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Studies on the contribution of enteric neuropathy and intestinal homeostasis to central nervous system degeneration using animal models have reported varying results. Recently, colonic myenteric plexus degeneration was observed in trimethyltin-treated rats. Further characterization of this animal model is necessary to determine its potential for investigating the relationship between the enteric nervous system and central nervous system degeneration. In this study, trimethyltin-treated rats (8 mg/kg body weight, i.p.) were used to measure colonic function, structure, and possible colon abnormalities. The colonic function was assessed by measuring fecal pellet output and transit time. Hematoxylin and eosin staining and immunohistochemistry were performed to evaluate inflammatory profiles and intestinal epithelial cell homeostasis. The expression of mRNA encoding tight junction proteins was quantified with quantitative PCR to determine colon permeability. Histological examination of the colon revealed mucosal immune cell infiltration, crypt damage, and high iNOS and arginase-1 expression in the mucosal layer of trimethyltin-treated rats. At the same time, trimethyltin induced high expression of iNOS, arginase-1, and GFAP and increased cell death in the colonic myenteric plexus. The low cell proliferation and low goblet cell distribution suggested altered intestinal epithelial cell homeostasis in trimethyltin-treated rats. Trimethyltin also upregulated claudin 1 expression. However, normal colon function was preserved. In conclusion, the results show that trimethyltin induces colon inflammation and cell death in the colonic myenteric plexus, and disrupts intestinal epithelial cell homeostasis. However, the balance between anti-inflammatory and pro-inflammatory responses maintains normal colon function in trimethyltin-treated rats.

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L-type voltage-gated calcium channels (L-VGCCs) are thought to be involved in epileptogenesis and acute excitotoxicity. However, little is known about the role of L-VGCCs in neuroinflammation or delayed neuronal death following excitotoxic insult. We examined the effects of repeated treatment with the L-VGCC blocker nimodipine on neuroinflammatory changes and delayed neuronal apoptosis in the dentate gyrus following trimethyltin (TMT)-induced convulsions. Male C57BL/6 N mice were administered TMT (2.6 mg/kg, i.p.), and the expression of the Cav1.2 and Cav1.3 subunits of L-VGCC were evaluated. The expression of both subunits was significantly decreased; however, the astroglial expression of Cav1.3 L-VGCC was significantly induced at 6 and 10 days after TMT treatment. Furthermore, astroglial Cav1.3 L-VGCCs colocalized with both the pro-inflammatory phenotype marker C3 and the anti-inflammatory phenotype marker S100A10 of astrocytes. Nimodipine (5 mg/kg, i.p. × 5 at 12-h intervals) did not significantly affect TMT-induced astroglial activation. However, nimodipine significantly attenuated the pro-inflammatory phenotype changes, while enhancing the anti-inflammatory phenotype changes in astrocytes after TMT treatment. Consistently, nimodipine reduced the levels of pro-inflammatory astrocytes-to-microglia mediators, while increasing the levels of anti-inflammatory astrocytes-to-microglia mediators. These effects were accompanied by an increase in the phosphorylation of extracellular signal-regulated kinase (ERK), supporting our previous finding that p-ERK is a signaling factor that regulates astroglial phenotype changes. In addition, nimodipine significantly attenuated TMT-induced microglial activation and delayed apoptosis of dentate granule neurons. Our results suggest that L-VGCC blockade attenuates neuroinflammation and delayed neurotoxicity following TMT-induced convulsions through the regulation of astroglial phenotypic changes by promoting ERK signaling.

