Protective effects of melatonin against ethanol-induced reactive gliosis in hippocampus and cortex of young and aged rats

Alcohol Use Disorder and Dementia: A Review

PURPOSE

By 2040, 21.6% of Americans will be over age 65, and the population of those older than age 85 is estimated to reach 14.4 million. Although not causative, older age is a risk factor for dementia: every 5 years beyond age 65, the risk doubles; approximately one-third of those older than age 85 are diagnosed with dementia. As current alcohol consumption among older adults is significantly higher compared to previous generations, a pressing question is whether drinking alcohol increases the risk for Alzheimer's disease or other forms of dementia.

SEARCH METHODS

Databases explored included PubMed, Web of Science, and ScienceDirect. To accomplish this narrative review on the effects of alcohol consumption on dementia risk, the literature covered included clinical diagnoses, epidemiology, neuropsychology, postmortem pathology, neuroimaging and other biomarkers, and translational studies. Searches conducted between January 12 and August 1, 2023, included the following terms and combinations: "aging," "alcoholism," "alcohol use disorder (AUD)," "brain," "CNS," "dementia," "Wernicke," "Korsakoff," "Alzheimer," "vascular," "frontotemporal," "Lewy body," "clinical," "diagnosis," "epidemiology," "pathology," "autopsy," "postmortem," "histology," "cognitive," "motor," "neuropsychological," "magnetic resonance," "imaging," "PET," "ligand," "degeneration," "atrophy," "translational," "rodent," "rat," "mouse," "model," "amyloid," "neurofibrillary tangles," "α-synuclein," or "presenilin." When relevant, "species" (i.e., "humans" or "other animals") was selected as an additional filter. Review articles were avoided when possible.

SEARCH RESULTS

The two terms "alcoholism" and "aging" retrieved about 1,350 papers; adding phrases-for example, "postmortem" or "magnetic resonance"-limited the number to fewer than 100 papers. Using the traditional term, "alcoholism" with "dementia" resulted in 876 citations, but using the currently accepted term "alcohol use disorder (AUD)" with "dementia" produced only 87 papers. Similarly, whereas the terms "Alzheimer's" and "alcoholism" yielded 318 results, "Alzheimer's" and "alcohol use disorder (AUD)" returned only 40 citations. As pertinent postmortem pathology papers were published in the 1950s and recent animal models of Alzheimer's disease were created in the early 2000s, articles referenced span the years 1957 to 2024. In total, more than 5,000 articles were considered; about 400 are herein referenced.

DISCUSSION AND CONCLUSIONS

Chronic alcohol misuse accelerates brain aging and contributes to cognitive impairments, including those in the mnemonic domain. The consensus among studies from multiple disciplines, however, is that alcohol misuse can increase the risk for dementia, but not necessarily Alzheimer's disease. Key issues to consider include the reversibility of brain damage following abstinence from chronic alcohol misuse compared to the degenerative and progressive course of Alzheimer's disease, and the characteristic presence of protein inclusions in the brains of people with Alzheimer's disease, which are absent in the brains of those with AUD.

The neuroimmune system - Where aging and excess alcohol intersect

As the percentage of the global population over age 65 grows, and with it a subpopulation of individuals with alcohol use disorder (AUD), understanding the effect of alcohol on the aged brain is of utmost importance. Neuroinflammation is implicated in both natural aging as well as alcohol use, and its role in alterations to brain morphology and function may be exacerbated in aging individuals who drink alcohol to excess. The neuroimmune response to alcohol in aging is complex. The few studies investigating this issue have reported heightened basal activity and either hypo- or hyper-reactivity to an alcohol challenge. This review of preclinical research will first introduce key players of the immune system, then explore changes in neuroimmune function with aging or alcohol alone, with discussion of vulnerable brain regions, changes in cytokines, and varied reactions of microglia and astrocytes. We will then consider different levels of alcohol exposure, relevant animal models of AUD, and neuroimmune activation by alcohol across the lifespan. By identifying key findings, challenges, and targets for future research, we hope to bring more attention and resources to this underexplored area of inquiry.

Melatonin Protects Against Titanium Oxide-Induced Neurotoxicity: Neurochemical, Neurobehavioral, and Histopathological Evidences

titania (titanium dioxide, TiO₂) is known to induce neurotoxicity and CNS dysfunctions. Numerous studies have explored the neuroprotective effects of melatonin against neurotoxicity. This study evaluates the potential of melatonin to protect against titania-induced neurotoxicity and the role of the Keap1/Nrf2/ARE signaling pathway. One group of animals were treated with Titania (0.045 and 0.075 g/rat) alone while the other with added melatonin (1 mg/kg and 3 mg/kg) and behavioral alterations were assessed using OFT (open field test). Neurochemical and histopathological changes were also studied in the hippocampus by analyzing kelch ECH associating protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nrf2), and antioxidant response element (ARE). It was seen that the animals with added Melatonin had improved behavioral scores in the OFT, like anxiety and motor dysfunction triggered by TiO₂. Melatonin also reduced lipid peroxidation, ROS, GSSG, IL1β, TNFα, Bax, and Keap1 levels, but boosted GSH, GPx, GR, SOD,IL10,IL4, Bcl2, Nrf2, and ARE levels and improved quadruple mitochondrial enzyme complex activity in titania-treated animals. Histopathological examination showed melatonin induced cytoprotection against vacuolization and necrosis in granular cells of DG and pyramidal cells of CA1 area of the hippocampus. In our study, pretreatment with melatonin reduced titania-induced neurotoxicity in the hippocampus through a mechanism potentially mediated by the Keap-1/Nrf2/ARE pathway.

