Effects of combined exposure to aluminium and ethanol on aluminium body burden and some neuronal, hepatic and haematopoietic biochemical variables in the rat

Aluminium Induced Neurodegeneration in Rat Cerebellum in the Presence of Ethanol Coexposure

Introduction:

Both aluminium and ethanol are pro-oxidants and neurotoxic. Moderately intake of alcohol may favor the body in coronary heart disease and diabetes mellitus etc. Being cheaper aluminium and increasing consumption of alcohol in India mixed with each other and may induce neurotoxicity. The present study was planned to identify the level of aluminium induced neurodegeneration in presence of ethanol coexposure in the cerebellum.

Materials and Methods:

An experimental study was carried out at Dr. RP Government Medical College, Kangra, and Government Medical College, Amritsar, India after due approval from the Institute Animal Ethics Committee. Thirty-two Wistar rats were divided into one vehicle control and three experimental groups. Group I received the normal saline water as the vehicle control group. Group II received aluminium chloride 4.2 mg/kg body weight as the experimental group. Group III received ethanol 1 g/kg body weight as the experimental group. Group IV received both aluminium chloride 4.2 mg/kg body weight and ethanol 1 g/kg body weight as the experimental group. After 3 months of treatment, cerebellum was processed for histopathological observation under the microscope.

Results:

Experimental group treated with aluminium and ethanol separately showed reduction in the number of Purkinje cells, without a prominent nucleolus and well-defined nuclear membrane. Eosinophilic swelling adjacent to Purkinje cell bodies observed. The effects of combined administration of aluminium ethanol treated groups showed with acute neurodegeneration of Purkinje cell layer and granular layer. Pyknosis and neurofibrillary tangle seen in Purkinje cells.

Conclusions:

It has been suggested that the ethanol-induced the effects of aluminium on the cerebellum and plays a significant role in neurotoxicity.

Determination of aluminium induced metabolic changes in mice liver: a Fourier transform infrared spectroscopy study

In this study, we made a new approach to evaluate aluminium induced metabolic changes in liver tissue of mice using Fourier transform infrared spectroscopy analysis taking one step further in correlation with strong biochemical evidence. This finding reveals the alterations on the major biochemical constituents, such as lipids, proteins, nucleic acids and glycogen of the liver tissues of mice. The peak area value of amide A significantly decrease from 288.278±3.121 to 189.872±2.012 between control and aluminium treated liver tissue respectively. Amide I and amide II peak area value also decrease from 40.749±2.052 to 21.170±1.311 and 13.167±1.441 to 8.953±0.548 in aluminium treated liver tissue respectively. This result suggests an alteration in the protein profile. The absence of olefinicCH stretching band and CO stretching of triglycerides in aluminium treated liver suggests an altered lipid levels due to aluminium exposure. Significant shift in the peak position of glycogen may be the interruption of aluminium in the calcium metabolism and the reduced level of calcium. The overall findings exhibit that the liver metabolic program is altered through increasing the structural modification in proteins, triglycerides and quantitative alteration in proteins, lipids, and glycogen. All the above mentioned modifications were protected in desferrioxamine treated mice. Histopathological results also revealed impairment of aluminium induced alterations in liver tissue. The results of the FTIR study were found to be in agreement with biochemical studies and which demonstrate FTIR can be used successfully to indicate the molecular level changes.

Role of ethanol on aluminum induced biochemical changes on rat brain

Aluminum and alcohol, both are well-accepted neurotoxin. The plausible mechanisms for their neurotoxicity are also common. Therefore, the effect of ethanol on aluminum induced biochemical changes in rat brain is being studied. In the present study, ethanol exposure significantly affected the aluminum and protein content of brain. The activities of acid phosphatase and alkaline phosphatase were also changed. Aluminum exposure, on the other hand, contributed significantly in the alterations of aluminum content, acid phosphatase acivity and aspartate aminotransferase activity. Though ethanol co-exposure significantly influenced the aluminum load of brain, the interactions of these two neurotoxins were found to be significant only in case of acid phosphatase activity of brain. Therefore, it can be suggested that general neurotoxicity produced by aluminum is not modified by ethanol. However, the aluminum load caused by aluminum exposure, may be influenced by ethanol co-exposure.

Does neurotransmission impairment accompany aluminium neurotoxicity?

Neurobehavioral disorders, except their most overt form, tend to lie beyond the reach of clinicians. Presently, the use of molecular data in the decision-making processes is limited. However, as details of the mechanisms of neurotoxic action of aluminium become clearer, a more complete picture of possible molecular targets of aluminium can be anticipated, which promises better prediction of the neurotoxicological potential of aluminium exposure. In practical terms, a critical analysis of current data on the effects of aluminium on neurotransmission can be of great benefit due to the rapidly expanding knowledge of the neurotoxicological potential of aluminium. This review concludes that impairment of neurotransmission is a strong predictor of outcome in neurobehavioral disorders. Key questions and challenges for future research into aluminium neurotoxicity are also identified.

