Publications by authors named "Sumonto Mitra"

16 Publications

  • Page 1 of 1

GluN2A-NMDA receptor-mediated sustained Ca influx leads to homocysteine-induced neuronal cell death.

J Biol Chem 2019 07 5;294(29):11154-11165. Epub 2019 Jun 5.

Department of Neurology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131

Homocysteine, a metabolite of the methionine cycle, is a known agonist of -methyl-d-aspartate receptor (NMDAR), a glutamate receptor subtype and is involved in NMDAR-mediated neurotoxicity. Our previous findings have shown that homocysteine-induced, NMDAR-mediated neurotoxicity is facilitated by a sustained increase in phosphorylation and activation of extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK MAPK). In the current study, we investigated the role GluN1/GluN2A-containing functional NMDAR (GluN2A-NMDAR) and GluN1/GluN2B-containing functional NMDAR (GluN2B-NMDAR) in homocysteine-induced neurotoxicity. Our findings revealed that exposing primary cortical neuronal cultures to homocysteine leads to a sustained low-level increase in intracellular Ca We also showed that pharmacological inhibition of GluN2A-NMDAR or genetic deletion of the GluN2A subunit attenuates homocysteine-induced increase in intracellular Ca Our results further established the role of GluN2A-NMDAR in homocysteine-mediated sustained ERK MAPK phosphorylation and neuronal cell death. Of note, the preferential role of GluN2A-NMDAR in homocysteine-induced neurotoxicity was distinctly different from glutamate-NMDAR-induced excitotoxic cell death that involves overactivation of GluN2B-NMDAR and is independent of ERK MAPK activation. These findings indicate a critical role of GluN2A-NMDAR-mediated signaling in homocysteine-induced neurotoxicity.
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http://dx.doi.org/10.1074/jbc.RA119.008820DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6643025PMC
July 2019

Innovative Therapy for Alzheimer's Disease-With Focus on Biodelivery of NGF.

Front Neurosci 2019 5;13:38. Epub 2019 Feb 5.

Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder associated with abnormal protein modification, inflammation and memory impairment. Aggregated amyloid beta (Aβ) and phosphorylated tau proteins are medical diagnostic features. Loss of memory in AD has been associated with central cholinergic dysfunction in basal forebrain, from where the cholinergic circuitry projects to cerebral cortex and hippocampus. Various reports link AD progression with declining activity of cholinergic neurons in basal forebrain. The neurotrophic molecule, nerve growth factor (NGF), plays a major role in the maintenance of cholinergic neurons integrity and function, both during development and adulthood. Numerous studies have also shown that NGF contributes to the survival and regeneration of neurons during aging and in age-related diseases such as AD. Changes in neurotrophic signaling pathways are involved in the aging process and contribute to cholinergic and cognitive decline as observed in AD. Further, gradual dysregulation of neurotrophic factors like NGF and brain derived neurotrophic factor (BDNF) have been reported during AD development thus intensifying further research in targeting these factors as disease modifying therapies against AD. Today, there is no cure available for AD and the effects of the symptomatic treatment like cholinesterase inhibitors (ChEIs) and memantine are transient and moderate. Although many AD treatment studies are being carried out, there has not been any breakthrough and new therapies are thus highly needed. Long-term effective therapy for alleviating cognitive impairment is a major unmet need. Discussion and summarizing the new advancements of using NGF as a potential therapeutic implication in AD are important. In summary, the intent of this review is describing available experimental and clinical data related to AD therapy, priming to gain additional facts associated with the importance of NGF for AD treatment, and encapsulated cell biodelivery (ECB) as an efficient tool for NGF delivery.
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http://dx.doi.org/10.3389/fnins.2019.00038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6370742PMC
February 2019

Increased Active OMI/HTRA2 Serine Protease Displays a Positive Correlation with Cholinergic Alterations in the Alzheimer's Disease Brain.

Mol Neurobiol 2019 Jul 25;56(7):4601-4619. Epub 2018 Oct 25.

