Neuroprotective Effects of Withania somnifera on 4-Hydroxynonenal Induced Cell Death in Human Neuroblastoma SH-SY5Y Cells Through ROS Inhibition and Apoptotic Mitochondrial Pathway.

The antioxidant, anti-inflammatory, and anticancer activities of Withania somnifera (WS) are known for a long time. This study was aimed to examine whether WS also diminishes 4-hydroxy-trans-2-nonenal (HNE)-induced neurotoxicity in human neuroblastoma (SH-SY5Y) cell line. The cytotoxic response of HNE (0.1-50 µM) and WS (6.25-200 µg/ml) was measured by MTT assay after exposing SH-SY5Y cells for 24 h. Then neuroprotective potential was assessed by exposing the cells to biologically safe concentrations of WS (12.5, 25, and 50 µg/ml) then HNE (50 µM). Results showed a concentration-dependent protective effect of WS at 12.5, 25, and 50 µg/ml against HNE (50 µM) induced cytotoxicity and cell inhibition. Pre-exposure to WS resulted in a strong inhibition of 24, 55 and 83% in malondialdehyde (MDA) level; 5, 27 and 60% in glutathione (GSH) level; 12, 36 and 68% in catalase activity; 11, 33 and 67% in LDH leakage; and 40, 80 and 120% in cellular LDH activity at 12.5, 25, and 50 µg/ml, respectively, induced by 50 µM HNE in SH-SY5Y cells. The HNE-mediated cellular changes (cell shrinkage, rounded bodies, and inhibition of outgrowth) and increased caspase-3 activity were also prevented by WS. The HNE-induced upregulation of proapoptotic markers (p53, caspase-3, and -9, and Bax) and downregulation of antiapoptotic marker Bcl-2 genes were also blocked by pretreatment with WS. Altogether, our findings indicate that WS possesses a protective potential against HNE-induced neurotoxicity.

The Implementation of the Three Rs in Regulatory Toxicity and Biosafety Assessment: The Indian Perspective.

Animal models have long served as a basis for scientific experimentation, biomedical research, drug development and testing, disease modelling and toxicity studies, as they are widely thought to provide meaningful, human-relevant predictions. However, many of these systems are resource intensive and time-consuming, have low predictive value and are associated with great social and ethical dilemmas. Often drugs appear to be effective and safe in these classical animal models, but later prove to be ineffective and/or unsafe in clinical trials. These issues have paved the way for a paradigm shift from the use of in vivo approaches, toward the 'science of alternatives'. This has fuelled several research and regulatory initiatives, including the ban on the testing of cosmetics on animals. The new paradigm has been shifted toward increasing the relevance of the models for human predictivity and translational efficacy, and this has resulted in the recent development of many new methodologies, from 3-D bio-organoids to bioengineered 'human-on-a-chip' models. These improvements have the potential to significantly advance medical research globally. This paper offers a stance on the existing strategies and practices that utilise alternatives to animals, and outlines progress on the incorporation of these models into basic and applied research and education, specifically in India. It also seeks to provide a strategic roadmap to streamline the future directions for the country's policy changes and investments. This strategic roadmap could be a useful resource to guide research institutions, industries, regulatory agencies, contract research organisations and other stakeholders in transitioning toward modern approaches to safety and risk assessment that could replace or reduce the use of animals without compromising the safety of humans or the environment.

Design, Synthesis, and Biological Evaluation of Novel 1,2,4-Trioxanes as Potential Antimalarial Agents.

A series of substituted 1,2,4-trioxanes were synthesized and evaluated for their antimalarial potential, in silico ADME properties and cytotoxicity on neuronal cell lines. Among the 15 synthesized substituted 1,2,4-trioxanes, two compounds (compound 15, IC50 = 25.71 nM; compound 21, IC50 = 19.6 nM) exhibited promising in vitro antimalarial potential comparable to those of the existing drugs chloroquine and artemisinin. Both of these compounds were found to be nontoxic up to 20 µM concentration in neuronal PC-12 cells. Compound 21 may serve as an optimized lead compound because of its less in vitro toxicity and lower probability to cross the blood brain barrier.

