Browsing by Author "Lalit Kumar Singh Chauhan"

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Bisphenol-A Impairs Myelination Potential During Development in the Hippocampus of the Rat Brain
(Humana Press Inc., 2015) Shashi Kant Tiwari; Swati Agarwal; Lalit Kumar Singh Chauhan; Vijay Nath Mishra; Rajnish Kumar Chaturvedi
Myelin is the functional implication of oligodendrocytes (OLs), which is involved in insulation of axons and promoting rapid propagation of action potential in the brain. OLs are derived from oligodendrocyte progenitor cells (OPCs), which proliferate, differentiate, and migrate throughout the central nervous system. Defects in myelination process lead to the onset of several neurological and neurodegenerative disorders. Exposure to synthetic xenoestrogen bisphenol-A (BPA) causes cognitive dysfunction, impairs hippocampal neurogenesis, and causes onset of neurodevelopmental disorders. However, the effects of BPA on OPC proliferation, differentiation and myelination, and associated cellular and molecular mechanism(s) in the hippocampus of the rat brain are still largely unknown. We found that BPA significantly decreased bromodeoxyuridine (BrdU)-positive cell proliferation and number and size of oligospheres. We observed reduced co-localization of BrdU with myelination markers CNPase and platelet-derived growth factor receptor-α (PDGFR-α), suggesting impaired proliferation and differentiation of OPCs by BPA in culture. We studied the effects of BPA exposure during prenatal and postnatal periods on cellular and molecular alteration(s) in the myelination process in the hippocampus region of the rat brain at postnatal day 21 and 90. BPA exposure both in vitro and in vivo altered proliferation and differentiation potential of OPCs and decreased the expression of genes and levels of proteins that are involved in myelination. Ultrastructural electron microscopy analysis revealed that BPA exposure caused decompaction of myelinated axons and altered g-ratio at both the developmental periods as compared to control. These results suggest that BPA exposure both during prenatal and postnatal periods alters myelination in the hippocampus of the rat brain leading to cognitive deficits. © 2014, Springer Science+Business Media New York.
Cellular internalization and stress response of ingested amorphous silica nanoparticles in the midgut of Drosophila melanogaster
(2013) Ashutosh Pandey; Swati Chandra; Lalit Kumar Singh Chauhan; Gopeshwar Narayan; Debapratim Kar Chowdhuri
Background: Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (< 30 nm) in the midgut of Drosophila melanogaster (Oregon R+) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles. Methods: Third instar larvae of D. melanogaster were exposed orally to 1-100 μg/mL of aSNPs for 12-36 h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints. Results: A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration. Conclusion: aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death. General significance: Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health. © 2012 Elsevier B.V. © 2012 Elsevier B.V. All rights reserved.
Correction to: Bisphenol-A Impairs Myelination Potential During Development in the Hippocampus of the Rat Brain (Molecular Neurobiology, (2015), 51, 3, (1395-1416), 10.1007/s12035-014-8817-3)
(Humana Press Inc., 2019) Shashi Kant Tiwari; Swati Agarwal; Lalit Kumar Singh Chauhan; Vijay Nath Mishra; Rajnish Kumar Chaturvedi
The original version of this article unfortunately contained a mistake. The authors regret that inadvertent errors were observed in Figure 2E and Figure 10 B&D. The corrected representative images are now incorporated. These corrections does not change the conclusions and text of the article. The authors would like to apologize for any inconvenience caused. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.