Effects of Acute Ethanol Administration on Brain Oxidative Status: The Role of Acetaldehyde

Hepatic Oxi-Inflammation and Neophobia as Potential Liver-Brain Axis Targets for Alzheimer's Disease and Aging, with Strong Sensitivity to Sex, Isolation, and Obesity

Research on Alzheimer's disease (AD) has classically focused on alterations that occur in the brain and their intra- and extracellular neuropathological hallmarks. However, the oxi-inflammation hypothesis of aging may also play a role in neuroimmunoendocrine dysregulation and the disease's pathophysiology, where the liver emerges as a target organ due to its implication in regulating metabolism and supporting the immune system. In the present work, we demonstrate organ (hepatomegaly), tissue (histopathological amyloidosis), and cellular oxidative stress (decreased glutathione peroxidase and increased glutathione reductase enzymatic activities) and inflammation (increased IL-6 and TNF𝛼) as hallmarks of hepatic dysfunction in 16-month-old male and female 3xTg-AD mice at advanced stages of the disease, and as compared to age- and sex-matched non-transgenic (NTg) counterparts. Moreover, liver-brain axis alterations were found through behavioral (increased neophobia) and HPA axis correlations that were enhanced under forced isolation. In all cases, sex (male) and isolation (naturalistic and forced) were determinants of worse hepatomegaly, oxidative stress, and inflammation progression. In addition, obesity in old male NTg mice was translated into a worse steatosis grade. Further research is underway determine whether these alterations could correlate with a worse disease prognosis and to establish potential integrative system targets for AD research.

Home-Cage Sipper Devices Reveal Age and Sex Differences in Ethanol Consumption Patterns

Free-choice paradigms such as two-bottle choice (2BC) are commonly used to characterize ethanol consumption and preference of rodent models used to study alcohol use disorder (AUD). However, these assays are limited by low temporal resolution that misses finer patterns of drinking behavior, including circadian drinking patterns that are known to vary with age and sex and are affected in AUD pathogenesis. Modern, cost-effective tools are becoming widely available that could elucidate these patterns, including open-source, Arduino-based home-cage sipper devices. We hypothesized that adaptation of these home-cage sipper devices would uncover distinct age- and sex-related differences in temporal drinking patterns. To test this hypothesis, we used the sipper devices in a continuous 2BC paradigm using water and ethanol (10%; v/v) for 14 days to measure drinking patterns of male and female adolescent (3-week), young adult (6-week), and mature adult (18-week) C57BL/6J mice. Daily grams of fluid consumption were manually recorded at the beginning of the dark cycle, while home-cage sipper devices continuously recorded the number of sips. Consistent with prior studies, females consumed more ethanol than males, and adolescent mice consumed the most out of any age group. Correlation analyses of manually recorded fluid consumption versus home-cage sipper activity revealed a statistically significant prediction of fluid consumption across all experimental groups. Sipper activity was able to capture subtle circadian differences between experimental groups, as well as distinct individual variation in drinking behavior among animals. Blood ethanol concentrations were significantly correlated with sipper data, suggesting that home-cage sipper devices can accurately determine individual timing of ethanol consumption. Overall, our studies show that augmenting the 2BC drinking paradigm with automated home-cage sipper devices can accurately measure ethanol consumption across sexes and age groups, revealing individual differences and temporal patterns of ethanol drinking behavior. Future studies utilizing these home-cage sipper devices will further dissect circadian patterns for age and sex relevant to the pathogenesis of AUD, as well as underlying molecular mechanisms for patterns in ethanol consumption.

Highlights

Female mice consume more ethanol than males in a continuous access paradigmAdolescent male and female mice consume more ethanol than young or mature adult miceAutomated home-cage sipper devices accurately measure ethanol consumptionDevices reveal sex- and age-dependent differences in circadian drinking patternsDevices reveal distinct individual variation in circadian drinking patterns.

Human Milk Antioxidative Modifications in Mastitis: Further Beneficial Effects of Cranberry Supplementation

Mastitis is the inflammation of one or several mammal lobes which can be accompanied by a mammary gland infection, and is the leading cause of undesired early weaning in humans. However, little information exists regarding the changes that this disease may induce in the biochemical composition of human milk, especially in terms of oxidative status. Given that newborns are subject to a significant increase in total ROS burden in their transition to neonatal life and that their antioxidant defense system is not completely developed, the aim of this study was to evaluate antioxidant defense (glutathione peroxidase (GPx), reduced glutathione (GSH), total polyphenol content (TPP), and total antioxidant capacity (TAC)) in milk samples from mothers suffering from mastitis and controls. We also measured the oxidative damage to lipids (malondyaldehyde (MDA)) and proteins (carbonyl group content (CGC)) in these samples. Finally, we tested whether dietary supplementation with cranberries (a product rich in antioxidants) in these breastfeeding mothers during 21 days could improve the oxidative status of milk. GPx activity, TPP, and TAC were increased in milk samples from mastitis-affected women, providing a protective mechanism to the newborn drinking mastitis milk. MDA concentrations were diminished in the mastitis group, confirming this proposal. Some oxidative damage might occur in the mammary gland since the CGC was increased in mastitis milk. Cranberries supplementation seems to strengthen the antioxidant system, further improving the antioxidative state of milk.

