الفهرس 
General side effects of SiO2 NPsOnly 14 pages are availabe for public view
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Abstract
Silicon dioxide nanoparticles are increasingly used in
various applications including agriculture, industrial,
medical and cosmetics despite of their toxicity. It causes
lipid peroxidation, oxidative DNA damage, disruption of
cell membrane, mitochondrial damage, apoptosis induction
and anti-proliferative activity. Vitamin B12 is used as an
antioxidant and offers protection against the oxidative
stress. The present study aimed to investigate the protective
role of vitamin B12 against the hepatotoxic potency of
silicon dioxide nanoparticles (SiO2 NPs) in adult male rats.
Sixty male albino rats were used to study the
biochemical analysis of liver function parameters,
including ALT, AST, ALP, and albumin in the blood serum
while, MDA, SOD and GSH were evaluated in liver tissue.
In addition, the histological alteration, histochemical
changes including polysaccharides and total proteins as
well as immunohistochemistry study was detected. The
experimental animals were divided into six groups, 10 rats
each. Group1 (control): Rats received 0.5 ml of 0.9% saline
orally for 8 weeks. group 2 (Vit.B12): Rats were treated
with saline for 4 weeks then treated with therapeutic dose
of Vit.B12 (0.6 mg/kg b.wt.) daily for another 4 weeks.
group 3 (SiO2 NPs): Rats were treated orally with saline
for 4 weeks then given SiO2 NPs (500 mg/kg b.wt.) twice a
week for another 4 weeks. group 4 (SiO2 NPs, Vit.B12 ):
Rats were administrated with SiO2 NPs at dose (500 mg/kg b.wt.) twice a week for 4 weeks then treated with vit.B12
(0.6 mg/kg b.wt.) daily for another 4 weeks. group 5 (SiO2
NPs + Vit.B12): Rats were treated orally with saline for 4
weeks then treated with SiO2 NPs along with Vit.B12 for
another 4 weeks. group 6 (Vit.B12, SiO2 NPs + Vit.B12):
(Protective group) Rats were treated with vit.B12 for 4
weeks then received SiO2 NPs in association with vit.B12 1
hour prior to Vit.B12 treatment for additional 4 weeks.
The results of the present study revealed that the
mean final body weight decreased and the absolute and
relative liver weights were increased after SiO2 NPs
administration. There was a very highly significant increase
in ALT, AST, ALP and MDA while, there was a significant
decrease in albumin, SOD and GSH levels.
The histological studies displayed deleterious
alterations in the hepatic tissue where SiO2 NPs caused
distortion of hepatic architecture with swollen vacuolar
degeneration and necrosis of hepatocytes. Some nuclei of
the degeneration cells showed pyknosis and the other
showed karyolysis. Inflammatory cellular infiltration and
dilatation of the blood vessels, meanwhile the collagen
fibers increased. Histochemical studies revealed that SiO2
NPs decreased polysaccharides and total proteins in the
hepatocytes. The immunohistochemical studies exposed an
increase in both caspase-3 and p53 activity after SiO2 NPs
administration.
In SiO2 NPs followed by vitamin B12 group and SiO2
NPs with vitamin B12 group, vitamin B12 showed slight and moderate improvement in all the previous parameters
according to antioxidative effect of vitamin B12.
On the other hand, vitamin B12 followed by SiO2 NPs
with vitamin B12 group showed marked recovery in all
these alterations induced by SiO2 NPs.