Aluminum trichloride induces bone impairment through TGF-ß1/Smad signaling pathway.

Aluminum (Al) is recognized worldwide as serious inorganic contaminants. Exposure to Al is associated with low BMD and an increased risk of osteoporosis. However, the precise molecular mechanisms remains unclear. Thus, in this study, rats were orally exposed to 0 (control group, CG) and 0.4g/L AlCl3 (AlCl3 treated group, AG) in drinking water for 120days; osteoblasts were treated with AlCl3 (0.12mg/mL) and/or TGF-ß1 (4.5ng/mL) for 24h. We found that AlCl3 decreased the BMD, damaged femoral ultrastructure, decreased the activities of GSH-Px and SOD, and increased the levels of ROS and MDA in bone, decreased the activity of B-ALP and content of PINP, and increased the activity of TRACP-5b and content of NTX-I in serum, decreased mRNA expressions of TGF-ß1, TßRI, TßRII and Smad4, protein expressions of TGF-ß1, p-Smad2/3 and Smad2/3/4 complex, and increased Smad7 mRNA expression in bone and in osteoblasts. Moreover, we found exogenous TGF-ß1 application reversed the inhibitory effect of AlCl3 on osteoblasts activity by activating the TGF-ß1/Smad signaling pathway and increasing the mRNA expressions of ALP and Col I in osteoblasts. These results demonstrate that AlCl3 induces bone impairment through inactivation of TGF-ß1/Smad signaling pathway.

Mangiferin ameliorates aluminium chloride-induced cognitive dysfunction via alleviation of hippocampal oxido-nitrosative stress, proinflammatory cytokines and acetylcholinesterase level.

Mangiferin is a phytochemical primarily present in the stem, leaves and bark of Mangifera indica. It offers neuroprotection mainly through inhibition of oxidative stress, and decreasing proinflammatory cytokines level in the brain. Aluminium has been reported to cause oxidative stress-associated damage in the brain. In the present investigation, protective effect of mangiferin against aluminium chloride (AlCl3)-induced neurotoxicity and cognitive impairment was studied in male Swiss albino mice. AlCl3 (100 mg/kg) was administered once daily through oral gavage for 42 days. Mangiferin (20 and 40 mg/kg, p.o.) was given to mice for last 21 days of the study. We found cognitive dysfunction in AlCl3-treated group, which was assessed by Morris water maze test, and novel object recognition test. AlCl3-treated group showed elevated level of oxidative stress markers, proinflammatory cytokines level and lowered hippocampal brain-derived neurotrophic factor (BDNF) content. Mangiferin (40 mg/kg) prevented the cognitive deficits, hippocampal BDNF depletion, and biochemical anomalies induced by AlCl3-treatment. In conclusion, our data demonstrated that mangiferin offers neuroprotection in AlCl3-induced neurotoxicity and it may be a potential therapeutic approach in the treatment of oxido-nitrosative stress and inflammation-associated neurotoxicity.

Role of propolis (bee glue) in improving histopathological changes of the kidney of rat treated with aluminum chloride.

Humans are frequently exposed to aluminum from various food additives, therapeutic treatments and the environment, and it can be potentially toxic. This study is aimed to elucidate the protective effects of propolis against aluminum chloride (AlCl3 )-induced histopathological and immunohistochemical changes in kidney tissues of rats. Sixty Wistar Albino male rats (average weight 250-300 g) were divided into three equal groups. The first served as a negative control. The second received AlCl3 (34 mg/kg bw, 1/ 25 LD 50). The third were administered AlCl3 (34 mg/kg bw, 1/ 25 LD 50) plus propolis (50 mg/kg bw). Doses were given once daily via a gavage for 8 weeks every day. The results showed that shrunken glomeruli, intraglomerular congestion, loss of apical microvilli, degeneration of mitochondria and widened rough endoplasmic reticulum were also observed in the Proximal Convoluted Tubules of these animals. Treatment with propolis ameliorated the harmful effects of AlCl3 ; this was also proved histopathologically by the noticeable improvement in the renal tissues. There were also significant variations in the expressed of ki-67 and p53 proteins. It can be concluded that propolis may be promising as a natural therapeutic agent in AlCl3 -induced renal toxicity and oxidative stress in rat kidneys.

Protective effects of N-acetylcysteine on aluminum phosphide-induced oxidative stress in acute human poisoning.