Division of Neurogeriatrics, Center for Alzheimer Research, NVS Department, Karolinska Institutet, 141 83, Huddinge, Sweden.

OMI/HTRA2 (high-temperature requirement serine protease A2) is a mitochondrial serine protease involved in several cellular processes, including autophagy, chaperone activity, and apoptosis. Few studies on the role of OMI/HTRA2 in Alzheimer's disease (AD) are available, but none on its relationship with the cholinergic system and neurotrophic factors as well as other AD-related proteins. In this study, immunohistochemical analyses revealed that AD patients had a higher cytosolic distribution of OMI/HTRA2 protein compared to controls. Quantitative analyses on brain extracts indicated a significant increase in the active form of OMI/HTRA2 in the AD brain. Activated OMI/HTRA2 protein positively correlated with stress-associated read-through acetylcholinesterase activity. In addition, α7 nicotinic acetylcholine receptor gene expression, a receptor also known to be localized on the outer membrane of mitochondria, showed a strong correlation with OMI/HTRA2 gene expression in three different brain regions. Interestingly, the activated OMI/HTRA2 levels also correlated with the activity of the acetylcholine-biosynthesizing enzyme, choline acetyltransferase (ChAT); with levels of the neurotrophic factors, NGF and BDNF; with levels of the soluble fragments of amyloid precursor protein (APP); and with gene expression of the microtubule-associated protein tau in the examined brain regions. Overall, the results demonstrate increased levels of the mitochondrial serine protease OMI/HTRA2, and a coherent pattern of association between the activated form of OMI/HTRA2 and several key proteins involved in AD pathology. In this paper, we propose a new hypothetical model to highlight the importance and needs of further investigation on the role of OMI/HTRA2 in the mitochondrial function and AD.
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http://dx.doi.org/10.1007/s12035-018-1383-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6657433PMC
July 2019

Cerebrospinal fluid from Alzheimer patients affects cell-mediated nerve growth factor production and cell survival in vitro.

Exp Cell Res 2018 10 6;371(1):175-184. Epub 2018 Aug 6.

Karolinska Institutet, Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Division of Neurogeriatrics, Stockholm, Sweden. Electronic address:

Alzheimer's disease (AD) is characterized by early degeneration of cholinergic neurons and decreased levels of nerve growth factor (NGF). Thus, increasing the NGF levels by for instance encapsulated cell bio-delivery (ECB) is a potential treatment strategy. The results from our previous first-in-human studies on ECB of NGF to the basal forebrain cholinergic neurons were promising, but indicated some variability of long-term viability of the encapsulated cells and associated reduced NGF-release. Here we studied the effect of amyloid beta-peptides (Aβ), interleukin 1-beta (IL-1β), and CSF from AD, Lewy body dementia (LBD) or subjective cognitive impairment (SCI) patients on the NGF overproducing cell line NGC-0295. At physiological concentrations, neither Aβ nor Aβ had any major impact on cell viability or NGF-production. In contrast, IL-1β dose-dependently affected NGF-production over time. Exposure of NGF-producing cells to CSF from AD patients showed significantly reduced NGF-release as compared to CSF from LBD or SCI patients. By mass spectrometry we found 3 proteins involved in inflammatory pathways to have an altered expression in AD CSF compared to LBD and SCI. Cell survival and NGF-release were not affected by Aβ. NGF-release was affected by IL-1β, suggesting that inflammation has a negative effect on ECB cells.
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http://dx.doi.org/10.1016/j.yexcr.2018.08.007DOI Listing
October 2018

Arsenic exposure impels CD4 commitment in thymus and suppress T cell cytokine secretion by increasing regulatory T cells.

Sci Rep 2017 08 2;7(1):7140. Epub 2017 Aug 2.

Immunotoxicology Laboratory, Food, Drug & Chemical Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31 Mahatma Gandhi Marg, Lucknow, 226001, Uttar Pradesh, India.

