Exposure to thimerosal induces behavioral abnormality in the early life stages of zebrafish via altering amino acid homeostasis

Thimerosal (THI) has become a significant source of organic mercury pollutants in aquatic ecosystems, but there is limited information regarding its adverse effects on fish. In this study, zebrafish embryos were exposed to THI at 0 (control), 5.0, and 50 ng/L from 0-5 days post fertilization (dpf), and variations in their survival, development, behavior, free amino acid contents, and the biochemical responses involved in monoaminergic systems were examined. Although THI exposure did not significantly affect the survival, heart rate, or hatching time of zebrafish embryos, it substantially increased swimming velocity (136-154 % of the control) and reduced exploratory behavior (141-142 % of the control) in zebrafish larvae at 5 dpf. Exposure also significantly altered the amino acid contents (51-209 % of the control) and monoamine levels (70-154 % of the control) in zebrafish larvae, some of which displayed significant correlations with behavioral traits. THI significantly elevated dopamine receptor gene expression and monoamine oxidase activity in zebrafish larvae. Adding extra phenylalanine or tryptophan to the E3 medium facilitates the recovery of zebrafish larvae from the abnormal behaviors induced by THI. These findings reveal for the first time that THI exposure at the level of ng/L is sufficient to induce neurobehavioral toxic effects in the early life stages of zebrafish, and disrupting amino acid homeostasis is a critical underlying mechanism. This study provides valuable insights into the toxicity of THI to fish and highlights the importance of assessing its potential risks to aquatic ecosystems.

Mercury-induced toxicity: Mechanisms, molecular pathways, and gene regulation

Mercury is a well-known neurotoxicant for humans and wildlife. The epidemic of mercury poisoning in Japan has clearly demonstrated that chronic exposure to methylmercury (MeHg) results in serious neurological damage to the cerebral and cerebellar cortex, leading to the dysfunction of the central nervous system (CNS), especially in infants exposed to MeHg in utero. The occurrences of poisoning have caused a wide public concern regarding the health risk emanating from MeHg exposure; particularly those eating large amounts of fish may experience the low-level and long-term exposure. There is growing evidence that MeHg at environmentally relevant concentrations can affect the health of biota in the ecosystem. Although extensive in vivo and in vitro studies have demonstrated that the disruption of redox homeostasis and microtube assembly is mainly responsible for mercurial toxicity leading to adverse health outcomes, it is still unclear whether we could quantitively determine the occurrence of interaction between mercurial and thiols and/or selenols groups of proteins linked directly to outcomes, especially at very low levels of exposure. Furthermore, intracellular calcium homeostasis, cytoskeleton, mitochondrial function, oxidative stress, neurotransmitter release, and DNA methylation may be the targets of mercury compounds; however, the primary targets associated with the adverse outcomes remain to be elucidated. Considering these knowledge gaps, in this article, we conducted a comprehensive review of mercurial toxicity, focusing mainly on the mechanism, and genes/proteins expression. We speculated that comprehensive analyses of transcriptomics, proteomics, and metabolomics could enhance interpretation of "omics" profiles, which may reveal specific biomarkers obviously correlated with specific pathways that mediate selective neurotoxicity.

p-Coumaric acid potential in restoring neuromotor function and oxidative balance through the Parkin pathway in a Parkinson disease-like model in Drosophila melanogaster

p-Coumaric acid is a significant phenolic compound known for its potent antioxidant activity. Thus, this study investigated the effects of p-coumaric acid on the behavioral and neurochemical changes induced in Drosophila melanogaster by exposure to rotenone in a Parkinson disease (PD)-like model. The flies were divided into four groups and maintained for seven days on different diets: a standard diet (control), a diet containing rotenone (500 μM), a control diet to which p-coumaric acid was added on the fourth day (0.3 μM), and a diet initially containing rotenone (500 μM) with p-coumaric acid added on the fourth day (0.3 μM). Exposure to p-coumaric acid ameliorated locomotor impairment and reduced mortality induced by rotenone. Moreover, p-coumaric acid normalized oxidative stress markers (ROS, TBARS, SOD, CAT, GST, and NPSH), mitigated oxidative damage, and reflected in the recovery of dopamine levels, AChE activity, and cellular viability post-rotenone exposure. Additionally, p-coumaric acid restored the immunoreactivity of Parkin and Nrf2. The results affirm that p-coumaric acid effectively mitigates PD-like model-induced damage, underscoring its antioxidant potency and potential neuroprotective effect.

