Effects of acute ethanol administration on the uptake of 59Fe-labeled transferrin by rat liver and cerebellum

Deep grey matter iron accumulation in alcohol use disorder

PURPOSE

Evaluate brain iron accumulation in alcohol use disorder (AUD) patients compared to controls using quantitative susceptibility mapping (QSM).

METHODS

QSM was performed retrospectively by using phase images from resting state functional magnetic resonance imaging (fMRI). 20 male AUD patients and 15 matched healthy controls were examined. Susceptibility values were manually traced in deep grey matter regions including caudate nucleus, combined putamen and globus pallidus, combined substantia nigra and red nucleus, dentate nucleus, and a reference white matter region in the internal capsule. Average susceptibility values from each region were compared between the patients and controls. The relationship between age and susceptibility was also explored.

RESULTS

The AUD group exhibited increased susceptibility in caudate nucleus (+8.5%, p=0.034), combined putamen and globus pallidus (+10.8%, p=0.006), and dentate nucleus (+14.9%, p=0.022). Susceptibility increased with age in two of the four measured regions - combined putamen and globus pallidus (p=0.013) and combined substantia nigra and red nucleus (p=0.041). AUD did not significantly modulate the rate of susceptibility increase with age in our data.

CONCLUSION

Retrospective QSM computed from standard fMRI datasets provides new opportunities for brain iron studies in psychiatry. Substantially elevated brain iron was found in AUD subjects in the basal ganglia and dentate nucleus. This was the first human AUD brain iron study and the first retrospective clinical fMRI QSM study.

Role for membrane fluidity in ethanol-induced oxidative stress of primary rat hepatocytes

The relationship between bulk membrane fluidizing effect of ethanol and its toxicity due to oxidative stress is still unknown. To elucidate this issue, membrane fluidity of primary rat hepatocytes was studied by measuring order parameter after inhibition of ethanol-induced oxidative stress. We showed that pretreating cells with either 4-methyl-pyrazole (to inhibit ethanol metabolism), thiourea [a reactive oxygen species (ROS) scavenger], or vitamin E (a free radical chain-breaking antioxidant) prevented the ethanol-induced increase in membrane fluidity, thus suggesting that ethanol metabolism and ROS formation were involved in this elevation. The effects of membrane stabilizing agents (ursodeoxycholic acid or ganglioside GM1), shown to prevent fluidification, next pointed to a role for this increase in membrane fluidity in the development of ethanol-induced oxidative stress. Indeed, ROS production, lipid peroxidation, and cell death were all inhibited by these agents. In contrast, the fluidizing compounds Tween 20 or 2-(2-methoxyethoxy) ethyl 8-(cis-2-n-octylcyclopropyl) octanoate, which increased the membrane fluidizing effect of ethanol, enhanced the related oxidative stress. Using electron paramagnetic resonance to determine low molecular weight iron, we finally demonstrated that membrane fluidity influence proceeded through an increase in low molecular weight iron to enhance oxidative stress. In conclusion, the present findings clearly highlight the pivotal role of membrane fluidity in ethanol-induced oxidative stress and the potential therapeutic effect of membrane stabilizing compounds.

Gradual micronutrient accumulation and depletion in Alzheimer's disease

Cadmium is a carcinogen that accumulates relentlessly with age, reaching high levels in the liver and kidneys. It is known to hyperactivate the Kupffer cells (hepatic macrophages). On the other hand, the risk of developing Alzheimer's disease increases considerably with age and it involves neuronal damage by hyperactive microglia (brain macrophages). Moreover, many of the metals that accumulate in the liver and kidneys, also accumulate in the brain (Fe, Cu, Zn, Mn, etc.). Therefore, it is possible that Cd also hyperactivates the microglia, playing a role in Alzheimer's disease (AD).Fe also accumulates in the brain as we age and catalyzes super oxide (O2-) formation, which reacts with nitric oxide (NO) to form the very harmful peroxynitrite (ONOO-). ONOO- causes considerable damage that exacerbates the damage caused by the hyperactive microglia, accelerating the progress of AD. Moreover, as we age we become less efficient at absorbing and retaining Cu, Zn and Mg. Since Cu and Zn are necessary for the synthesis of copper-zinc superoxide dismutase (CuZnSOD), which disables the noxious O2-, the deficiencies cause considerable damage as we age. Similarly, Mg is a cofactor for CuZnSOD and is necessary for NO to leave the cell and perform its vasodilating job. Unfortunately, a Mg deficiency traps the NO in the cell, where it reacts with O2-, forming the harmful ONOO-. Furthermore, Se and vitamins B6 and D are required for Mg absorption and vitamin E is required to minimize the oxidative damage.

Effect of gradual accumulation of iron, molybdenum and sulfur, slow depletion of zinc and copper, ethanol or fructose ingestion and phlebotomy in gout

Gout affects mostly males over 40 years old and, occasionally, postmenopausal women. This pattern coincides with the pattern of iron accumulation. On the other hand, menstruating women are seldom afflicted by gout, because the monthly blood loss causes them to accumulate iron to a much lesser degree. Gout involves seven aspects: (1) uric acid overproduction from increased purines in the diet; (2) uric acid overproduction from ATP degradation; (3) uric acid overproduction from increased de novo synthesis of purines; (4) uric acid overproduction from increased DNA breakdown from cell damage; (5) decreased uric acid elimination, caused by molybdenum and sulfur binding to copper in the kidneys; (6) precipitation of sodium urate-iron crystals in the joints due to high ferritin and saturated transferrin and low CuZn-SOD and Cu-thionein in the joint; (7) development of inflammation, triggered by tyrosine bonding to the sodium-urate-iron crystals and being transformed by tyrosine kinase. Alcohol and iron greatly affect most of these aspects. Therefore, phlebotomy is suggested as therapy for gout patients, in order to eliminate the accumulated Fe. Furthermore, yearly blood donation is recommended for males with a family history of gout, so as to prevent Fe accumulation and avoid gout.

