Ketamine plus Alcohol: What We Know and What We Can Expect about This.

Drug abuse has become a public health concern. The misuse of ketamine, a psychedelic substance, has increased worldwide. In addition, the co-abuse with alcohol is frequently identified among misusers. Considering that ketamine and alcohol share several pharmacological targets, we hypothesize that the consumption of both psychoactive substances may synergically intensify the toxicological consequences, both under the effect of drugs available in body systems and during withdrawal. The aim of this review is to examine the toxicological mechanisms related to ketamine plus ethanol co-abuse, as well the consequences on cardiorespiratory, digestive, urinary, and central nervous systems. Furthermore, we provide a comprehensive discussion about the probable sites of shared molecular mechanisms that may elicit additional hazardous effects. Finally, we highlight the gaps of knowledge in this area, which deserves further research.

Contributing to Understand the Crosstalk between Brain and Periphery in Methylmercury Intoxication: Neurotoxicity and Extracellular Vesicles.

Human exposure to methylmercury (MeHg) is currently high in regions such as the Amazon. Understanding the molecular changes associated with MeHg-induced neurotoxicity and the crosstalk with the periphery is essential to support early diagnoses. This work aimed to evaluate cellular and molecular changes associated with behavioral alterations in MeHg acute exposure and the possible changes in extracellular vesicles (EVs) number and S100ß content. Adults male Wistar rats were orally treated with 5 mg/kg for four days. Behavioral performance, molecular and histological changes in the cerebellum, and plasma EVs were assessed. MeHg-intoxicated animals performed significantly worse in behavioral tests. MeHg increased the number of GFAP+ cells and GFAP and S100ß mRNA expression in the cerebellum but no change in NeuN+ or IBA-1+ cells number was detected. The number of exosomes isolated from plasma were decreased by the metal. S100B mRNA was detected in circulating plasma EVs cargo in MeHg exposure. Though preliminary, our results suggest astrocytic reactivity is displaying a protective role once there was no neuronal death. Interestingly, the reduction in exosomes number could be a new mechanism associated with MeHg-induced neurotoxicity and plasma EVs could represent a source of future biomarkers in MeHg intoxication.

From Molecules to Behavior in Long-Term Inorganic Mercury Intoxication: Unraveling Proteomic Features in Cerebellar Neurodegeneration of Rats.

Mercury is a severe environmental pollutant with neurotoxic effects, especially when exposed for long periods. Although there are several evidences regarding mercury toxicity, little is known about inorganic mercury (IHg) species and cerebellum, one of the main targets of mercury associated with the neurological symptomatology of mercurial poisoning. Besides that, the global proteomic profile assessment is a valuable tool to screen possible biomarkers and elucidate molecular targets of mercury neurotoxicity; however, the literature is still scarce. Thus, this study aimed to investigate the effects of long-term exposure to IHg in adult rats' cerebellum and explore the modulation of the cerebellar proteome associated with biochemical and functional outcomes, providing evidence, in a translational perspective, of new mercury toxicity targets and possible biomarkers. Fifty-four adult rats were exposed to 0.375 mg/kg of HgCl2 or distilled water for 45 days using intragastric gavage. Then, the motor functions were evaluated by rotarod and inclined plane. The cerebellum was collected to quantify mercury levels, to assess the antioxidant activity against peroxyl radicals (ACAPs), the lipid peroxidation (LPO), the proteomic profile, the cell death nature by cytotoxicity and apoptosis, and the Purkinje cells density. The IHg exposure increased mercury levels in the cerebellum, reducing ACAP and increasing LPO. The proteomic approach revealed a total 419 proteins with different statuses of regulation, associated with different biological processes, such as synaptic signaling, energy metabolism and nervous system development, e.g., all these molecular changes are associated with increased cytotoxicity and apoptosis, with a neurodegenerative pattern on Purkinje cells layer and poor motor coordination and balance. In conclusion, all these findings feature a neurodegenerative process triggered by IHg in the cerebellum that culminated into motor functions deficits, which are associated with several molecular features and may be related to the clinical outcomes of people exposed to the toxicant.

Alveolar bone loss induced by chronic ethanol consumption from adolescence to adulthood in Wistar rats.