Monocrotophos induced oxidative stress and alterations in brain dopamine and serotonin receptors in young rats.

Human exposure to monocrotophos, an organophosphate pesticide, could occur due to its high use in agriculture to protect crops. Recently, we found that postlactational exposure to monocrotophos impaired cholinergic mechanisms in young rats and such changes persisted even after withdrawal of monocrotophos exposure. In continuation to this, the effect of monocrotophos on noncholinergic targets and role of oxidative stress in its neurotoxicity has been studied. Exposure of rats from postnatal day (PD)22 to PD49 to monocrotophos (0.50 or 1.0 mg kg(-1) body weight, perorally) significantly impaired motor activity and motor coordination on PD50 as compared to controls. A significant decrease in the binding of (3)H-spiperone to striatal membrane (26%, p < 0.01; 30%, p < 0.05) in rats exposed to monocrotophos at both the doses and increase in the binding of (3)H-ketanserin to frontocortical membrane (14%, p > 0.05; 37%, p < 0.05) in those exposed at a higher dose, respectively, was observed on PD50 compared with the controls. Alterations in the binding persisted even after withdrawal of monocrotophos exposure on PD65. Increased oxidative stress in brain regions following exposure of rats to monocrotophos was also observed on PD50 that persisted 15 days after withdrawal of exposure on PD65. The results suggest that monocrotophos exerts its neurobehavioral toxicity by affecting noncholinergic functions involving dopaminergic and serotonergic systems associated with enhanced oxidative stress. The results also exhibit vulnerability of developing brain to monocrotophos as most of the changes persisted even after withdrawal of its exposure.

Critical role of the miR-200 family in regulating differentiation and proliferation of neurons.

The generation of differentiated and functional neurons is a complex process, which requires coordinated expression of several proteins and microRNAs (miRNAs). The present study using nerve growth factor (NGF)-differentiated PC12 cells led to the identification of miR-200, miR-221/222 and miR-34 families as major up-regulated miRNAs in fully differentiated neurons. Similar to PC12 cells, induction of miR-200 family was observed in differentiating neural stem cells, demonstrating a direct role of miR-200 family in neuronal differentiation. Over-expression of miR-200 induced neurite formation in PC12 cells and regulated neuronal markers in favour of differentiation. However, inhibition of miR-200 induced proliferation of PC12 cells. In differentiating PC12 cells and neural stem cells, an inverse relationship was observed between expression of reprogramming transcription factors (SOX2, KLF4, NANOG, OCT4 and PAX6) and miR-200. Over-expression of miR-200 in PC12 cells significantly down-regulated mRNA and protein levels of SOX2 and KLF4. Moreover, we observed two phases of dramatic down-regulation of miR-200 expression in developing rat brains correlating with periods of neuronal proliferation. In conclusion, our results indicate that increased expression of the miR-200 family promotes neuronal differentiation, while decreased expression of the miR-200 family promotes neuronal proliferation by targeting SOX2 and KLF4.

Quercetin decreases steroidogenic enzyme activity, NF-κB expression, and oxidative stress in cultured Leydig cells exposed to atrazine.

Quercetin has been reported to protect testicular cells from oxidative damage induced by environmental chemicals. In this study, we isolated interstitial Leydig cells (ILCs) from immature rats, set-up ILCs culture, co-treated cells with atrazine (ATZ) and quercetin (QT), evaluated toxicity, and measured the expression levels of antioxidant enzymes and nuclear factor-kappaB (NF-κB) and levels of steroidogenic enzymes. ATZ decreased ILCs viability at concentrations higher than 10 µg/mL and increased reactive oxygen species, malondialdehyde (MDA), and glutathione levels. ATZ also increased glutathione peroxidase, glutathione reductase, and glutathione-S-transferase and decreased superoxide dismutase-1 (sod1) and superoxide dismutase-2 (sod2) messenger RNA (mRNA) levels which were prevented by QT. The changes in the MDA levels and lactate dehydrogenase leakage induced by ATZ (50 µg/mL) were also prevented on co-treatment with QT (50 µM). Furthermore, ATZ-induced 3ß- and 17ß-hydroxysteroid dehydrogenase activities and NF-κB-expressions at the mRNA and protein levels were also recovered to control value on co-treatment with QT. These data showed that QT protected against ATZ-induced ILCs toxicity by restoring the expression of NF-κB and steroidogenic activity and by preventing the oxidative stress.

miR-497 and miR-302b regulate ethanol-induced neuronal cell death through BCL2 protein and cyclin D2.