Arsenic is globally infamous for inducing immunosuppression associated with prevalence of opportunistic infection in exposed population, although the mechanism remains elusive. In this study, we investigate the effect of arsenic exposure on thymocyte lineage commitment and the involvement of regulatory T cells (T) in arsenic-induced immunosuppression. Male Balb/c mice were exposed to 0.038, 0.38 and 3.8 ppm sodium arsenite for 7, 15 and 30 days through oral gavage. Arsenic exposure promoted CD4 lineage commitment in a dose dependent manner supported by the expression of ThPOK in thymus. Arsenic also increased splenic CD4 T cells and promoted their differentiation into T cells. In parallel, arsenic exposure induced immunosuppression characterized by low cytokine secretion from splenocytes and increased susceptibility to Mycobacterium fortuitum (M. fortuitum) infection. Therefore, we linked arsenic-induced rise in T cells with suppressed T1 and T2 related cytokines, which has been reversed by inhibition of T cells in-vivo using wortmannin. Other parameters like body weight, kidney and liver function, histoanatomy of thymus and spleen as well as thymocyte and splenocytes viability were unaltered by arsenic exposure. Taken together our findings indicated that environmentally relevant dose of arsenic enhanced differentiation of T cells which in turn induce immunosuppression in experimental animals.
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http://dx.doi.org/10.1038/s41598-017-07271-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5541098PMC
August 2017

Long term impact of the endocrine disruptor tributyltin on male fertility following a single acute exposure.

Environ Toxicol 2017 Oct 14;32(10):2295-2304. Epub 2017 Jul 14.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow, India.

Declining rate of human fertility is a growing concern, where lifestyle and environmental factors play an important role. We recently demonstrated that tributyltin (TBT), an omnipresent endocrine disruptor, affects testicular cells in vitro. In this study, male Wistar rats were gavaged a single dose of 10, 20, and 30 mg/kg TBT-chloride (TBTC) (to mimic accidental exposure in vivo) and sacrificed on day 3 and day 7, respectively. TBT bioavailability was evaluated by estimating total tin content, and essential metal levels were analyzed along with redox molecules (ROS and GSH/GSSG) to understand the effect on physiological conditions. Blood-testicular barrier (BTB) disruption, levels of associated proteins and activity of proteolytic enzymes were evaluated to understand the effect on BTB. Histological analysis of tissue architecture and effect on protein expression of steroidogenic, stress and apoptotic markers were also evaluated. Widespread TBTC pollution can be an eventual threat to male fertility worldwide.
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http://dx.doi.org/10.1002/tox.22446DOI Listing
October 2017

C-Phycocyanin protects against acute tributyltin chloride neurotoxicity by modulating glial cell activity along with its anti-oxidant and anti-inflammatory property: A comparative efficacy evaluation with N-acetyl cysteine in adult rat brain.

Chem Biol Interact 2015 Aug 14;238:138-50. Epub 2015 Jun 14.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow, India. Electronic address:

Spirulina is a widely used health supplement and is a dietary source of C-Phycocyanin (CPC), a potent anti-oxidant. We have previously reported the neurotoxic potential of tributyltin chloride (TBTC), an environmental pollutant and potent biocide. In this study, we have evaluated the protective efficacy of CPC against TBTC induced neurotoxicity. To evaluate the extent of neuroprotection offered by CPC, its efficacy was compared with the degree of protection offered by N-acetylcysteine (NAC) (a well known neuroprotective drug, taken as a positive control). Male Wistar rats (28 day old) were administered with 20mg/kg TBTC (oral) and 50mg/kg CPC or 50mg/kg NAC (i.p.), alone or in combination, and various parameters were evaluated. These include blood-brain barrier (BBB) damage; redox parameters (ROS, GSH, redox pathway associated enzymes, oxidative stress markers); inflammatory, cellular, and stress markers; apoptotic proteins and in situ cell death assay (TUNEL). We observed increased CPC availability in cortical tissue following its administration. Although BBB associated proteins like claudin-5, p-glycoprotein and ZO-1 were restored, CPC/NAC failed to protect against TBTC induced overall BBB permeability (Evans blue extravasation). Both CPC and NAC remarkably reduced oxidative stress and inflammation. NAC effectively modulated redox pathway associated enzymes whereas CPC countered ROS levels efficiently. Interestingly, CPC and NAC were equivalently capable of reducing apoptotic markers, astroglial activation and cell death. This study illustrates the various pathways involved in CPC mediated neuroprotection against this environmental neurotoxicant and highlights its capability to modulate glial cell activity.
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http://dx.doi.org/10.1016/j.cbi.2015.06.016DOI Listing
August 2015

