rats. Moreover, we also examined the effects of one antioxidant treatment (N-acetylcysteine (NAC) + deferoxamine (DFX)) on cholinergic system. Our results showed that the chronic administration of L-tyrosine decreases the ChAT activity in the cerebral cortex, while the AChE activity was increased in the hippocampus, striatum, and cerebral cortex. Moreover, we found that the antioxidant treatment was able to prevent the decrease in the ChAT activity in the cerebral cortex. However, the increase in AChE activity induced by L-tyrosine was partially prevented the in the hippocampus and striatum, but not in the cerebral cortex. Our results also showed no differences in the aversive and spatial memory after chronic administration of L-tyrosine. In conclusion, the results of this study demonstrated an increase in AChE activity in the hippocampus, striatum, and cerebral cortex and an increase of ChAT in the cerebral cortex, without cognitive impairment. Furthermore, the alterations in the cholinergic system were partially prevented by the co-administration of NAC and DFX. Thus, the restored central cholinergic system by antioxidant treatment further supports the view that oxidative stress may be involved in the pathophysiology of tyrosinemia type II.

Omega-3 fatty acid supplementation decreases DNA damage in brain of rats subjected to a chemically induced chronic model of Tyrosinemia type II

Tyrosinemia type II is an inborn error of metabolism caused by a mutation in a gene encoding the enzyme tyrosine aminotransferase leading to an accumulation of tyrosine in the body, and is associated with neurologic and development difficulties in numerous patients. Because the accumulation of tyrosine promotes oxidative stress and DNA damage, the main aim of this study was to investigate the possible antioxidant and neuroprotective effects of omega-3 treatment in a chemically-induced model of Tyrosinemia type II in hippocampus, striatum and cerebral cortex of rats. Our results showed chronic administration of L-tyrosine increased the frequency and the index of DNA damage, as well as the 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the hippocampus, striatum and cerebral cortex. Moreover, omega-3 fatty acid treatment totally prevented increased DNA damage in the striatum and hippocampus, and partially prevented in the cerebral cortex, whereas the increase in 8-OHdG levels was totally prevented by omega-3 fatty acid treatment in hippocampus, striatum and cerebral cortex. In conclusion, the present study demonstrated that the main accumulating metabolite in Tyrosinemia type II induce DNA damage in hippocampus, striatum and cerebral cortex, possibly mediated by free radical production, and the supplementation with omega-3 fatty acids was able to prevent this damage, suggesting that could be involved in the prevention of oxidative damage to DNA in this disease. Thus, omega-3 fatty acids supplementation to Tyrosinemia type II patients may represent a new therapeutic approach and a possible adjuvant to the curren t treatment of this disease.

Role of antioxidant treatment on DNA and lipid damage in the brain of rats subjected to a chemically induced chronic model of tyrosinemia type II

Tyrosine levels are abnormally elevated in tissues and body fluids of patients with inborn errors of tyrosine metabolism. Tyrosinemia type II, which is caused by tyrosine aminotransferase deficiency, provokes eyes, skin, and central nervous system disturbances in affected patients. However, the mechanisms of brain damage are still poorly known. Considering that studies have demonstrated that oxidative stress may contribute, along with other mechanisms, to the neurological dysfunction characteristic of hypertyrosinemia, in the present study we investigated the effects of antioxidant treatment (NAC and DFX) on DNA damage and oxidative stress markers induced by chronic administration of L-tyrosine in cerebral cortex, hippocampus, and striatum of rats. The results showed elevated levels of DNA migration, and thus DNA damage, after chronic administration of L-tyrosine in all the analyzed brain areas, and that the antioxidant treatment was able to prevent DNA damage in cerebral cortex and hippocampus. However, the co-administration of NAC plus DFX did not prevent the DNA damage in the striatum. Moreover, we found a significant increase in thiobarbituric acid-reactive substances (TBA-RS) and DCFH oxidation in cerebral cortex, as well as an increase in nitrate/nitrite levels in the hippocampus and striatum. Additionally, the antioxidant treatment was able to prevent the increase in TBA-RS levels and in nitrate/nitrite levels, but not the DCFH oxidation. In conclusion, our findings suggest that reactive oxygen and nitrogen species and oxidative stress can play a role in DNA damage in this disorder. Moreover, NAC/DFX supplementation to tyrosinemia type II patients may represent a new therapeutic approach and a possible adjuvant to the current treatment of this disease.

