• Molecular mechanisms and predictive markers of neurotoxic potential of chemicals and prevention of neurodegeneration.

• Development and validation of in vitro models for studying neurotoxicity mechanisms.

• Validation of biomarkers for risk assessment.

• Neuroprotective effect of curcumin and Acorus calamus against neurotoxicants: 
  Studies were undertaken to investigate the mechanisms involved in neurodegeneration caused by lead and acrylamide and study the pretreatment and therapeutic effect of selected plant extracts viz. curcumin and Acorus calamus, being extensively used in traditional system of medicine. Rats treated with acrylamide and ethanolic extract of Acorus calamus (1:1) AC-002 in combination had lower incidence of paralysis and exhibited recovery in motor activity compared with those treated with acrylamide alone on day 10th of the experiment. The levels of reduced glutathione and glutathione-s-tranferase activity were increased and dopamine receptors decreased in corpus striatum in rats co-exposed to acrylamide and AC-002 as compared to those treated with ACR alone. The results suggest that neurobehavioral changes produced by acrylamide are prevented following treatment with ethanolic extract (1:1) of Acorus calamus. Likewise co-treatment of curcumin with lead caused a significant decrease in oxidative stress parameters with concomitant decrease in lead levels in corpus striatum, frontal cortex, hippocampus and cerebellum as compared to those treated with lead alone.

• Platelets: A peripheral model for neurotoxicity and neurological disorders: 
  Studies undertaken on platelets to validate their usefulness as a peripheral model revealed that similar to that observed in brain striatum, exposure of manganese, an heavy metal or cypermethrin, a type II synthetic pyrethroid in rats caused a significant increase in membrane fluidity, superoxide dismutase, monoamine oxidase activity and intracellular calcium levels and a decrease in dopamine receptors, reduced glutathione levels and catalase activity in the blood platelets. Parallel changes both in striatum and platelets, as observed in the present study, strengthen the usefulness of platelets as a peripheral neuronal model. 
  
  Studies undertaken to investigate the status of platelet 5-HT2A receptors in clinical cases of tension type headache revealed that the binding of 3H-Ketanserin, known to label 5-HT2A receptors, to platelet membranes was decreased both in cases of migraine and tension type headache as compared to controls. Scatchard analysis showed that this decrease in the binding in cases was due to decreased number of receptor binding sites (Bmax) suggesting serotonergic dysfunctions in headache.

• Influence of stress on the neurobehavioral toxicity of environmental chemicals: 
  Concurrent exposure to deltamethrin and immobilization stress caused a significant modification in neurotoxicity as evident by a significant decrease in cholinergic receptors, enhanced oxidative stress and alterations in the neurobehavioral parameters.

• In vitro Neurotransmitter Receptor assays for screening psychoactive potential: 
  A high throughput neurotransmitter receptor screen has been developed for rapid assessment of psychoactive potential and identify the active extracts (herbal, microbial, fungal, Unani and Siddha samples) and bioactive molecules that could be used in the treatment of neuro-psychiatric disorders including Parkinson's disease, depression, dementia and anxiety.

• Cytochrome P450s (CYPs) in mammalian brain:
  Our studies provided evidence for the expression of xenobiotic metabolizing cytochrome P450 1A1 (CYP1A1), 1A2, CYP2B1, 2B2, CY2E1 and CYP3A isoenzymes in rat brain and brain regions. Lindane, an organ chlorine insecticide, and deltamethrin, a pyrethroid insecticide was found to modulate the expression of xenobiotic metabolizing CYPs in rat brain and liver. Induction studies have demonstrated the involvement of CYPs in the neurobehavioral toxicity of these pesticides. 
  
  Our data further revealed relatively higher expression of xenobiotic metabolizing CYP1A-, CYP2B- and CYP2E1 in cultured rat brain neuronal cells when compared to the glial cells. Responsiveness of cultured neuronal and glial CYPs have suggested that CYPs may not only have a potential role in the toxication-detoxication mechanism but may be associated with alteration in specific neurotransmitter pathways and intricate signaling mechanisms in brain.

• Blood cytochrome P450 (CYPs): Biomarker of chemical exposure and effect: 
  Regulation of xenobiotic metabolizing CYPs was studied in freshly isolated rat blood lymphocytes for generating CYP expression profile in blood lymphocytes as a sensitive and mechanistic based biomarker of chemical exposure. Significant mRNA and protein expression of CYP1A1, 1A2, 2E1 and 3A isoenzymes in rat blood lymphocytes. Our data demonstrating similarities in the regulation of CYPs in blood lymphocytes with that of liver isoenzymes indicate that blood CYPs can be used as a surrogate to monitor hepatic changes of these enzymes.

