Neurodegenerative and Hepatorenal Disorders Induced Via Aluminum Chloride in Murine System: Impact of β-Secretase, MAPK, and KIM

Protective effects of L-arginine on Alzheimer's disease: Modulating hippocampal nitric oxide levels and memory deficits in aluminum chloride-induced rat model

There is evidence that high daily intake of aluminum (Al) is associated with an increased risk of dementia or cognitive decline. We injected L-arginine into the dorsal hippocampus (DH) of an AlCl3-induced Alzheimer's model and studied memory deficit, β-amyloid (βA) accumulation, neurodegeneration, and molecular changes. Male Wistar rats were cannulated unilaterally in the DH under a stereotaxic apparatus and a dose of AlCl3 (1-200 μg/rat) was injected into the CA1. After recovery, L-arginine and L-NAME (0.05-25 μg/rat) were injected into CA1 and animals were tested in novelty seeking task. One group received βA (2 μg/rat, intra CA1) as a reference group. Control groups received saline (1 μL/rat, intra-CA1) and galantamine (25 μg/rat, intra-CA1), respectively. Finally, rats were anesthetized and hippocampal tissues were isolated on ice. Levels of neuronal NO synthase (nNOS), β-secretase and soluble guanylyl cyclase (sGC) were measured by western blotting. βA formation and the number of CA1 neurons were assessed by Congo red and Nissl staining. NOS activation by NADPH-diaphorase (NADPH-d) was investigated. All data were analyzed using analysis of variance (ANOVA) at α = 0.05 level. Like βA, AlCl3 (25 μg/rat) caused accumulation of βA in the DH and increased stopping of the animal on the novel side (indicating a recall deficit). CA1 neurons decreased, and nNOS and β-secretase, but not sGC, showed a change consistent with Alzheimer's. However, prophylactic intervention of L-arginine at 3-9 μg/rat was protective, probably by nNOS stimulation in DH, as shown by NADPH-d assay. L-arginine may protect against Alzheimer's by increasing hippocampal NO levels.

Febuxostat attenuates aluminum chloride-induced hepatorenal injury in rats with the impact of Nrf2, Crat, Car3, and MNK-mediated apoptosis

Aluminum (Al) is a ubiquitous xenobiotic with known toxicity for both humans and animals. Our study was conducted to investigate the protective role of febuxostat (Feb) against aluminum chloride (AlCl3)-induced hepatorenal injury in rats. Hepatorenal injury was induced by oral administration of AlCl3 (40 mg/kg b.w.), for 2 months. Twenty-four male Sprague-Dawley rats were randomly allocated into four groups (six rats/group). The first group received the vehicle thought the experiment. The second group was considered as a control positive group. The third and fourth groups received oral treatment of Feb (10 mg/kg.b.w.) and (15 mg/kg.b.w.), respectively with AlCl3, concurrently for 2 months. Twenty-four hours, after the last treatment, serum biochemical, molecular, histopathology, and immunohistochemical studies were evaluated. Our findings showed that rats intoxicated with Alcl3 had disturbed biochemical picture. In addition, intoxication with AlCl3 increased oxidative stress and apoptosis, as demonstrated by an increase in malodialdeyde (MDA), carnitine o-acetyltransferase (Crat), and carbonic anhydrase (Car3) with a decrease in glutathione (GSH), MAP kinase-interacting serine/threonine kinase (MNK) and nuclear factor-erythroid 2-related factor 2 (Nrf2) mRNA expression. Furthermore, the levels of tumor necrosis factor-alpha (TNF-α) and the levels of caspase-3 were elevated with sever hepatic and renal pathological changes. Conversely, Feb (15 mg/kg.b.w.) could improve the serum biochemical indices and repressed MDA, Crat, and Car3 levels, whereas it increased GSH, MNK, and Nrf2 levels. Feb inhibited the apoptotic effect of AlCl3 in the liver and kidney by decreasing caspase-3 and TNF-α expression. The protective effect of Feb against AlCl3 toxicity was confirmed by histopathological findings. Moreover, molecular docking studies supported the anti-inflammatory effect of Feb due to its significant binding interactions with cyclooxygenase-1 (COX-1), NF-kappa-B-inducing kinase (NIK), and mitogen-activated protein kinases-p38 (MAPK-p38). The findings suggest that Feb system Feb can avert Alcl3-induced hepatotoxicity and nephrotoxicity by enhancing the antioxidant defense system, and inhibiting the inflammatory cascade and apoptosis.