In chronic alcoholism, brain shrinkage and cognitive defects because of neuronal death are well established, although the sequence of molecular events has not been fully explored yet. We explored the role of microRNAs (miRNAs) in ethanol-induced apoptosis of neuronal cells. Ethanol-sensitive miRNAs in SH-SY5Y, a human neuroblastoma cell line, were identified using real-time PCR-based TaqMan low-density arrays. Long-term exposure to ethanol (0.5% v/v for 72 h) produced a maximum increase in expression of miR-497 (474-fold) and miR-302b (322-fold). Similar to SH-SY5Y, long-term exposure to ethanol induced miR-497 and miR-302b in IMR-32, another human neuroblastoma cell line. Using in silico approaches, BCL2 and cyclin D2 (CCND2) were identified as probable target genes of these miRNAs. Cotransfection studies with 3'-UTR of these genes and miRNA mimics have demonstrated that BCL2 is a direct target of miR-497 and that CCND2 is regulated negatively by either miR-302b or miR-497. Overexpression of either miR-497 or miR-302b reduced expression of their identified target genes and increased caspase 3-mediated apoptosis of SH-SY5Y cells. However, overexpression of only miR-497 increased reactive oxygen species formation, disrupted mitochondrial membrane potential, and induced cytochrome c release (mitochondria-related events of apoptosis). Moreover, ethanol induced changes in miRNAs, and their target genes were substantially prevented by pre-exposure to GSK-3B inhibitors. In conclusion, our studies have shown that ethanol-induced neuronal apoptosis follows both the mitochondria-mediated (miR-497- and BCL2-mediated) and non-mitochondria-mediated (miR-302b- and CCND2-mediated) pathway.

Dietary antioxidant, quercetin, protects sertoli-germ cell coculture from atrazine-induced oxidative damage.

Quercetin (QT), a dietary-derived flavonoid, is ubiquitous in fruits and vegetables and plays an important role in human health by virtue of its antioxidant function. The present study was designed to examine the effects of QT on oxidative damage that was induced by the herbicide, atrazine (ATZ), in mixed cultures of Sertoli-germ cells. Results showed that treatment with QT increased cell viability and decreased catalase activity, malondialdehyde, and reactive oxygen species (ROS) levels. QT treatment also increased the mRNA expression of glutathione peroxidase (GSH-Px), glutathione reductase (GR), glutathione-S-transferase, and superoxide dismutase-1 and could not reversed to the control levels ATZ-induced steady-state mRNA levels of these antioxidant genes as well as the level of glutathione and activities of GSH-Px and GR. QT has protective effect against ATZ-induced oxidative stress through a reduction in ROS levels and lipid peroxidation.

Kolaviron biflavanoids of Garcinia kola seeds protect atrazine-induced cytotoxicity in primary cultures of rat Leydig cells.

We sought to explore the mechanism by which kolaviron (Kol) protects against atrazine (ATZ)-induced toxicity of cultured interstitial Leydig cells (ILCs). In our experiments, treatment with Kol improved Leydig cell viability and significantly reduced malondialdehyde (MDA) and reactive oxygen species (ROS) levels. Further investigations revealed a reduction in glutathione peroxidase (GSH-Px), glutathione reductase (GR), glutathione-S-transferase (GST) and elevation of superoxide dismutase 1 (SOD-1) and superoxide dismutase 2 (SOD-2) as measured by messenger RNA (mRNA) expression. Additionally, the ATZ-induced alterations in the mRNA transcript copy numbers of steroidogenesis genes: steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage enzyme (CYP11A1), and 3ß-hydroxysteroid dehydrogenase (3ß-HSD) were shifted toward the control values by Kol. Taken together, these findings indicate that Kol protects ILCs from ATZ-induced toxicity via the reduction in ROS and MDA levels and induce normalization of mRNA levels of all the tested genes.