N-acetylcysteine treatment attenuates the cognitive impairment and synaptic plasticity loss induced by streptozotocin

Alzheimer's disease (AD) is a neurodegenerative disorder pathologically characterized by severe neuronal and glial structural changes and progressive cognitive decline. N-acetylcysteine (NAC) is a well-known pharmacological agent with pro-neurogenic properties and neuroprotective effects. In this study, we evaluated NAC protective effects on cognitive impairment and associated pathological markers in a streptozotocin (STZ)-induced sporadic dementia of AD type mice model. Animals were divided into six groups: I) Sham, II) NAC, III) physostigmine (PHY), IV) STZ, V) NAC + STZ and VI) PHY + NAC. NAC (5 mg/kg) and PHY (0.25 mg/kg) were administrated orally for 30 consecutive days and STZ (2.5 mg/kg) intracerebroventricularly at the first and third days. Novel object recognition (NOR, days 26-27) and Morris water maze (MWM, days 26-30) tasks were assessed to evaluate learning and memory. On the thirty-first day animals were euthanized and brains collected for biochemical analysis. Interestingly, our results showed that STZ treatment induced cognitive impairment in mice in the NOR and MWM tasks. Both NAC and PHY treatments prevented from this impairment. The increase in AChE activity and decrease in pTrkB and MnSOD levels caused by STZ in the cerebral cortex and hippocampus, were prevented by the NAC and PHY treatments. The decrease in SYN, MAP2 and GFAP expressions were also prevented by NAC and PHY treatments. In conclusion, NAC treatment prevented the cognitive impairment induced by STZ, normalizing the AChE activity and rescuing the synaptic plasticity loss. Our results suggest that NAC is a promising therapeutic strategy for the treatment of AD.

Tissue accumulation of microplastics in mice and biomarker responses suggest widespread health risks of exposure

Microplastics (MPs) are a significant environmental health issue and increasingly greater source of concern. MPs have been detected in oceans, rivers, sediments, sewages, soil and even table salts. MPs exposure on marine organisms and humans has been documented, but information about the toxicity of MPs in mammal is limited. Here we used fluorescent and pristine polystyrene microplastics (PS-MPs) particles with two diameters (5 μm and 20 μm) to investigate the tissue distribution, accumulation, and tissue-specific health risk of MPs in mice. Results indicated that MPs accumulated in liver, kidney and gut, with a tissue-accumulation kinetics and distribution pattern that was strongly depended on the MPs particle size. In addition, analyses of multiple biochemical biomarkers and metabolomic profiles suggested that MPs exposure induced disturbance of energy and lipid metabolism as well as oxidative stress. Interestingly, blood biomarkers of neurotoxicity were also altered. Our results uncovered the distribution and accumulation of MPs across mice tissues and revealed significant alteration in several biomarkers that indicate potential toxicity from MPs exposure. Collectively, our data provided new evidence for the adverse consequences of MPs.

Jaburetox affects gene expression and enzyme activities in Rhodnius prolixus, a Chagas' disease vector

Jaburetox, a recombinant peptide of ∼11kDa derived from one of the Canavalia ensiformis (Jack Bean) urease isoforms, is toxic and lethal to insects belonging to different orders when administered orally or via injection. Previous findings indicated that Jaburetox acts on insects in a complex fashion, inhibiting diuresis and the transmembrane potential of Malpighian tubules, interfering with muscle contractility and affecting the immune system. In vitro, Jaburetox forms ionic channels and alters permeability of artificial lipid membranes. Moreover, recent data suggested that the central nervous system (CNS) is a target organ for ureases and Jaburetox. In this work, we employed biochemical, molecular and cellular approaches to explore the mode of action of Jaburetox using Rhodnius prolixus, one of the main Chagas' disease vectors, as experimental model. In vitro incubations with fluorescently labeled Jaburetox indicated a high affinity of the peptide for the CNS but not for salivary glands (SG). The in vitro treatment of CNS or SG homogenates with Jaburetox partially inhibited the activity of nitric oxide synthase (NOS), thus disrupting nitrinergic signaling. This inhibitory effect was also observed in vivo (by feeding) for CNS but not for SG, implying differential modulation of NOS in these organs. The inhibition of NOS activity did not correlate to a decrease in expression of its mRNA, as assessed by qPCR. UDP-N-acetylglucosamine pyrophosphorylase (UAP), a key enzyme in chitin synthesis and glycosylation pathways and a known target of Jaburetox in insect CNS, was also affected in SG, with activation of the enzyme seen after both in vivo or in vitro treatments with the peptide. Unexpectedly, incubation of Jaburetox with a recombinant R. prolixus UAP had no effect on its activity, implying that the enzyme's modulation by the peptide requires the participation of other factor(s) present in CNS or SG homogenates. Feeding Jaburetox to R. prolixus decreased the mRNA levels of UAP and chitin synthase, indicating a complex regulation exerted by the peptide on these enzymes. No changes were observed upon Jaburetox treatment in vivo and in vitro on the activity of the enzyme acid phosphatase, a possible link between UAP and NOS. Here we have demonstrated for the first time that the Jaburetox induces changes in gene expression and that SG are another target for the toxic action of the peptide. Taken together, these findings contribute to a better understanding of the mechanism of action of Jaburetox as well as to the knowledge on basic aspects of the biochemistry and neurophysiology of insects, and might help in the development of optimized strategies for insect control.

