Browsing by Author "Swati Agarwal"

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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.
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.
Correction to: Inhibitory Effects of Bisphenol-A on Neural Stem Cells Proliferation and Differentiation in the Rat Brain Are Dependent on Wnt/β-Catenin Pathway (Molecular Neurobiology, (2015), 52, 3, (1735-1757), 10.1007/s12035-014-8940-1)
(Humana Press Inc., 2019) Shashi Kant Tiwari; Swati Agarwal; Brashket Seth; Anuradha Yadav; Ratan Singh Ray; Vijay Nath Mishra; Rajnish Kumar Chaturvedi
The original version of this article unfortunately contained a mistake. The authors observed inadvertent error in Figure 3A and 6C wish to correct it. The corrected representative images are incorporated below. This correction in no way changes the text of the article, conclusion and figure legend. The authors regret for this error and would like to apologize for any inconvenience caused to the readers. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
Inhibitory Effects of Bisphenol-A on Neural Stem Cells Proliferation and Differentiation in the Rat Brain Are Dependent on Wnt/β-Catenin Pathway
(Humana Press Inc., 2015) Shashi Kant Tiwari; Swati Agarwal; Brashket Seth; Anuradha Yadav; Ratan Singh Ray; Vijay Nath Mishra; Rajnish Kumar Chaturvedi
Neurogenesis, a process of generation of new neurons, occurs throughout the life in the hippocampus and sub-ventricular zone (SVZ). Bisphenol-A (BPA), an endocrine disrupter used as surface coating for packaged food cans, injures the developing and adult brain. However, the effects of BPA on neurogenesis and underlying cellular and molecular mechanism(s) are still unknown. Herein, we studied the effect(s) of prenatal and early postnatal exposure of low dose BPA on Wnt/β-catenin signaling pathway that controls different steps of neurogenesis such as neural stem cell (NSC) proliferation and neuronal differentiation. Pregnant rats were treated with 4, 40, and 400 μg BPA/kg body weight orally daily from gestational day 6 to postnatal day 21. Both in vivo and in vitro studies showed that BPA alters NSC proliferation and differentiation. BPA impaired NSC proliferation (5′-bromo-2′-deoxyuridine (BrdU+) and nestin+ cells) and neuronal differentiation (BrdU/doublecortin+ and BrdU/neuronal nuclei (NeuN+) cells) in the hippocampus and SVZ as compared to control. It significantly altered expression/protein levels of neurogenic genes and the Wnt pathway genes in the hippocampus. BPA reduced cellular β-catenin and p-GSK-3β levels and decreased β-catenin nuclear translocation, and cyclin-D1 and TCF/LEF promoter luciferase activity. Specific activation and blockage of the Wnt pathway suggested involvement of this pathway in BPA-mediated inhibition of neurogenesis. Further, blockage of GSK-3β activity by SB415286 and GSK-3β small interfering RNA (siRNA) attenuated BPA-induced downregulation of neurogenesis. Overall, these results suggest significant inhibitory effects of BPA on NSC proliferation and differentiation in the rat via the Wnt/β-catenin signaling pathway. © 2014, Springer Science+Business Media New York.