Interplay between diphenyl diselenide and copper: Impact on D. melanogaster survival, behavior, and biochemical parameters

Copper (Cu2+) is a biologically essential element that participates in numerous physiological processes. However, elevated concentrations of copper have been associated with cellular oxidative stress and neurodegenerative diseases. Organo‑selenium compounds such as diphenyl diselenide (DPDS) have in vitro and in vivo antioxidant properties. Hence, we hypothesized that DPDS may modulate the toxicity of Cu2+ in Drosophila melanogaster. The acute effects (4 days of exposure) caused by a high concentration of Cu2+ (3 mM) were studied using endpoints of toxicity such as survival and behavior in D. melanogaster. The potential protective effect of low concentration of DPDS (20 μM) against Cu2+ was also investigated. Adult flies aged 1-5 days post-eclosion (both sexes) were divided into four groups: Control, DPDS (20 μM), CuSO4 (3 mM), and the combined exposure of DPDS (20 μM) and CuSO4 (3 mM). Survival, biochemical, and behavioral parameters were determined. Co-exposure of DPDS and CuSO4 increased acetylcholinesterase (AChE) activity and the generation of reactive oxygen species (ROS as determined by DFCH oxidation). Contrary to our expectation, the co-exposure reduced survival, body weight, locomotion, catalase activity, and cell viability in relation to control group. Taken together, DPDS potentiated the Cu2+ toxicity.

Sex-specific impacts of thimerosal on the behaviors and brain monoaminergic systems in zebrafish (Danio rerio)

Thimerosal (THI) is the most widely used form of organic mercury in pharmaceutical and personal care products, and has become a major source of ethylmercury pollution in aquatic ecosystems. However, knowledge about its potential risk to aquatic species is limited. In this study, zebrafish were exposed to THI for 7 days, and variations in their behavioral traits, brain monoaminergic neurotransmitter contents, and related gene expression were investigated. After the 7-day exposure, THI reduced locomotor activity and thigmotaxis in males but not females. Exposure to THI increased the social interaction between females but decreased that between males. The THI exposure also significantly reduced the serotonin (5-HT), 5-hydroxyindoleacetic acid, dopamine (DA), and 3,4-dihydroxyphenylacetic acid contents in the brain of males, but only significantly decreased the DA content in females. Correlation analysis revealed that the neurochemical alterations in the brain of zebrafish play critical roles in the behavioral abnormalities induced by THI exposure. Moreover, THI also significantly altered the expression of some genes associated with the synthesis, metabolism, and receptor binding of 5-HT and DA in the brain of zebrafish. The differences in these gene expressions between female and male zebrafish exposed to THI seem to be an important mechanism underlying their sex-specific responses to this chemical. This is the first report on the sex-specific effects of THI on behaviors and brain monoaminergic neurotransmitter contents in zebrafish, which can further improve our understanding of its toxic effects on teleost.

Does acute exposure to thimerosal, an organic mercury compound, affect the mitochondrial function of an infant model?

BACKGROUND

Thimerosal (TM) is a toxic, organometallic mercury compound (which releases ethyl-mercury-containing compounds in aqueous solutions) used as a preservative in vaccines. Mitochondria are organelle which are highly vulnerable to many chemical compounds, including mercury (Hg) and its derivatives.

METHOD

Wistar rats (at 21 days of age) were used to model a child's TM exposure following childhood vaccination, divided in two groups: TM exposed (20 μg/kg/day) and unexposed controls (saline solution), both for 24 h. Atomic Fluorescence Spectrometry was used to quantify the amounts of mercury in tissues. The electron transport chain (ETC) from isolated mitochondria was evaluated using an oxygen electrode. The mitochondrial membrane potential and H2O2 production were analyzed using selective fluorescence probes. The activity of some enzymes (SOD, CAT, GPx, and AChE) and secondary markers of oxidative stress (GSH, GSSG, total free thiol) were also examined in tissues.

RESULTS

Hg accumulation in the brain and liver was higher in exposed animals when compared to the control. Liver-isolated mitochondria showed that TM improved respiratory control by 23%; however, states 3 and 4 of the ETC presented a decrease of 16% and 37%, respectively. Furthermore, brain-isolated mitochondria presented an improvement of 61% in respiratory control. Brain enzyme activities were significantly impacted in TM-exposed rats compared to unexposed rats as follows: decreases in SOD (32%) and AChE (42%) and increases in GPx (79%) and CAT (100%). GPx enzyme activity in the liver was significantly increased (37%). Among secondary oxidative stress markers, the brain's total reduced thiol (SH) concentration was significantly increased (41%).