Release and toxicity of dental resin composite.

Dental resin composite that are tooth-colored materials have been considered as possible substitutes to mercury-containing silver amalgam filling. Despite the fact that dental resin composites have improved their physico-chemical properties, the concern for its intrinsic toxicity remains high. Some components of restorative composite resins are released in the oral environment initially during polymerization reaction and later due to degradation of the material. In vitro and in vivo studies have clearly identified that these components of restorative composite resins are toxic. But there is a large gap between the results published by research laboratories and clinical reports. The objective of this manuscript was to review the literature on release phenomenon as well as in vitro and in vivo toxicity of dental resin composite. Interpretation made from the recent data was also outlined.

Elevated tumor necrosis factor in serum is associated with increased retinal ischemia in proliferative eales' disease.

OBJECTIVE: Tumor necrosis factor (TNF) was evaluated in the serum of patients with proliferative stage of Eales' disease to study its relation with the area of retinal capillary non-perfusion (ischemic retina). METHODS: Quantification of the levels of TNF was done using sandwich ELISA in 52 cases with proliferative Eales' disease and in 32 healthy controls. Seven 50° photographs of different fields of the fundus were taken on fluorescein angiography. The area of retinal capillary non-perfusion denoting retinal cell death was assessed in terms of optic disc areas. RESULTS: TNF levels were found to be significantly increased in the proliferative stage of the disease (mean 23.64 ± 3.7 pg/ml) as compared to controls (mean 12.49 ± 2.9 pg/ml; p < 0.001). Higher levels of TNF were found to be associated with an increased area of retinal capillary non-perfusion on fluorescein angiography. TNF levels of 20-31 pg/ml were observed in cases with neovascularization at the disc (n = 33) as compared to 17-21 pg/ml in cases with neovascularization elsewhere (n = 19). CONCLUSIONS: An increased level of TNF is associated with an increased area of the ischemic retina. It is hypothesized that retinal cell death signaling in proliferative Eales' disease is related to an increased TNF level.

In-silico Studies and Wet-Lab Validation of Camptothecin Derivatives for Anti-Cancer Activity Against Liver (HepG2) and Lung (A549) Cancer Cell Lines.

BACKGROUND: In the present study, we have explored the utility of QSAR modelling, in silico ADMET, docking, chemical semi-synthesis, and in vitro evaluation studies for the identification of active camptothecin (CPT) derivatives against cancer-targeting human liver (HepG2) and lung (A549) cancer cell lines. METHODS: Two QSAR models were developed as screenings tools using the multiple linear regression (MLR) method followed by ADMET and docking studies. The regression coefficient (r2) and cross-validation regression coefficients (rCV2T) of the QSAR model for the HepG2 cell line was 0.95 and 0.90, respectively, and for the A549 cell line, it was 0.93 and 0.81, respectively. RESULTS: In silico studies show that CPT derivatives (CPT-1 and CPT-6) possess drug-like properties. Docking performed on DNA Topoisomerase-I showed significant binding affinity. Finally, predicted active derivatives were chemically semi synthesized, spectroscopically characterized, and evaluated in-vitro for cytotoxic/anticancer activity against HepG2 and A549 cell lines. CONCLUSION: The experimental results are consistent with the predicted results. These findings may be of immense importance in the anticancer drug development from an inexpensive and widely available natural product, camptothecin.

Genotoxic potential of copper oxide nanoparticles in human lung epithelial cells.