OBJECTIVE: Aluminum phosphide is used as a fumigant. It produces phosphine gas (PH3). PH3 is a mitochondrial poison which inhibits cytochrome c oxidase, it leads to generation of reactive oxygen species; so one of the most important suggested mechanisms for its toxicity is induction of oxidative stress. In this regard, it could be proposed that a drug like N-acetylcysteine (NAC) as an antioxidant would improve the tolerance of aluminum phosphide-intoxicated cases. The objective of this study was to evaluate the protective effects of NAC on acute aluminum phosphide poisoning. METHODS: This was a prospective, randomized, controlled open-label trial. All patients received the same supportive treatments. NAC treatment group also received NAC. The blood thiobarbituric acid reactive substances as a marker of lipid peroxidation and total antioxidant capacity of plasma were analyzed. RESULTS: Mean ingested dose of aluminum phosphide in NAC treatment and control groups was 4.8 ± 0.9 g vs. 5.4 ± 3.3 g, respectively (p = 0.41). Significant increase in plasma malonyldialdehyde level in control group was observed (139 ± 28.2 vs. 149.6 ± 35.2 µmol/L, p = 0.02). NAC infusion in NAC treatment group significantly decreased malondialdehyde level (195.7 ± 67.4 vs. 174.6 ± 48.9 µmol/L, p = 0.03), duration of hospitalization (2.7 ± 1.8 days vs. 8.5 ± 8.2 days, p = 0.02), rate of intubation and ventilation (45.4% vs. 73.3%, p = 0.04). Mortality rate in NAC treatment and control groups were 36% and 60%, respectively with odds ratio 2.6 (0.7-10.1, 95% CI). CONCLUSION: NAC may have a therapeutic effect in acute aluminum phosphide poisoning.

Biochemical and molecular aspects of aluminium chloride-induced neurotoxicity in mice and the protective role of Crocus sativus L. extraction and honey syrup.

Aluminium has been proposed as an environmental factor that may affect several enzymes and other biomolecules related to neurotoxicity and Alzheimer's disease (AD). The promising protective effect of aqueous saffron extract and honey syrup on neurotoxicity induced by aluminuim chloride (AlCl(3)) may be derived from their own antioxidant properties. Balb/c and C57BL/6 mice (35-40 g) were injected with AlCl(3), 40 mg/kg/day for 45 days. Each mice strain was divided into four groups: AlCl(3) treated group, AlCl(3) plus water saffron extract group (administered with saffron extract at 200 mg/kg b.w. once a day for the experimental period), AlCl(3) plus honey syrup group (administered with honey syrup at 500 mg/kg b.w. for 45 days). The control group received no treatment. Oxidative stress and antioxidant status were estimated in the brain and differential display was performed for both mice strains to scan the mRNA in the treated and non treated groups. In addition, the up and down regulated genes were isolated, cloned and sequenced. The sequence analysis was performed and compared with the other genes cited on GenBank. The results show that there was a decrease in the activity of the antioxidant enzymes (P≤0.001) such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the AlCl3 groups of both mice strains. The level of brain thiobarbituric acid reactive substances (TBARS) showed a significant increase (P≤0.001) of lipid peroxidation (LPO) in the AlCl(3) groups. There was an indication of carcinogenicity in the AlCl(3) treated group representing an increase in serum tumor markers such as arginase and a-l-fucosidase. More than 350 band patterns were obtained and about 22 different up-down regulated genes were observed. The sequence analysis of the three selected up-regulated genes revealed that they are similar to B-cell lymphoma 2 (Bcl-2), R-spondin and the inositol polyphosphate 4-phosphatase genes (INPP4B), respectively. The R-spondin gene was up-regulated in all examined animals except the control ones but the other two genes were only induced in the animals treated with AlCl(3) and honey syrup. We conclude that the biochemical and molecular studies showed the neurotoxicity of AlCl(3) in the brains of mice. In addition, there was an ameliorative change with saffron extract and honey syrup against AlCl(3) neurotoxicity. The obtained molecular results suggest that AlCl(3) made induction for BCL-W gene, which is an anticancer gene or belongs to the DNA repair system in the brain cells, as well as for R-spondin and inositol polyphosphate 4-phosphatase genes, which help in cell proliferation.

Propolis prevents aluminium-induced genetic and hepatic damages in rat liver.