CONCLUSION

Acute TM treatment exposure in a Wistar rat model mimicking TM exposure in an infant following childhood vaccination significantly damaged brain bioenergetic pathways. This study supports the ability of TM exposure to preferentially damage the nervous system.

Polyvinylpyrrolidone-Capped Copper Oxide Nanoparticles-Anchored Pramipexole Attenuates the Rotenone-Induced Phenotypes in a Drosophila Parkinson's Disease Model

Parkinson's disease (PD) is a progressive, age-related neurodegenerative disease. The disease is characterized by the loss of dopaminergic neurons in the substantia nigra, pars compacta of the midbrain. Pramipexole (PPX) is a novel drug used for the treatment of PD. It has a high affinity for the dopamine (DA) D2 receptor subfamily and acts as a targeted mitochondrial antioxidant. It is less effective in the treatment of PD due to its short half-life, highly inconvenient dosing schedule, and long-term side effects. In recent years, PPX-loaded nanoformulations have been actively reported to overcome these limitations. In the current study, we focused on increasing the effectiveness of PPX by minimizing the dosing frequency and improving the treatment strategy for PD. Herein, we report the synthesis of biodegradable polyvinylpyrrolidone (PVP)-capped copper oxide nanoparticles (PVP-CuO NPs), followed by PPX anchoring on the surface of the PVP-CuO NPs (PPX-PVP-CuO NC), in a simple and inexpensive method. The newly formulated PPX-PVP-CuO NC complex was analyzed for its chemical and physical properties. The PPX-PVP-CuO NC was tested to protect against rotenone (RT)-induced toxicity in the Drosophila PD model. The in vivo studies using the RT-induced Drosophila PD model showed significant changes in negative geotaxis behavior and the level of DA and acetylcholinesterase. In addition, oxidative stress markers such as glutathione-S-transferase, total glutathione, thiobarbituric acid reactive species, and protein carbonyl content showed significant amelioration. The positive changes of PPX-PVP-CuO NC treatment in behavior, neurotransmitter level, and antioxidant level suggest its potential role in mitigating the PD phenotype. The formulation can be used for treatment or pharmacological intervention against PD.

Effects of Rosmarinus officinalis L. (Laminaceae) essential oil on adult and larvae of Drosophila melanogaster

Rosmarinus officinalis (Lamiaceae family), also known as "alecrim," is a perennial herb, typical of the Mediterranean region and widely distributed in Brazilian territory. Despite having demonstrated several properties of human interest, insecticide/larvicidal effect of essential oil from R. officinalis on insects remains unclear. In this study, we tested the effects of R. officinalis essential oil on biomarkers of oxidative damage in Drosophila melanogaster. Exposure to R. officinalis essential oil increased adult mortality and decreased geotaxis behavior in adult fruit flies. In addition, essential oil increased of larval mortality and impaired the developmental success in D. melanogaster. R. officinalis essential oil showed a significant repellent effect, with duration time of about 6 h. To understand the mechanism underlying the toxicity of essential oil both pro-oxidant effects and biomarkers of oxidative damage were evaluated in exposed flies. Exposure to essential oil caused a significant redox imbalance with impairment of both enzymatic and non-enzymatic antioxidant system and increased the lipid peroxidation levels. These results suggest that R. officinalis essential oil can be used as a bioinsecticide and/or larvicide as well as an alternative insect repellent.

Toxicological Effects of Thimerosal and Aluminum in the Liver, Kidney, and Brain of Zebrafish (Danio rerio)

Vaccination programs in the first years of a child's life are effective and extremely important strategies for the successful eradication of diseases. However, as no intervention is without risks, the metal-based components of some vaccines, such as thimerosal (TMS), a preservative composed of ethylmercury, and aluminum (Al), have begun to generate distrust on the part of the population. Therefore, this study evaluated the effects of exposure to thimerosal and aluminum hydroxide (alone or in mixture) on Danio rerio (zebrafish) specimens. The fish were exposed to thimerosal and/or aluminum hydroxide intraperitoneally. The liver, kidney, and brain were removed for a biochemical biomarker analysis, histopathological analysis, and metal quantification. As a result, we observed changes in the activity of the analyzed enzymes (SOD, GST, GPx) in the kidney and brain of the zebrafish, a reduction in GSH levels in all analyzed tissues, and a reduction in MT levels in the kidney and liver as well as in the brain. Changes in AChE enzyme activity were observed. The biochemical results corroborate the changes observed in the lesion index and histomorphology sections. We emphasize the importance of joint research on these compounds to increase the population's safety against their possible toxic effects.