Though there are literature indicating the bone loss due to alcohol consumption, studies on the association between ethanol consumption and periodontal breakdown in animals are either scarce or have provided conflicting results. Here, we investigated the effects of chronic alcohol exposure from adolescence to adulthood on the alveolar bone in rats. Wistar rats were exposed to ethanol (6.5 g/kg/day) in a solution of 22.5% (w/v) or distilled water (control) by gavage from 35 days of age (adolescent) until 90 days (adulthood). Evaluation of the bone loss was performed using scanning electronic microscopy, in which the distances between the cement-enamel junction and the alveolar bone crest from the palatal side of the first molar mandibular were measured. The measurements obtained were tabulated and analyzed using Student's t-test. Alcohol-treated group revealed greater bone loss in comparison to the control group. These findings indicate that heavy chronic alcohol exposure from adolescent to adulthood can induce alveolar bone loss in rats associated to absence of periodontitis.

Physical training mitigates alveolar bone and blood enzymatic antioxidants defense impairment induced by binge ethanol consumption in rats.

We aimed to investigate the effectiveness of physical training as a protective strategy to mitigate alveolar bone damage and blood antioxidant defense caused by ethanol (EtOH) consumption in a binge-drinking pattern. Male Wistar rats aged approximately 90 days were divided into four groups: control, training, EtOH, and training + EtOH. The physical training protocol was conducted on a treadmill for four consecutive weeks, while the animals in the EtOH group were administered EtOH via orogastric gavage for three consecutive days each week, following the binge drink pattern. After the training period, blood and mandibles were collected for plasma oxidative biochemistry analysis, and the alveolar bone was subjected to physicochemical composition analysis, tissue evaluation, and microtomography evaluation. Our results showed that EtOH induced oxidative stress and physical exercise promoted the recovery of antioxidant action. Physical training minimized the damage to the mineral/matrix composition of the alveolar bone due to EtOH consumption and increased the density of osteocytes in the trained group treated with EtOH than in those exposed only to EtOH. Furthermore, physical training reduced damage to the alveolar bone caused by EtOH consumption. Our findings suggest that physical training can serve as an effective strategy to reduce systemic enzymatic oxidative response damage and alleviate alveolar bone damage resulting from alcohol consumption. Further investigations are warranted to elucidate the underlying mechanisms and explore, in addition to physical training, the potential effects of other activities with varying intensities on managing alcohol-induced bone damage.

Ethanol binge drinking exposure during adolescence displays long-lasting motor dysfunction related to cerebellar neurostructural damage even after long-term withdrawal in female Wistar rats.

Ethanol is one of the psychoactive substances most used by young individuals, usually in an intermittent and episodic manner, also called binge drinking. In the adolescent period, brain structures undergo neuromaturation, which increases the vulnerability to psychotropic substances. Our previous studies have revealed that ethanol binge drinking during adolescence elicits neurobehavioral alterations associated with brain damage. Thus, we explored the persistence of motor function impairment and cerebellum damage in the context of ethanol withdrawal periods (emerging adulthood and adult life) in adolescent female rats. Female Wistar rats (35 days old) received orally 4 cycles of ethanol (3.0 g/kg/day) or distilled water in 3 days on-4 days off paradigm (35th until 58th day of life). Motor behavioral tests (open field, grip strength, beam walking, and rotarod tests) and histological assays (Purkinje's cell density and NeuN-positive cells) were assessed on the 1-, 30-, and 60-days of binge alcohol exposure withdrawal. Our findings demonstrate that the adolescent binge drinking exposure paradigm induced cerebellar cell loss in all stages evaluated, measured through the reduction of Purkinje's cell density and granular layer neurons. The cerebellar tissue alterations were accompanied by behavioral impairments. In the early withdrawal, the reduction of spontaneous movement, incoordination, and unbalance was seen. However, the grip strength reduction was found at long-term withdrawal (60 days of abstinence). The cerebellum morphological changes and the motor alterations persisted until adulthood. These data suggest that binge drinking exposure during adolescence causes motor function impairment associated with cerebellum damage, even following a prolonged withdrawal, in adult life.

Neurotoxicology of alcohol: a bibliometric and science mapping analysis.