Aberrant neurogenesis and late onset suppression of synaptic plasticity as well as sustained neuroinflammation in the hippocampal dentate gyrus after developmental exposure to ethanol in rats

Drinking alcohol during pregnancy may cause fetal alcohol spectrum disorder. The present study investigated the effects of maternal oral ethanol (EtOH) exposure (0, 10, or 12.5 % in drinking water) from gestational day 6 until day 21 post-delivery (weaning) on postnatal hippocampal neurogenesis at weaning and in adulthood on postnatal day 77 in rat offspring. At weaning, type-3 neural progenitor cells (NPCs) were decreased in the subgranular zone (SGZ), accompanied by Chrnb2 downregulation and Grin2b upregulation in the dentate gyrus (DG). These results suggested suppression of CHRNB2-mediated cholinergic signaling in γ-aminobutyric acid (GABA)ergic interneurons in the DG hilus and increased glutamatergic signaling through the NR2B subtype of N-methyl-d-aspartate (NMDA) receptors, resulting in NPC reduction. In contrast, upregulation of Chrna7 may increase CHRNA7-mediated cholinergic signaling in immature granule cells, and upregulation of Ntrk2 may cause an increase in somatostatin-immunoreactive ⁽⁺⁾ GABAergic interneurons, suggesting a compensatory response against NPC reduction. Promotion of SGZ cell proliferation increased type-2a NPCs. Moreover, an increase in calbindin-d-29 K⁺ interneurons and upregulation of Reln, Drd2, Tgfb2, Il18, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptor subunit genes might participate in this compensatory response. In adulthood, reduction of FOS⁺ cells and downregulation of Fos and Arc suggested suppression of granule cell synaptic plasticity, reflecting upregulation of Tnf and downregulation of Cntf, Ntrk2, and AMPA-type glutamate receptor genes. In the DG hilus, gliosis and hyper-ramified microglia, accompanying upregulation of C3, appeared at weaning, suggesting contribution to suppressed synaptic plasticity in adulthood. M1 microglia increased throughout adulthood, suggesting sustained neuroinflammation. These results indicate that maternal EtOH exposure temporarily disrupts hippocampal neurogenesis and later suppresses synaptic plasticity. Induction of neuroinflammation might initially ameliorate neurogenesis (as evident by upregulation of Tgfb2 and Il18) but later suppress synaptic plasticity (as evident by upregulation of C3 at weaning and Tnf in adulthood).

Morin attenuates ifosfamide-induced neurotoxicity in rats via suppression of oxidative stress, neuroinflammation and neuronal apoptosis

Ifosfamide (IFA), a commonly used chemotherapeutic drug, has been frequently associated with encephalopathy and central nervous system toxicity. The present study aims to investigate whether morin could protect against acute IFA-induced neurotoxicity. Morin was administered to male rats once daily for 2 consecutive days at doses of 100 and 200 mg/kg body weight (BW) orally. IFA (500 mg/kg BW; i.p.) was administered on second day. The results showed that morin markedly inhibited the production of acetylcholinesterase (AChE), butrylcholinesterase (BChE), carbonic anhydrase (CA), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and nuclear factor erythroid 2-related factor 2 (Nrf-2) induced by IFA. Morin ameliorated IFA-induced lipid peroxidation, glutathione (GSH) depletion, and decrease antioxidant enzyme activities, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx). Histopathological changes and immunohistochemical expressions of c-Jun N-terminal kinase (JNK) and c-Fos in the IFA-induced brain tissues were decreased after administration of morin. Furthermore, morin was able to down regulate the levels of inflammatory and apoptotic markers such as nuclear factor kappa B (NF-κB), neuronal nitric oxide synthase (nNOS), tumor necrosis factor-α (TNF-α), p53, cysteine aspartate specific protease-3 (caspase-3) and B-cell lymphoma-2 (Bcl-2). Taken together, our results demonstrated that morin elicited a typical chemoprotective effect on IFA-induced acute neurotoxicity.

Comparative study on the effects of cigarette smoke exposure, ethanol consumption and association: Behavioral parameters, apoptosis, glial fibrillary acid protein and S100β immunoreactivity in different regions of the rat hippocampus

Exposure to cigarette smoke and ethanol are proposed to trigger neurotoxicity, apoptosis, and to impair neuronal signaling. However, it is little known how the combination of both might trigger astrogliosis and the morphological changes capable of affecting a differential susceptibility of hippocampal regions to these licit drugs. The present study investigated the chronic effects of exposure to cigarette smoke and/or ethanol on behavioral parameters, apoptosis, and alteration in immunoreactivity of glial fibrillary acid protein (GFAP) and S100β in the CA1, CA3, and dentate gyrus (DG) of the rat hippocampus. Adult male Wistar rats (n = 32) were divided into four groups: vehicle (VE, glucose 3% in water, 10 mL/kg), cigarette smoke (TOB, total 12 cigarettes per day), ethanol (ethanol, 2 g/kg), and cigarette smoke plus ethanol (TOB plus ethanol, total 12 cigarettes per day plus ethanol 2 g/kg) for 54 days. The groups were submitted to tail-flick, open-field, and inhibitory avoidance tasks. The results showed that ethanol per se worsened the short-term memory. The association between TOB and ethanol increased the immunoreactivity of cleaved caspase-3 in the CA3 and DG regions. The TOB plus ethanol group showed a lower immunoreactivity to GFAP in all regions of the hippocampus. In addition, ethanol and TOB per se also reduced the immunoreactivity for GFAP in the DG. Ethanol increased S100β immunoreactivity only in the DG. In conclusion, this study showed that only ethanol worsened short-term memory, and the DG became more susceptible to changes in the markers investigated. This evidence suggests that DG is more sensitive to neurotoxicity induced by cigarette smoke and ethanol.

