الفهرس 
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Abstract
Exposure to environmental pollution from ionizing
radiation as well as aluminum had been connected with the
manifestation of neurodegenerative changes after long-term
exposure.
Aloe vera (barbadensis) was shown to possess anti-tumor
activity, anti-inflammatory, anti-bacterial, anti-diabetic, antimicrobial
and antioxidant properties.
The objective of the present study is to elucidate the
neurotoxic potentials of exposure to aluminum and/or -
radiation induces oxidative stress and neurotransmitter
alterations in rat’s brain tissue. In addition, the role of Aloe vera
in modulating the severity of biochemical and histological
changes that occur in the brain of irradiated and aluminum
exposed rats.
Adult male albino rats Sprague Dawley (100 ± 10 g),
were used as experimental animals. Aloe vera was dissolved in
distilled water and administered via gavages, to rats at doses of
200 mg/Kg body weight/day. Aloe vera was freshly prepared
just before its daily administration.
Summary and Conclusion
152
Experimental animals (144) were divided into eight
groups (18 rats each) as follows:
group I (Control group): rats received distilled water
via gavages daily for a period of 4 weeks.
group II (Aloe vera group): rats received Aloe vera gel
powder (200 mg/Kg b.w/day) via gavages for a period of 4
weeks.
group III (Ir group): rats were whole body -irradiated
with 8 Gy administered in four fractions of 2 Gy once a week
during 4 weeks.
group IV (Aloe vera+Ir group): rats received Aloe vera
gel powder (200 mg/Kg b.w/day) via gavages for a period of 4
weeks. On the 7th day of every week one hour post Aloe vera
treatment rats were whole body -irradiated with 2 Gy once a
week during four weeks .
group V (Al group): rats received Al2(SO4)3
(0.2 mg/Kg b.w/day) via gavages for a period of 4 weeks.
group VI (Aloe vera+Al group): rats received Aloe
vera gel powder (200 mg/Kg b.w/day) one hour before the
administration of Al2(SO4)3 (0.2 mg/Kg b.w/day) for a period of
4 weeks.
Summary and Conclusion
153
group VII (Al+Ir group): rats received Al2(SO4)3
(0.2 mg/Kg b.w/day) via gavages for a period of 4 weeks. On
the 7th day of every week 1 hour post Al2(SO4)3 treatment rats
were whole body -irradiated with 2 Gy once a week during
four weeks.
group VIII (Aloe vera+Al+Ir group): rats received
Aloe vera gel powder (200 mg/Kg b.w/day) via gavages 1 hour
before the administration of Al2(SO4)3 (0.2 mg/Kg b.w/day) for
a period of 4 weeks. On the 7th day every week one hour post
Al2(SO4)3 treatment rats were whole body -irradiated with
2 Gy once a week during four weeks.
Animals were sacrificed one day post the last dose of -
radiation. The two cerebral hemispheres were separated and
rapidly excised, washed in ice cold saline, wiped dry with a
filter paper and weighed for the further biochemical analysis.
The results obtained could be summarized as follows:
1- Oxidative stress in brain tissues:
Whole body gamma irradiation of rats with 8 Gy
administered in four fractions of 2 Gy/week for a period of 4
weeks and exposure to Al2(SO4)3 at a dose of 0.2 mg/kg body
weight/day, induced a significant increase in the levels of brain
oxidant biomarkers: thiobarbituric acid reactive substances
Summary and Conclusion
154
(TBARS), protein carbonyl group (CO) and aluminum (Al)
associated with a significant decrease in the levels of brain
superoxide dismutase (SOD), catalase (CAT), glutathione
peroxidase (GSH-Px) activities and reduced glutathione (GSH)
content compared to control values.
2- Neurotransmitter alterations in brain tissues:
Whole body gamma irradiation of rats with 8 Gy
administered in four fractions of 2 Gy/week for a period of 4
weeks and exposure to Al2(SO4)3 at a dose of 0.2 mg/kg body
weight/day, induced a significant decrease in the levels of brain
catecholamines: dopamine (DA), nor epinephrine (NE),
epinephrine (EPI) and serotonin (5-HT). A significant increase
in 5-hydroxy indole acetic acid (5-HIAA), monoamine-oxidase
(MAO) activity and serotonergic activity (5-HIAA/5-HT). A
significant decrease in catecholamines / serotonin ratio while a
significant increase in glutamic (Glu) and aspartic (Asp) acids
levels, was recorded compared to control values.
3- Modulator effect of Aloe vera:
Supplementation of rats with Aloe vera gel powder at a
dose of 200 mg/Kg body weight/day, via gavages for 4 weeks
during exposure to Al2(SO4)3 and whole body gamma
irradiation has significantly attenuated the severity of radiationSummary
and Conclusion
155
induced oxidative stress and neurotransmitter alterations in
brain tissues evidenced by a significant increase in SOD, CAT,
GSH-Px and GSH content, associated with a significant
decrease in TBARS, CO and Al levels, compared to their
respective values in aluminum and/or irradiated rats not
receiving Aloe vera.
Amelioration of oxidative stress in brain tissues was
associated with improvement of the histopathological changes
noticeable by less thrombotic vessels and slight deposition of β-
amyloid protein. Furthermore, a significant amelioration in the
levels of DA, NE, EPI, 5-HT, 5-HIAA, MAO activity,
serotonergic activity, catecholamines / serotonin ratio, glutamic
and aspartic acid levels was recorded in brain tissues.
4- Histopathological changes in brain tissues:
Oxidative stress in brain tissues of rats exposed to
-radiation, aluminum as well as aluminum combined with
-radiation was accompanied by histopathological changes
manifested by large thrombotic vessels and β-amyloid protein
deposition, The damage in brain tissues was aggravated by
exposure of rats to the combined effect of Al and -radiation as
beside large thrombotic vessels, cytotoxic edema, eosinophilia,
macrophages and intensive β-amyloid protein deposition were
observed.
Summary and Conclusion
156
Conclusion:
Exposure to aluminum and/or -radiation induced
oxidative stress and histopathological damage in brain tissues
with concomitant alteration in neurotransmitters. Exposure to
aluminum combined with -radiation increased the severity of
these changes
The oral administration of Aloe vera gel powder offer
protection against aluminum and/or -radiation biochemical and
histopathological disorders in brain tissues, probably by
exerting its effect via its free radical scavenging and membrane
stabilizing ability