Alcohol consumption is common in many societies and has increased considerably, resulting in many socioeconomic and public health problems. In this sense, studies have been carried out in order to understand the mechanisms involved in alcohol consumption and related harmful effects. This study aimed to identify and map the knowledge and to perform bibliometric analysis of the neurotoxicology of alcohol based on the 100 most cited articles. A search was carried out in the Web of Science Core Collection database and information was extracted regarding the journal, authors, keywords, year of publication, number of citations, country and continent of the corresponding author. For each selected manuscript, the study design, alcohol exposure model, dose, period of exposure, and effect on the central nervous system and research hotspots were mapped. The journal with the highest number of publications was Alcoholism: Clinical and Experimental Research (n = 11 papers), the author who contributed the most was Crews FT (n = 8 papers), the studies had a total of 288 keywords and 75% of the publications were from the United States of America. The experimental studies evaluated the effects of prenatal and postnatal exposure and were conducted in rats and mice using doses ranging from 2.5 to 14 g/kg/day, with administration by subcutaneous, intraperitoneal, intragastric, or inhalation route or with free access through drinking bottles. Among the studies mapped, the oldest one (1989) aimed to understand the systemic damage and mechanisms of action involved, while the most recent focused on understanding the receptors and mechanisms involved in addiction, as well as genetic factors. Our results show the panorama of the most widespread scientific production in the scientific community on the neurotoxicology of ethanol, a high prevalence was observed in studies that addressed fetal alcohol syndrome and/or the effects of ethanol on neurodevelopment.

Physical Exercise Mitigates Salivary Gland and Saliva Damages in Rats Exposed to Binge-like Ethanol Pattern.

Heavy episodic ethanol (EtOH) consumption is a typical pattern, especially among younger people. The therapeutic effect of exercise on EtOH damage has not yet been fully elucidated. Therefore, this study aims to investigate whether moderate exercise can reduce the damage generated by ethanol consumption in salivary glands and saliva. Thus, 32 male Wistar rats were divided into four groups: control (sedentary animals treated with water); training (trained animals treated with EtOH); EtOH (sedentary animals treated with EtOH); and EtOH + training (trained animals treated with ethanol). EtOH was administered to the animals at a dose of 3 g/kg/day at a concentration of 20% w/v for three consecutive days per week via intragastric gavage. The training was performed on a treadmill for five successive days. At the end of the 4-week experimental protocol, the animals were euthanized, and salivary glands and saliva were collected for oxidative biochemistry analysis. Our results showed that EtOH consumption generated changes in the oxidative biochemistry of the salivary glands and saliva. Thus, it was possible to conclude that moderate physical exercise can significantly recover antioxidant activity, reducing the damage generated by EtOH.

Aerobic Physical Training Attenuates Oxidative Stress in the Spinal Cord of Adult Rats Induced by Binge-like Ethanol Intake.

Binge drinking is the most frequent consumption pattern among young adults and remarkably changes the central nervous system; thus, research on strategies to protect it is relevant. This study aimed to investigate the detrimental effects of binge-like EtOH intake on the spinal cord of male rats and the potential neuroprotective effects provided by moderate-intensity aerobic physical training. Male Wistar rats were distributed into the 'control group', 'training group', 'EtOH group', and 'training + EtOH'. The physical training protocol consisted of daily 30-min exercise on a treadmill for 5 consecutive days followed by 2 days off during 4 weeks. After the fifth day of each week, distilled water ('control group' and 'training group') or 3 g/kg of EtOH diluted at 20% w/v ('EtOH group' and 'training + EtOH group') was administered for 3 consecutive days through intragastric gavage to simulate compulsive consumption. Spinal cord samples were collected for oxidative biochemistry and morphometric analyses. The binge-like EtOH intake induced oxidative and tissue damage by decreasing reduced glutathione (GSH) levels, increasing lipid peroxidation (LPO), and reducing motor neurons (MN) density in the cervical segment. Even under EtOH exposure, physical training maintained GSH levels, reduced LPO, and prevented MN reduction at the cervical segment. Physical training is a non-pharmacological strategy to neuroprotect the spinal cord against oxidative damage induced by binge-like EtOH intake.

One binge-type cycle of alcohol plus ketamine exposure induces emotional-like disorders associated with oxidative damage in adolescent female rats.