Restraint stress exacerbates cell degeneration induced by acute binge ethanol in the adolescent, but not in the adult or middle-aged, brain

Restraint stress (RS) induces neurotoxicity in the hippocampus, yet most of the studies have employed protracted RS (i.e., ≈ 21 days). Binge ethanol can induce brain toxicity, an effect affected by age. It could be postulated that RS may facilitate ethanol-induced neurotoxicity, perhaps to a greater extent in adolescent vs. older subjects. We analyzed whether adolescent, adult or middle-aged male rats exposed to five episodes of RS followed, 72h later, by binge ethanol (i.e., two administrations of 2.5 g/kg ethanol) exhibited hippocampal neurotoxicity. Adolescents, but not adult or middle-aged rats, exhibited sensitivity to the neurotoxic effects of ethanol at dorsal CA2, ventral CA3 and ventral DG, and a neurotoxic effect of stress at dorsal CA1. Moreover, the combination of ethanol and stress exerted a synergistic effect upon cell degeneration at ventral CA1 and CA2, which was restricted to adolescents. Ethanol also increased cell degeneration, irrespective of age or stress, in dorsal CA3 and in dorsal DG; and ethanol and stress had, across all ages, a synergistic effect upon cell degeneration at the dorsal CA1. The greater neurotoxic response of adolescents to ethanol, stress, or ethanol+stress can put them at risk for the development of alcohol problems.

Acute dose of melatonin via Nrf2 dependently prevents acute ethanol-induced neurotoxicity in the developing rodent brain

BACKGROUND

Melatonin is a well-known potent endogenous antioxidant pharmacological agent with significant neuroprotective actions. Here in the current study, we explored the nuclear factor erythroid 2-related factor 2 (Nrf2) gene-dependent antioxidant mechanism underlying the neuroprotective effects of the acute melatonin against acute ethanol-induced elevated reactive oxygen species (ROS)-mediated neuroinflammation and neurodegeneration in the developing rodent brain.

METHODS

In vivo rat pups were co-treated with a single dose of acute ethanol (5 g/kg, subcutaneous (S.C.)) and a single dose of acute melatonin (20 mg/kg, intraperitoneal (I.P.)). Four hours after a single S.C. and I.P. injections, all of the rat pups were sacrificed for further biochemical (Western blotting, ROS- assay, LPO-assay, and immunohistochemical) analyses. In order to corroborate the in vivo results, we used the in vitro murine-hippocampal HT22 and microglial BV2 cells, which were subjected to knockdown with small interfering RNA (siRNA) of Nrf2 genes and exposed with melatonin (100 μM) and ethanol (100 mM) and proceed for further biochemical analyses.

RESULTS

Our biochemical, immunohistochemical, and immunofluorescence results demonstrate that acute melatonin significantly upregulated the master endogenous antioxidant Nrf2 and heme oxygenase-1, consequently reversing the acute ethanol-induced elevated ROS and oxidative stress in the developing rodent brain, and in the murine-hippocampal HT22 and microglial BV2 cells. In addition, acute melatonin subsequently reduced the activated MAPK-p-P38-JNK pathways and attenuated neuroinflammation by decreasing the expression of activated gliosis and downregulated the p-NF-K-B/p-IKKβ pathway and decreased the expression levels of other inflammatory markers in the developing rodent brain and BV2 cells. Of note, melatonin acted through the Nrf2-dependent mechanism to attenuate neuronal apoptosis in the postnatal rodent brain and HT22 cells. Immunohistofluorescence results also showed that melatonin prevented ethanol-induced neurodegeneration in the developing rodent brain. The in vitro results indicated that melatonin induced neuroprotection via Nrf2-dependent manner and reduced ethanol-induced neurotoxicity.

CONCLUSIONS

The pleiotropic and potent neuroprotective antioxidant characteristics of melatonin, together with our in vivo and in vitro findings, suppose that acute melatonin could be beneficial to prevent and combat the acute ethanol-induced neurotoxic effects, such as elevated ROS, neuroinflammation, and neurodegeneration in the developing rodent brain.

Astrocyte Dysfunction Induced by Alcohol in Females but Not Males

Chronic alcohol abuse is associated with brain damage in a sex-specific fashion, but the mechanisms involved are poorly described and remain controversial. Previous results have suggested that astrocyte gene expression is influenced by ethanol intoxication and during abstinence in vivo. Here, bioinformatic analysis of astrocyte-enriched ethanol-regulated genes in vivo revealed ubiquitin pathways as an ethanol target, but with sexually dimorphic cytokine signaling and changes associated with brain aging in females and not males. Consistent with this result, astrocyte activation was observed after exposure in female but not male animals, with reduced S100β levels in the anterior cingulate cortex and increased GFAP(+) cells in the hippocampus. In primary culture, the direct effects of chronic ethanol exposure followed by recovery on sex-specific astrocyte function were examined. Male astrocyte responses were consistent with astrocyte deactivation with reduced GFAP expression during ethanol exposure. In contrast, female astrocytes exhibited increased expression of Tnf, reduced expression of the neuroprotective cytokine Tgfb1, disrupted bioenergetics and reduced excitatory amino acid uptake following exposure or recovery. These results indicate widespread astrocyte dysfunction in ethanol-exposed females and suggest a mechanism that may underlie increased vulnerability to ethanol-induced neurotoxicity in females.

Alcohol and adult hippocampal neurogenesis: promiscuous drug, wanton effects

Adult neurogenesis is now widely accepted as an important contributor to hippocampal integrity and function but also dysfunction when adult neurogenesis is affected in neuropsychiatric diseases such as alcohol use disorders. Excessive alcohol consumption, the defining characteristic of alcohol use disorders, results in a variety of cognitive and behavioral impairments related wholly or in part to hippocampal structure and function. Recent preclinical work has shown that adult neurogenesis may be one route by which alcohol produces hippocampal neuropathology. Alcohol is a pharmacologically promiscuous drug capable of interfering with adult neurogenesis through multiple mechanisms. This review will discuss the primary mechanisms underlying alcohol-induced changes in adult hippocampal neurogenesis including alcohol's effects on neurotransmitters, CREB and its downstream effectors, and the neurogenic niche.