Antioxidants reverse the changes in energy metabolism of rat brain after chronic administration of L.-tyrosine

Tyrosinemia type II is a rare autosomal recessive disease caused by deficiency of hepatic tyrosine aminotransferase and is associated with neurologic and development difficulties in numerous patients. Considering that the mechanisms underlying the neurological dysfunction in hypertyrosinemic patients are poorly known and that high concentrations of tyrosine provoke mitochondrial dysfunction and oxidative stress, in the present study we investigated the in vivo influence of antioxidants (N-acetylcysteine, NAC; and deferoxamine, DFX) administration on the inhibitory effects on parameters of energy metabolism in cerebral cortex, hippocampus and striatum of rats, provoked by chronic administration of L.-tyrosine. Our results showed that chronic administration of L.-tyrosine results in a marked decrease in the activity of citrate synthase in all the analyzed structures and succinate dehydrogenase activities in hippocampus and striatum, and that antioxidants administration can prevent this inhibition in hippocampus and striatum. Moreover, chronic administration of L.-tyrosine inhibited the activity of complex I, II-III and IV in the striatum, which can be prevented by antioxidant treatment. However, the co-administration of NAC plus DFX could not prevent the inhibition of creatine kinase activity in the striatum. In conclusion, the present study demonstrates that the administration of antioxidants NAC and DFX attenuates the L.-tyrosine effects on enzymes of the Krebs cycle and the mitochondrial respiratory chain, suggesting that impairment of energy metabolism can be involved with oxidative stress. These results also indicate a possible neuroprotective role for NAC and DFX as a potential adjuvant therapy to the patients with Tyrosinemia type II.

A Novel Genetic Screen Identifies Modifiers of Age-Dependent Amyloid β Toxicity in the Drosophila Brain

The accumulation of amyloid β peptide (Aβ) in the brain of Alzheimer's disease (AD) patients begins many years before clinical onset. Such process has been proposed to be pathogenic through the toxicity of Aβ soluble oligomers leading to synaptic dysfunction, phospho-tau aggregation and neuronal loss. Yet, a massive accumulation of Aβ can be found in approximately 30% of aged individuals with preserved cognitive function. Therefore, within the frame of the "amyloid hypothesis", compensatory mechanisms and/or additional neurotoxic or protective factors need to be considered and investigated. Here we describe a modifier genetic screen in Drosophila designed to identify genes that modulate toxicity of Aβ42 in the CNS. The expression of Aβ42 led to its accumulation in the brain and a moderate impairment of negative geotaxis at 18 days post-eclosion (d.p.e) as compared with genetic or parental controls. These flies were mated with a collection of lines carrying chromosomal deletions and negative geotaxis was assessed at 5 and 18 d.p.e. Our screen is the first to take into account all of the following features, relevant to sporadic AD: (1) pan-neuronal expression of wild-type Aβ42; (2) a quantifiable complex behavior; (3) Aβ neurotoxicity associated with progressive accumulation of the peptide; and (4) improvement or worsening of climbing ability only evident in aged animals. One hundred and ninety-nine deficiency (Df) lines accounting for ~6300 genes were analyzed. Six lines, including the deletion of 52 Drosophila genes with human orthologs, significantly modified Aβ42 neurotoxicity in 18-day-old flies. So far, we have validated CG11796 and identified CG17249 as a strong candidate (whose human orthologs are HPD and PRCC, respectively) by using RNAi or mutant hemizygous lines. PRCC encodes proline-rich protein PRCC (ppPRCC) of unknown function associated with papillary renal cell carcinoma. HPD encodes 4-hydroxyphenylpyruvate dioxygenase (HPPD), a key enzyme in tyrosine degradation whose Df causes autosomal recessive Tyrosinemia type 3, characterized by mental retardation. Interestingly, lines with a partial Df of HPD ortholog showed increased intraneuronal accumulation of Aβ42 that coincided with geotaxis impairment. These previously undetected modifiers of Aβ42 neurotoxicity in Drosophila warrant further study to validate their possible role and significance in the pathogenesis of sporadic AD.

