RESUMEN
Neurogenesis occurs throughout life in the hippocampus of the brain, and many environmental toxicants inhibit neural stem cell (NSC) function and neuronal generation. Bisphenol-A (BPA), an endocrine disrupter used for surface coating of plastic products causes injury in the developing and adult brain; thus, many countries have banned its usage in plastic consumer products. BPA analogs/alternatives such as bisphenol-F (BPF) and bisphenol-S (BPS) may also cause neurotoxicity; however, their effects on neurogenesis are still not known. We studied the effects of BPF and BPS exposure from gestational day 6 to postnatal day 21 on neurogenesis. We found that exposure to non-cytotoxic concentrations of BPF and BPS significantly decreased the number/size of neurospheres, BrdU+ (proliferating NSC marker) and MAP-2+ (neuronal marker) cells and GFAP+ astrocytes in the hippocampus NSC culture, suggesting reduced NSC stemness and self-renewal and neuronal differentiation and increased gliogenesis. These analogs also reduced the number of BrdU/Sox-2+, BrdU/Dcx+, and BrdU/NeuN+ co-labeled cells in the hippocampus of the rat brain, suggesting decreased NSC proliferation and impaired maturation of newborn neurons. BPF and BPS treatment increases BrdU/cleaved caspase-3+ cells and Bax-2 and cleaved caspase protein levels, leading to increased apoptosis in hippocampal NSCs. Transmission electron microscopy studies suggest that BPF and BPS also caused degeneration of neuronal myelin sheath, altered mitochondrial morphology, and reduced number of synapses in the hippocampus leading to altered cognitive functions. These results suggest that BPF and BPS exposure decreased the NSC pool, inhibited neurogenesis, induced apoptosis of NSCs, caused myelin degeneration/synapse degeneration, and impaired learning and memory in rats.
RESUMEN
Heavy metal contamination in river Ganga is one of the factors for deterioration in its water quality and also adds to human health risks. We designed our study to achieve a holistic approach by not only estimating the concentration of heavy metals (lead, manganese, chromium, and cadmium) in the river water at different sites based on human anthropogenic activities but also in the fishes residing in the same sites that are collected for human consumption on daily basis. We found that Ganga River in Varanasi is highly loaded with metals (PLI = 6.698). Mean concentration in water was 1.29 mg/L for Pb, 1.325 mg/L for Mn, 0.169 mg/L for Cr, and 0.161 mg/L for Cd, which were above the permissible limits stated by Environment Protection Agency (EPA) in drinking water. Fish, including exotic and invasive species, were collected from the wild and were processed for the presence of these metals in their tissues. Degree of heavy metal concentration followed liver > gills > muscles. The highest accumulation of Pb was observed in Carpio (Cyprinus carpio) liver (8.86 µg/g) and lowest in Baikari (Clupisoma garua) muscles (0.07 µg/g). Total target hazard quotient (THQ) value, i.e., hazard index (HI) showed values in following sequence: Cyprinus carpio > Oreochromis niloticus > Channa gachua > Johnius coitor > Mastacembelus armatus > Mystus tengara > Clupisoma garua. Maximum HI value was recorded in C. carpio, which is highly consumed fish by humans, hence, may be harmful to them.