Aluminium is present in several manufactured foods and medicines and is also used in water purification. Therefore, the present experiment was undertaken to determine the effectiveness of propolis in modulating the aluminium chloride (AlCl(3)) induced genotoxicity and hepatotoxicity in liver of rats. Animals were assigned to 1 of 4 groups: control; 34 mg AlCl(3)/kg bw; 50mg propolis/kg bw; AlCl(3) (34 mg/kg bw) plus propolis (50mg/kg bw), respectively. Rats were orally administered their respective doses daily for 30 days. At the end of the experiment, rats were anesthetized and hepatocytes (HEP) were isolated for counting the number of micronucleated hepatocytes (MNHEPs). In addition, the levels of serum enzymes and histological alterations in liver were investigated. AlCl(3) caused a significant increase in MNHEPs, alkaline phosphatase, transaminases (AST and ALT) and lactate dehydrogenase (LDH). Furthermore, severe pathological damages such as: sinusoidal dilatation, congestion of central vein, lipid accumulation and lymphocyte infiltration were established in liver. On the contrary, treatment with propolis alone did not cause any adverse effect on above parameters. Moreover, simultaneous treatments with propolis significantly modulated the toxic effects of AlCl(3). It can be concluded that propolis has beneficial influences and could be able to antagonize AlCl(3) toxicity.

Propolis alleviates aluminium-induced lipid peroxidation and biochemical parameters in male rats.

Aluminium is present in many manufactured foods and medicines and is also added to drinking water during purification purposes. Therefore, the present experiment was undertaken to determine the effectiveness of propolis in alleviating the toxicity of aluminium chloride (AlCl3) on biochemical parameters, antioxidant enzymes and lipid peroxidation of male Wistar Albino rats. Animals were assigned to 1 of 4 groups: control; 34 mg AlCl3/kg bw; 50 mg propolis/kg bw; AlCl3 (34 mg/kg bw) plus propolis (50 mg/kg bw), respectively. Rats were orally administered their respective doses daily for 70 days. The levels of thiobarbituric acid reactive substances (TBARS) was increased, and the activities of glutathione S-transferase, superoxide dismutase, catalase and glutathione peroxidase were decreased in liver, kidney and brain of rats treated with AlCl3. While, TBARS was decreased and the antioxidant enzymes were increased in rats treated with propolis alone. Plasma transaminases, lactate dehydrogenase, glucose, urea, creatinine, bilirubin, total lipid, cholesterol, triglyceride and LDL-c were increased, while total protein, albumin and high HDL-c were decreased due to AlCl3 administration. The presence of propolis with AlCl3 alleviated its toxic effects in rats treated with AlCl3. It can be concluded that propolis has beneficial influences and could be able to antagonize AlCl3 toxicity.

Propolis protection from reproductive toxicity caused by aluminium chloride in male rats.

Different forms of aluminium (Al) are environmental xenobiotics that induce free radical-mediated cytotoxicity and reproductive toxicity. Propolis has been reported to be important antioxidant. Therefore, this study aimed at elucidating the protective effects of propolis against reproductive toxicity of aluminium chloride (AlCl3) in male rats. The first group served as control. Group 2 received 34 mg AlCl3/kg bw (1/25 LD50). Group 3 was administered 50 mg propolis/kg bw/day. Group 4 was treated with AlCl3 plus propolis. Treatment was continued for 70 days. AlCl3 caused a decrease in testes, seminal vesicle and epididymis weights, sperm concentration, motility, testosterone level and the activities of 17-ketosteroid reductase, CAT and GST, and GSH content. While, dead and abnormal sperm and testes TBARS concentrations were increased. In the AlCl3-treated group, histopathologic examinations revealed apparent alterations in the testes, where it induced marked lesions in seminiferous tubules. Propolis alone decreased dead and abnormal sperm and TBARS, and increased testosterone, GSH, 17-ketosteroid reductase, CAT and GST. Results showed that propolis antagonized the harmful effects of AlCl3. This was proved histopathologically by the great improvement in testes. In conclusion propolis could be effective in the protection against the reproductive toxicity of AlCl3.

Aluminum-induced maternal and developmental toxicity and oxidative stress in rat brain: response to combined administration of Tiron and glutathione.