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Exposure to the neurotoxin trimethyltin (TMT) selectively induces hippocampal neuronal injury and astrocyte activation accompanied with resultant neuroinflammation, which causes severe behavioral, cognitive, and memory impairment. A large body of evidence suggests that flaxseed oil (FSO), as one of the richest sources of essential omega-3 fatty acids, i.e., α-linolenic acids (ALA), displays neuroprotective properties. Here, we report the preventive effects of dietary FSO treatment in a rat model of TMT intoxication. The administration of FSO (1 mL/kg, orally) before and over the course of TMT intoxication (a single dose, 8 mg/kg, i.p.) reduced hippocampal cell death, prevented the activation of astrocytes, and inhibited their polarization toward a pro-inflammatory/neurotoxic phenotype. The underlying protective mechanism was delineated through the selective upregulation of BDNF and PI3K/Akt and the suppression of ERK activation in the hippocampus. Pretreatment with FSO reduced cell death and efficiently suppressed the expression of inflammatory molecules. These beneficial effects were accompanied by an increased intrahippocampal content of n-3 fatty acids. In vitro, ALA pretreatment prevented the TMT-induced polarization of cultured astrocytes towards the pro-inflammatory spectrum. Together, these findings support the beneficial neuroprotective properties of FSO/ALA against TMT-induced neurodegeneration and accompanied inflammation and hint at a promising preventive use of FSO in hippocampal degeneration and dysfunction.

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OBJECTIVE: Trimethyltin (TMT) chloride is an organotin compound used in industry. It has been linked to generating reactive oxygen species (ROS), inflammatory processes, and neuronal death. Carvacrol is a monoterpene phenol found in the Lamiaceae plant family, modulating inflammatory conditions and necroptosis in neural tissue. This study aimed to investigate the neuroprotective effects of carvacrol in a rat model of hippocampal neuronal injury induced by TMT. MATERIALS AND METHODS: In this experimental study, sixty male Wistar rats were randomly divided into five groups (n=12): group 1 receiving saline, group 2 received dimethyl sulfoxide (DMSO) as a vehicle for 21 days, group 3 receiving a single dose of TMT (8 mg/kg) and groups 4 and 5 receiving carvacrol 40 and 70 mg/kg daily for 21 days after a single dose of TMT. All injections were intraperitoneal (I.P.). Caspase-3, Bax, Bcl-2, and Bdnf gene expression and the number of pyknotic neurons in the hippocampus were quantified. Spatial memory was assessed with a radial arm maze. RESULTS: Statistical analysis of histological data revealed the carvacrol significantly attenuated cognitive dysfunction and the number of pyknotic neurons in the hippocampal CA1 region of rats treated with TMT. Based on real-time polymerase chain reaction (PCR), carvacrol modulated the expression of genes involved in apoptosis (Bax and Caspase-3) and upregulated anti-apoptotic (Bcl-2) and brain derived neurotrophic factor (Bdnf) genes in the hippocampal tissue. CONCLUSION: These findings revealed neuroprotective effects of carvacrol which might be mediated by apoptotic and anti-apopetotic factors.

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Trimethyltin chloride (TMT) is a highly toxic organotin pollutant frequently found in aquatic environments, posing a significant threat to the ecological system. The kidney plays a vital role in the body's detoxification processes, and TMT present in the environment tends to accumulate in the kidneys. However, it remained unclear whether exposure to different doses of TMT could induce pyroptosis and immune dysfunction in grass carp kidney cells (CIK cells). For this purpose, after assessing the half-maximal inhibitory concentration (IC50) of TMT on CIK cells, we established a model for exposure of CIK cells at varying concentrations of TMT. CIK cells were treated with various doses of TMT (2.5, 5, 10 µM) for 24 h. Oxidative stress levels were measured using kits and fluorescence methods, whereas the expression of related genes was verified through western blot and quantitative real-time PCR (qRT-PCR). The results indicated that TMT exposure led to oxidative stress, with increased levels of ROS, H2O2, MDA, and GSH, and inhibited activities of T-AOC, SOD, and CAT. It activated the NF-κB pathway, leading to the upregulation of NF-κB p65, NF-κB p50, GSDMD, NLRP3, ASC, and Caspase-1. Furthermore, TMT exposure also resulted in increased expression of cytokines (IL-18, IL-6, IL-2, IL-1ß, and TNF-α) and decreased expression of antimicrobial peptides (LEAP2, HEPC, and ß-defensin). In summary, exposure to TMT induces dose-dependent oxidative stress that activates the NF-κB pathway, leading to pyroptosis and immune dysfunction in grass carp CIK cells.