Neurotoxicity effect of formaldehyde on occupational exposure and influence of individual susceptibility to some metabolism parameters

Over the years, neurotoxicity and cognitive dysfunction have separately been associated with endogenous formaldehyde and reduction of acetylcholine signals. However, a limited number of studies have shown a relationship between cholinergic neurotransmitter and formaldehyde exposure. Therefore, the aim of this study was to assess the neurological effect on workers from melamine-dish preparation workshop, who were exposed to formaldehyde. A total of 35 formaldehyde-exposed workers were compared with 32 control employees from the food industry. Occupational exposure to formaldehyde was conducted using the National Institute of Occupational Safety and Health 3500 methods. Using the Ellman method, acetylcholinesterase (AChE) as a biomarker for neurotoxicity was analyzed in blood erythrocyte. The effects of alcohol dehydrogenase III (ADH3) and Mn-superoxide dismutase (Mn-SOD) polymorphism were used to survey the level of AChE activity. In this study, it was found that exposure to airborne formaldehyde increased from 0.024 to 0.74 ppm and the median personnel exposure was 0.057. Induction of AChE activity was observed in formaldehyde-exposed workers as compared with the control group (p < 0.01), while AChE activity increased in 64 % of the exposed subjects. Spearman's correlation (p < 0.02) was used to evaluate the association between AChE activity and occupational exposure to formaldehyde. Exposed subjects containing ADH3_2-2 genotype had higher AChE than others. The findings of this study suggest that the neurotoxic effect of formaldehyde depends on the AChE activity, which is affected by metabolism. It can be concluded that cholinergic signal reduction in cases of cognitive dysfunction could be associated with endogenous formaldehyde.

Influence of the Melissa officinalis Leaf Extract on Long-Term Memory in Scopolamine Animal Model with Assessment of Mechanism of Action

Melissa officinalis (MO, English: lemon balm, Lamiaceae), one of the oldest and still most popular aromatic medicinal plants, is used in phytomedicine for the prevention and treatment of nervous disturbances. The aim of our study was to assess the effect of subchronic (28-fold) administration of a 50% ethanol extract of MO leaves (200 mg/kg, p.o.) compared with rosmarinic acid (RA, 10 mg/kg, p.o.) and huperzine A (HU, 0.5 mg/kg, p.o.) on behavioral and cognitive responses in scopolamine-induced rats. The results were linked with acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and beta-secretase (BACE-1) mRNA levels and AChE and BuChE activities in the hippocampus and frontal cortex of rats. In our study, MO and HU, but not RA, showed an improvement in long-term memory. The results were in line with mRNA levels, since MO produced a decrease of AChE mRNA level by 52% in the cortex and caused a strong significant inhibition of BACE1 mRNA transcription (64% in the frontal cortex; 50% in the hippocampus). However, the extract produced only an insignificant inhibition of AChE activity in the frontal cortex. The mechanisms of MO action are probably more complicated, since its role as a modulator of beta-secretase activity should be taken into consideration.

The characterization of neuroenergetic effects of chronic L-tyrosine administration in young rats: evidence for striatal susceptibility

Tyrosinemia type II is an inborn error of metabolism caused by a deficiency in hepatic cytosolic aminotransferase. Affected patients usually present a variable degree of mental retardation, which may be related to the level of plasma tyrosine. In the present study we evaluated effect of chronic administration of L-tyrosine on the activities of citrate synthase, malate dehydrogenase, succinate dehydrogenase and complexes I, II, II-III and IV in cerebral cortex, hippocampus and striatum of rats in development. Chronic administration consisted of L-tyrosine (500 mg/kg) or saline injections 12 h apart for 24 days in Wistar rats (7 days old); rats were killed 12 h after last injection. Our results demonstrated that L-tyrosine inhibited the activity of citrate synthase in the hippocampus and striatum, malate dehydrogenase activity was increased in striatum and succinate dehydrogenase, complexes I and II-III activities were inhibited in striatum. However, complex IV activity was increased in hippocampus and inhibited in striatum. By these findings, we suggest that repeated administrations of L-tyrosine cause alterations in energy metabolism, which may be similar to the acute administration in brain of infant rats. Taking together the present findings and evidence from the literature, we hypothesize that energy metabolism impairment could be considered an important pathophysiological mechanism underlying the brain damage observed in patients with tyrosinemia type II.