Shortening time for access to alcohol drives up front-loading behavior, bringing consumption in male rats to the level of females

Background

Incentives to promote drinking (“happy hour”) can encourage faster rates of alcohol consumption, especially in women. Sex differences in drinking dynamics may underlie differential health vulnerabilities relating to alcohol in women versus men. Herein, we used operant procedures to model the happy hour effect and gain insight into the alcohol drinking dynamics of male and female rats.

Methods

Adult male and female Wistar rats underwent operant training to promote voluntary drinking of 10% (w/v) alcohol (8 rats/sex). We tested how drinking patterns changed after manipulating the effort required for alcohol (fixed ratio, FR), as well as the length of time in which rats had access to alcohol (self-administration session length). Rats were tested twice within the 12 h of the dark cycle, first at 2 h (early phase of the dark cycle, “early sessions”) and then again at 10 h into the dark cycle (late phase of the dark cycle, “late sessions”) with an 8-h break between the two sessions in the home cage.

Results

Adult females consumed significantly more alcohol (g/kg) than males in the 30-min sessions with the FR1 schedule of reinforcement when tested late in the dark cycle. Front-loading of alcohol was the primary factor driving higher consumption in females. Changing the schedule of reinforcement from FR1 to FR3 reduced total consumption. Notably, this manipulation had minimal effect on front-loading behavior in females, whereas front-loading behavior was significantly reduced in males when more effort was required to access alcohol. Compressing drinking access to 15 min to model a happy hour drove up front-loading behavior, generating alcohol drinking patterns in males that were similar to patterns in females (faster drinking and higher intake).

Conclusions

This strategy could be useful for exploring sex differences in the neural mechanisms underlying alcohol drinking and related health vulnerabilities. Our findings also highlight the importance of the time of testing for detecting sex differences in drinking behavior.

Voluntary alcohol drinking is higher in adult female rats compared to adult male rats. This sex difference is most pronounced in the later phase of the dark cycle, and when the operant effort is minimal (when 1 lever press gives 1 reward: fixed ratio 1, FR1).

Higher alcohol intake in females is primarily due to “front-loading”, or the rapid consumption of alcohol within the first 5 min of access.

Increasing the effort required to obtain alcohol from FR1 to FR3 dampens front-loading drinking behavior, resulting in similar levels of total intake in males and females.

Compressing the time of access to 15 min drives up front-loading to such a degree that rats end up consuming more alcohol in total than they do in 30-min sessions. In males, this increase in drinking is large enough that it eliminates the sex difference in total alcohol intake.

α-Synuclein E46K Mutation and Involvement of Oxidative Stress in a Drosophila Model of Parkinson's Disease

Parkinson's disease (PD) is an age-associated neurodegenerative condition in which some genetic variants are known to increase disease susceptibility on interaction with environmental factors inducing oxidative stress. Different mutations in the SNCA gene are reported as the major genetic contributors to PD. E46K mutation pathogenicity has not been investigated as intensive as other SNCA gene mutations including A30P and A53T. In this study, based on the GAL4-UAS binary genetic tool, transgenic Drosophila melanogaster flies expressing wild-type and E46K-mutated copies of the human SNCA gene were constructed. Western blotting, immunohistochemical analysis, and light and confocal microscopy of flies' brains were undertaken along with the survival rate measurement, locomotor function assay, and ethanol and paraquat (PQ) tolerance to study α-synuclein neurotoxicity. Biochemical bioassays were carried out to investigate the activity of antioxidant enzymes and alterations in levels of oxidative markers following damages induced by human α-synuclein to the neurons of the transgenic flies. Overexpression of human α-synuclein in the central nervous system of these transgenic flies led to disorganized ommatidia structures and loss of dopaminergic neurons. E46K α-synuclein caused remarkable climbing defects, reduced survivorship, higher ethanol sensitivity, and increased PQ-mediated mortality. A noticeable decline in activity of catalase and superoxide dismutase enzymes besides considerable increase in the levels of lipid peroxidation and reactive oxygen species was observed in head capsule homogenates of α-synuclein-expressing flies, which indicates obvious involvement of oxidative stress as a causal factor in SNCA^E46K neurotoxicity. In all the investigations, E46K copy of the SNCA gene was found to impose more severe defects when compared to wild-type SNCA. It can be concluded that the constructed Drosophila models developed PD-like symptoms that facilitate comparative studies of molecular and cellular pathways implicated in the pathogenicity of different α-synuclein mutations.