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The present study investigated the neural health benefit of beta-sitosterol (BSS) against trimethyltin (TMT)-induced neurodegeneration in mice. Forty male ICR mice were randomly divided into Sham-veh, TMT-veh, TMT-BSS50, and TMT-BSS100. A one-time intraperitoneal injection of 2.6 mg/kg of TMT was given to mice in TMT groups. Vehicle (veh), BSS 50 mg/kg or BSS 100 mg/kg were orally given for 2 weeks. Spatial learning and memory were evaluated. Brain oxidative status, hippocampal neuropathology, and reactive astrocytes were done. White matter pathology was also evaluated. The results indicated the massy effect of TMT on induced motor ability and spatial memory deficits in accordance with increased neuronal degeneration in CA1, CA3, and DG and internal capsule white matter damage. TMT also induced the reduction of reactive astrocytes in CA1 and DG. Brain's catalase activity was significantly reduced by TMT, but not in mice with BSS treatments. Both doses of BSS treatment exhibited improvement in motor ability and spatial memory deficits in accordance with the activation of reactive astrocytes in CA1, CA3, and DG. However, they successfully prevented the increase of neuronal degeneration in CA1 found only with the BSS dose of 100 mg/kg, and it was indicated as the effective dose for neuroprotection in the vulnerable brain area. This study demonstrated mitigative effects of BSS against motor ability and memory deficits with neural health benefits, including a protective effect against CA1 neurodegeneration and a nurturing effect on hippocampal reactive astrocytes.

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We have recently shown delayed increases in GABAB receptor (GABABR) subunit protein levels in the hippocampal dentate gyrus (DG), but not in the pyramidal CA1 and CA3 regions, at 15-30 days after the systemic single administration of trimethyltin (TMT) in mice. An attempt was thus made to determine whether the delayed increases return to the control levels found in naive mice afterward. In the DG on hippocampal slices obtained at 90 days after the administration, however, marked increases were still seen in protein levels of both GABABR1 and GABABR2 subunits without significant changes in calbindin and glial fibrillary acidic protein (GFAP) levels on immunoblotting analysis. Fluoro-Jade B staining clearly revealed the absence of degenerated neurons from the DG at 90 days after the administration. Although co-localization was invariably detected between GABABR2 subunit and GFAP in the DG at 30 days on immunohistochemical analysis, GABABR2-positive cells did not merge well with GFAP-positive cells in the DG at 90 days. These results suggest that both GABABR1 and GABABR2 subunits would be tardily and sustainably up-regulated by cells other than neurons and astrocytes in the murine DG at 90 days after a systemic single injection of TMT.

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A novel trimethyltin(IV) complex (Me3SnL), derived from 3-(4-methyl-2-oxoquinolin-1(2H)-yl)propanoate ligand, has been synthesized and characterized by elemental microanalysis, UV/Vis spectrophotometry, FT-IR and multinuclear (1H, 13C and 119Sn) NMR spectroscopies. Furthermore, the structure of the ligand precursor HL was solved using SC-XRD (single-crystal X-ray diffraction). The prediction of UV/Vis and NMR spectra by quantum-chemical methods was performed and compared to experimental findings. The protein binding affinity of Me3SnL towards BSA was determined by spectrofluorometric titration and subsequent molecular docking simulations. Me3SnL has been evaluated for its in vitro anticancer activity against three human cell lines, MCF-7 (breast adenocarcinoma), A375 (melanoma) and HCT116 (colorectal carcinoma), and three mouse tumor cell lines, 4T1 (breast carcinoma), B16 (melanoma) and CT26 (colon carcinoma), using MTT and CV assays. The strong inhibition of A375 cell proliferation, ROS/RNS upregulation and robust lipid peroxidation lead to autophagic cell death upon treatment with Me3SnL.