Reserpine and PCPA reduce heat tolerance in Drosophila melanogaster

Drosophila melanogaster is a model organism to study molecular mechanisms and the role of the genes and proteins involved in thermal nociception. Monoamines (i.e. dopamine) have been involved in temperature preference behavior in D. melanogaster. Therefore, we investigated whether the monoamines, particularly dopamine and serotonin, participate in the response to thermal nociceptive stimuli in D. melanogaster. Flies were treated with reserpine (an inhibitor of vesicular monoamines transporter, 3-300 μM), 3-Iodo-L-tyrosine (3-I-T, an inhibitor of tyrosine hydroxylase, 16.28-65.13 mM), and para-Chloro-DL-phenylalanine (PCPA, an inhibitor of tryptophan hydroxylase, 20-80 mM); then, the flies were subjected to tests of thermal tolerance and avoidance of noxious heat. Climbing behavior was used as a test to evaluate locomotor activity. Reserpine reduces the thermal tolerance profile of the D. melanogaster, as well as the avoidance of noxious heat and locomotor activity depending on the concentration. PCPA, but not 3-I-T, decreased heat tolerance and avoidance of noxious heat. These data suggest that monoamines, particularly serotonin, are associated with the impaired avoidance of noxious heat which could be related to the reduction of heat tolerance in D. melanogaster.

Exposure to trans fat during the developmental period ofDrosophila melanogasteralters the composition of fatty acids in the head and induces depression-like behavior

Given the importance of understanding the disorders caused by trans fatty acids (TFAs), this study sought to add different concentrations hydrogenated vegetable fat (HVF) to the diet of Drosophila melanogaster during the developmental period and evaluate the effects on neurobehavioral parameters. Longevity, hatching rate, and behavioral functions were assessed, such as negative geotaxis, forced swimming, light/dark, mating, and aggressiveness. The fatty acids (FAs) present in the heads of the flies were quantified as well as serotonin (5HT) and dopamine (DA) levels. Our findings showed that flies that received HVF at all concentrations during development showed reduced longevity and hatching rates, in addition to increased depression-like, anxious-like, anhedonia-like, and aggressive behaviors. As for the biochemical parameters, there was a more significant presence of TFA in flies exposed to HVF at all concentrations evaluated and lower 5HT and DA levels. This study shows that HVF during the developmental phase can cause neurological changes and consequently induce behavioral disorders, thereby highlighting the importance of the type of FA offered in the early stages of life.

MeHg exposure impairs both the catecholaminergic and cholinergic systems resulting in motor and non-motor behavioral changes in Drosophila melanogaster

Human exposure to the natural environmental contaminant methylmercury (MeHg) has been associated to adverse health effects. Importantly, the mechanisms by which this organomercurial exerts its neurotoxicity have yet to be fully clarified. Therefore, the aim of this study was to evaluate whether exposure to MeHg alters dopamine (DA) and octopamine (OA) levels, acetylcholinesterase (AChE) activity and impacts both motor and non-motor behaviours. We studied the effect of MeHg by feeding 1-2 d old flies (male and females) with 25 and 50 μM MeHg for 4 d and determined effects on survival, motor and non-motor behaviours, oxidative stress, AChE and tyrosine hydroxylase (TH) activities, as well as DA and OA levels. We found that Drosophila melanogaster (D. melanogaster) exposed to MeHg showed a reduction in survival rate, associated with the inhibition of AChE and TH activities in head of flies and decreased DA and OA levels. These changes were accompanied by behavioural alterations, such as locomotor deficit and increased grooming behaviour, in addition to an increase in oxidative stress markers both in head and in body of flies, and an increase in glutathione-S-transferase (GST) activity in head of flies. Collectively, our data support the hypothesis that MeHg neurotoxicity is associated with altered OA and DA levels, AChE inhibition, which may serve, at least in part, as the underpinnings of both motor and non-motor behavioural changes.