Alcohol, phospholipase A2-associated neuroinflammation, and ω3 docosahexaenoic acid protection

Chronic alcohol (ethanol) abuse causes neuroinflammation and brain damage that can give rise to alcoholic dementia. Insightfully, Dr. Albert Sun was an early proponent of oxidative stress as a key factor in alcoholism-related brain deterioration. In fact, oxidative stress has proven to be critical to the hippocampal and temporal cortical neurodamage resulting from repetitive "binge" alcohol exposure in adult rat models. Although the underlying mechanisms are uncertain, our immunoelectrophoretic and related assays in binge alcohol experiments in vivo (adult male rats) and in vitro (rat organotypic hippocampal-entorhinal cortical slice cultures) have implicated phospholipase A(2) (PLA(2))-activated neuroinflammatory pathways, release of pro-oxidative arachidonic acid (20:4 ω6), and elevated oxidative stress adducts (i.e., 4-hydroxynonenal-protein adducts). Also, significantly increased by the binge alcohol treatments was aquaporin-4 (AQP4), a water channel enriched in astrocytes that, when augmented, may trigger brain (esp. cellular) edema and neuroinflammation; of relevance, glial swelling is known to provoke increased PLA(2) activities or levels. Concomitant with PLA(2) activation, the results have further implicated binge alcohol-elevated poly (ADP-ribose) polymerase-1 (PARP-1), an oxidative stress-responsive DNA repair enzyme linked to parthanatos, a necrotic-like neuronal death process. Importantly, supplementation of the brain slice cultures with docosahexaenoic acid (22:6 ω3) exerted potent suppression of the induced changes in PLA(2) isoforms, AQP4, PARP-1 and oxidative stress footprints, and prevention of the binge alcohol neurotoxicity, by as yet unknown mechanisms. These neuroinflammatory findings from our binge alcohol studies and supportive rat binge studies in the literature are reviewed.

Role of melatonin in the prevention of morphine-induced hyperalgesia and spinal glial activation in rats: protein kinase C pathway involved

PURPOSES

Morphine can induce tolerance and hyperalgesia after long-term administration. Glial activation is believed to cause and maintain a state of morphine-induced pain hypersensitivity. The present study examines the effect of melatonin on tolerance, hyperalgesia, and reactive gliosis induced by morphine in rats.

METHODS

The study examines the effect of melatonin on morphine-induced hyperalgesia using tail-flick test. Immunohistochemistry and Western blot was performed to investigate the expression of glial fibrillary acidic protein (GFAP) indicative of spinal glial activity. This study also measures protein kinase C (PKC) activity and cyclic adenosine monophosphate (cAMP) levels in spinal cords to investigate the mechanisms which melatonin involved.

RESULTS

When coadministered intragastrically (i.g.) with morphine, melatonin in doses of 50 or 100 mg/kg significantly prevented hyperalgesia after termination of morphine. Immunohistochemistry and Western blot with GFAP revealed that melatonin significantly decreased morphine-induced over-expression of GFAP in spinal cord (p < .05). By measuring PKC activity and cAMP levels, the upregulated PKC activity and cAMP levels induced by morphine were significantly inhibited by melatonin.

CONCLUSIONS

Melatonin can prevent morphine-withdrawal-induced hyperalgesia and glial reactivity. This effect of melatonin after morphine administration may mediated by inhibiting PKC activity and cAMP upregulation.

Upregulated vimentin suggests new areas of neurodegeneration in a model of an alcohol use disorder

Excessive alcohol intake, characteristic of an alcohol use disorder (AUD), results in neurodegeneration as well as cognitive deficits that may recover in abstinence. Neurodegeneration in psychiatric disorders such as AUDs is due to various effects on tissue integrity. Several groups report that alcohol-induced neurodegeneration and recovery include a role for adult neurogenesis. Therefore, the initial purpose of this study was to investigate the effect of alcohol on the temporal profile of neural progenitor cells using the radial glia marker, vimentin, in a model of an AUD. However, striking vimentin expression throughout corticolimbic regions led, instead, to the discovery of a significant gliosis response in this model. Adult male rats were subjected to a 4-day binge model of an AUD and brains harvested for immunohistochemistry at 0, 2, 4, 7, 14, and 28 days following the last dose of ethanol. A prominent increase in vimentin immunoreactivity was apparent at 4 and 7 days post binge that returned to control levels by 14 days in the corticolimbic regions examined. Vimentin-positive cells co-labeled with glial fibrillary acidic protein (GFAP), which suggested that cells were reactive astrocytes. A second experiment supported that increased vimentin was not primarily due to alcohol withdrawal seizures and is more likely due to alcohol-induced cell death. As this gliosis was remarkably distinct in regions where cell death had not previously been reported in this model, adjacent tissue sections were processed for FluoroJade B staining for cell death. FluoroJade B-positive cells were evident immediately following the last ethanol dose as expected, but were significantly elevated in the hippocampal dentate gyrus and CA3 regions and corticolimbic regions from 2 to 7 days post binge. Intriguingly, vimentin labeling of astrogliosis is more widespread than FluoroJade B labeling of cell death, which suggests that 4-day binge ethanol consumption is more damaging than originally realized.

