الفهرس 
IntroductionOnly 14 pages are availabe for public view
Abstract
Posttraumatic stress disorder (PTSD) is a debilitating
psychiatric disorder which develops after exposure to a
traumatic highly stressful events such as those occurring
during natural disasters, sexual abuse, massive accidents and
wars. Post traumatic stress disorder (PTSD) is complicated by
other related disorders such as substance abuse, depression
and memory impairments. It is associated with deterioration
of the ability to function in social and family life, leading to
marital problems, occupational instability and other social
problems. Stress is the most potent negative modulator of
hippocampal neurogenesis. The hippocampus is an important
region in the limbic system of the brain and is known to
regulate cognition and memory.
Most of the previous studies focused on the effect of
chronic stress on the hippocampus, but little work was
performed on the effects of single prolonged stress on the
hippocampus, particularly on the histological light and
electron microscopic level.
The current study was designed to evaluate the effect
of single prolonged stress on the structure of hippocampus in
adult male albino rats.
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The experiment was conducted on 40 adult male
albino rats weighing 200-250 grams. Rats were randomly
divided into two groups:
group I: Control group
This group included twenty rats that were left without
any interference. This group was further subdivided into four
subgroups five animals each. Rats in each subgroup were
sacrificed simultaneously with their corresponding stressed
subgroup.
group II: (Stress group):
This group included twenty rats that were subjected to
single prolonged stress (SPS). Rats were restrained by
placing them in plastic restrainers, immediately followed by
20 minutes of forced swimming in 20–24◦C water. Rats were
generally anasethized by ether then they were removed and
placed in their home cages.
This group was further subdivided into four subgroups
five animals each:
1. Subgroup IIa: rats in this subgroup were sacrificed 24
hours after exposure to single prolonged stress.
2. Subgroup IIb: rats were sacrificed four days after
exposure to single prolonged stress.
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3. Subgroup IIc: rats were sacrificed seven days after
exposure to single prolonged stress.
4. Subgroup IId: rats were sacrificed fourteen days after
exposure to single prolonged stress.
Biochemical results revealed an increase in blood
cortisol level of rats in Subgroups IIa, IIb, IIc followed by
reduction in cortisol level in subgroup IId.
Examination of Hx&E stained sections of groupI
(control group) showed the hippocampal formation
components: the dentate gyrus (DG), the hippocampus
proprius (cornu ammonis: CA1, CA2, CA3 and CA4). The
cells forming the hippocampus proper were the molecular,
the pyramidal and the polymorphic layer. The pyramidal cell
layer was the principle layer of the hippocampus. It was
formed of closely packed, regularly arranged pyramidal cells
containing single, central, large, rounded, vesicular nucleus
with prominent nucleolus and basophilic cytoplasm. In
Subgroup IIa the pyramidal cells lost their normal, crowded
arrangement. Few pyramidal cells were shrunken with
condensed, deeply stained and fragmented nuclei. In
Subgroup IIb the pyramidal layer showed apparent increase
in the number of shrunken, deeply stained neurons with
pyknotic nuclei as compared to Subgroup IIa. Subgroup IIc
showed the pyramidal layer with deeply stained neurons and
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pyknotic nuclei with apparent decrease in the thickness of the
pyramidal cell layer as compared to that of Subgroup IIa.
Subgroup IId showed many shrunken deeply stained
neurons with pyknotic nuclei and marked reduction in the
thickness of the pyramidal cell layer as compared to
Subgroups IIa, IIb, IIc which was confirmed by statistical
analysis. Apparent progressive decrease in the thickness of
the CA3 region with passage of time from Subgroup IIa to
Subgroup IId was detected.
Immunohistochemical expression of glial fibrillary
acidic protein (GFAP) showed positive reaction in the
control group. There was increased reaction, number and size
of astrocytes with elongated processes in subgroups IIa, IIb.
While there was decreased reaction, number and size of
astrocytes in subgroups IIc, IId.
Examination of toluidine blue stained sections
revealed pyramidal cells of the control group with rounded
vesicular nuclei and apparent Nissl granules. Pyramidal cells
of Subgroups IIa, IIb, IIc, IId showed the pyramidal
neurons with pyknotic deeply stained nuclei and unapparent
Nissl granules.
Transmission electron microscopic examination of
the control group showed nuclei of the pyramidal cells with
regular nuclear membrane. Mitochondria with regular cristae.
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Regular cisternae of rER, lysosome, regular Golgi apparatus
and numerous free ribosomes. The pyramidal cells of
Subgroup IIa showed irregular nucleus, dilated cisternae of
rER and vacuolated mitochondria. Golgi apparatuses
appeared with dilated saccules. In Subgroup IIb shrunken
pyramidal cell with peripherally located irregular nucleus.
The cytoplasm showed dilated cisternae of rER,
mitochondria appeared vacuolated, Golgi apparatus appeared
with dilated saccules. Many lysosomes were also observed.
Subgroup IIc showed severly degenerated shrunken
pyramidal neuron with irregular cell membrane,
heterochromatic irregular nucleus and condensed chromatin
crescents and electron dense cytoplasm. Pyramidal cells
showed dilated cisternae of rER with dispersed numerous
free ribosomes in between. Mitochondria appeared
vacuolated with distorted cristae. Autophagosome containing
vacuolated mitochondria were observed. Subgroup IId
showed many markedly degenerated shrunken pyramidal
neurons with irregular cell membrane heterochromatic
nucleus and electron dense cytoplasm. Pyramidal cells
showed dilated cisternae of rER. Mitochondria appeared
vacuolated with distorted cristae. More numerous lysosomes
were observed.