Toxic metals that interact with thiol groups and alteration in insect behavior

Toxic metals, such as mercury (Hg), lead (Pb), cadmium (Cd), and copper (Cu), are widespread in the biosphere, and human activities have contributed to their continuous release into the ecosystems. Metal-induced toxicity has been extensively studied in mammals; however, the effects of these metals on insects' behavior have been explored to far lesser degree. As the main mechanism of toxicity, the cationic metals, explored in this review, have high affinity for thiol-containing molecules, disrupting the function of several proteins and low-molecular-weight thiol-containing molecules. Existing literature has corroborated that Hg, Pb, Cd, and Cu can disrupt locomotor and mating behaviors, but their effects on insects' memory and learning have yet to be fully characterized. Though field studies on metal-induced toxicity in insects are limited, results from Drosophila melanogaster as an experimental model suggest that insects living in contaminated environments can have behavioral foraging and reproductive deficits, which may cause population decline. In this review, we address the interaction between metals and endogenous thiol groups, with emphasis on alterations in insect behavior.

Consequences of thimerosal on human erythrocyte hemoglobin: Assessing functional and structural protein changes induced by an organic mercury compound

BACKGROUND

Thimerosal (TM) is an organic mercury compound used as a preservative in many pharmacological inputs. Mercury toxicity is related to structural and functional changes in macromolecules such as hemoglobin (Hb) in erythrocytes (Ery).

METHOD

Human Hb and Ery were used to evaluate O2 uptake based on the TM concentration, incubation time, and temperature. The influence of TM on the sulfhydryl content, production of reactive oxygen species (ROS), and membrane fragility was also evaluated. Raman spectra and atomic force microscopy (AFM) profiles for Ery in the presence and absence of TM were calculated, and docking studies were performed.

RESULTS

At 37 °C, with 2.50 μM TM (higher concentration) and after 5 min of incubation in Hb and Ery, we observed a reduction in O2 uptake of up to 50 %, while HgCl2, which was used as a positive control, showed a reduction of at least 62 %. Total thiol assays in the presence of NEM (thiol blocker) quantified the preservation of almost 60 % of free SH in Ery. Based on the Raman spectrum profile from Ery-TM, structural differences in the porphyrinic ring and the membrane lipid content were confirmed. Finally, studies using AFM showed changes in the morphology and biomechanical properties of Ery. Theoretical studies confirmed these experimental results and showed that the cysteine (Cys) residues present in Hb are involved in the binding of TM.

CONCLUSION

Our results show that TM binds to human Hb via free Cys residues, causing conformation changes and leading to harmful effects associated with O2 transport.

Effect of Solanum vegetables on memory index, redox status, and expressions of critical neural genes in Drosophila melanogaster model of memory impairment

African eggplant (Solanum macrocarpon L) (AE) and Black Nightshade (Solanum nigrum L) (BN) leaves are green leafy vegetables with nutritional and ethnobotanical values. We have previously characterized the vegetables via HPLC/LC-MS to reveal notable phenolic acids, flavonoids and alkaloids. In this present study, we addressed the efficacy of the two vegetables in mitigating mercuric chloride (HgCl₂)-induced neurotoxicity and memory impairment in Drosophila melanogaster. Flies were exposed to HgCl₂ (0.30 mg/g) alone or in combination with the vegetables (0.1 and 1.0%) of both samples in their diets for seven days. The results showed that HgCl₂ (Hg)-exposed flies had significantly reduced survival rate and memory index, which were ameliorated in the Hg-exposed flies fed AE or BN. This was accompanied by increased reactive oxygen species (ROS) levels, reduced total thiol, as well as catalase, glutathione transferase (GST) and acetylcholine esterase (AChE) activities in Hg-exposed fly heads, but ameliorated in Hg-exposed flies fed dietary inclusions of the vegetables. In addition, the Hg-induced alterations in SOD, NF-ҝB/Relish, Dronc and Reaper mRNA levels were statistically indistinguishable from controls in Hg-treated flies fed diets containing AE or BN. Normalization of cnc/Nrf2 and FOXO were observed only in Hg-treated flies fed BN. These findings suggest that dietary AE or BN leaves offer protection against Hg-induced memory impairment and neurotoxicity in D. melanogaster, and further justify them as functional foods with neuroprotective properties.

Short exposure to ethyl and methylmercury prompts similar toxic responses in Drosophila melanogaster

Methylmercury (MeHg) and ethylmercury (EtHg) are important mercury organic forms in terms of human poisoning. Since the comparative effects of compounds are mainly in vitro, this study was designed to investigate the toxicities induced by MeHg and EtHg in an in vivo study using adult Drosophila melanogaster (D. melanogaster). Firstly, we performed a survival curve, where the flies were fed on a medium containing MeHg and EtHg at concentrations ranging from 2.5 to 200 μM, until the end of their lifespan. After that, the concentrations 25 and 200 μM of MeHg and EtHg were chosen to be tested in a short exposure for 5 days. The analysis of survival by Kaplan-Meier plot revealed that all concentrations of MeHg and EtHg reduced significantly the lifespan of the flies. Short exposure to both concentrations of MeHg and EtHg impaired the ability of flies in the climbing assay and induced lipid peroxidation. Only the flies exposed to the highest concentration had viability loss, thiol depletion, and increased reactive species (RS) and Hg levels in the whole body. Our findings indicate that MeHg and EtHg exhibit similar toxic effects in vivo, and that oxidative stress is a phenomenon behind the toxicity of both mercurials. The data obtained also reinforce the use of D. melanogaster as a useful organism for basic toxicological research.