Rosmarinus officinalis L. leaf extract improves memory impairment and affects acetylcholinesterase and butyrylcholinesterase activities in rat brain

Rosmarinus officinalis L. leaf as part of a diet and medication can be a valuable proposal for the prevention and treatment of dementia. The aim of the study was to assess the effects of subchronic (28-fold) administration of a plant extract (RE) (200 mg/kg, p.o.) on behavioral and cognitive responses of rats linked with acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activity and their mRNA expression level in the hippocampus and frontal cortex. The passive avoidance test results showed that RE improved long-term memory in scopolamine-induced rats. The extract inhibited the AChE activity and showed a stimulatory effect on BuChE in both parts of rat brain. Moreover, RE produced a lower mRNA BuChE expression in the cortex and simultaneously an increase in the hippocampus. The study suggests that RE led to improved long-term memory in rats, which can be partially explained by its inhibition of AChE activity in rat brain.

Effect of acute and chronic administration of L-tyrosine on nerve growth factor levels in rat brain

Most inborn errors of tyrosine catabolism produce hypertyrosinemia. Neurological manifestations are variable and some patients are developmentally normal, while others show different degrees of developmental retardation. Considering that current data do not eliminate the possibility that elevated levels of tyrosine and/or its derivatives may have noxious effects on central nervous system development in some patients, the present study evaluated nerve growth factor (NGF) levels in hippocampus, striatum and posterior cortex of young rats. In our acute protocol, Wistar rats (10 and 30 days old) were killed 1 h after a single intraperitoneal administration of L-tyrosine (500 mg/kg) or saline. Chronic administration consisted of L-tyrosine (500 mg/kg) or saline injections 12 h apart for 24 days in Wistar rats (7 days old); the rats were killed 12 h after the last injection. NGF levels were then evaluated. Our findings showed that acute administration of L-tyrosine decreased NGF levels in striatum of 10-day-old rats. In the 30-day-old rats, NGF levels were decreased in hippocampus and posterior cortex. On the other hand, chronic administration of L-tyrosine increased NGF levels in posterior cortex. Decreased NGF may impair growth, differentiation, survival and maintenance of neurons.

Acute administration of l-tyrosine alters energetic metabolism of hippocampus and striatum of infant rats

Tyrosinemia type II is an inborn error of metabolism caused by mutations in the gene that encodes tyrosine aminotransferase, which leads to increased blood tyrosine levels. Considering that tyrosine levels are highly elevated in fluids of patients with tyrosinemia type II, and that previous studies demonstrated significant alterations in brain energy metabolism of young rats caused by l-tyrosine, the present study aimed to evaluate the effect of acute administration of l-tyrosine on the activities of citrate synthase, malate dehydrogenase, succinate dehydrogenase, and mitochondrial respiratory chain complexes I, II, II-III, and IV in posterior cortex, hippocampus, and striatum of infant rats. Wistar rats (10 days old) were killed 1h after a single intraperitoneal injection of tyrosine (500 mg/kg) or saline. The activities of energy metabolism enzymes were evaluated in brain of rats. Our results demonstrated that acute administration of l-tyrosine inhibited the activity of citrate synthase activity in striatum and increased the activities of malate dehydrogenase and succinate dehydrogenase in hippocampus. On the other hand, these enzymes were not affected in posterior cortex. The activities of complex I and complex II were inhibited by acute administration of l-tyrosine in striatum. On the other hand, the acute administration of l-tyrosine increased the activity of activity of complex II-III in hippocampus. Complex IV was not affected by acute administration of l-tyrosine in infant rats. Our results indicate an alteration in the energy metabolism in hippocampus and striatum of infant rats after acute administration of l-tyrosine. If the same effects occur in the brain of the patients, it is possible that energy metabolism impairment may be contribute to possible damage in memory and cognitive processes in patients with tyrosinemia type II.