Abstract
Effects of a soy protein diet on oxidant and anti-oxidant levels in selected rodent tissues were investigated under simulated microgravity. Methods: Adult Male Rats were maintained either on a regular Purina Rat chow or on a 9.6% soy protein diet and allowed to remain in either non-suspended (control) or hind-limb-suspended (HLS) state via their tails at a 30 degree angle for 14 days. Body weights, food and water intakes were monitored daily during the entire study period. Hematological parameters, oxidant and. antioxidant levels in the brain, liver and pancreatic tissues were measured. Results: At term, the body weights of the hind limb suspended animals were found significantly decreased when compared with the non-suspended controls, p<0.05. There was no significant change in blood hematocrit and hemoglobin levels. After HLS, malondialdehyde (MDA) levels of brain tissues were marginally increased in the Purina chow group as compared to a significant increase in the soy suspended group (p<0.05). Similar observations were noted with liver and pancreatic tissues. In response to HLS, glutathione levels in brain and pancreatic tissues were increased in the Purina chow group (p<0.05) while in soy group, glutathione (GT) levels in both of these tissues were found relatively lower. Superoxide dismutase (SOD) levels were increased in all three tissues after HLS regardless of the dietary conditions. Conclusions: Data suggest that HLS induced a differential tissue specific oxidative response regardless of the dietary differences. Dietary soy protein lowered the oxidant levels under basal state but their effects were not sustained under HLS conditions significantly.
Highlights
It is well known that the Imbalance in the oxidant-antioxidant defense system occurs due to the severity of the oxidative stress and it has been documented during space flight and in aging [1,2]
The physiologic alterations caused by oxidative stress can be monitored by measurements of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GT) levels
The body weights did not change with diet, and weights of HLS rats remained lower than their control (p
Summary
It is well known that the Imbalance in the oxidant-antioxidant defense system occurs due to the severity of the oxidative stress and it has been documented during space flight and in aging [1,2]. Oxidative stress during aging is attributed to a generalized increase in free radical production causing a decrease in antioxidant activity. The physiologic alterations caused by oxidative stress can be monitored by measurements of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GT) levels. Oxidative stress induces an increase in oxidation of membrane fatty acid moieties leading to production of unstable lipid peroxides which tend to degrade rapidly into products such as malondialdehyde [6]. The formation of these aldehydes contributes to the mechanisms of oxidant-induced injury. Superoxide dismutase (SOD) levels were known to out-compete the damaging reactions of superoxide, protecting the cell from superoxide toxicity [7] and it was measured to determine whether its activation is triggered in concert with lipid peroxidation
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