Chronic ethanol ingestion-induced changes in open-field behavior and oxidative stress in the rat

The effects of chronic ethanol intoxication on the open-field behavior, on antioxidant enzyme activities, and the degree of lipid peroxidation were investigated. Rats consuming a liquid diet containing 7% ethanol for 4, 7, 14, or 21 days exhibited a significantly decreased ambulation activity, accompanied by a reduced frequency and duration of explorative rearing in an open-field task 4, 7, and 14 days after chronic ethanol ingestion, whereas presumed adaptation to the neurologic effects of ethanol was observed on day 21. Changes in the activities of glutathione peroxidase (GSH-Px): glutathione reductase (GSH-R), and catalase, and in the content of reduced glutathione (GSH) in blood samples were determined by means of biochemical methods. The degree of lipid peroxidation was measured via thiobarbituric acid assays. Chronic ethanol ingestion elicited a significant increase in GSH-Px activity (by a maximum of approximately 32% on day 14), whereas opposite alterations in GSH-R and catalase activities were recorded (49% of the control value on day 4 and 17% on day 21, respectively). Highly elevated contents of thiobarbituric acid reactive substances reflected extensive lipid peroxidation processes throughout the experiment. These changes indicate that ethanol toxicity induces profound changes in explorative behavior, mediated, at least partly, by changes in the free radical metabolism.

Changes in some pro- and antioxidants in rat cerebellum after chronic alcohol intake

Some pro- and antioxidants were measured in the cerebellum from ethanol-fed rats using ethanol administration in drinking water as a model of moderate alcohol intoxication. After 4 weeks of ethanol intake, a 30% increase in the nonheme iron content in the cerebellum occurred in ethanol-fed rats as compared to control animals. The low-molecular-weight-chelated iron (LMWC-Fe) content as well as the percentage of total nonheme iron represented by LMWC-Fe were increased in the cerebellar cytosol after chronic ethanol administration. Cerebellar copper and selenium concentrations were lower and zinc concentration higher in ethanol-fed rats than in controls. Ethanol consumption decreased the cerebellar vitamin E level. Glutathione S-transferase [EC 2. 5. 1. 18] activity was higher, whereas glutathione peroxidase [glutathione: H2O2 oxidoreductase, EC 1. 11. 1. 9] activity was not altered by ethanol treatment. No significant changes in cerebellar lipid peroxidation, carbonyl protein content, or glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming) EC 6. 3. 1. 2] activity were observed. These results suggest that adaptative increases in some elements of the antioxidant defense may counteract the increase in LMWC-Fe, a pro-oxidant factor, and prevent the occurrence of overt cellular lipid and protein damage. However, after 8 weeks of ethanol intake, the activity of glutamine synthetase, an enzyme specially sensitive to inactivation by oxygen radicals, was decreased, suggesting that this prevention was not totally achieved.

Chemical modulation of metallothionein I and III mRNA in mouse brain

Metallothioneins (MTs) are sulfhydryl-rich proteins. MT-I and MT-II are found in all tissues of the body, while MT-III exists only in brain. Regulation of MT-I and MT-III mRNA was studied in brain and liver of control C57BL/6J mice and mice given chemicals known to increase MT-I, namely, lipopolysaccharide (LPS), zinc chloride (Zn), cadmium chloride (Cd), dexamethasone (Dex), ethanol, and kainic acid (KA). Northern blot analysis revealed that MT-I mRNA levels in liver were induced dramatically (12-27-fold over basal levels) by all of the chemicals, while in brain only LPS produced an increase in MT-I mRNA (2-fold). Interestingly, the MT-I inducers, Cd, Dex, ethanol, and KA, down-regulated brain MT-III mRNA levels by approx. 30%. Because brain is such a heterogenous tissue, in situ hybridization was used to localize MT-I and MT-III mRNA in control and treated mice. MT-I mRNA signal, which was most abundant in the glial cells of the Purkinje cell layer of the cerebellum in control mice, appeared to be enhanced in mice given the MT-I inducers (LPS, Zn, Cd, Dex, ethanol, and KA). MT-I mRNA hybridization signal was also enhanced in the olfactory bulbs from LPS- and Cd-treated mice, while this signal was present but weak in control brains. MT-III mRNA hybridization signals were localized in hippocampus and co-localized with MT-I message in the glial cells of the Purkinje cell layer of the cerebellum. In addition, diffuse MT-III mRNA signals were visible in areas of the cerebral cortex, and in the molecular layer of the cerebellum. Signals for MT-III in hippocampus appeared to be reduced by KA, Dex and LPS treatment, while in the cortical region, MT-III mRNA signals appeared to be enhanced by KA, Cd, and ethanol treatment. In conclusion, both MT-I and MT-III expression in brain appears to be modulated by exogenous treatment, however, the changes are small in relation to those observed in liver. Chemical-induced alterations of MT mRNA are non-uniform throughout the brain, and thus best studied in a region-specific manner.