Copper oxide nanoparticles (CuO NPs) are increasingly used in various applications. Recent studies suggest that oxidative stress may be the cause of the cytotoxicity of CuO NPs in mammalian cells. However, little is known about the genotoxicity of CuO NPs following exposure to human cells. This study was undertaken to investigate CuO NPs induced genotoxic response through p53 pathway in human pulmonary epithelial cells (A549). In addition, cytotoxicity and oxidative stress markers were also assessed. Results showed that cell viability was reduced by CuO NPs and degree of reduction was dose dependent. CuO NPs were also found to induce oxidative stress in dose-dependent manner indicated by depletion of glutathione and induction of lipid peroxidation, catalase and superoxide dismutase. The expression of Hsp70, the first tier biomarker of cellular damage was induced by CuO NPs. Further, CuO NPs up-regulated the cell cycle checkpoint protein p53 and DNA damage repair proteins Rad51 and MSH2 expression. These results demonstrate that CuO NPs possess a genotoxic potential in A549 cells which may be mediated through oxidative stress. Our short-term exposure study of high level induction of genotoxic response of CuO NPs will need to be further investigated to determine whether long-term exposure consequences may exist for CuO NPs application.

Attenuation of arsenic neurotoxicity by curcumin in rats.

In view of continued exposure to arsenic and associated human health risk including neurotoxicity, neuroprotective efficacy of curcumin, a polyphenolic antioxidant, has been investigated in rats. A significant decrease in locomotor activity, grip strength (26%) and rota-rod performance (82%) was observed in rats treated with arsenic (sodium arsenite, 20 mg/kg body weight, p.o., 28 days) as compared to controls. The arsenic treated rats also exhibited a decrease in the binding of striatal dopamine receptors (32%) and tyrosine hydroxylase (TH) immunoreactivity (19%) in striatum. Increased arsenic levels in corpus striatum (6.5 fold), frontal cortex (6.3 fold) and hippocampus (7.0 fold) associated with enhanced oxidative stress in these brain regions, as evident by an increase in lipid perioxidation, protein carbonyl and a decrease in the levels of glutathione and activity of superoxide dismutase, catalase and glutathione peroxidase with differential effects were observed in arsenic treated rats compared to controls. Simultaneous treatment with arsenic (sodium arsenite, 20 mg/kg body weight, p.o., 28 days) and curcumin (100 mg/kg body weight, p.o., 28 days) caused an increase in locomotor activity and grip strength and improved the rota-rod performance in comparison to arsenic treated rats. Binding of striatal dopamine receptors and TH expression increased while arsenic levels and oxidative stress decreased in these brain regions in co-treated rats as compared to those treated with arsenic alone. No significant effect on any of these parameters was observed in rats treated with curcumin (100 mg/kg body weight, p.o., 28 days) alone compared to controls. A significant protection in behavioral, neurochemical and immunohistochemical parameters in rats simultaneously treated with arsenic and curcumin suggest the neuroprotective efficacy of curcumin.

Galactose-grafted chylomicron-mimicking emulsion: evaluation of specificity against HepG-2 and MCF-7 cell lines.

OBJECTIVES: A chylomicron-mimicking lipid emulsion was prepared and loaded with paclitaxel (paclitaxel-CM) and was further grafted with galactose (paclitaxel-GCM) using palmitoyl-galactosamine, which was synthesized by reacting galactosamine hydrochloride with N-hydroxy succinimide ester of palmitic acid. Palmitoyl-galactosamine was used as a ligand for asialoglycoprotein receptors. METHODS: The uptake characteristics of the emulsions were evaluated in HepG-2 cells (human hepatocarcinaoma), which express asialoglycoprotein receptors, and MCF-7 (breast cancer) cells, which are devoid of these receptors. KEY FINDINGS: The incorporation efficiency of paclitaxel-CM was 68.05 +/- 4.80% and that of paclitaxel-GCM was 72.10 +/- 3.93% when the emulsion was prepared with 7.5% (w/w) paclitaxel/lipid phase. The globule size of paclitaxel-GCM and paclitaxel-CM was 124 +/- 8.67 and 96.45 +/- 5.78 nm, respectively. The release of paclitaxel from both of the formulations was fairly sustained: 50 +/- 3.2% of paclitaxel in 24 h. The cytotoxicity and uptake of paclitaxel-GCM were significantly higher (P < 0.05) in HepG-2 cells than MCF-7 cells, while for paclitaxel-CM cytotoxicity and uptake were similar in the two cell lines. This study clearly demonstrates that upon surface modification palmitoyl-galactosamine remains an integral part of the formulation. Paclitaxel solubility can be improved using optimum paclitaxel/lipid phase ratios. The paclitaxel-GCM formulation recognizes asialoglycoprotein receptors overexpressed on HepG-2 cells. CONCLUSIONS: Under our experimental conditions, the proposed paclitaxel-GCM formulation is an ideal delivery vehicle for specific targeting to liver cancer cells, which is anticipated to result in improved efficacy and reduced toxicity to normal cells.