Oxidative stress and decreased dopamine levels induced by imidacloprid exposure cause behavioral changes in a neurodevelopmental disorder model in Drosophila melanogaster

Neurodevelopmental disorders, such as Autism Spectrum Disorder (ASD) and Attention Deficit Hyperactivity Disorder (ADHD) are responsible for behavioral deficits in children. Imidacloprid is a nicotinic acetylcholine receptor agonist, capable of causing behavioral changes in Drosophila melanogaster, similar to the ADHD-like phenotypes. We assess whether behavioral damage induced by imidacloprid exposure in Drosophila melanogaster is associated with neurochemical changes and whether these changes are similar to those observed in neurodevelopmental disorders such as ASD and ADHD. The fruit flies were divided into four groups, exposed to either a standard diet (control) or a diet containing imidacloprid (200, 400 or 600 ρM) and allowed to mate for 7 days. After hatching, the progeny was subjected to in vivo and ex vivo tests. The ones exposed to imidacloprid showed an increase in hyperactivity, aggressiveness, anxiety and repetitive movements, as well as, a decrease in social interaction. Furthermore, exposure to imidacloprid decreased dopamine levels, cell viability and increased oxidative stress in the flies' progeny. These results demonstrated that the behavioral damage induced by imidacloprid exposure involves a reduction in dopamine levels and oxidative stress and that these neurochemical changes are in line with the events that occur in ASD and ADHD-like phenotypes in other models.

Protective effect of gamma-oryzanol against manganese-induced toxicity in Drosophila melanogaster

Manganese (Mn) is an essential element that, in excess, seems to be involved in the development of different neurodegenerative conditions. Gamma-oryzanol (Ory) was previously reported to possess antioxidant and neuroprotective properties. Thus, we conducted this study to test the hypothesis that Ory can also protect flies in an Mn intoxication model. Adult wild-type flies were fed over 10 days with Mn (5 mM) and/or Ory (25 μM). Flies treated with Mn had a decrease in locomotor activity and a higher mortality rate compared to those in controls. Mn-treated flies also had a significant increase in acetylcholinesterase (AChE) activity, in Mn accumulation and in oxidative stress markers. Moreover, flies treated with Mn exhibited a significant decrease in dopamine levels and in tyrosine hydroxylase activity, as well as in mitochondrial and cellular viability. Particularly important, Ory protected against mortality and avoided locomotor and biochemical changes associated with Mn exposure. However, Ory did not prevent the accumulation of Mn. The present results support the notion that Ory effectively attenuates detrimental changes associated with Mn exposure in Drosophila melanogaster, reinforcing its neuroprotective action/potential.

Iron overload during the embryonic period develops hyperactive like behavior and dysregulation of biogenic amines in Drosophila melanogaster

Iron (Fe) is used in various cellular functions, and a constant balance between its uptake, transport, storage, and use is necessary to maintain its homeostasis in the body. Changes in Fe metabolism with a consequent overload of this metal are related to neurological changes and cover a broad spectrum of diseases, mainly when these changes occur during the embryonic period. This work aimed to evaluate the effect of exposure to Fe overload during the embryonic period of Drosophila melanogaster. Progenitor flies (male and female) were exposed to ferrous sulfate (FeSO₄) for ten days in concentrations of 0.5, 1, and 5 ​mM. After mating and oviposition, the progenitors were removed and the treatment bottles preserved, and the number of daily hatches and cumulative hatching of the first filial generation (F1) were counted. Subsequently, F1 flies (separated by sex) were subjected to behavioral tests such as negative geotaxis test, open field test, grooming, and aggression test. They have evaluated the levels of dopamine (DA), serotonin (5-HT), octopamine (OA), tryptophan and tyrosine hydroxylase (TH), acetylcholinesterase, reactive species, and the levels of Fe in the progenitor flies and F1. The Fe levels of F1 flies are directly proportional to what is incorporated during the period of embryonic development; we also observed a delay in hatching and a reduction in the number of the hatch of F1 flies exposed during the embryonic period to the 5mM Fe diet, a fact that may be related to the reduction of the cell viability of the ovarian tissue of progenitor flies. The flies exposed to Fe (1 and 5 ​mM) showed an increase in locomotor activity (hyperactivity) and a significantly higher number of repetitive movements. In addition to a high number of aggressive encounters when compared to control flies. We can also observe an increase in the levels of biogenic amines DA and 5-HT and an increase in TH activity in flies exposed to Fe (1 and 5 ​mM) compared to the control group. We conclude that the hyperactive-like behavior demonstrated in both sexes by F1 flies exposed to Fe may be associated with a dysregulation in the levels of DA and 5-HT since Fe is a cofactor of TH, which had its activity increased in this study. Therefore, more attention is needed during the embryonic development period for exposure to Fe overload.