Isoimperatorin therapeutic effect against aluminum induced neurotoxicity in albino mice

Background: Although aluminum (Al) is not biologically crucial to the human body, classical studies have demonstrated that excessive human exposure to Al can induce oxidative damage, neuroinflammatory conditions and neurotoxic manifestations implicated in Alzheimer's disease (AD). Exposure to Al was reported to be associated with oxidative damage, neuroinflammation, and to enhance progressive multiregional neurodegeneration in animal models. Several plant-derived natural biomolecules have been recently used to reduce the toxic effects of Al through decreasing the oxidative stress and the associated diseases. A good candidate still to be tested is an active natural furanocoumarin, the isoimperatorin (IMP) that can be extracted from Lemon and lime oils and other plants. Here, we examined the neuroprotective effects of IMP on aluminum chloride (AlCl3)-induced neurotoxicity in albino mice. Methods: Twenty-four male albino mice were used in this study. Mice were randomly devided into 5 groups. The first group was given distilled water as a control, the second group was given AlCl3 orally (10 mg/wt/day) starting from the 2nd week to the end of the 6th week, the third group received AlCl3 orally and IMP interperitoneally, i. p. (30 mg/wt/day) starting from week 2 till week 6 where IMP was supplement 1st and then 4 h later AlCl3 was given to mice. The fourth group received the control (IMP 30 mg/wt, i. p.) from the 2nd week till the end of the experiment. Rodent models of central nervous system (CNS) disorders were assessed using object location memory and Y-maze tests in 6th week began. Essential anti-inflammatory and oxidative stress indicators were evaluated, including interleukin-1 β (IL-1β), tumor necrosis factor α (TNF-α), malondialdehyde (MDA), total antioxidant capacity (TAC), and catalase activity (CAT). In addition, serum levels of brain neurotransmitters such as corticosterone, acetylcholine (ACh), dopamine and serotonin in brain homogenates were measured calorimetrically. Results: The study results revealed that the daily treatment of AlCl3 upregulated the TNF-α and IL-1β levels, increased MDA accumulation, and decreased TAC and CAT activity. In addition, aluminum induced a reduction in concentrations of ACh, serotonin and dopamine in the brain. However, IMP significantly ameliorates the effect of AlCl3 through modulating the antioxidant and regulating the inflammatory response through targeting Nrf2 (NF-E2-related factor 2) and mitogen-activated protein kinase (MAPK). Conclusion: Thus, IMP might be a promising treatment option for neurotoxicity and neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease, which are associated with neuro-inflammation and oxidative stress.

Protective Effect of N-Acetylcysteine Against Aluminum-Induced Kidney Tissue Damage in Rats

Aluminum (AL) is an important nephrotoxic agent with a high daily exposure rate and property of accumulation in tissues. This study aimed to investigate the potential protective efficacy of N-acetylcysteine (NAC) against AL exposure-induced nephrotoxicity in rats. Twenty-eight rats were randomly divided into 4 groups as control, N-acetylcysteine group (NC), AL, and AL + NC, with an equal number of rats in each group (n = 7). No application was made to the control group. A total of 150 mg/kg/day NAC was administered to the NC group and 30 mg/kg/day AL was administered to the AL group intraperitoneally (i.p.). The AL + NC group received 30 mg/kg/day AL and 150 mg/kg/day NAC i.p. Biochemical parameters in blood serum and histopathological changes in kidney tissue, oxidative stress parameters, spexin (SPX), and apoptotic protein levels were examined after 15 days. Histopathological changes, biochemical parameters, oxidative stress parameters, and apoptotic protein levels were significantly irregular in the AL group compared to the control group. Moreover, SPX levels increased in the AL group. However, NAC treatment regulated AL exposure-related changes in the AL + NC group. NAC treatment may have a prophylactic effect against nephrotoxicity due to AL exposure. SPX may play a role in AL-induced nephrotoxicity.