Drug abuse is a global public health problem among adolescents, with alcohol often used in association with other psychotropic drugs, such as ketamine. Considering the scarcity of evidence, this study aimed to investigate emotional behavioral effects induced by ethanol plus ketamine co-abuse, as well as oxidative biochemistry, and neurotrophic mediator in the prefrontal cortex and hippocampus in the early withdrawal of adolescent female rats. Animals were divided into control, ethanol, ketamine, and ethanol plus ketamine groups. The protocol administration was performed for 3 consecutive days (binge-like pattern). Behavioral assays of open field, elevated plus maze, and forced swim test were performed. After that, the prefrontal cortex and hippocampus were collected to evaluate oxidative biochemistry (reactive oxygen species-ROS; Antioxidant capacity against peroxyl radicals-ACAP; and lipid peroxidation). We found that isolated or combined ethanol and ketamine exposure displayed anxiety- and depressive-like profile, in a non-synergistically manner during early withdrawal. However, oxidative damage was aggravated in the co-administered animals than in isolated exposed subjects. We concluded that ethanol plus ketamine co-abuse may intensify oxidative damage in the hippocampus and prefrontal cortex in the early withdrawal of adolescent female rats, which was not reflected in the emotional behavioral phenotype. DATA AVAILABILITY STATEMENT: The datasets used and/or analyzed during the current investigation are available upon reasonable request from the corresponding author.

Deciphering the Global Proteomic Profile Involved in Methylmercury-Induced Cerebellar Neurodegeneration and Motor Dysfunction in Adult Rats.

Mercury is a ubiquitous pollutant in the environment with potential neurotoxic effects. Several populations are susceptible to mercurial exposure, especially methylmercury (MeHg) at low doses for long periods through food consumption. Given this, the present work aimed to assess the effects of long-term MeHg exposure on the cerebellum of rats from a translational perspective using a representative dose, assessing molecular, biochemical, morphological, and behavioral parameters. The model was produced by administering 40 µg/kg of MeHg for 60 days to adult male Wistar rats by oral gavage. As a result of this exposure, the animals presented motor deficits in open field and rotarod tests which were associated with an increase in total mercury content in cerebellar parenchyma, a reduction in antioxidant competence against peroxyl radicals, and increased nitrite and lipid peroxidation levels. The proteomic approach showed 317 modulated proteins. Such findings were associated with reductions in mature neuron and Purkinje cell densities and glial fibrillary acidic protein immunostained areas and increased microglial density. In addition, decreases in myelin basic protein and synaptophysin immunostaining were also observed. The results thus provided new evidence of the mechanisms underlying complex MeHg-induced neurodegeneration, especially the proteins underlying the biochemical and morphological features associated with motor dysfunction.

Methylmercury exposure during prenatal and postnatal neurodevelopment promotes oxidative stress associated with motor and cognitive damages in rats: an environmental-experimental toxicology study.

The environmental contamination by methylmercury (MeHg) is a major concern for public health. The effects of MeHg in the central nervous system (CNS) of adult animals have been extensively investigated; however, little is known about the effects of MeHg exposure during intrauterine and lactation periods on motor and cognitive functions of adolescent rats. Therefore, this study aimed to investigate the effect of MeHg exposure during intrauterine life and lactation on both motor and cognitive functions of offspring rats. Ten female Wistar rats were exposed to 40 µg/kg/day of MeHg through cookie treats from the first day of pregnancy until the last day of breastfeeding. Both motor and cognitive functions of offspring male rats were assessed by open field, rotarod, and step-down inhibitory avoidance tests. Forty-one days after birth, the hippocampus and cerebellum were collected to determine total Hg content, antioxidant capacity against peroxyl radicals (ACAP), reduced glutathione (GSH) levels, lipid peroxidation (LPO), and nitrite levels. MeHg exposure during CNS development increased Hg levels in both hippocampal and cerebellar parenchymas, triggered oxidative stress throughout ACAP and GSH decrease, increased LPO and nitrite levels. These alterations resulted in reduced spontaneous and stimulated locomotion and short- and long-term memory deficits. Therefore, damages triggered by MeHg exposure during intrauterine life and lactation had detrimental effects on oxidative biochemistry and motor and cognitive functions of offspring rats.

Repeated Cycles of Binge-Like Ethanol Exposure Induces Neurobehavioral Changes During Short- and Long-Term Withdrawal in Adolescent Female Rats.