Acetyl-L-carnitine protects neuronal function from alcohol-induced oxidative damage in the brain

The studies presented here demonstrate the protective effect of acetyl-L-carnitine (ALC) against alcohol-induced oxidative neuroinflammation, neuronal degeneration, and impaired neurotransmission. Our findings reveal the cellular and biochemical mechanisms of alcohol-induced oxidative damage in various types of brain cells. Chronic ethanol administration to mice caused an increase in inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine adduct formation in frontal cortical neurons but not in astrocytes from brains of these animals. Interestingly, alcohol administration caused a rather selective activation of NADPH oxidase (NOX), which, in turn, enhanced levels of reactive oxygen species (ROS) and 4-hydroxynonenal, but these were predominantly localized in astrocytes and microglia. Oxidative damage in glial cells was accompanied by their pronounced activation (astrogliosis) and coincident neuronal loss, suggesting that inflammation in glial cells caused neuronal degeneration. Immunohistochemistry studies indicated that alcohol consumption induced different oxidative mediators in different brain cell types. Thus, nitric oxide was mostly detected in iNOS-expressing neurons, whereas ROS were predominantly generated in NOX-expressing glial cells after alcohol ingestion. Assessment of neuronal activity in ex vivo frontal cortical brain tissue slices from ethanol-fed mice showed a reduction in long-term potentiation synaptic transmission compared with slices from controls. Coadministration of ALC with alcohol showed a significant reduction in oxidative damage and neuronal loss and a restoration of synaptic neurotransmission in this brain region, suggesting that ALC protects brain cells from ethanol-induced oxidative injury. These findings suggest the potential clinical utility of ALC as a neuroprotective agent that prevents alcohol-induced brain damage and development of neurological disorders.

Genistein suppresses spontaneous oviduct tumorigenesis in quail

Spontaneous leiomyomas of the oviduct are common tumors of the Japanese quail (Coturnix coturnix japonica) and laying hens. This makes it a good animal model for screening potential agents for testing in the prevention and treatment of human myoma uteri. Genistein has been shown to inhibit the growth of various cancer cells. We investigated the effects of genistein supplementation on the development of fibroid tumors in the oviduct, serum oxidative stress markers [malondialdehyde (MDA), 8-isoprostane, 4-hydroxyalkenal (HAE), 8-hydroxy-2' -deoxyguanosine (8-OHdG) levels], soy isoflavone levels, and tissue biomarkers [Connexin 43 (Cx43), Bcl-2, and Bax and heat shock protein 70 (Hsp70) expression] in Japanese quail. One hundred and fifty quail (12 mo old) were assigned to 3 experimental groups as 5 replicates of pens containing 10 birds in each. Birds were fed either a basal diet or the basal diet supplemented with 400 mg or 800 mg of genistein/kg of diet. The animals were sacrificed after 315 days, and the tumors were identified. Genistein supplementation significantly decreased the incidence of fibroid tumors as compared to control birds (P = 0.04). The tumors in genistein-fed birds were smaller than those found in control birds (P = 0.02). Serum MDA, 8-isoprostane, and HAE levels were lower in treatment groups than in control group (MDA: 2.01 vs. 0.82; 8-isoprostane: 135 vs. 101; HAE: 1.45 vs. 0.73; P <or= 0.01). The concentrations of serum 8-OHdG, which is a marker of oxidative damage, in the groups were 27.5, 22.4, and 21.3 ng/ml, respectively (P = 0.05). The expression of cell cycle regulatory proteins, Bcl-2, was 4.18 and 4.61 in the genistein groups and 6.21 in the control group, and the expression of Bax was 10.93 and 16.78 in the genistein groups and 7.60 in the control group (P < 0.001 for Bax). Cx43 level was 2.56 and 2.40 in the genistein groups compared with 5.15 in the control group. None of the differences in the Cx43 and Bcl-2 of the groups were significant. The expression of heat shock proteins, Hsp60 and Hsp70, were not different between groups, although Hsp70 level of the genistein groups (19.73) was lower than the control group (27.8). The results indicate that dietary supplementation of genistein reduces the incidence and size of spontaneously occurring leiomyoma of the oviduct in the Japanese quail. Clinical trials should be conducted to investigate the efficacy of genistein supplementation in the prevention and treatment of uterine leiomyoma in humans.

Zinc picolinate in the prevention of leiomyoma in Japanese quail

Epidemiologic studies suggest that zinc deficiency may be associated with increased risk of cancer. We investigated the effects of zinc picolinate supplementation on the development of leiomyomas, malondialdehyde (MDA), 8-isoprostane, 4-hydroxyalkenal (HAE), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, and heat shock protein 70 (Hsp70) expression in Japanese quails. One hundred fifty quails (6 months old) were assigned to three treatment groups consisting of 50 birds in each group. Birds were fed either a basal diet or the basal diet supplemented with 30 mg or 60 mg of zinc/kg of diet. The animals were sacrificed after 350 days, and the tumors were identified. Zinc picolinate supplementation did not affect the number of leiomyomas compared to control birds (P > .05). However, the tumors in zinc-fed birds were smaller than those found in control birds (P = .01) Serum MDA, 8-isoprostane, and HAE levels were lower in the treatment groups than in the control group: MDA, 1.95 versus 0.93 micromol/L; 8-isoprostane, 108 versus 85 pg/mL; HAE, 1.55 versus 0.96 micromol/L (P = .01 for all three parameters). The concentrations of serum 8-OHdG, which is a marker of oxidative damage, in the groups were 28.5, 23.6, and 20.1 ng/mL, respectively (P = .01). Hsp70 expression was significantly decreased in zinc-treated birds (P < .01). The results indicate that dietary zinc picolinate supplementation reduces the growth of spontaneously occurring leiomyomas of the oviduct in the Japanese quail. Clinical trials should be conducted to investigate the efficacy of zinc supplementation in the prevention and treatment of uterine leiomyoma in humans.

Anthocyanins: are they beneficial in treating ethanol neurotoxicity?