Exposure to lutein-loaded nanoparticles attenuates Parkinson's model-induced damage in Drosophila melanogaster: Restoration of dopaminergic and cholinergic system and oxidative stress indicators

Parkinson's is a neurodegenerative disease, characterized by the loss of dopaminergic neurons, cholinergic alterations and oxidative damages. Lutein is widely known by its antioxidants properties. In the present study, we investigated whether lutein-loaded nanoparticles protects against locomotor damage and neurotoxicity induced by Parkinson's disease model in Drosophila melanogaster, as well as possible mechanisms of action. First, the nanoparticles were characterized by physicochemical methods, demonstrating that water affinity was improved by the encapsulation of lutein into the polymeric encapsulant matrix. The fruit flies of 1-4 days old were divided into four groups and exposed to a standard diet (control), a diet containing either rotenone (500 μM), lutein-loaded nanoparticles (6 μM) or rotenone (500 μM) and lutein-loaded nanoparticles (6 μM) for 7 days. The survival percentage was assessed, the flies were submitted to negative geotaxis, open field tasks and the determination of dopamine levels, tyrosine hydroxylase (TH) and acetylcholinesterase activities and oxidative stress indicators (superoxide dismutase, catalase, thiobarbituric acid reactive substances and glutathione S-transferase) were carried out. The exposure to lutein-loaded nanoparticles protected against locomotor damage and the decrease survival rate induced by rotenone, besides, it restored the dopamine levels, TH and acetylcholinesterase activities and oxidative stress indicators. These results provide evidence that lutein-loaded nanoparticles are an alternative treatment for rotenone-induced damage, and suggest the involvement of dopaminergic and cholinergic system and oxidative stress.

A study on the potential reprotoxic effects of thimerosal in male albino rats

Thimerosal is ethyl mercury based compound which is being used as a preservative in vaccines since decades. Pharmaceutical products and vaccines that contain thimerosal are among the potential source of mercury exposure. Current research was intended to ascertain the reprotoxic effects of thimerosal on rat testes. Twenty-four adult male albino rats were sorted into four groups (n = 6). The first group was a control group. Rats of experimental Group 2, 3 and 4 were treated with various dosages of thimerosal (0.5, 10, 50 mg/kg) respectively. Rats were decapitated after thirty days of trial and different parameters were analyzed. Thimerosal exposure resulted in a significant decrease in antioxidant enzyme activities including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione reductase (GSR) and increased levels of thiobarbituric acid reactive substances (TBARS). Different doses of thimerosal significantly decreased (p < 0.05) the concentration of plasma testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH). Additionally, Daily sperm production (DSP) and efficiency of daily sperm production were significantly reduced followed by thimerosal exposure. Moreover, thimerosal significantly (p < 0.05) decreased the primary spermatocytes, secondary spermatocytes, number of spermatogonia along with spermatids. Thimerosal induced adverse histopathological and morphological changes in testicular tissues such as decreased Leydig cells, diameter of seminiferous tubules, tunica albuginea height and epithelial height. On the other hand, the increase in tubular lumen and interstitial spaces was observed due to thimerosal. These outcomes indicated that thimerosal has potential reprotoxic effects in male albino rats.