N-acetylcysteine effectively mitigates cadmium-induced oxidative damage and cell death in Leydig cells in vitro.

Drug Chem Toxicol 2016 17;39(1):74-80. Epub 2015 Apr 17.

a Immunotoxicology Division , Indian Institute of Toxicology Research , Lucknow, Uttar Pradesh , India and.

Context: Cadmium (Cd) is known to cause severe damage to various organs including lung, liver, kidney, brain and reproductive system. Several studies have reported the induction of oxidative stress pathways following Cd exposure.

Objective: Since oxidative stress is also deemed responsible for inducing male infertility, a growing worldwide concern, we tried to understand whether the antioxidant N-acetylcysteine (NAC) can be a potential therapeutic agent to counter Cd toxicity using primary Leydig cells.

Materials And Methods: This study highlights the initial cellular alterations which culminate in cell death induction. Primary Leydig cells were isolated from 28-day-old male Wistar rats, exposed to various concentrations of Cd in vitro and biochemical and cell death parameters were evaluated to understand the effect of Cd. NAC pre-treatment was done to understand its protective efficacy.

Results: Following Cd exposure to Leydig cells in vitro, we found simultaneous intracellular calcium (Ca(2+)) increase and reduction in mitochondrial membrane polarization at 30 min, followed by significant induction of reactive oxygen species and MAPK-extracellular-regulated kinases with concurrent glutathione depletion at 1 h, and significant cell death (both necrotic and apoptotic) at 6 and 18 h, respectively. Pre-treatment with NAC abrogated all these toxic manifestations and showed significantly reduced cell death. NAC also rescued the expression of 3-βHSD, a major steroidogenic protein.

Discussion And Conclusion: Taken together, these data illustrated that NAC can be used as a potential protective agent against Cd-induced testicular toxicity, especially with regards to oxidative stress-induced Leydig cell toxicity.
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http://dx.doi.org/10.3109/01480545.2015.1028068DOI Listing
October 2016

Differential susceptibility of brain regions to tributyltin chloride toxicity.

Environ Toxicol 2015 Dec 3;30(12):1393-405. Epub 2014 Jun 3.

Immunotoxicology Division, Council of Scientific and Industrial Research-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow, India.

Tributyltin (TBT), a well-known endocrine disruptor, is an omnipresent environmental pollutant and is explicitly used in many industrial applications. Previously we have shown its neurotoxic potential on cerebral cortex of male Wistar rats. As the effect of TBT on other brain regions is not known, we planned this study to evaluate its effect on four brain regions (cerebellum, hippocampus, hypothalamus, and striatum). Four-week-old male Wistar rats were gavaged with a single dose of TBT-chloride (TBTC) (10, 20, and 30 mg/kg) and sacrificed on days 3 and 7, respectively. Effect of TBTC on blood-brain barrier (BBB) permeability and tin (Sn) accumulation were measured. Oxidative stress indexes such as reactive oxygen species (ROS), reduced and oxidized glutathione (GSH/GSSG) ratio, lipid peroxidation, and protein carbonylation were analyzed as they play an imperative role in various neuropathological conditions. Since metal catalyzed reactions are a major source of oxidant generation, levels of essential metals like iron (Fe), zinc (Zn), and calcium (Ca) were estimated. We found that TBTC disrupted BBB and increased Sn accumulation, both of which appear significantly correlated. Altered metal homeostasis and ROS generation accompanied by elevated lipid peroxidation and protein carbonylation indicated oxidative damage which appeared more pronounced in the striatum than in cerebellum, hippocampus, and hypothalamus. This could be associated to the depleted GSH levels in striatum. These results suggest that striatum is more susceptible to TBTC induced oxidative damage as compared with other brain regions under study.
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http://dx.doi.org/10.1002/tox.22009DOI Listing
December 2015

Early cellular responses against tributyltin chloride exposure in primary cultures derived from various brain regions.

