As oxidative stress is a cellular and physiological condition of
elevated concentration of reactive oxygen species (ROS), it causes
molecular damage to vital structures and functions. Several factors
can affect the antioxidants status or free radical generation such as
air pollution, alcohol, cigarette smoke, non ionizing radiation and
psychological stress.
Oxidative stress is viewed as a continuous battle between
inducers (pnooxidants) and a vast array of different protective
factors (antioxidants). There is an expanding list of antioxidants,
which can be divided into enzymatic such as superoxide dismutase
(SOD) , catalase (CAT) and glutathione peroxidase (GSHPx) and
non enzymatic such as vitamin C and vitamin E. Tissues have
different oxidative loads and aggregated antioxidant capacity differs
as a result The aim of this work is to study the changes which can
happen in the lipid peroxidation and enzymatic antioxidant defense
of liver and heart as a result of immobilization stress; possible
modification by vitamin C and E supplementation.
The present study was conducted on 40 male albino rats. They
were divided into 4 groups; group(Thcontrol of 10 rats , group
(2);stressed of 10 rats subjected to immobilization stress for 4 hours,
4
group (3) of 10 rats which received an oily solution of alpha
tocopherol orally at a dose of 10mg/Kg body weight for 2 weeks prior
to immobilization and group (4) of 10 rats which received 0.5 mg/Kg
body weight of ascorbic acid for 2 weeks dissolved in the drinking
water before immobilization. After the experimental period, all rats
were anaesthetized by ether then sacrificed by decapitation, liver and
heart were separated, weighed, homogenized and centrifuged. The
supernatant was separated for estimation of SOD, GSHPx, catalase
activity and lipid peroxides level.
The present study showed that, restraint stress significantly
reduced the activity of the liver and heart antioxidant enzymes. The
impairment of antioxidant defensive mechanisms was associated with
increased levels of peroxides indicating the toxic effects of the
unantagonized free radicals formed during immobilization stress.
Fortifring the endogenous antioxidant defense mechanisms with
exogenously administered free radical scavengers, ascorbic acid and
a-tocopherol (VII. E) significantly reduced liver and heart peroxides.
Moreover, the antioxidant enzymes which were decreased during
stress showed significant increase. Such change may be due to
stimulation of their synthesis or reduction of their consumption.
In conclusion, The present study showed that the enzymatic
antioxidant defensive mechanisms of rat liver and heart were
impaired during exposure to restraint stress. Oxygen free radicals
are formed during stress; attack all membranes producing
peroxidation of phospholipids followed by membrane damage ,
scavenging the free radicals by the exogenously administered
scavengers (ascorbic acid) or (a -tocopherol) offered organs
protection. This may open the way for trying a new strategy for
treatment of heart and liver affection depcnding on combination of
classic drugs with antioxidants to obtain full protection. |