The current study was performed to assess the potential of 4,5-dihydroxy 1,3-benzene disulfonic acid di sodium salt (Tiron) and glutathione (GSH) either individually or in combination against aluminum (Al)-induced developmental toxicity in fetuses and sucklings of Wistar rats. Female rats were exposed to aluminum chloride at a dose of 345 mg/(kg day) oral from days 0 to 16 of gestation and 0 to 16 of post-partum (P.P.). Tiron and GSH were administered at a dose of 471 mg/(kg day) i.p. and 100 mg/(kg day) oral, respectively, on days 5, 7, 9, 11, 13, 15 and 17 of gestation and post-partum. Al caused reduction in number of corpora lutea, number of implantation sites, placental and fetal weight and stunted growth. Skeletal malformations were also observed in fetuses. Maternal toxicity was demonstrated by reduction in body weight gain. Induction of oxidative stress was also recorded in the brain of mother as well as in fetuses and sucklings after Al exposure. Significant decrease was recorded in reduced glutathione, glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), acetyl cholinesterase (AChE) and increase was observed in TBARS and glutathione-S-transferase (GST) in brain of pregnant mothers, fetuses and sucklings. Most of the above parameters responded positively with individual therapy with Tiron, but more pronounced beneficial effects on the above-described parameters were observed when Tiron was administered in combination with GSH. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) studies also showed significantly high concentration of Al in suckling's brain and maternal blood, brain, placenta and fetal brain. Treatment with Tiron individually or in combination with glutathione, reduced the accumulation of the Al in almost all the organs studied. It is concluded that chelating agents reduced the Al-induced toxicity and Tiron was more effective in reducing blood Al concentration than glutathione when given individually.

Effect of N-acetylcysteine and L-NAME on aluminium phosphide induced cardiovascular toxicity in rats.

AIM: To investigate the protective effects of N-acetylcysteine (NAC) and Nomega-Nitro-L-arginine methyl ester (L-NAME) on aluminium phosphide (AlP) poisoning induced hemodynamic changes, myocardial oxygen free radical injury and on survival time in rats. METHODS: AlP (12.5 mg/kg) was administered intragastrically under urethane anaesthesia. The effect of pre- and post-treatment with NAC and L-NAME alone and in combination was studied on haemodynamic parameters [blood pressure (BP), heart rate (HR), and electrocardiogram (ECG)] and biochemical parameters (malonyldialdehyde, catalase, and glutathione peroxidase). RESULTS: AlP caused significant hypotension, tachycardia, ECG abnormalities, and finally marked bradycardia. The mean survival time was (90 +/- 10) min. There was significant increase in myocardial malonyldialdehyde (MDA), and decrease in catalase and glutathione peroxidase (GSH Px) levels. NAC infusion (6.25 mg . kg-1 . min-1, iv for 30 min) caused insignificant hemodynamic and biochemical changes. Pre- and post-treatment of NAC with AlP significantly increased the survival time, stabilized BP, HR, and ECG, decreased MDA and increased GSH Px levels compared to AlP group. L-NAME infusion (1 mg . kg-1 . min-1, iv for 60 min) as such caused significant rise in BP but precipitated ECG abnormalities. Pre- and post-treatment of L-NAME with AlP neither improved the survival time nor the biochemical parameters despite significant rise in BP. Co-administration of both the drugs with AlP worsened the hemodynamic and biochemical parameters with reduction in the survival time as compared to AlP. CONCLUSION: NAC increased the survival time by reducing myocardial oxidative injury whereas L-NAME showed no such protective effects in rats exposed to AlP.

Neomycin inhibition of hormone-stimulated smooth muscle contractions in myometrial tissue.

These studies sought to determine the effects of neomycin, a phospholipase C inhibitor, on hormone-stimulated myometrial contractions. For these studies, computer digitalized in vitro isometric contraction data were analyzed for changes in contractile activity in response to oxytocin and aluminum fluoride with and without neomycin. Neomycin (1-5 mM) produced dose-related inhibition of oxytocin and aluminum fluoride-stimulated myometrial contractions. This neomycin effect was apparent within 2-3 minutes of addition and was completely reversible, with resolution of its inhibitory effects within 6-8 minutes of washout. This study is the first to demonstrate the functional effect of neomycin inhibition of the phosphatidylinositol signaling pathway in myometrial smooth muscle tissue.

Ca(2+)-independent arachidonic acid release by vascular endothelium requires protein synthesis de novo.

