الفهرس 
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Abstract
Aging is a normal physiological process causing changes in neuronal
circuitry and, in some individuals, resulting in impaired cognition and behavior.
Alzheimer’s disease (AD) is the most prevalent neurodegenerative
disorder, and its incidence is increasing markedly worldwide. It causes
progressive cognitive decline and is the most common cause of dementia in the
elderly.
On the other hand, Ozone proved to have anti-aging effects on the brain
and multiple desirable characteristics for a neuroprotective agent. The present
study tried to evaluate the effects of aging on the structure of rat hippocampus
(which is essential for the learning processes & memory) & the possible
protective role of ozone. The main objective in our study was to study the role
of ozone therapy in delaying the hippocampal degenerative changes in the aged
rats.
Material & Methods:
Thirty male albino rats were used in this study. They were classified
according to age into 10 adult & 20 aged rat (ten rat aged 20 months & ten rat
aged 22 months).
(group I) control group: comprised 15 rats that kept without any treatment and were divided into the following subgroups according to age
into:
Subgroup (Ia): aged 6 months consisted of 5 rats.
Subgroup (Ib): aged 20 months consisted of 5 rats.
Subgroup (Ic): aged 22 months consisted of 5 rats. (group II) ozone treated group: comprised 15 rats that received ozone
therapy at a dose of 0.7gm/kg interpertonially three times per week for 8
weeks and were divided into the following subgroups
Subgroup (IIa): aged 6 months consisted of 5 rats.
Subgroup (IIb): aged 20 months consisted of 5 rats.
Subgroup (IIc): aged 22 months consisted of 5 rats.
At the end of the experiment, all rats were anaesthetized by diethyl ether
inhalation. The skull vault was removed by dissection and the brain was
immediately placed in 10% boun’s solution. After 10 minutes, when the brain
soft tissue was hardened to avoid soft tissue dissipation, the temporal lobe of
right cerebral hemisphere was separated and coronal slices of 5-7mm-thickness
were taken at the level of hippocampus. The slices were fixed in 10% boun’s
solution for 24 hours and processed to prepare paraffin blocks. Five μm sections
were obtained and stained by:
1. Haematoxylin & Eosin stain (Hx & E).
2. Toulidine blue stain.
3. Silver stain.
4. Immunohistochemical staining of GFAP of the astrocytes.
5. Immunohistochemical staining of MAP2.
Morphometric measurements were done by the image analyzer for: 1. The number of the pyramidal cells.
2. The thickness of the hippocampus.
3. The area percentage of the positive GFAP immunostaining.
4. The area percentage of the positive MAP2 immunostaining.
5. The color intensity of MAP2 immunostaining. In the adult rats, no changes in the structure of the hippocampus were
observed in the adult control group & adult group received ozone. There was
increase in Nissl granule density. A decrease in the number & size of the GFAP
immunoreaction astrocytes was also observed and there were intense brown
MAP2 immunoreaction in the cytoplasm and the dendrites of the pyramidal
cells.
In the aged rats, the hippocampus sections showed disturbed
arrangement of the pyramidal cell layer, a significant decrease in the pyramidal
cell number & many degenerated shrunken pyramidal cells were observed.
vacuolations appeared in the molecular & polymorphic layers. There was
decrease in Nissl granule density. Appearance of the senile plaques,
neurofibrillary tangles and vacuolated neuropilic areas. An increase in the
number & size of the astrocytes with dense brown GFAP immunoreaction, and
there was decrease in the dendritic length and their arborization, reduction in the
density of the dendrites of the pyramidal cells with MAP2 immunoreactions.
The previous pathological changes were more observed and detected in
the rat aged 22 months than the rat aged 20 months.
In the aged rats received ozone, the structure of the hippocampus was
more or less similar to that of adult control rats. A significant increase in the
pyramidal cell number was observed. An increase in the Nissl granule content
in the cytoplasm of the pyramidal cell was noticed. An observable decrease in
the number & size of the GFAP immunoreactive astrocytes was also detected as
compared to aged control rats. Also an observable increase in the MAP2 immunoreaction in the cytoplasm and the dendrites of the pyramidal cells.