Aluminum-induced oxidative stress in rat brain: response to combined administration of citric acid and HEDTA

Aluminum, a known neurotoxic substance, has been suggested as a contributing factor in the pathogenesis of Alzheimer's disease. Therapeutic efficacy of combined administration of citric acid (CA) and N-(2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA) was evaluated in decreasing blood and brain aluminum concentration and parameters indicative of hematological disorders and brain oxidative stress. Adult male wistar rats were exposed to drinking water containing 0.2% aluminum nitrate for 8 months and treated once daily for 5 consecutive days with CA (50 mg/kg, orally) or HEDTA (50 mg/kg, intraperitoneally) either individually or in combination. Aluminum exposure significantly inhibited blood delta-aminolevulinic acid dehydratase while increased zinc protoporphyrin confirming changed heme biosynthesis. Significant decrease in the level of glutathione S-transferase in various brain regions and an increase in whole brain thiobarbituric acid reactive substance, and oxidized glutathione (GSSG) levels were also observed. Glutathione peroxidase activity showed a significant increase in cerebellum of aluminum exposed rats. Most of the above parameters responded moderately to the individual treatment with CA and HEDTA, but significantly reduced blood and brain aluminum burden. However, more pronounced beneficial effects on some of the above described parameters were observed when CA and HEDTA were administered concomitantly. Blood and brain aluminum concentration however, showed no further decline on combined treatment over the individual effect with HEDTA or CA. We conclude that in order to achieve an optimum effect of chelation, combined administration of CA and HEDTA might be preferred. However, further work is needed before a final recommendation could be made.

Aluminum: impacts and disease

Aluminum is the most widely distributed metal in the environment and is extensively used in modern daily life. Aluminum enters into the body from the environment and from diet and medication. However, there is no known physiological role for aluminum within the body and hence this metal may produce adverse physiological effects. The impact of aluminum on neural tissues is well reported but studies on extraneural tissues are not well summarized. In this review, the impacts of aluminum on humans and its impact on major physiological systems are summarized and discussed. The neuropathologies associated with high brain aluminum levels, including structural, biochemical, and neurobehavioral changes, have been summarized. In addition, the impact of aluminum on the musculoskeletal system, respiratory system, cardiovascular system, hepatobiliary system, endocrine system, urinary system, and reproductive system are discussed.

Effects of combined exposure to aluminium and ethanol on food intake, motor behaviour and a few biochemical parameters in pubertal rats

Combined daily administration of aluminium chloride (260 mg/kg, oral) and ethanol (2 g/kg, oral), to pubertal male rats for 30 days was found to significantly decrease food intake, body weight gain and serum protein levels. Spontaneous motor activity and rota-rod motor coordination were also significantly impaired. Acetylcholinesterase activity was significantly diminished in the cerebrum and cerebellum. The results obtained in the present study are suggestive of a potentiation of cholinotoxic effects of the two compounds when administered together. Thus, when combined, ethanol may increase pubertal rat's susceptibility to the toxic effects of aluminium.

Altered dopamine turnover in murine hypothalamus after low-dose continuous oral administration of aluminum

Aluminum, a known neurotoxic substance, has been suggested as a possible contributing factor in the pathogenesis of Alzheimer's disease. Ground-water pollution by aluminum has been recently reported. In the current study groups of 5 male BALB/c mice were administered aluminum ammonium sulfate in drinking water ad libitum at 0, 5, 25, and 125 mg/L aluminum for 4 weeks. At the termination of aluminum exposure, their brains were removed and dissected into cerebrum, cerebellum, medulla oblongata, midbrain, corpus striatum, and hypothalamus. The concentration of norepinephrine (NE), dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA), were determined in each brain area. DA, DOPAC, and HVA levels were lower in the hypothalamus of aluminum-treated mice, most notably in the low-dose group, as compared with control. No marked alterations in NE, 5-HT, and 5-HIAA levels were detected in any brain region. Changes in the concentration of DA and its metabolites measured in the hypothalamus suggest an inhibition of DA synthesis by aluminum.

Oral aluminum administration to rats with normal renal function. 2. Body distribution

Aluminum (Al) has no known physiological function and is not considered an essential dietary compound. Nowadays, it is recognized as an element that can produce adverse effects on biological systems. The present study determined Al partitioning in the body compartments of rats that have been orally exposed for 15 weeks. Three experimental groups were studied: Controls (C, n=19), TAl-1 (n=10) rats receiving daily doses of Al citrate (1.0 micromol/g body weight) by gavage and TAl-2 (n=13), receiving Al citrate with the drinking water (100 mmol/ l). At the end of the experimental period, the Al contents of organs and sera were determined. Results are expressed as median and range values. Comparing the TAl-2 rats with the control ones, remarkable Al accumulation could be observed in serum (4.8/2.7-16.3 vs 0.4/0.2-1.2 micromol/l, P<0.001), bone (3.33/1.78-4.85 vs 1.00/0.48-1.59 micromol/ g, P<0.001), kidney (2.33/0.96-3.15 vs 0.52/0.22-2.07 micromol/g, P<0.001), spleen (2.22/0.70-4.19 vs 0.27/ 0.11 - 0.36 micromol/g, P< 0.001) and liver (0.60/0.42-0.91 vs 0.24/0.14-0.78 micromol/g, P<0.01) while brain Al content was not significantly increased. Aluminum levels were raised in the TAl-1 group only in serum (2.8/1.3 - 10.4 micromol/ g, P < 0.001), bone (1.85/1.00-3.41 micromol/g, P < 0.001) and kidney (1.74/0.96-2.07 micromol/g, P<0.01). Bone Al concentration increased in a dose-dependent manner (TAl-2 vs TAl-1, P<0.001). The results demonstrate different tissue Al accumulation in rats chronically exposed to Al citrate, irrespective of their intact renal function.