Environ Toxicol Pharmacol 2014 May 6;37(3):1048-59. Epub 2014 Apr 6.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow, India. Electronic address:

Tributyltin (TBT) is a potent biocide and commonly used in various industrial sectors. Humans are mainly exposed through the food chain. We have previously demonstrated tin accumulation in brain following TBT-chloride (TBTC) exposure. In this study, effect of TBTC on dissociated cells from different brain regions was evaluated. Cytotoxicity assay (MTT), mode of cell death (Annexin V/PI assay), oxidative stress parameters (ROS and lipid peroxidation), reducing power of the cell (GSH), mitochondrial membrane potential (MMP) and intracellular Ca(2+) were evaluated to ascertain the effect of TBTC. Expression of glial fibrillary acidic protein (GFAP) was measured to understand the effect on astroglial cells. TBTC as low as 30 nM was found to reduce GSH levels, whereas higher doses of 300 and 3000 nM induced ROS generation and marked loss in cell viability mainly through apoptosis. Striatum showed higher susceptibility than other regions, which may have further implications on various neurological aspects.
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http://dx.doi.org/10.1016/j.etap.2014.03.020DOI Listing
May 2014

Isolation and characterization of microglia from adult mouse brain: selected applications for ex vivo evaluation of immunotoxicological alterations following in vivo xenobiotic exposure.

Chem Res Toxicol 2014 May 8;27(5):895-903. Epub 2014 May 8.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research , Lucknow-226001, Uttar Pradesh, India.

Microglia play a dual role in neuroprotection as well as in neurodegeneration and thus occupy the focal interest in neurodegenerative disease research. In vitro studies either by using cell lines or neonatal mouse primary microglia correlated xenobiotic induced microglial activation and neuronal death. However, these in vitro studies cannot portray the in vivo scenario. Therefore, environmental pollutant induced in vivo alteration in microglial function can be best assessed by ex vivo analysis, which is not in use because of limitations in the isolation procedure. Therefore, in the first part of the study we describe an optimized isolation procedure and characterization of isolated cells. The second part of the study demonstrates the utility of the isolated cells in evaluation of immunotoxicological alterations following arsenic, as a model xenobiotic, exposure. Purity of the isolated microglia was checked by immunostaining of microglial (CD11b and CD68) and nonmicroglial (GFAP) markers. Immunostaining of activation marker Iba1 proves that cells were not activated during the isolation procedure. Microglia yield and viability from the treated group shows no significant alterations compared to that of the control group. Proinflammatory cytokines (IL-6 and TNF-α) were upregulated following arsenic treatment as in the case of the LPS stimulated group without alterations in anti-inflammatory IL-10. Phagocytic potential was affected significantly following arsenic exposure without alteration in viability. Thus, our protocol can be proficiently used for quick isolation of primary microglia from adult mouse brain without altering their activation status, and most importantly, the isolated cells can be of aid to the ex vivo evaluation of immunotoxicological alterations.
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http://dx.doi.org/10.1021/tx500046kDOI Listing
May 2014

Consequences of tributyltin chloride induced stress in Leydig cells: an ex-vivo approach.