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The endogenous regenerative capacity of the brain is quite weak; however, a regenerative reaction, the production of new neurons (neurogenesis), has been reported to occur in brain lesions. In addition, leukocytes are well known to infiltrate brain lesions. Therefore, leukocytes would also have a link with regenerative neurogenesis; however, their role has not been fully elucidated. In this study, we investigated leukocyte infiltration and its influence on brain tissue regeneration in a trimethyltin (TMT)-injected mouse model of hippocampal regeneration. Immunohistochemically, CD3-positive T lymphocytes were found in the hippocampal lesion of TMT-injected mice. Prednisolone (PSL) treatment inhibited T lymphocyte infiltration and increased neuronal nuclei (NeuN)-positive mature neurons and doublecortin (DCX)-positive immature neurons in the hippocampus. Investigation of bromodeoxyuridine (BrdU)-labeled newborn cells revealed the percentage of BrdU/NeuN- and BrdU/DCX-positive cells increased by PSL treatment. These results indicate that infiltrated T lymphocytes prevent brain tissue regeneration by inhibiting hippocampal neurogenesis.

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Reliable fluid biomarkers for evaluating neurotoxicity have yet to be established. However, recent studies have reported neurofilament light chain as a fluid biomarker of several neurodegenerative disorders. In this study, we investigated changes in the cerebrospinal fluid and plasma levels of neurofilament light chain in mice treated with trimethyltin as a neurotoxicant. Trimethyltin diluted with saline was administered by intraperitoneal injection to mice at dose levels of 0 (vehicle control), 1.0, and 2.6 mg/kg body weight (dosage volume: 10 mL/kg). At 3 or 7 days after administration, animals were euthanized by exsanguination under 2-3% isoflurane inhalation anesthesia. Increased neurofilament light chain levels in both the cerebrospinal fluid and plasma were observed in animals from the trimethyltin 2.6 mg/kg body weight group, which indicated the brain lesions including neuronal cell death. Animals from the trimethyltin 1.0 mg/kg body weight group exhibited changes neither in neurofilament light chain levels in the cerebrospinal fluid and plasma nor in the histopathology of the brain at any time point. These data indicate that plasma neurofilament light chain can serve as a useful peripheral biomarker for detecting brain lesions such as neuronal necrosis in mice.

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Trimethyltin chloride (TMT) is a highly toxic organotin compound often used in plastic heat stabilizers, chemical pesticides, and wood preservatives. TMT accumulates mainly through the environment and food chain. Exposure to organotin compounds is associated with disorders of glucolipid metabolism and obesity. The mechanism by which TMT damages pancreatic tissue is unclear. For this purpose, a subacute exposure model of TMT was designed for this experiment to study the mechanism of damage by TMT on islet. The fasting blood glucose and blood lipid content of mice exposed to TMT were significantly increased. Histopathological and ultrastructural observation and analysis showed that the TMT-exposed group had inflammatory cell infiltration and necrosis. Then, mouse pancreatic islet tumour cells (MIN-6) were treated with TMT. Autophagy levels were detected by fluorescence microscopy. Real-time quantitative polymerase chain reaction and Western blotting were used for verification. A large amount of autophagy occurred at a low concentration of TMT but stagnated at a high concentration. Excessive autophagy activates apoptosis when exposed to low levels of TMT. With the increase in TMT concentration, the expression of necrosis-related genes increased. Taken together, different concentrations of TMT induced apoptosis and necrosis through autophagy disturbance. TMT impairs pancreatic (islet ß cell) function.

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We investigated the neurological effects of the varied erinacine composition of different mycelia cultures in mice with trimethyltin (TMT)-induced neurodegeneration. Forty male ICR mice were randomly divided into five groups of Sham-veh, TMT-veh, TMT-EME, TMT-EMR and TMT-EME/R. The TMT groups received 2.6 mg/kg one-time intraperitoneal injections of TMT. Oral dosages of 200 mg/kg erinacine combination from each Hericium erinaceus mycelia (EM) cultivated formula (100% eucalyptus wood [E], 100% rubber wood [R], or 40% eucalyptus wood/60% rubber wood [E/R]) were given for two weeks. Spatial learning, memory, flexibility, and anxious behaviour were evaluated alongside brain tissues' oxidative status and histological analyses. Erinacine composition from EME/R exhibited significant positive effects on spatial learning, memory, flexibility, and anxiety (p < 0.05). These findings emerged concurrently with the significant mitigation of hippocampal lipid peroxidation, CA1 hippocampal, cortical neuron, and corpus callosum white matter degeneration (p < 0.05). These neurological benefits were associated with the EME/R composition of erinacine A, C, D, G, H, I, K and R. The best neuroprotective effect against TMT-induced neurodegeneration in mice is offered by the EME/R erinacine composition according to its anti-lipid peroxidation, its nurturing effect on neuronal and white matter, and mitigation of behavioural deficits.