Kinetics of aluminum-induced inhibition of delta-aminolevulinic acid dehydratase in vitro

Anemia, one consequence of aluminum toxicity, may be due to inhibition of enzymes in the heme biosynthetic pathway. In this study, the in vitro effect of aluminum on rat liver and erythrocyte delta-aminolevulinic acid dehydratase (delta-ALA dehydratase), an enzyme that is sensitive to a number of metal ions, was investigated. The presence of 1-10 microM AlCl3 caused a concentration-dependent inhibition of liver delta-ALA dehydratase activity. The Ki for AlCl3-induced inhibition of delta-ALA dehydratase was 4.1 microM, and 10 microM AlCl3 virtually abolished delta-ALA dehydratase activity (99% inhibition). Erythrocyte delta-ALA dehydratase was also inhibited by similar concentrations of AlCl3 and displayed a Ki of 1.1 microM. AlCl3 (5 microM) decreased the Vmax by 50% but did not change the Km, suggestive of reversible, noncompetitive inhibition. Sodium citrate (50 microM) when added with AlCl3 completely restored delta-ALA dehydratase activity to basal levels. Thus, disruption of delta-ALA dehydratase occurred at low micromolar levels of AlCl3 in vitro, which may help to explain abnormalities in the heme pathway in cases of aluminum poisoning.

Serotonin and alcohol intake, abuse, and dependence: findings of animal studies

Despite a relatively large body of literature on the role of the neurotransmitter serotonin (5-hydroxytryptamine, or 5-HT) in the regulation of alcohol intake, the functional significance of serotonergic neurotransmission and its relationship to alcohol intake, abuse, and dependence remains to be fully elucidated. In part two of this review, the experimental (animal) data is summarized along two lines: the effects of serotonergic manipulations on the intake of alcohol, and the effects of acute and chronic alcohol intake, as well as the withdrawal of chronic alcohol, on the serotonergic system. It is concluded that serotonin mediates ethanol intake as a part of its larger role in behavior modulation, such that increases in serotonergic functioning decrease ethanol intake, and decreased serotonergic functioning increases ethanol intake. Ethanol produces transient increases in serotonergic functioning that activate the mesolimbic dopaminergic reward system. The results are discussed in light of recent theories describing the regulatory role of serotonin in general behavior.

Is aluminium an etiologic contributor to alcoholic amnesia and dementia?

Neurotoxicity from excess brain exposure to aluminium (Al) is well-documented, from both clinical observations and animal experiments, to impair learning, memory and cognition. The etiology of the cognitive impairment in chronic abusers of ethanol--alcoholic amnesia or dementia--is not known, but it is likely to be multifactorial. We hypothesize that a slowly-progressive accumulation of Al in the brain, so as to reach functionally-toxic levels, may be one such factor. This could occur because of an increased permeability of intestinal mucosa to entry of Al, arising from sustained exposure of the gastrointestinal tract to alcoholic beverages, plus a trend for more frequent ingestion of antacids based on Al salts for treating gastritis or ulcers caused by such exposure. If this be true, use of Al-containing medications, as well as all avoidable exposures to Al, should be contra-indicated for chronic heavy drinkers.

Sequential expression of biomarkers in Bluegill Sunfish exposed to contaminated sediment

The temporal expression of various biological rsponses was determined in Bluegill SunfishLepomis macrochirus exposed under controlled laboratory conditions to sediment containing high concentrations of polynuclear aromatic hydrocarbons, polychlorinated biphenyls and heavy metals. Liver, gill, blood, kidney, brain, spleen and intestine were removed from Sunfish sampled at 1, 2, 4, 8, 16, and 40 weeks post-exposure. Biomarker data were recorded for specific proteins, enzymatic activities, DNA integrity, and histopathology. Biomarkers in the laboratory exposed fish were similar to those of indigenous Sunfish sampled from the site of origin of the contaminated sediment. Several patterns of development of biomarkers over time were also evident. For example, the responses of certain biomarkers are not time-dependent (i.e., intestine and gill ATPase activities) while that of others, such as brain ATPase activity, liver cytochrome P450 and NADPH content, stress proteins, chromatin proteins and DNA strand breaks, fluctuate over time. Still other biomarkers, such as EROD activity, zinc protoporphyrin content of the blood, and DNA adducts, showed marked increases over time. Such patterns need to be considered when comparing laboratory and field results and deciding which biomarkers to use for biomonitoring programs. Implications for natural selection and population/community level responses are also discussed.