Environ Toxicol Pharmacol 2014 Mar 3;37(2):850-60. Epub 2014 Mar 3.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), P.O. Box 80, Mahatma Gandhi Marg, Lucknow-226001, India. Electronic address:

Tributyltin (TBT), a member of the organotin family, is a known endocrine disruptor. It persists long in the environment and is widely used in various industrial applications. This study was planned to understand its toxic influence on Leydig cells isolated from 28 day old wistar rats. In-vitro exposure to TBT-Chloride (TBTC) (300-3000 nM) reduced cell viability (DNA fragmentation, nuclear condensation and MTT assay) and affected testosterone production. TBTC induced both apoptotic and necrotic cell death (AnnexinV/PI binding assay). Involvement of calcium (Ca(2+)), redox imbalance (ROS, GSH and TBARS) and mitochondria in TBTC toxicity was evaluated by using Ca(2+) inhibitors (BAPTA-AM, EGTA, Ruthenium Red), free radical scavengers (NAC, C-Phycocyanin) and mitochondrial permeability transition pore inhibitor (Cyclosporine A). Protein expression analysis of phosphorylated MAPKinases (ERK1/2, JNK1/2, & p38), steroidogenic proteins (3β-HSD, StAR & TSPO) and apoptotic proteins (Bax, Bcl2) illustrates the cytotoxic and anti-steroidogenic activity of TBTC.
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http://dx.doi.org/10.1016/j.etap.2014.02.018DOI Listing
March 2014

Comparative toxicity of low dose tributyltin chloride on serum, liver, lung and kidney following subchronic exposure.

Food Chem Toxicol 2014 Feb 1;64:335-43. Epub 2013 Dec 1.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, India. Electronic address:

Tributyltin (TBT) pollution is rampant worldwide and is a growing threat due to its bio-accumulative property. Isolated studies of TBT toxicity on different organs are available but consolidated information is greatly lacking. We planned this study to delineate the effect of subchronic (1 month) exposure to low dose TBT-chloride (TBTC) (1 and 5 mg/kg) in male Wistar rats. Total tin concentration was found to be significantly increased in liver, kidney and blood, and marginally in lungs. Organo-somatic indices were seen to be altered with little effect on serum biochemical markers (liver and kidney function, and general parameters). Reactive oxygen species but not lipid peroxidation content was observed to be significantly elevated both in the tissues and serum. TBTC was found to act as a hyperlipidemic agent and it also affected heme biosynthetic pathway. Hematological analysis showed that TBTC exposure resulted in minor alterations in RBC parameters. Histological studies demonstrated marked tissue damage in all the 3 organs. Calcium inhibitors (BAPTA-AM, EGTA) and antioxidants (NAC, C-PC) significantly restored TBTC induced loss in cell viability, under ex-vivo conditions. Antioxidants were evidently more efficient in comparison to the calcium inhibitors, implying major role of oxidative stress pathways in TBTC toxicity.
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http://dx.doi.org/10.1016/j.fct.2013.11.031DOI Listing
February 2014

Tributyltin chloride induced testicular toxicity by JNK and p38 activation, redox imbalance and cell death in sertoli-germ cell co-culture.

Toxicology 2013 Dec 17;314(1):39-50. Epub 2013 Sep 17.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), P.O. Box 80, Mahatma Gandhi Marg, Lucknow 226001, India.

The widespread use of tributyltin (TBT) as biocides in antifouling paints and agricultural chemicals has led to environmental and marine pollution. Human exposure occurs mainly through TBT contaminated seafood and drinking water. It is a well known endocrine disruptor in mammals, but its molecular mechanism in testicular damage is largely unexplored. This study was therefore, designed to ascertain effects of tributyltin chloride (TBTC) on sertoli-germ cell co-culture in ex-vivo and in the testicular tissue in-vivo conditions. An initial Ca(2+) rise followed by ROS generation and glutathione depletion resulted in oxidative damage and cell death. We observed p38 and JNK phosphorylation, stress proteins (Nrf2, MT and GST) induction and mitochondrial depolarization leading to caspase-3 activation. Prevention of TBTC reduced cell survival and cell death by Ca(2+) inhibitors and free radical scavengers specify definitive role of Ca(2+) and ROS. Sertoli cells were found to be more severely affected which in turn can hamper germ cells functionality. TBTC exposure in-vivo resulted in increased tin content in the testis with enhanced Evans blue leakage into the testicular tissue indicating blood-testis barrier disruption. Tesmin levels were significantly diminished and histopathological studies revealed marked tissue damage. Our data collectively indicates the toxic manifestations of TBTC on the male reproductive system and the mechanisms involved.
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http://dx.doi.org/10.1016/j.tox.2013.09.003DOI Listing
December 2013

Tributyltin induces oxidative damage, inflammation and apoptosis via disturbance in blood-brain barrier and metal homeostasis in cerebral cortex of rat brain: an in vivo and in vitro study.