We investigated the mechanism by which the G-protein activators aluminium fluoride and vanadate stimulate arachidonic acid release in pig aortic endothelial cells. Our previous study demonstrated a novel Ca(2+)-independent pathway of phospholipase A2 (PLA2) activation stimulated by aluminium fluoride in this model. In the present study, we found that sodium metavanadate stimulated a rapid concentration-dependent release of [3H]arachidonic acid from prelabelled cells. A more than 3-fold enhancement of arachidonic acid release was achieved in cells treated with 1 mM vanadate for 20 min. Synthesis of prostaglandin products was similarly enhanced. The release of arachidonic acid was not dependent on the presence of extracellular Ca2+, but did require protein synthesis de novo. Both cycloheximide and actinomycin D completely blocked aluminium fluoride- and vanadate-stimulated arachidonic acid release. Because fluoride and vanadate are known protein tyrosine phosphatase inhibitors, it is possible that PLA2 activation occurred secondarily to changes in protein tyrosine phosphorylation. Both aluminium fluoride and vanadate stimulated the rapid phosphorylation of 58, 93 and 120 kDa tyrosine-containing protein substrates. However, in contrast with arachidonic acid release, this response was found to be sensitive to the presence of extracellular Ca2+ and insensitive to blockers of protein synthesis de novo. Furthermore H2O2 treatment resulted in rapid tyrosine phosphorylation of the same substrates without a concomitant increase in arachidonic acid release. These results suggest that the effects of aluminium fluoride and vanadate on PLA2 are not due to changes in protein tyrosine phosphorylation, but do require rapid protein synthesis de novo.

Mechanisms underlying phasic contractions of pregnant rat myometrium stimulated with aluminum fluoride.

OBJECTIVE: The mechanisms underlying phasic myometrial contractions are unknown at this time. Phasic contractions, however, are characterized by repetitive cycles of elevated intracellular calcium (i.e., calcium oscillations). These studies were performed to test the hypothesis that mechanisms underlying phasic myometrial contractions are similar to those producing classic cytosolic calcium oscillations. STUDY DESIGN: Uterine tissue was obtained from pregnant Sprague-Dawley rats (i.e., day 18 to 22 of gestation). In vitro isometric contraction studies were performed with longitudinal strips of myometrial tissue; computer-digitized data were analyzed for contraction area and normalized for tissue cross-section area. Dose-response studies were performed with aluminum fluoride and various inhibitors of cytosolic calcium oscillations. RESULTS: Aluminum fluoride stimulated a significant increase in phasic contractions. In contrast, the addition of 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (an inhibitor of phosphoinositide-specific phospholipase C), adenine (an inhibitor of calcium-induced calcium release), and phorbol 12,13-dibutyrate (an activator of protein kinase C) resulted in significant suppression of aluminum fluoride-stimulated contractions. Similarly, nifedipine (an L-type calcium channel blocker) and removal of extracellular calcium significantly inhibited phasic myometrial contractions. CONCLUSIONS: These studies have confirmed that phosphoinositide-specific phospholipase C, calcium-induced calcium release, protein kinase C, and transmembrane calcium influx are important components of the intracellular calcium oscillator that generates agonist-stimulated phasic contractions of pregnant myometrial tissue.

Partial reversal of aluminium-induced neurofibrillary degeneration by desferrioxamine in adult male rabbits.

Desferrioxamine, a chelating agent with a high affinity for aluminium, has been reported to slow the clinical progression of dementia associated with Alzheimer's disease [4]. We report here the effects of desferrioxamine treatment on aluminium-induced neurofibrillary degeneration in rabbits. Adult male New Zealand white rabbits received a single injection of aluminium-maltolate into the lateral cerebral ventricle. Three days later, one group of rabbits was treated with intramuscular injections of desferrioxamine twice daily; a second group received saline instead of desferrioxamine. Both groups were sacrificed 4 or 5 days following initiation of desferrioxamine or saline treatment. Minimal neurofibrillary degeneration was found in two of six desferrioxamine-treated rabbits, while all six rabbits treated with saline showed extensive neurofibrillary degeneration, particularly in the ventral horn of the lower spinal cord. Quantitation of the neurofibrillary degeneration in ventral horn neurons of lumbar cord revealed 30% to be affected in saline-treated animals compared to zero-affected neurons following desferrioxamine treatment. When sacrificed just 3 days after aluminium treatment, 50% of the rabbits already revealed neurofibrillary degeneration, corresponding to the time-point when desferrioxamine treatment was begun in the above animals; on quantitation, 7.5% of ventral lumbar cord neurons were involved. These findings indicate a partial reversal of aluminium-induced neurodegeneration by desferrioxamine. Delaying desferrioxamine treatment to 6 days after aluminium administration prevented any reversal of the aluminium effect; all animals had abundant neurofibrillary degeneration as well as a striking basophilic spicular deposit of calcium and argyrophilic material in the leptomeninges, lateral ventricles and brain parenchyma adjacent to these areas.(ABSTRACT TRUNCATED AT 250 WORDS)