Effect of the Reelin-Dab1 signaling pathway on the abnormal metabolism of Aβ protein induced by aluminum

Aluminum (Al) is a common neurotoxic element that can exacerbate intracellular β-amyloid (Aβ) deposition. Reelin is a highly conserved extracellular glycoprotein that is involved in intracellular Aβ deposition. However, the action of Reelin on aluminum-induced Aβ deposition is not fully understood. Here, we investigated the effects of the Reelin-Dab1 signaling pathway on Aβ deposition in aluminum maltol (Al(mal)₃) exposure in rat pheochromocytoma-derived cells (PC12). Our results showed that Al(mal)₃ exposure decreased activity of PC12, increased expression of Aβ₄₂, and decreased expression of Aβ₄₀. Moreover, Al(mal)₃ exposure in PC12 induced Reelin-Dab1 signaling pathway-associated proteins changed, decreased expression of Reelin and Dab1, and increased expression of pdab1. Moreover, the expression of Reelin, Dab1, and Aβ₄₀ was found to be elevated in PC12 exposed to Al(mal)₃ and corticosterone compared to those exposed to Al(mal)₃. Also, the expression of Reelin, Dab1, and Aβ₄₀ was found to be depressed in PC12 exposed to Al(mal)₃ and streptozotocin compared with cells exposed to Al(mal)₃ alone. These results suggested that Al(mal)₃ inhibits the expression of the Reelin-Dab1 signaling pathway, promoting Aβ deposition. Thus, our findings provided important evidence to better understand how the Reelin-Dab1 signaling pathway may be a potential mechanism of Aβ deposition induced by aluminum.

Natural inhibitors for acetylcholinesterase and autophagy modulators as effective antagonists for tau and β-amyloid in Alzheimer's rat model

Background: Phytochemicals have amazing biological effects in relation to age-related illnesses and are increasingly being studied in clinical trials. The goal of this study was to examine the effectiveness of the aqueous extracts of Rosmarinus officinalis L. (Rosemary) and Crocus sativus L. (Saffron) and their combinations as tau and β-amyloid antagonists in an Alzheimer's rat model. Methods: AlCl₃ and D-galactose (150 & 300 mg/kg) were used to create the Alzheimer's neuroinflammation rat model. The animals were subsequently given the two extracts and their combinations (500 mg/kg) along 15 days. The cognitive impairment, oxidative stress, tau & amyloid neuroproteins, acetylcholine, acetylcholinesterase neurotransmitters, proinflammatory cytokines, LC3 as an autophagy marker, computational analysis, and morphological alterations were all assessed. Results: When compared to the conventional donepezil and normal groups, the treated groups showed a significant improvement in all calculated parameters. The cortex and hippocampus have a better morphological appearance. In silico analysis found that these extracts may have an affinity for and impede the activity of some proteins thought to be essential regulators of disease progression. Conclusion: Rosemary and Saffron extracts by the power of their constituents were able to alleviate the neurotoxicity of AlCl₃ & D-galactose and regulate the natural autophagy process.