Heavy alcohol exposure produces profound damage to the developing central nervous system (CNS) as well as the adult brain. Children with fetal alcohol spectrum disorders (FASD) have a variety of cognitive, behavioral, and neurological impairments. FASD currently represents the leading cause of mental retardation. Excessive alcohol consumption is associated with Wernicke-Korsakoff syndrome (WKS) and neurodegeneration in the adult brain. Although the cellular/molecular mechanism underlying ethanol's neurotoxicity has not been fully understood, it is generally believed that oxidative stress plays an important role. Identification of neuroprotective agents that can ameliorate ethanol neurotoxicity is an important step for developing preventive/therapeutic strategies. Targeting ethanol-induced oxidative stress using natural antioxidants is an attractive approach. Anthocyanins, a large subgroup of flavonoids present in many vegetables and fruits, are safe and potent antioxidants. They exhibit diverse potential health benefits including cardioprotection, anti-atherosclerotic activity, anti-cancer, anti-diabetic, and anti-inflammation properties. Anthocyanins can cross the blood-brain barrier and distribute in the CNS. Recent studies indicate that anthocyanins represent novel neuroprotective agents and may be beneficial in ameliorating ethanol neurotoxicity. In this review, we discuss the evidence and potential of anthocyanins in alleviating ethanol-induced damage to the CNS. Furthermore, we discuss possible underlying mechanisms as well as future research approaches necessary to establish the therapeutic role of anthocyanins.

Radiation-induced reductions in neurogenesis are ameliorated in mice deficient in CuZnSOD or MnSOD

Ionizing irradiation significantly affects hippocampal neurogenesis and is associated with cognitive impairments; these effects may be influenced by an altered microenvironment. Oxidative stress is a factor that has been shown to affect neurogenesis, and one of the protective pathways that deal with such stress involves the antioxidant enzyme superoxide dismutase (SOD). This study addressed what impact a deficiency in cytoplasmic (SOD1) or mitochondrial (SOD2) SOD has on radiation effects on hippocampal neurogenesis. Wild-type (WT) and SOD1 and SOD2 knockout (KO) mice received a single X-ray dose of 5 Gy, and quantification of the survival and phenotypic fate of newly generated cells in the dentate subgranular zone was performed 2 months later. Radiation exposure reduced neurogenesis in WT mice but had no apparent effect in KO mice, although baseline levels of neurogenesis were reduced in both SOD KO strains before irradiation. Additionally, there were marked and significant differences between WT and both KO strains in how irradiation affected newly generated astrocytes and activated microglia. The mechanism(s) responsible for these effects is not yet known, but a pilot in vitro study suggests a "protective" effect of elevated levels of superoxide. Overall, these data suggest that under conditions of SOD deficiency, there is a common pathway dictating how neurogenesis is affected by ionizing irradiation.

Effects of chromium histidinate on renal function, oxidative stress, and heat-shock proteins in fat-fed and streptozotocin-treated rats

OBJECTIVE

Chromium is an essential element for carbohydrate, fat, and protein metabolism. The therapeutic potential of chromium histidinate (CrHis) in the treatment of diabetes has been elucidated. The present study investigated the effects of CrHis on serum parameters of renal function, on oxidative stress markers (malondialdehyde [MDA] and 8-isoprostane), and on the expression of heat-shock proteins (HSPs) in rats.

METHODS

Male Wistar rats (n=60, 8 weeks old) were divided into four groups. Group 1 received a standard diet (12% of calories as fat). Group 2 received a standard diet, plus CrHis. Group 3 received a high-fat diet (40% of calories as fat) for 2 weeks, and was then injected with streptozotocin (STZ) on day 14 (STZ, 40 mg/kg intraperitoneally). Group 4 was treated in the same way as group 3 (HFD/STZ), but was supplemented with 110 microg CrHis/kg/body weight/day. Oxidative stress in the kidneys of diabetic rats was evidenced by an elevation in levels of MDA and 8-isoprostane. Protein concentrations of HSP60 and HSP70 in renal tissue were determined by Western blot analyses.

RESULTS

Chromium histidinate supplementation lowered kidney concentrations of MDA, 8-isoprostane levels, serum urea-N, and creatinine, and reduced the severity of renal damage in the STZ-treated group (i.e., the diabetes-induced group). The expression of HSP60 and HSP70 was lower in the STZ group that received CrHis than in the group that did not. No significant effect of CrHis supplementation was detected in regard to the overall measured parameters in the control group.

CONCLUSIONS

Chromium histidinate significantly decreased lipid peroxidation levels and HSP expression in the kidneys of experimentally induced diabetic rats. This study supported the efficacy of CrHis in reducing renal risk factors and impairment because of diabetes.

The effects of vitamin C and E supplementation on heat shock protein 70 response of ovary and brain in heat-stressed quail

1. The effects of vitamin C (L-ascorbic acid) and vitamin E (alpha-tocopherol acetate) supplementation on egg production and heat shock protein 70 (Hsp70) response of ovary and brain in the Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature were evaluated. 2. The birds (n = 540; 55 d old) were randomly assigned to 18 groups consisting of 3 replicates of 10 birds each in a 2 x 3 x 3 factorial arrangement of treatments. Birds were kept in wire cages in a temperature-controlled room at either 22 degrees C (thermo-neutral, TN) or 34 degrees C (heat stress, HS) for 8 h/d (09:00 to 17:00 h; until the end of the study) and fed on a basal diet or the basal diet supplemented with either three levels of vitamin C (0, 250 and 500 mg of L-ascorbic acid/kg of diet) or three levels of vitamin E (0, 250 and 500 mg of dl-alpha-tocopheryl acetate/kg of diet). 3. Feed intake and egg production were not affected by vitamin C and E supplementation under thermo-neutral conditions. However, feed intake and egg production were increased with the vitamin C or E supplementation either singly or in combination in heat-stressed quail. When vitamin was added, feed intake and egg production of quails under TN were different from those raised under HS. However, in the absence of supplemental vitamins, feed intake and egg production at TN and HS were no different. 4. Heat exposure increased serum corticosterone levels and Hsp70 expression. Serum corticosterone level was significantly decreased by vitamin C or E supplementation in HS groups for quail. Ovary and brain Hsp70 expression linearly decreased as dietary vitamin C or vitamin E supplementation increased in heat-stressed groups. However, Hsp70 expression of ovary and brain was not affected by vitamin C or E supplementation under thermo-neutral conditions. 5. The present study showed that a combination of dietary vitamin C (500 mg) and E supplementation (500 mg) may alleviate some heat stress effects of heat shock proteins of ovary and brain and egg production of Japanese quail.