Alcohol consumption is spread worldwide and can lead to an abuse profile associated with severe health problems. Adolescents are more susceptible to addiction and usually consume ethanol in a binge drinking pattern. This form of consumption can lead to cognitive and emotional disorders, however scarce studies have focused on long-term hazardous effects following withdrawal periods after binge drinking in adolescents. Thus, the present study aims at investigating whether behavioral and cognitive changes persist until mid and late adulthood. Female Wistar rats (9-10 animals/group) received intragastric administration of four cycles of ethanol binge-like pattern (3.0 g/kg/day, 20% w/v; 3 days-on/4 days-off) from 35th to 58th days old, followed withdrawal checkpoints 1 day, 30 days, and 60 days. At each checkpoint period, behavioral tests of open field, object recognition test, elevated plus maze, and forced swimming test were performed, and blood and hippocampus were collected for oxidative biochemistry and brain-derived neurotrophic factor (BDNF) levels analysis, respectively. The results demonstrated that adolescent rats exposed to binge drinking displayed anxiogenic- and depressive-like phenotype in early and midadulthood, however, anxiety-like profile persisted until late adulthood. Similarly, short-term memory was impaired in all withdrawal periods analysed, including late adult life. These behavioral data were associated with oxidative damage in midadulthood but not BDNF alterations. Taken together, the present work highlights the long-lasting emotional and cognitive alterations induced by ethanol binge drinking during adolescence, even after a long period of abstinence, which might impact adult life.

"K-Powder" Exposure during Adolescence Elicits Psychiatric Disturbances Associated with Oxidative Stress in Female Rats.

Ketamine, also called 'K-powder' by abusers, an analog of phencyclidine, primarily acts as an antagonist of N-methyl-D-aspartic acid (NMDA) receptors, therapeutically used as an anesthetic agent. Ketamine also stimulates the limbic system, inducing hallucinations and dissociative effects. At sub-anesthetic doses, ketamine also displays hallucinatory and dissociative properties, but not loss of consciousness. These behavioral consequences have elicited its recreational use worldwide, mainly at rave parties. Ketamine is generally a drug of choice among teenagers and young adults; however, the harmful consequences of its recreational use on adolescent central nervous systems are poorly explored. Thus, the aim of the present study was to characterize the behavioral and biochemical consequences induced by one binge-like cycle of ketamine during the early withdrawal period in adolescent female rats. Adolescent female Wistar rats (n = 20) received intraperitoneally administered ketamine (10 mg/kg/day) for 3 consecutive days. Twenty-four hours after the last administration of ketamine, animals were submitted to behavioral tests in an open field, elevated plus-maze, and forced swimming test. Then, animals were intranasally anesthetized with 2% isoflurane and euthanized to collect prefrontal cortex and hippocampus to assess lipid peroxidation, antioxidant capacity against peroxyl radicals, reactive oxygen species, reduced glutathione, and brain-derived neurotrophic factor (BDNF) levels. Our results found that 24 h after recreational ketamine use, emotional behavior disabilities, such as anxiety- and depression-like profiles, were detected. In addition, spontaneous ambulation was reduced. These negative behavioral phenotypes were associated with evidence of oxidative stress on the prefrontal cortex and hippocampus.

Ganoderma lucidum Ameliorates Neurobehavioral Changes and Oxidative Stress Induced by Ethanol Binge Drinking.

Ganoderma lucidum, mushroom used for centuries by Asian peoples as food supplement, has been shown interesting biological activities, including over the Central Nervous System. Besides, these mushroom bioactive compounds present antioxidant and anti-inflammatory activities. On the side, binge drinking paradigm consists of ethanol exposure that reflects the usual consumption of adolescents, which elicits deleterious effects, determined by high ethanol consumption, in a short period. In this study, we investigated whether the Aqueous Extract of G. lucidum (AEGl) reduces the behavioral disorders induced by alcohol. Male (n = 30) and female Wistar rats (n = 40), seventy-two days old, were used for behavioral/biochemical and oral toxicity test, respectively. Animals were exposed to 5 binges (beginning at 35 days old) of ethanol (3 g/kg/day) or distilled water. Twenty-four hours after the last binge administration, animals received AEGl (100 mg/kg/day) or distilled water for three consecutive days. After treatment protocol, open field, elevated plus maze, forced swim, and step-down inhibitory avoidance tests were performed. Oxidative stress parameters were measured to evaluate the REDOX balance. Our results demonstrated that AEGl elicited the recovery of spontaneous horizontal exploration capacity, anxiogenic- and depressive-profile, as well as short-term memory damage induced by binge-ethanol exposure. The behavioral effects of the extract were associated to the reequilibrium of the animals' REDOX balance. Thus, AEGl, a medicinal mushroom, ameliorates behavioral alteration on a model of motor, cognitive and psychiatric-like disorders induced by binge drinking paradigm and emerges as a useful tool as a food supplement in the management of disorders of alcoholic origin.