Correction to: Differentiating neurons derived fromhuman umbilical cord blood stem cells work as a test system for developmental neurotoxicity.

The original version of this article unfortunately contained a mistake. The acknowledgment published was incomplete.

Ionic liquid based ultrasound assisted dispersive liquid-liquid micro-extraction for simultaneous determination of 15 neurotransmitters in rat brain, plasma and cell samples.

Neurotransmitters are signaling molecules which play a key role in the central nervous system allowing signal transmission in the neuronal synapses. The role of these compounds is very crucial in the biological systems. A rapid, sensitive, economical and derivatisation free method has been developed for the analysis of 15 neurotransmitters in a single run on liquid chromatography tandem mass spectrometry. These 15 neurotransmitters are categorized into 5 groups on the basis of their fragmentation pattern. The proposed method "ionic liquid based ultrasound assisted dispersive liquid-liquid microextraction" hyphenated with tandem mass spectrometry is the first report for the analysis of neurotransmitters in cell samples along with other two matrices (rat brain and plasma). All the parameters that influence the extraction efficiency are optimized with aid of response surface methodology and desirability profile. Under these optimized conditions the developed method has been validated. The limit of detection was in the range of (1) 0.021-0.912 µg L-1 for rat brain samples, (2) 0.028-0.978 µg L-1 for plasma samples and (3) 0.025-0.945 µg L-1 for cell samples with good linearity behavior for all analytes in the concentration range of 0.04-200 µg L-1 in all the three matrices. The coefficient of determination for all the neurotransmitters was found in the range of (1) (R2) ≥ 0.996 to 0.999 for rat brain samples and (2) (R2) ≥ 0.991 to 0.999 for plasma and cell samples. The intra-day and inter-day variations were found less than (1) 1.78% and 8.94% for rat brain samples, (2) 1.83% and 8.37% for plasma samples and (3) 1.64% and 8.04% for cell samples respectively. The method has mean recoveries varied between (1) 81-128% for brain samples, (2) 88-107% for plasma samples and (3) 91-104% for cell samples at different spiking levels. The optimized and validated method was found free from matrix interferences and successfully applied for quantitative determination of 15 neurotransmitters in the rat brain, plasma and cell samples.

Protective Effect of Curcumin by Modulating BDNF/DARPP32/CREB in Arsenic-Induced Alterations in Dopaminergic Signaling in Rat Corpus Striatum.

Earlier, protective role of curcumin in arsenic-induced dopamine (DA)-D2 receptor dysfunctions in corpus striatum has been demonstrated by us. In continuation to that, the present study is focused to decipher the molecular mechanisms associated with alterations in dopaminergic signaling on arsenic exposure in corpus striatum and assess the protective efficacy of curcumin. Exposure to arsenic (20 mg/kg, body weight p.o. for 28 days) in rats resulted to decrease the expression of presynaptic proteins-tyrosine hydroxylase and VMAT2 while no effect was observed on the expression of DAT in comparison to controls. A significant decrease in the expression of DA-D2 receptors associated with alterations in the expression of PKA, pDARPP32 (Thr 34), and PP1 α was clearly evident on arsenic exposure. Expression of BDNF and pGSK3ß in corpus striatum was found decreased in arsenic-exposed rats. Simultaneous treatment with curcumin (100 mg/kg, body weight p.o. for 28 days) resulted to protect arsenic-induced alterations in the expression of DA-D2 receptors, PKA, pDARPP32, pCREB, and pPP1α. Neuroprotective efficacy of curcumin can possibly be attributed to its antioxidant potential which significantly protected arsenic-induced mitochondrial dysfunctions by modulating the ROS generation and apoptosis. Modulation in the expression of BDNF and pGSK3ß in corpus striatum by curcumin exhibits the importance of neuronal survival pathway in arsenic-induced dopaminergic dysfunctions. Interestingly, curcumin was also found to protect arsenic-induced ultrastructural changes in corpus striatum. The results exhibit that curcumin modulates BDNF/DARPP32/CREB in arsenic-induced alterations in dopaminergic signaling in rat corpus striatum.