Ethanol alters the physiology of neuron-glia communication

In the central nervous system (CNS), both neurones and astrocytes play crucial roles. On a cellular level, brain activity involves continuous interactions within complex cellular circuits established between neural cells and glia. Although it was initially considered that neurones were the major cell type in cerebral function, nowadays astrocytes are considered to contribute to cerebral function too. Astrocytes support normal neuronal activity, including synaptic function, by regulating the extracellular environment with respect to ions and neurotransmitters. There is a plethora of noxious agents which can lead to the development of alterations in organs and functional systems, and that will end in a chronic prognosis. Among the potentially harmful external agents we can find ethanol consumption, whose consequences have been recognized as a major public health concern. Deregulation of cell cycle has devastating effects on the integrity of cells, and has been closely associated with the development of pathologies which can lead to dysfunction and cell death. An alteration of normal neuronal-glial physiology could represent the basis of neurodegenerative processes. In this review we will pay attention on to the recent findings in astrocyte function and their role toward neurons under ethanol consumption.

Mechanisms of neurodegeneration and regeneration in alcoholism

AIMS

This is a review of preclinical studies covering alcohol-induced brain neuronal death and loss of neurogenesis as well as abstinence-induced brain cell genesis, e.g. brain regeneration. Efforts are made to relate preclinical studies to human studies.

METHODS

The studies described are preclinical rat experiments using a 4-day binge ethanol treatment known to induce physical dependence to ethanol. Neurodegeneration and cognitive deficits following binge treatment mimic the mild degeneration and cognitive deficits found in humans. Various histological methods are used to follow brain regional degeneration and regeneration.

RESULTS

Alcohol-induced degeneration occurs due to neuronal death during alcohol intoxication. Neuronal death is related to increases in oxidative stress in brain that coincide with the induction of proinflammatory cytokines and oxidative enzymes that insult brain. Degeneration is associated with increased NF-kappaB proinflammatory transcription and decreased CREB transcription. Corticolimbic brain regions are most sensitive to binge-induced degeneration and induce relearning deficits. Drugs that block oxidative stress and NF-kappaB transcription or increase CREB transcription block binge-induced neurodegeneration, inhibition of neurogenesis and proinflammatory enzyme induction. Regeneration of brain occurs during abstinence following binge ethanol treatment. Bursts of proliferating cells occur across multiple brain regions, with many new microglia across brain after months of abstinence and many new neurons in neurogenic hippocampal dentate gyrus. Brain regeneration may be important to sustain abstinence in humans.

CONCLUSIONS

Alcohol-induced neurodegeneration occurs primarily during intoxication and is related to increased oxidative stress and proinflammatory proteins that are neurotoxic. Abstinence after binge ethanol intoxication results in brain cell genesis that could contribute to the return of brain function and structure found in abstinent humans.

Incorporation in polymeric nanocapsules improves the antioxidant effect of melatonin against lipid peroxidation in mice brain and liver

It has been recently shown that the association of melatonin with polymeric nanoparticles causes a significant increase of the in vitro effect against lipid peroxidation. Hence, the aim of the present study was to compare the in vivo acute antioxidant effect of intraperitoneal administration of melatonin-loaded polysorbate 80-coated nanocapsules with that of melatonin aqueous solution in mice brain (frontal cortex and hippocampus) and liver. The lipid peroxidation through thiobarbituric acid reactive substance levels, the total antioxidant reactivity (luminol-enhanced chemiluminescence) and the free radical levels (formed dichlorofluorescein) has been carried out. Our results show that a single melatonin aqueous solution injection exerted no antioxidant activity in the evaluated range, while the administration of the melatonin-loaded polysorbate 80-coated nanocapsules caused a marked reduction on lipid peroxidation levels in all studied tissues. No differences on free radical content were found in the tissues. The melatonin-loaded nanocapsules also increased the total antioxidant reactivity in the hippocampus. These in vivo results are in accordance with our previous in vitro findings and confirm the hypothesis that polymeric nanocapsules improve the antioxidant effect of melatonin against lipid peroxidation.

Modulation of tyrosine hydroxylase expression by melatonin in human SH-SY5Y neuroblastoma cells

We have previously reported in vivo preservation of tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis, following treatment with physiological doses of melatonin, in a 6-hydroxydopamine model of Parkinson's disease. Based on these findings, we postulated that melatonin would similarly modulate the expression of TH in vitro. Therefore, using human SH-SY5Y neuroblastoma cells which can differentiate into dopaminergic neurons following treatment with retinoic acid, we first examined whether these cells express melatonin receptors. Subsequently, the physiological dose-dependent effects of melatonin on TH expression were examined in both undifferentiated and differentiated cells. The novel detection of the G protein-coupled melatonin MT(1) receptor in SH-SY5Y cells by RT-PCR was confirmed by sequencing and Western blotting. In addition, following treatment of SH-SY5Y cells with melatonin (0.1-100 nM) for 24h, Western analysis revealed a significant increase in TH protein levels. A biphasic response, with significant increases in TH protein at 0.5 and 1 nM melatonin and a reversal at higher doses was seen in undifferentiated cells; whereas in differentiated cells, melatonin was effective at doses of 1 and 100 nM. These findings suggest a physiological role for melatonin in modulating TH expression, possibly via the MT(1) receptor.