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Trimethyltin chloride (TMT) is a potent neurotoxin widely used as a constituent of polyvinyl chloride plastic in the industrial and agricultural fields. However, the underlying mechanisms by which TMT leads to neurotoxicity remain elusive. In the present study, we constructed a dose and time dependent neurotoxic mouse model of TMT exposure to explore the molecular mechanisms involved in TMT-induced neurological damage. Based on this model, the cognitive ability of TMT exposed mice was assessed by the Morris water maze test and a passive avoidance task. The ultrastructure of hippocampus was analyzed by the transmission electron microscope. Subsequently, proteomics integrated with bioinformatics and experimental verification were employed to reveal potential mechanisms of TMT-induced neurotoxicity. Gene ontology (GO) and pathway enrichment analysis were done by using Metascape and GeneCards database respectively. Our results demonstrated that TMT-exposed mice exhibited cognitive disorder, and mitochondrial respiratory chain abnormality of the hippocampus. Proteomics data showed that a total of 7303 proteins were identified in hippocampus of mice of which 224 ones displayed a 1.5-fold increase or decrease in TMT exposed mice compared with controls. Further analysis indicated that these proteins were mainly involved in tricarboxylic acid (TCA) cycle and respiratory electron transport, proteasome degradation, and multiple metabolic pathways as well as inflammatory signaling pathways. Some proteins, including succinate-CoA ligase subunit (Suclg1), NADH dehydrogenase subunit 5 (Nd5), NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 4-like 2 (Ndufa4l2) and cytochrome c oxidase assembly factor 7 (Coa7), which were closely related to mitochondrial respiratory electron transport, showed TMT dose and time dependent changes in the hippocampus of mice. Moreover, apoptotic molecules Bax and cleaved caspase-3 were up-regulated, while anti-apoptotic Bcl-2 was down-regulated compared with controls. In conclusion, our findings suggest that impairment of mitochondrial respiratory chain transport and promotion of apoptosis are the potential mechanisms of TMT induced hippocampus toxicity in mice.

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The assessment of the sensitivity and specificity of any potential biomarker against the gold standard is an important step in the process of its qualification by regulatory authorities. Such qualification is an important step towards incorporating the biomarker into the panel of tools available for drug development. In the current study we analyzed the sensitivity and specificity of T2 MRI relaxometry to detect trimethyltin-induced neurotoxicity in rats. Seventy-five male Sprague-Dawley rats were injected with a single intraperitoneal dose of either TMT (8, 10, 11, or 12 mg/kg) or saline (2 ml/kg) and imaged with 7 T MRI before and 3, 7, 14, and 21 days after injection using a quantitative T2 mapping. Neurohistopathology (the gold standard in the case of neurotoxicity) was performed at the end of the observation and used as an outcome qualifier in receiver-operator characteristic (ROC) curve analysis of T2 changes as a predictor of neurotoxicity. TMT treatment led to a significant increase in T2 values in many brain areas. The biggest changes in T2 values were seen around the lateral ventricles, which was interpreted as ventricular dilation. The area under the ROC curve for the volume of the lateral ventricles was 0.878 with the optimal sensitivity/specificity of 0.805/0.933, respectively. T2 MRI is a promising method for generating a non-invasive biomarkers of neurotoxicity, which shows the dose-response behavior with substantial sensitivity and specificity. While its performance was strong in the TMT model, further characterization of the sensitivity and specificity of T2 MRI with other neurotoxicants is warranted.