Addition of Saturated and Trans-fatty Acids to the Diet Induces Depressive and Anxiety-like Behaviors in Drosophila melanogaster

This study aimed to evaluate the effects of the addition of saturated fat and hydrogenated vegetable fat (HVF) to the diet on depressive and anxiety-like behaviors in Drosophila melanogaster. Flies were exposed to experimental diets: regular diet (RD), or HVF in the concentrations of the substitute (SHVF), HVF 10% and HVF 20%, or Lard (L) in the concentrations of the substitute (SL), L 10% and L 20%, during seven days. Our results showed that flies fed with the HVF diet presented similar behaviors to depression, anxiety, and a higher number of aggressive events. Flies exposed to L showed only depressive-like behavior. Regarding serotonin levels (5HT), there was a significant reduction in the flies exposed to SHVF, HVF 10%, HVF 20%, and L 20%. Regarding the levels of octopamine (OA), there was a significant reduction in the flies exposed to both HVF and L rich diets when compared with the RD group. Also, there was a significant negative correlation between 5HT or OA levels and behaviors of aggressiveness, negative geotaxis, immobility time, light/dark, and grooming in the flies. This study shows that D. melanogaster can serve as a valuable model for understanding psychiatric disorders and that the type of fatty acid (FA) offered in the diet can influence these disorders. This demonstrates the importance of the composition of the FAs in the neural pathways, being able to influence the signaling of neurotransmitters, such as 5HT and OA, and thus, cause behavioral changes.

Alpha lipoic acid ameliorates THIM-induced prefrontal cell loss and abnormal enzymatically contents in the developing rat

Thimerosal (THIM) is a common preservative used in many pharmaceutical drugs, vaccines, cosmetics and many other products. Today, it was somewhat clear that Thimerosal (THIM) is a neurotoxicant preservative. We aimed to use of a suitable agent for preventing of THIM side effects on brain. Therefore, in this research, the protective effects of Alpha Lipoic Acid (ALA), against THIM-induced brain cell loss, changes in neuroimmune cell and enzymatically contents were examined. Male Wistar rats (n = 60) were randomly distributed into five groups: 1- THIM group; this group received THIM at dose of 300 μg /kg on 7, 9, 11, 15 days after birth 2- ALA group; received ALA (20 mg/kg) in the same order. 3- THIM & ALA group; this group received ALA in the same dose, 30 min before THIM administration.4& 5; Saline and ALA vehicle groups were also included. At 56th postnatal day, samples of the prefrontal cortex were collected and prepared for stereological, immune-histochemical, and enzymatic evaluations. The result showed that ALA, prevents the adverse effects of THIM on brain cell loss, abnormal changes in neuroimmune cells (p < 0.05), prefrontal cortex volume (p < 0.05), and the glutathione content of prefrontal cortex (p < 0.05). In conclusion, neonatal exposure to THIM can induce abnormal alterations in neuroimmune cells and brain cell density as well as prefrontal cortex volume & glutathione content, and ALA can ameliorate these abnormalities.

Effect of Majun Baladur on life span, climbing ability, oxidative stress and dopaminergic neurons in the transgenic Drosophila model of Parkinson's disease

The effect of a poly herbal drug Majun Baladur (MB) was studied on the transgenic Drosophila melanogaster expressing human alpha synuclein in the neurons (PD flies). The equivalents of recommended dose for human were established for 20 g of fly food i.e. 0.0014, 0.0028, 0.0042 and 0.0056 g per 20 g of diet. The PD flies were allowed to feed on it for 24 days before performing the assays. The exposure to MB increased the life span and improves the activity of PD flies. The PD flies exposed to 0.0014, 0.0028, 0.042 and 0.0056 g of MB showed a dose dependent significant delay of 1.47, 1.88, 2.52 and 3.05 folds in the climbing ability compared to unexposed PD flies. A dose dependent significant decrease of 1.38, 1.45, 1.48 and 1.65 folds in TBARS; 1.08, 1.11, 1.17 and 1.20 folds in the GST activity; 1.20, 1.28, 1.39 and 1.52 folds in the PC content; 1.43, 1.53, 1.65 and 1.79 folds in the Caspase-9 activity; 1.21, 1.31, 1.53 and 1.64 folds in the activity of Caspase-3 and 1.24, 1.42, 1.50 and 1.79 folds in the activity of catalase; 1.50, 1.63, 1.88 and 2.06 folds in the activity of SOD in PD flies exposed to 0.0014, 0.0028, 0.042 and 0.0056 g of MB, respectively. A significant dose dependent increase of 1.20, 1.29, 1.33 and 1.44 folds in as NPSH content was observed in PD flies exposed to 0.0014, 0.0028, 0.042 and 0.0056 g of MB, respectively. The exposure to MB protects the loss of dopaminergic neurons as is evident by immunohistochemistry. It is concluded that MB is potent in reducing the PD symptoms being mimicked in the transgenic flies.