Lack of extracellular superoxide dismutase (EC-SOD) in the microenvironment impacts radiation-induced changes in neurogenesis

Ionizing irradiation results in significant alterations in hippocampal neurogenesis that are associated with cognitive impairments. Such effects are influenced, in part, by alterations in the microenvironment within which the neurogenic cells exist. One important factor that may affect neurogenesis is oxidative stress, and this study was done to determine if and how the extracellular isoform of superoxide dismutase (SOD3, EC-SOD) mediated radiation-induced alterations in neurogenic cells. Wild-type (WT) and EC-SOD knockout (KO) mice were irradiated with 5 Gy and acute (8-48 h) cellular changes and long-term changes in neurogenesis were quantified. Acute radiation responses were not different between genotypes, suggesting that the absence of EC-SOD did not influence mechanisms responsible for acute cell death after irradiation. On the other hand, the extent of neurogenesis was decreased by 39% in nonirradiated KO mice relative to WT controls. In contrast, while neurogenesis was decreased by nearly 85% in WT mice after irradiation, virtually no reduction in neurogenesis was observed in KO mice. These findings show that after irradiation, an environment lacking EC-SOD is much more permissive in the context of hippocampal neurogenesis. This finding may have a major impact in developing strategies to reduce cognitive impairment after cranial irradiation.

Suppressive Effects of Melatonin on Amyloid-β-induced Glial Activation in Rat Hippocampus

BACKGROUND

Growing evidence indicates that activated glia, as a result of chronic inflammation, are associated with amyloid-beta peptide (Abeta) deposits in the brain of Alzheimer's disease (AD) patients. The purpose of the present study was to investigate, in vivo, the effects of melatonin on glia activation, which may contribute to improved learning and memory in amnesic rats induced by amyloid-beta peptide 25-35 (Abeta25-35).

METHODS

We examined cognitive function using the Morris water maze test. Expression of interleukin 1alpha (IL-1alpha) or complement 1q (C1q) in rat hippocampal tissue was determined by immunohistochemistry.

RESULTS

It was found that Abeta25-35 injected into rat hippocampus induced an impairment in learning and memory and a marked increase of positive glial cells expressing IL-1alpha and C1q in hippocampus, compared with the controls. This suggests that glial activation triggered by Abeta25-35 parallels the dysfunction of learning and memory. Melatonin, at doses of 0.01, 0.1, and 1 mg/kg (i.g. for 10 days), improved learning and memory of rats treated with Abeta25-35. Cells expressing IL-1alpha and C1q were significantly decreased in hippocampus by pretreatment with melatonin at doses of 0.1 mg/kg and 1 mg/kg, but not at the dose of 0.01 mg/kg.

CONCLUSIONS

Our data indicate that melatonin inhibited expressions of proinflammatory factors, which may contribute to improvement of learning and memory function in AD.

Evidence supporting the use of melatonin in short gestation infants

Pineal melatonin regulates circadian rhythms and influences sleep. Melatonin also has protective actions against tissue damage from free-radicals and other toxins. Evidence is presented that this indoleamine is involved in pre- and postnatal brain (and ocular) development and intrauterine growth. In the absence of maternal melatonin, short gestation infants have a prolonged period of melatonin deficiency. Melatonin supplementation, which has a benign safety profile, may help reduce complications in the neonatal period that are associated with short gestation. We believe that this treatment might result in a wide range of health benefits, improved quality of life and reduced healthcare costs.

Binge ethanol administration enhances the MDMA-induced long-term 5-HT neurotoxicity in rat brain

RATIONALE

Ecstasy abuse commonly occurs in hot, overcrowded environments in combination with alcohol. Around 90% of ecstasy users take ethanol; over 70% of these users also often drink alcohol at hazardous levels.

OBJECTIVES

We wished to examine whether binge ethanol administration enhanced the long-lasting 5-HT neurotoxicity induced by 3,4-methylenedioxymethamphetamine (MDMA) in rats maintained at high ambient temperature and the role of acetaldehyde.

MATERIALS AND METHODS

Rats were treated with a 4-day ethanol regimen leading to plasma ethanol levels of around 450 mg/dl. On day 5, rats were placed at 30 degrees C and administered MDMA (5 mg/kg). Rectal temperature and hydroxyl radical formation were measured immediately before and up to 6 h after MDMA. 5-HT concentration and 5-HT transporter density were determined 7 days later. A group of rats received cyanamide (50 mg/kg) on days 1 and 3 of the 4-day-ethanol inhalation.

RESULTS

In ethanol treated rats, MDMA produced a hyperthermic response similar to that observed in controls but enhanced the loss of 5-HT concentration and 5-HT transporter density in the hippocampus. Cyanamide elevated the plasma acetaldehyde concentration fivefold to sevenfold, reduced the MDMA-induced hyperthermia and increased the neuronal damage with neurotoxicity also appearing in the cortex. MDMA increased hydroxyl radical production in the hippocampus, the effect being more marked in rats pre-exposed to ethanol.

CONCLUSIONS

Binge ethanol administration enhances the MDMA-induced long-term 5-HT neurotoxicity by a mechanism not related to changes in acute hyperthermia but probably involving hydroxyl radical formation. The magnitude of this effect is more pronounced after increasing plasma acetaldehyde levels by aldehyde dehydrogenase inhibition.