Involvement of PKA/DARPP-32/PP1α and ß- arrestin/Akt/GSK-3ß Signaling in Cadmium-Induced DA-D2 Receptor-Mediated Motor Dysfunctions: Protective Role of Quercetin.

Given increasing risk of cadmium-induced neurotoxicity, the study was conducted to delineate the molecular mechanisms associated with cadmium-induced motor dysfunctions and identify targets that govern dopaminergic signaling in the brain involving in vivo, in vitro, and in silico approaches. Selective decrease in dopamine (DA)-D2 receptors on cadmium exposure was evident which affected the post-synaptic PKA/DARPP-32/PP1α and ß-arrestin/Akt/GSK-3ß signaling concurrently in rat corpus striatum and PC12 cells. Pharmacological inhibition of PKA and Akt in vitro demonstrates that both pathways are independently modulated by DA-D2 receptors and associated with cadmium-induced motor deficits. Ultrastructural changes in the corpus striatum demonstrated neuronal degeneration and loss of synapse on cadmium exposure. Further, molecular docking provided interesting evidence that decrease in DA-D2 receptors may be due to direct binding of cadmium at the competitive site of dopamine on DA-D2 receptors. Treatment with quercetin resulted in the alleviation of cadmium-induced behavioral and neurochemical alterations. This is the first report demonstrating that cadmium-induced motor deficits are associated with alteration in postsynaptic dopaminergic signaling due to a decrease in DA-D2 receptors in the corpus striatum. The results further demonstrate that quercetin has the potential to alleviate cadmium-induced dopaminergic dysfunctions.

PI3K/Akt/GSK3ß induced CREB activation ameliorates arsenic mediated alterations in NMDA receptors and associated signaling in rat hippocampus: Neuroprotective role of curcumin.

Protective efficacy of curcumin in arsenic induced NMDA receptor dysfunctions and PI3K/Akt/ GSK3ß signalling in hippocampus has been investigated in vivo and in vitro. Exposure to sodium arsenite (in vivo - 20 mg/kg, body weight p.o. for 28 days; in vitro - 10 µM for 24 h) and curcumin (in vivo - 100 mg/kg body weight p.o. for 28 days; in vitro - 20 µM for 24 h) was carried out alone or simultaneously. Treatment with curcumin ameliorated sodium arsenite induced alterations in the levels of NMDA receptors, its receptor subunits and synaptic proteins - pCaMKIIα, PSD-95 and SynGAP both in vivo and in vitro. Decreased levels of BDNF, pAkt, pERK1/2, pGSK3ß and pCREB on sodium arsenite exposure were also protected by curcumin. Curcumin was found to decrease sodium arsenite induced changes in hippocampus by modulating PI3K/Akt/GSK3ß neuronal survival pathway, known to regulate various cellular events. Treatment of hippocampal cultures with pharmacological inhibitors for ERK1/2, GSK3ß and Akt individually inhibited levels of CREB and proteins associated with PI3K/Akt/GSK3ß pathway. Simultaneous treatment with curcumin was found to improve sodium arsenite induced learning and memory deficits in rats assessed by water maze and Y-maze. The results provide evidence that curcumin exercises its neuroprotective effect involving PI3K/Akt pathway which may affect NMDA receptors and downstream signalling through TrKß and BDNF in arsenic induced cognitive deficits in hippocampus.