Aerobic Physical Exercise as a Neuroprotector Strategy for Ethanol Binge-Drinking Effects in the Hippocampus and Systemic Redox Status in Rats.

The heavy and episodic EtOH drinking pattern, equivalent to weekend consumption, characterizes the binge-drinking pattern and promotes a misbalance of encephalic metabolic functions, concurring to neurodegeneration and cerebral dysfunction. And for being a legal drug, it has global public health and social relevance. In this way, we aimed to investigate the effects of physical training, in a treadmill, on the deleterious effects of EtOH on hippocampal functions, related to memory and learning. For this, we used 40 Wistar rats, divided into four groups: Control group, Trained group (trained animals with doses of distilled water), EtOH group (nontrained animals with doses of 3 g/kg/day of EtOH, 20% w/v), and Trained+EtOH group (trained animals exposed to EtOH). The physical exercise was performed by running on a treadmill for 5 days a week for 4 weeks, and all doses of EtOH were administered through intragastric gavage in four repeated cycles of EtOH in binge. After the experimental period, the animals were submitted to the object recognition task and Morris water maze test, and after being euthanized, the blood and hippocampus were collected for Trolox Equivalent Antioxidant Capacity (TEAC), Reduced Glutathione Content (GSH), and Nitrite and Lipid Peroxidation (LPO) level measurements. Our results showed that EtOH caused marked oxidative stress and mnemonic damage, and the physical exercise promoted neuroprotective effects, among them, the modulation of oxidative biochemistry in plasma (by restoring GSH levels) and in the hippocampus (by reducing LPO levels and increasing antioxidant parameters) and cognitive function improvement. Therefore, physical exercise can be an important prophylactic and therapeutic tool in order to ameliorate and even prevent the deleterious effects of EtOH on cognitive functions.

Physical Exercise Attenuates Oxidative Stress and Morphofunctional Cerebellar Damages Induced by the Ethanol Binge Drinking Paradigm from Adolescence to Adulthood in Rats.

Ethanol (EtOH) binge drinking is characterized by high EtOH intake during few hours followed by withdrawal. Protection strategies against the damages generated by this binge are poorly explored. Thus, this study is aimed at investigating the protective role of treadmill physical exercise (PE) on the damage caused after repeated cycles of binge-like EtOH exposure in the oxidative biochemistry, morphology, and cerebellar function of rats from adolescence to adulthood. For this, animals were divided into four groups: control group (sedentary animals with doses of distilled water), exercised group (exercised animals with doses of distilled water), EtOH group (sedentary animals with doses of 3 g/kg/day of EtOH, 20% w/v), and exercised+EtOH group (exercised animals with previous mentioned doses of EtOH). The PE occurred on a running treadmill for 5 days a week for 4 weeks, and all doses of EtOH were administered through intragastric gavage in four repeated cycles of EtOH in a binge-like manner. After the EtOH protocol and PE, animals were submitted to open field and beam walking tests. In sequence, the cerebellums were collected for the biochemical and morphological analyses. Biochemical changes were analyzed by measurement of Trolox equivalent antioxidant capacity (TEAC), reduced glutathione content measurements (GSH), and measurement of nitrite and lipid peroxidation (LPO). In morphological analyses, Purkinje cell density evaluation and immunohistochemistry evaluation were measured by antimyelin basic protein (MBP) and antisynaptophysin (SYP). The present findings demonstrate that the binge drinking protocol induced oxidative biochemistry misbalance, from the decrease of TEAC levels and higher LPO related to tissue damage and motor impairment. In addition, we have shown for the first time that treadmill physical exercise reduced tissue and functional alterations displayed by EtOH exposure.