Toxicology 2013 Aug 3;310:39-52. Epub 2013 Jun 3.

Immunotoxicology Division, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Mahatma Gandhi Marg, Lucknow 226001, India.

Tributyltin (TBT), a member of the organotin family, is primarily used for its biocidal activity. Persistent environmental levels of TBT pose threat to the ecosystem. Since neurotoxic influence of TBT remains elusive, we therefore, studied its effect on cerebral cortex of male Wistar rats. A single oral dose of Tributyltin-Chloride (TBTC) (10, 20, 30mg/kg) was administered and the animals were sacrificed on day 3 and day 7. Blood-brain barrier permeability remained disrupted significantly till day 7 with all the doses of TBTC. Pro-oxidant metal levels (Fe, Cu) were increased with a concomitant decrease in Zn. ROS generation was substantially raised resulting in oxidative damage (increased protein carbonylation and lipid peroxidation) with marked decline in tissue antioxidant status (GSH/GSSG levels). Protein expression studies indicated astrocyte activation, upregulation of inflammatory molecules (IL-6, Cox-2 and NF-κB) and simultaneous elevation in the apoptotic index (Bax/Bcl2). Neurodegeneration was evident by reduced neurofilament expression and increased calpain cleaved Tau levels. The in-vitro study demonstrated involvement of calcium and signaling molecules (p38), with downstream activation of caspase-3 and -8, and apoptotic cell death was evident by nuclear fragmentation, DNA laddering and Annexin V binding experiments. Ca(2+) inhibitors (BAPTA-AM, EGTA, and RR) and free radical scavengers (NAC and biliprotein [C-PC]) increased cell viability (MTT assay), signifying specific roles of Ca(2+) and ROS. Significance of p38 signaling was evaluated on pro-apoptotic proteins by using SB203580, a selective p38 inhibitor. Our data collectively illustrates that TBTC can disrupt BBB, induce oxidative stress, cause cell death and initiate neurodegeneration in rat brain.
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http://dx.doi.org/10.1016/j.tox.2013.05.011DOI Listing
August 2013

Cadmium induces thymocyte apoptosis via caspase-dependent and caspase-independent pathways.

J Biochem Mol Toxicol 2013 Mar 11;27(3):193-203. Epub 2013 Jan 11.

Department of Pharmaceutical Sciences, Birla Institute of Technology, Mesra, Ranchi, 635 215, India.

Based on our recent findings that 25 µM cadmium triggers oxidative stress-mediated caspase-dependent apoptosis in murine thymocytes, this study is designed to explore whether Cd also induces caspase-independent apoptosis. We found that pretreatment with caspase inhibitors fails to prevent Cd-induced apoptosis completely, suggesting the possibility of an additional pathway. Western blot and flow cytometry techniques indicated marked expression of apoptosis-inducing factor and endonuclease G in nuclear fraction, signifying their translocation from mitochondria to nucleus. Intracellular Ca²⁺ and reactive oxygen species (ROS) levels significantly raised by Cd were restored by ruthenium red, which had no influence on mitochondrial membrane depolarization and caspase activity and apoptosis. Using cyclosporin A, ROS formation and mitochondrial membrane depolarization were completely abolished, whereas apoptosis was partly attenuated. These results clearly demonstrate more than one apoptotic pathway in thymocytes and support the role of mitochondrial permeability transition pore in the regulation of caspase-independent cell death triggered by Cd.
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http://dx.doi.org/10.1002/jbt.21468DOI Listing
March 2013