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Trimethyltin chloride (TMT), a common component in fungicides and plastic stabilizers, presents environmental risks, particularly to fish farming. The precise toxicological mechanisms of TMT in L8824 grass carp liver cells remain undefined. Our study investigates TMT's effects on these cells, focusing on its potential to induce hepatotoxicity via oxidative stress and NF-κB pathway activation. First, we selected 0, 3, 6, and 12 µM as the challenge doses, according to the inhibitory concentration of 50% (IC50) of TMT. Our results demonstrate that TMT decreases cell viability dose-dependently and triggers oxidative stress, as evidenced by increased ROS staining and MDA content. Concurrently, it inhibited the antioxidant activities of T-AOC, T-SOD, CAT, and GSH. The activation of the NF-κB pathway was confirmed by gene expression changes. Furthermore, we observed an increase in cell apoptosis rate by AO/EB staining and cell flow cytometry, and the downregulation of Bcl-2 and the upregulation of Bax, Cytc, Caspase-9, and casp3 verified that TMT passed through the BCL2/BAX/casp3 pathway induces apoptosis. DNA damage was validated by the comet assay and γH2AX gene overexpression. Lastly, our data showed increased expression of TNF-α, IL-1ß, IL-6, and INF-γ and decreased antimicrobial peptides, validating immune dysfunction. In conclusion, our findings establish that TMT induces apoptosis and DNA damage via ROS/NF-κB in grass carp liver cells, causing immune dysfunction. This study provides novel insights into the toxicology research of TMT and sheds light on the immunological effects of TMT toxicity, enriching our understanding of the immunotoxicity of TMT on aquatic organisms and contributing to the protection of ecosystems.

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Trimethyltin chloride is a highly toxic substance, which is absorbed through respiratory tract, skin and digestive tract, with central nervous system injury as the main clinical manifestations, and can be accompanied by damage to various organs. In this paper, the treatment process of 3 patients with acute trimethyltin chloride poisoning was reviewed, and their clinical manifestations, auxiliary examination, diagnosis and treatment were analyzed. Three patients were misdiagnosed as mental abnormality, encephalitis, and hepatic encephalopathy in different hospitals in the early stage of medical treatment, suggesting that clinicians should pay attention to the occupational contact history of poisoned patients and conduct toxicant detection in time to avoid misdiagnosis and mistreatment.

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Gastrointestinal symptoms are common health problems found during aging and neurodegenerative diseases. Trimethyltin-induced rat is known as an animal model of hippocampal degeneration with no data on enteric neurodegeneration. This study aimed to investigate the effect of trimethyltin (TMT) induction on the gastrointestinal tract. A 28-day animal study with male Sprague-Dawley rats (3 months old, 150-200 g) given a single TMT injection (8 mg/kg body weight, intraperitoneal) was conducted. The number of neurons in the colonic myenteric plexus was measured using stereological estimation. Histological scoring of colon inflammation, immunohistochemistry of tumor necrosis factor-α (TNF-α), and quantitative PCR were conducted. This study showed neuronal loss in the colonic myenteric plexus of TMT-induced rat model of neurodegeneration. Minor colon inflammation characterized by inflammatory cell infiltration and slightly higher expression of TNF-α in the colon mucosa were observed in the TMT-induced rat. However, the gut microbiota composition of the TMT-induced rat was not different from that of the control rats. This study demonstrates that TMT induces colonic myenteric plexus neurodegeneration and minor colon inflammation, which suggests the potential of this animal model to elucidate the communication between the gastrointestinal tract and central nervous system in neurodegenerative diseases.