"Special K" Drug on Adolescent Rats: Oxidative Damage and Neurobehavioral Impairments.

Ketamine is used in clinical practice as an anesthetic that pharmacologically modulates neurotransmission in postsynaptic receptors, such as NMDA receptors. However, widespread recreational use of ketamine in "party drug" worldwide since the 1990s quickly spread to the Asian orient region. Thus, this study aimed at investigating the behavioral and oxidative effects after immediate withdrawal of intermittent administration of ketamine in adolescent female rats. For this, twenty female Wistar rats were randomly divided into two groups: control and ketamine group (n = 10/group). Animals received ketamine (10 mg/kg/day) or saline intraperitoneally for three consecutive days. Three hours after the last administration, animals were submitted to open field, elevated plus-maze, forced swim tests, and inhibitory avoidance paradigm. Twenty-four hours after behavioral tests, the blood and hippocampus were collected for the biochemical analyses. Superoxide dismutase, catalase, nitrite, and lipid peroxidation (LPO) were measured in the blood samples. Nitrite and LPO were measured in the hippocampus. The present findings demonstrate that the early hours of ketamine withdrawal induced oxidative biochemistry unbalance in the blood samples, with elevated levels of nitrite and LPO. In addition, we showed for the first time that ketamine withdrawal induced depressive- and anxiety-like profile, as well as short-term memory impairment in adolescent rodents. The neurobehavioral deficits were accompanied by the hippocampal nitrite and LPO-elevated levels.

Low doses of methylmercury exposure during adulthood in rats display oxidative stress, neurodegeneration in the motor cortex and lead to impairment of motor skills.

Despite the vast distribution among tissues, the central nervous system (CNS) represents the main target of methylmercury (MeHg) toxicity. However, few studies have evaluated the effects of MeHg exposure on the CNS at equivalent doses to human environmental exposure. In our study, we evaluated the motor cortex, an important area of motor control, in adult rats chronically exposed to MeHg in a concentration equivalent to those found in fish-eating populations exposed to mercury (Hg). The parameters evaluated were total Hg accumulation, oxidative stress, tissue damage, and behavioral assessment in functional actions that involved this cortical region. Our results show in exposed animals a significantly greater level of Hg in the motor cortex; increase of nitrite levels and lipid peroxidation, associated with decreased antioxidant capacity against peroxyl radicals; reduction of neuronal and astrocyte density; and poor coordination and motor learning impairment. Our data showed that chronic exposure at low doses to MeHg is capable of promoting damages to the motor cortex of adult animals, with changes in oxidative biochemistry misbalance, neurodegeneration, and motor function impairment.

Unravelling motor behaviour hallmarks in intoxicated adolescents: methylmercury subtoxic-dose exposure and binge ethanol intake paradigm in rats.

Methylmercury (MeHg) is a hazardous environmental pollutant, affecting Amazon basin communities by anthropogenic activities. The exact safe level of MeHg exposure is unclear, despite the efforts of health international societies to avoid mercury (Hg) poisoning. Central nervous system is severely impacted by Hg intoxication, reflecting on motor impairment. In addition, alcohol has been associated to an overall brain damage. According to lifestyle of Amazon riverside communities, alcohol intake occurs frequently. Thus, we investigated if continuous MeHg exposure at low doses during adolescence displays motor deficits (experiment 1). In the experiment 2, we examine if the co-intoxication (i.e. MeHg plus ethanol exposure) during adolescence intensify motor damage. In the experiment 1, Wistar adolescent rats (31 days old) received chronic exposure to low dose (CELD) of MeHg (40 µg/kg/day) for 35 days. For the experiment 2, five sessions of alcohol binge drinking paradigm (3ON-4OFF; 3.0 g/kg/day) were employed associated to MeHg intoxication. Motor behaviour was evaluated by the open field, pole test, beam walking and rotarod paradigms. CELDS of MeHg display motor function damage, related to hypoactivity, bradykinesia-like behaviour, coordination deficits and motor learning impairment. Co-intoxication of MeHg plus ethanol reduced cerebellar Hg content, however also resulted in motor behavioural impairment, as well as additive effects on bradykinesia and fine motor evaluation.