Abstract:
The application of cerium oxide nanoparticle or nanoceria (CeO2NPs) in biomedical
sciences as an antioxidant agent has gained prominence in recent times. Further
medical application of CeO2NPs is still evolving. However, this approach has not been
fully elucidated. In this research report, I evaluated the outcome of CeO2NPs treatment
on the liver and testis, and its ameliorative potential in diethylnitrosamine (DEN)-
induced hepatotoxicity and, N-Nitroso-N-methylurea (NMU) and Benz[a]pyrene
(BaP)-induced mammary toxicity.
Twenty male Swiss mice (30.0±2.1g) were divided into four groups (n=5): control,
100, 200 and 300 µg/kg CeO2NPs. Nanoceria was administered intraperitoneally three
times per week for 5 recurring weeks. Mice were sacrificed, blood was collected and
testes were harvested for analyses. The second study consist of six groups (n=6) and
treated thus: Control, DEN, [DEN+CeO2NPs (100 µg/kg)], [DEN+CeO2NPs (200
µg/kg)], CeO2NPs (100 µg/kg) and CeO2NPs (200 µg/kg). Mice were pre-treated with
CeO2NPs daily for eight days and, hepatotoxicity was induced by single administration
of DEN (200 mg/kg, i.p). In the third study, 24 female rats were allocated into 4
groups (n=6), and treated thus: Control, [NMU+BaP], [NMU+BaP+CeO2NPs] and
[NMU+BaP+Vincristine]. The NMU and BaP were administered at 50 mg/kg thrice (at
week 7, 10 and 13), while Vincristine [(positive control) (0.5 µg/kg)] and CeO2NPs
(200 µg/kg) were administered twice and thrice per week, respectively.
Haematological [Haemoglobin (Hb), Packed cell volume (PCV) and red blood cell
(RBC) count] and biochemical indices [Alanine Aminotransferase (ALT), urea,
antioxidant enzymes and Malondialdehyde (MDA)] were determined by standard
methods. Hormones: Luteinizing hormone (LH), follicle stimulating hormone (FSH)
and prolactin were estimated by ELISA, while inflammatory markers; inducible Nitric
Oxide Synthase (iNOS) and Cyclooxygenase-2 (COX-2), and apoptotic indices; Bcl-2
associated X-protein (Bax), p53 and Caspase-3 were determined by
immunohistochemistry. Micro-section of tissues were stained with Haematoxylin and
Eosin and viewed under light microscope. Data were analysed using ANOVA at α0.05.
In study one, nanoceria reduced Haemoglobin by 71% and 35%, packed cell volume
by 69% and 26% and red blood cell count by 69% and 36% at 100 and 300μg/kg
CeO2NPs, respectively compared to control. The LH (11.30±1.52 and 10.30±0.57 vsvii
19.51±0.52), FSH (9.66±1.15 and 7.33±0.57 vs 18.40±0.50) and prolactin (6.05±1.00
and 4.33±0.57 vs 9.31±0.43) were decreased in 200 and 300μg/kg CeO2NPs-treated
mice, respectively compared to control. Testicular MDA level was increased by 67%
and 78% in 200 and 300 µg/kg CeO2NPs-treated mice respectively, and an attendant
decrease in activities of antioxidant enzymes. In the second study, pre-treating using
CeO2NPs (100 and 200 µg/kg) decreased ALT activity by 24% and 23%, respectively.
Likewise, CeO2NPs at 200 µg/kg caused 35% reduction in MDA level and
concomitant increase in antioxidant enzymes. The liver showed weak expression of
iNOS and Cox-2 when pre-treated with CeO2NPs. In the third study, the [NMU+BaP]
decreased the activities of mammary antioxidant enzymes while increasing MDA
level. Caspase-3, Bax and p53 were reduced in [NMU+BaP] animals. Histology
revealed severe peri-vascular infiltration of inflammatory cells in hepatocytes of DENtreated mice, and malignancy in mammary tissues of [NMU+BaP] animals. Treatment
with CeO2NPs (200μg/kg b.wt) attenuated altered biochemical, inflammatory and
antioxidant markers, and cyto-architectures of liver and mammary tissues in DEN- and
[NMU+BaP]-treated animals.
Nanoceria ameliorated chemically induced hepatic, reproductive and mammary gland
toxicity in animals via induction of apoptosis and antioxidant enzymes.
