THE EFFECTS OF TOCOTRIENOL RICH FRACTION ON CHRONIC RESTRAINT STRESSINDUCED CHANGES IN THE HIPPOCAMPUS OF MALE RATS
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Date
2012
Authors
SAIFUL BAHRI, TALIP
Journal Title
Journal ISSN
Volume Title
Publisher
Pusat Pengajian Sains Perubatan Universiti Sains Malaysia
Abstract
Tocotrienol is a member of natural vitamin E that consists of 4 chemically
distinct forms: α-, β-, γ- and δ-tocotrienol. Tocotreinol has anti oxidant capacity.
Several studies showed the potential protective effect of tocotrienol on stress related
organ injury. However the role of tocotrienol on hippocampus after exposure to
stress is still largely unknown. Stress is one of the psychological problems which
affects most of the individuals in their daily life. Stress may damage the brain
especially the hippocampus if it occurs for a long period of time. It is a well known
fact that the oxygen radical generated by stress and excess of corticosterone secreted
during prolong stress are hazardous on human wellbeing. The purpose of this study
was to examine the neuroprotective effect of tocotrienol on hippocampus under
restraint stress by observing the histopathological and histomorphometric changes
and quantifying the serum corticosterone level in rats after exposure to stress for 21
days. Thirty six male Sprague Dawley rats aged 5 weeks old were divided into four
groups: control, restraint stress, tocotrienol and restraint stress treated with
tocotrienol. Restraint stress and restraint stress treated with tocotrienol groups were
exposed to 5 hours of restraint stress daily for 21 days. Tocotrienol group and
restraint stress treated with tocotrienol group received 200 mg/kg body weight of
tocotrienol rich fraction (TRF) by oral gavage daily. Control group and restraint
stress group received normal saline by oral gavage. Body weight was monitored
daily. At the end of experimental period, the rats were sacrificed and the sections of
hippocampus were sampled by adopting the systemic random sampling method and
were stained with hematoxylin and eosin, cresyl fast violet and immunohistostaining
using anti Ki-67 antibody and anti GAP-43 antibody. The serum collected was
assessed for corticosterone level by ELISA. Data was analysed by using, PASW
statistical software (version 18). The study had found that the level of corticosterone
was significantly higher in the restraint stress group as compared to control group
and tocotrienol group and this was reflected in the weight of the adrenal gland mass.
However, TRF supplementation failed to alter the corticosterone level and the
adrenal gland mass. The study also showed the number of proliferative cells in the
subgranular zone of the dentate gyrus in the restraint stress group as labelled by Ki-
67 antibody was significantly lower as compared to control group. However, TRF
supplementation failed to provide protection against the effect of stress on cell
proliferation in the dentate gyrus. The histopathological assessment showed no
significant difference in granular cell and pyramidal cell counts between all group
comparisons. The histomorphometric assessment also showed no significant different
of hippocampal thickness and optical density of GAP-43 in all groups. Therefore the
present study shows that TRF supplementation is not effective to prevent the changes
in the hippocampus after exposure to chronic restraint stress.
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CLINICAL ANATOMY