Role of Autophagy and Apoptosis in Aluminum Exposure-Induced Liver Injury in Rats

Aluminum (Al) exposure can lead to different degrees of damage to various organ systems of the body. It has been previously revealed that Al exposure can damage the liver, causing liver dysfunction. However, the specific mechanism remains unclear. This research aims to uncover the damaging effect of Al exposure on rat liver and to demonstrate the role of autophagy and apoptosis in this effect. Thirty-two Wistar rats were randomly divided into the control group (C group), low-dose Al exposure group (L group), middle-dose Al exposure group (M group), and high-dose Al exposure group (H group) (n = 8). The rats, respectively, received intraperitoneal injections of 0, 5, 10, and 20 mg/kg·day AlCl₃ solution for 4 weeks (5 times/week). After the experiment, changes in the ultrastructure and autolysosome in rat liver were observed; the liver function, apoptosis rate, as well as levels of apoptosis-associated proteins and autophagy-associated proteins were detected. The results indicated that Al exposure damaged rat liver function and structure and resulted in an increase in autolysosomes. TUNEL staining revealed an elevated number of apoptotic hepatocytes after Al exposure. Moreover, we found from Western blotting that the levels of autophagy-associated proteins Beclin1 and LC3-II were increased; apoptotic protein Caspase-3 level was elevated and the Bcl-2/Bax ratio was reduced. Our research suggested that Al exposure can lead to high autophagy and apoptosis levels of rat hepatocytes, accompanied by hepatocyte injury and impaired liver function. This study shows that autophagy and apoptosis pathways participate in Al toxication-induced hepatocyte injury.

Aluminum exposure induces nephrotoxicity via fibrosis and apoptosis through the TGF-β1/Smads pathway in vivo and in vitro

Aluminum (Al), the most common element in nature, can enter the body through various routes. Unfortunately, excessive accumulation of Al in the body can cause chronic toxicity. In this study, rats were randomly allocated to 4 groups and intraperitoneally injected with AlCl₃ solution at 0, 5, 10, and 20 mg/(kg·d), respectively, for 4 weeks. The kidney function of rats and Al contents in the kidney were measured, and the pathological structural changes and apoptosis of the kidney were observed. Meanwhile, the expression of fibrosis- and apoptosis-related proteins was detected with western blot. For the in vitro assay, HK-2 cells were used to construct a model to evaluate the effects of Al exposure on cell viability, cell apoptosis, and the expression of fibrosis- and apoptosis-related proteins. Additionally, the TGF-β1/Smads pathway was also altered in HK-2 cells, followed by the measurement of changes in apoptosis and fibrosis-related proteins. The results revealed that Al could accumulate in kidney tissues, then leading to histopathological changes and kidney function impairment, promoting renal tubular cell apoptosis and renal collagen fiber deposition, and also elevating the expression of TGF-β1/Smads pathway-related proteins. In vitro experiments also exhibited that Al exposure increased apoptosis and the expression of fibrosis-related factors in HK-2 cells, accompanied by activation of the TGF-β1/Smads pathway. Further modulation of the TGF-β1/Smads pathway manifested that activation of the TGF-β1/Smads pathway facilitated Al-induced apoptosis and fibrosis-related factor expression, while inhibition of the pathway negated this effect of Al. In conclusion, the findings of the present study illustrate that Al exposure damages kidney function and facilitate apoptosis and kidney fibrosis, which may be achieved through the activation of the TGF-β1/Smads pathway. This study provides a new theoretical basis for the study of nephrotoxicity induced by excessive Al exposure.

Combination of Alpinia Oxyphylla Fructus and Schisandra Chinensis Fructus ameliorates aluminum-induced Alzheimer's disease via reducing BACE1 expression

