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environmental toxicology
WILEY
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Abstract: |
A human is exposed to a chemical mixture rather than a single chemical, particularly
with the wide spread of nanomaterials. Therefore, the present study evaluated the
combined exposure of lead acetate (Pb) and zinc oxide-nanoparticles (ZnO-NPs) compared
to each metal alone on the thyroid gland of adult rats. A total of 30 adult male
albino rats were divided into four groups, group I (control), group II received Pb
(10 mg/kg), group III received ZnO-NPs (85 mg/kg) and group IV co-administrated
the two metals in the same previous doses. The materials were gavaged for 8 weeks.
The toxicity was assessed through several biochemical parameters. Our results revealed
significant body weight reduction relative to increased thyroid weights,
decreased both of serum-free triiodothyronine (FT3), tetra-iodothyronine (FT4),
increased thyroid-stimulating hormone (TSH), increased serum and thyroid levels of
Pb and zinc, significant elevation in tumor necrosis factor-α (TNF-α), reduction in
interleukin 4 (IL4), upregulation of Bax, and downregulation of Bcl-2 genes. Additionally,
there was significant overexpression of nuclear factor erythroid 2-related
factor 2(Nrf2), 8-Hydroxydeoxyguanosine(8-OHdG), the elevation of tissues
malondialdehyde (MDA), reduction of tissues total antioxidant capacity (TAC), and
disruptive thyroid structural alterations in all metals groups with marked changes in
the combined metals group. In conclusion, the combined exposure of Pb and ZnONPs
induced pronounced toxic thyroid injury, pointing to additive effects in rats than
the individual metal effects through different significant changes of disruptive thyroid
structural alterations related to the loading of thyroid tissues with Pb and zinc metals
producing oxidative stress that mediated inflammation and apoptosis.
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