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BACKGROUND: Moderate-intensity intermittent exercise (MIIE) has been proposed as an effective method for preventing Alzheimer's dementia (AD). AIM: This study aimed to investigate the effects of MIIE on the spatial memory and protein level of AD markers in the hippocampus of trimethyltin (TMT)-induced rat model of hippocampal degeneration. METHODS: Male Sprague Dawley (SD) rats were randomly assigned into four groups: normal control (N), exercise control (E), TMT control (T), and exercise and TMT (ET). Rats of the exercise groups (E and ET) were forced to run on a treadmill for 30 min each day at maximum for 12 weeks. Intraperitoneal injection of 8 mg/kgBW TMT was administered as a single dose, 10 days before the last exercise treatment for the T and ET groups. The spatial memory of rats was examined using Morris water maze (MWM) test after the exercise period. After euthanasia, the hippocampal tissue was dissected out and the level of hippocampal presenilin-1 (PSEN-1) and phosphorylated tau (p-tau) protein were measured using ELISA. The total number of hippocampal pyramidal neurons was estimated using unbiased stereological analysis. Qualitative immunohistochemistry was performed to examine the expression of brain-derived neurotrophic factor (BDNF), tumor necrosis factor-alpha (TNF-α), and interleukin-10 (IL-10) in paraffin sections of the hippocampus. RESULTS: TMT exposure induced memory impairment indicated by the T group having the lowest percentage of time and percentage of path length in the target quadrant compared to other groups. MIIE prevented the memory impairment effect of TMT exposure indicated by the ET group having no significantly different MWM performance compared to the E and N groups. The ET group had significantly lower levels of hippocampal AD markers, p-tau and PSEN-1, as well as significantly higher estimated total number of pyramidal neurons of hippocampal CA1 and CA2-3 regions compared to the T group. Expressions of TNF-α was weak, while the expression of IL-10 was stronger in the ET group compared to the control group. The TMT-induced group exhibited stronger expression of BDNF. CONCLUSION: MIIE prevents neuronal loss and impaired spatial memory upon TMT exposure most probably via preventing elevated levels of hippocampal AD markers and neuroinflammation. WC:350.

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We studied the neuroprotective properties of the non-competitive NMDA receptor antagonist memantine, in combination with a positive allosteric modulator of metabotropic glutamate receptors of Group III, VU 0422288. The treatment was started 48 h after the injection of neurotoxic agent trimethyltin (TMT) at 7.5 mg/kg. Three weeks after TMT injection, functional and morphological changes in a rat hippocampus were evaluated, including the expression level of genes characterizing glutamate transmission and neuroinflammation, animal behavior, and hippocampal cell morphology. Significant neuronal cell death occurred in the CA3 and CA4 regions, and to a lesser extent, in the CA1 and CA2 regions. The death of neurons in the CA1 field was significantly reduced in animals with a combined use of memantine and VU 0422288. In the hippocampus of these animals, the level of expression of genes characterizing glutamatergic synaptic transmission (Grin2b, Gria1, EAAT2) did not differ from the level in control animals, as well as the expression of genes characterizing neuroinflammation (IL1b, TGF beta 1, Aif1, and GFAP). However, the expression of genes characterizing neuroinflammation was markedly increased in the hippocampus of animals treated with memantine or VU 0422288 alone after TMT. The results of immunohistochemical studies confirmed a significant activation of microglia in the hippocampus three weeks after TMT injection. In contrast to the hilus, microglia in the CA1 region had an increase in rod-like cells. Moreover, in the CA1 field of the hippocampus of the animals of the MEM + VU group, the amount of such microglia was close to the control. Thus, the short-term modulation of glutamatergic synaptic transmission by memantine and subsequent activation of Group III mGluR significantly affected the dynamics of neurodegeneration in the hippocampus.

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Exposure to toxic substances during postnatal period is one of the major factors causing retinal developmental defects. The developmental toxicity of trimethyltin chloride (TMT), a byproduct of an organotin compound widely used in agriculture and industrial fields, has been reported; however, the effect on the mammalian retina during postnatal development and the mechanism have not been elucidated to date. We exposed 0.75 and 1.5 mg/kg of TMT to neonatal ICR mice (1:1 ratio of male and female) up to postnatal day 14 and performed analysis of the retina: histopathology, apoptosis, electrophysiological function, glutamate concentration, gene expression, and fluorescence immunostaining. Exposure to TMT caused delayed eye opening, eye growth defect and thinning of retinal layer. In addition, apoptosis occurred in the retina along with b-wave and spiking activity changes in the micro-electroretinogram. These changes were accompanied by an increase in the concentration of glutamate, upregulation of astrocyte-related genes, and increased expression of glial excitatory amino acid transporter (EAAT) 1 and 2. Conversely, EAAT 3, 4, and 5, mainly located in the neurons, were decreased. Our results are the first to prove postnatal retinal developmental neurotoxicity of TMT at the mammalian model and analyze the molecular, functional as well as morphological aspects to elucidate possible mechanisms: glutamate toxicity with EAAT expression changes. These mechanisms may suggest not only a strategy to treat but also a clue to prevent postnatal retina developmental toxicity of toxic substances.

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