Long-Term Exposure of Alcohol Induced Behavioral Impairments and Oxidative Stress in the Brain Mitochondria and Synaptosomes of Adult Zebrafish

Alcoholism causes deleterious effects such as physiological and neuronal alterations leading to the cognitive and other behavioral impairments. Mitochondrial and synaptosomal deteriorations in the brain of alcoholic persons exhibited metabolic, biochemical changes and other related risk factors, which mainly affect the brain function. This study aimed to assess the effect of chronic alcohol-induced mitochondrial and synaptosomal oxidative damage along with behavioral impairment in adult zebrafish. Zebrafish of control group received the system water and normal diet ad libitum (group I); the other groups were treated with 0.20% alcohol (group II) and 0.40% alcohol (group III) directly in fish tank for 22 days. The result revealed significant increase in lipid peroxidation, protein carbonylation, superoxide dismutase, and glutathione, and significant decline in the activity of catalase and Na⁺/K⁺ ATPase compared to control. Furthermore, the alcohol-treated zebrafish also showed significant behavioral alterations. Collectively, this regulatory mechanism demonstrates the effect of long-term alcohol consumption in the zebrafish. Our results indicate that this recreational drug "alcohol" is harmful to brain mitochondria and synaptosomes, which are the main organelles, and play an important role in memory, learning, cognitive function, and ATP formation in the brain, which may represent a significant public health concern.

Biochemical and Behavioral Consequences of Ethanol Intake in a Mouse Model of Metabolic Syndrome

Ethanol abuse is a common issue in individuals with sedentary lifestyles, unbalanced diets, and metabolic syndrome. Both ethanol abuse and metabolic syndrome have negative impacts on the central nervous system, with effects including cognitive impairment and brain oxidative status deterioration. The combined effects of ethanol abuse and metabolic syndrome at a central level have not yet been elucidated in detail. Thus, this work aims to determine the effects of ethanol intake on a mouse model of metabolic syndrome at the behavioral and biochemical levels. Seven-week-old male control (B6.V-Lep ob/+JRj) and leptin-deficient (metabolic syndrome) (B6.V-Lep ob/obJRj) mice were used in the study. Animals were divided into four groups: control, ethanol, obese, and obese-ethanol. Ethanol consumption was monitored for 6 weeks. Basal glycemia, insulin, and glucose overload tests were performed. To assess short- and long-term memory, an object recognition test was used. In order to assess oxidative status in mouse brain samples, antioxidant enzyme activity was analyzed with regard to glutathione peroxidase, glutathione reductase, glutathione, glutathione disulfide, lipid peroxidation products, and malondialdehyde. Ethanol intake modulated the insulin response and impaired the oxidative status in the ob mouse brain.

Neurochemical mechanisms underlying acute and chronic ethanol-mediated responses in zebrafish: The role of mitochondrial bioenergetics

Ethanol (EtOH) is a socially-accepted drug, whose consumption is a risk factor for non-intentional injuries, development of pathologies, and addiction. In the brain, EtOH affects redox signaling and increases reactive oxygen species (ROS) production after acute and chronic exposures. Here, using a high-resolution respirometry assay, we investigated whether changes in mitochondrial bioenergetics play a role in both acute and chronic EtOH-mediated neurochemical responses in zebrafish. For the first time, we showed that acute and chronic EtOH exposures differently affect brain mitochondrial function. Acutely, EtOH stimulated mitochondrial respiration through increased baseline state, CI-mediated OXPHOS, OXPHOS capacity, OXPHOS coupling efficiency, bioenergetic efficiency, and ROX/ETS ratio. Conversely, EtOH chronically decreased baseline respiration, complex I- and II-mediated ETS, as well as increased ROX state and ROX/ETS ratio, which are associated with ROS formation. Overall, we observed that changes in mitochondrial bioenergetics play a role, at least partially, in both acute and chronic effects of EtOH in the zebrafish brain. Moreover, our findings reinforce the face, predictive, and construct validities of zebrafish models to explore the neurochemical bases involved in alcohol abuse and alcoholism.