Being the most common form of dementia, Alzheimer's disease (AD) has a series of modifiable risk factors, including metal ions represented by aluminium. Aluminium (Al) exhibits its neurotoxic effects, especially mainly by affecting amyloid-β protein (Aβ) aggregation and Tau hyperphosphorylation. As reported in our previous study, the combination of Alpinia Oxyphylla Fructus and Schisandra Chinensis Fructus (AS) had a neuroprotective effect. This study aimed to evaluate the anti-AD effect of AS and the mechanism by which AS reduces the neurotoxic effect of Al. Firstly, we used aluminium-maltol (Al(mal)₃) to construct a mouse model of AD and performed oral administration of AS, followed by behavioral experiments, and we collected the mouse brain for immunohistochemistry analysis. In vivo results showed that AS significantly improved Al-induced cognitive decline in mice, and reduced the levels of Aβ_1-42 and P-Tau in the brain, which further proved the anti-AD effect of AS. Then, in order to explore the mechanism by which AS reduced Aβ_1-42, Al-induced PC12 cells were used for the in vitro experiments. Compared with other ratios, the ratio of Alpinia Oxyphylla Fructus: Schisandra Chinensis Fructus (AO:SC) = 1:2 could better improve the cell viability and reduce the Aβ_1-42 level. According to western blot and quantitative real-time polymerase chain reaction (qPCR) results, AS ameliorated the pathological process by downregulating the expression of β-secretase (BACE1), rather than by reducing the expression of amyloid precursor protein (APP) or Tau. These results suggest that AS ameliorated Al-induced AD by affecting the expression of BACE1 and reducing the level of Aβ_1-42, thereby exerting a neuroprotective effect. Combined with previous studies, this study shows that AS has potential for further research and development in AD treatment.

Ovarian Toxicity Induced by Aluminum Chloride: Alteration of Cyp19a1, Pcna, Puma, and Map1lc3b genes Expression

Aluminum (Al) is an abundant metal with wide application in our daily lives including medicine, industry, cosmetics, and packaging. After entrance to the body, aluminum binds to transferrin and reaches different tissues. Al is a metalloestrogen that can lead to oxidative stress (OxS) and endocrine disruption. No detailed study can be found addressing the effect of Al on the ovary and granulosa cells (GCs). In this study, the focus is on the treated ovaries and GCs of NMRI mice exposed to low, middle, and high doses of aluminum chloride (AlCl₃) via in vitro and in vivo assays. The steroidogenic, proliferative, apoptotic, and autophagic-related genes were examined. Up-regulated expression of steroidogenic and proliferative genes was detected. The observed apoptotic and autophagic genes had variable expression. Interrupted ovarian structure, disrupted folliculogenesis, presence of Call-Exner bodies, overexpression of steroidogenic gene, and unbalanced apoptosis/autophagy and proliferation resembled features of granulosa cell tumor (GCT).

Quercetin-Conjugated Superparamagnetic Iron Oxide Nanoparticles Protect AlCl3-Induced Neurotoxicity in a Rat Model of Alzheimer's Disease via Antioxidant Genes, APP Gene, and miRNA-101

Alzheimer's disease (AD) is a neurodegenerative disease with cognitive impairment. Oxidative stress in neurons is considered as a reason for development of AD. Antioxidant agents such as quercetin slow down AD progression, but the usage of this flavonoid has limitations because of its low bioavailability. We hypothesized that quercetin-conjugated superparamagnetic iron oxide nanoparticles (QT-SPIONs) have a better neuroprotective effect on AD than free quercetin and regulates the antioxidant, apoptotic, and APP gene, and miRNA-101. In this study, male Wistar rats were subjected to AlCl3, AlCl3 + QT, AlCl3 + SPION, and AlCl3 + QT-SPION for 42 consecutive days. Behavioral tests and qPCR were used to evaluate the efficiency of treatments. Results of behavioral tests revealed that the intensity of cognitive impairment was decelerated at both the middle and end of the treatment period. The effect of QT-SPIONs on learning and memory deficits were closely similar to the control group. The increase in expression levels of APP gene and the decrease in mir101 led to the development of AD symptoms in rats treated with AlCl3 while these results were reversed in the AlCl3 + QT-SPIONs group. This group showed similar results with the control group. QT-SPION also decreased the expression levels of antioxidant enzymes along with increases in expression levels of anti-apoptotic genes. Accordingly, the antioxidant effect of QT-SPION inhibited progression of cognitive impairment via sustaining the balance of antioxidant enzymes in the hippocampus of AD model rats.