• Predictive toxicology and single nucleotide polymorphism (SNPs):
  The information on the individuals that are in high-risk category because of their genetic predisposition, will be helpful in protecting them from the harmful effects of environmental toxicants as well as adverse drug effects. Studies were initiated in a CSIR network program coordinated by IGIB, N. Delhi to identify SNPs in the enzymes (CYPs, GSTs, oxidative stress enzymes etc) involved in xenobiotic metabolism and toxicity in the Indian population. Our data revealed the presence of several of the SNPs in these genes in representative samples of Indian populations. Further studies are in progress to validate these SNPs in these populations. 
  
  In a case-control study, association of SNPs in CYP1B1 and glutathione S-transferases (GSTs) was investigated with head and neck cancer (HNSCC). An increase in risk to HNSCC was observed in the patients with deletion genotypes of GST (GSTM1) or variant genotypes of CYP1B1 (CYP1B1*2). Patients carrying combination of deletion genotypes of GST or certain haplotypes of CYP1B1(G-T-C-A and G-T-G-A) were at greater risk indicating the role of gene-gene interaction in HNSCC. Furthermore, interaction between tobacco chewing or alcohol drinking and null genotypes of GSTM1 or GSTT1 or CYP1B1*2 and CYP1B1*3 resulted in several fold increase in the risk in the patients demonstrating the importance of gene-environment interactions in modulating the risk to HNSCC.

• Molecular mechanisms of DNA damage and repair and its use in risk assessment: 
  Studies on the DNA damage and repair due to environmental chemicals including nanoparticles using in vitro and in vivo models employing conventional cytogenetic techniques such as micronucleus assay, chromosomal aberrations and more recent and sensitive techniques viz. comet assay and flow micronucleus assay. The mechanism of DNA damage is studied using DNA repair mutants of Drosophila melanogaster and pathway specific real time PCR arrays and metabolomic approaches. The studies are conducted using state of the art equipment such as Komet Image analysis system for comet assay, Leica Q-Fluoro image analysis system and Zetasizer nanoZS for measurement of Zeta size, potential and molecular weight of nanoparticles. Human monitoring studies using DNA damage as a biomarker of exposure and effect are conducted on normal and exposed population. To predict the toxicity at an early stage as well as to understand the mechanism of toxicity, in silico quantitative structure toxicity relationships (QSTR) and modeling studies are also conducted.

• In Vitro Models for Cerebral Stroke: 
  Studies carried out to develop cerebral ischemia model using primary cultures of rat brain neuronal cells and PC-12 cells, a rat pheochromocytoma cell line following oxygen and glucose deprivation (OGD) and then re-oxygenation (24h) under regular atmospheric oxygen in medium with glucose (4-6 mg/ml) revealed that these model systems were found to mimic the events similar to the pathophysiological events occurring in vivo following cerebral stroke. Validation of these models is currently in process using herbal drugs with known antioxidant properties.

• In addition to R&D, this Division is also engaged in providing service to Industries by undertaking sponsored studies on routine toxicity assessment. These studies include safety assessment of plastic and polymeric products, polyelectrolytes etc. Cytotoxicity assessment and endotoxin detection in plastic biomedical products and other health related items are also being carried out routinely. Based on these reports, BIS have revised specifications for safety evaluation of plastics and polymer products. The laboratory is NABL accredited for chemical and biological testing as per ISO/IEC 17025 guidelines.
  
  In vitro studies using human neuroblastoma cell lines (SHY-SY-5Y, IMR-32) & rodent lines viz. rat pheochoromocytoma cell line (PC-12) and rat glioma cell line (C-6) have also been developed as an in vitro screening system for studying efficacy of newer psychoactive drugs or neurotoxicity of environmental chemicals. These models have been standardized and are now being used to evaluate the efficacy and toxicity of newer psychoactive drugs and environmental chemicals.

• Medium throughput facility for receptor binding

• Neurobehavioral facility

• In vitro facility for toxicity assessment

• Safety evaluation of plastics and polymers (NABL accredited)

• Comet assay facility

• In-silico facility

• Real Time-PCR

Research Fellows:
Dr. Kavita Seth, Scientist Fellow
Ms. Ashu Johri, ICMR-SRF
Ms. Madhu Singh, CSIR-SRF
Ms. Santosh Yadav, ICMR-SRF
Ms. Nishi Srivastava, CSIR-SRF
Mr. Arvind P. Singh, CSIR-SRF
Mr. Anwar J. Khan, ICMR-SRF
Ms. Sushila Patel, CSIR-SRF
Mr. Munindra Ruwali, ICMR-JRF
Ms. Vyom Sharma, CSIR-JRF
Mr. R.K. Shukla, UGC-JRF
Ms. Poonam Singh, UGC-JRF
Mr. Deepak Gurbani, CSIR-JRF
Mr. M.P. Kashyap, UGC-JRF
Ms Madulata Sankhwar, CSIR-JRF
Mr. R.S. Yadav, UGC-JRF

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