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Attenuation of tissue oxidative stress by dietary restriction in rats on simulated microgravity
John Jayroe1, Michael Soulsby, Parimal Chowdhury
1University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Introduction:
Physiologic alterations caused by oxidative stress can be assessed by measuring tissue malondialdehyde (MDA) levels, a biomarker for oxidative stress. The goal of this study is to determine the consequences of a twenty percent caloric restriction on the increased oxidative stress documented in tissues from rats exposed to simulated microgravity.
Materials/Methods:
Three groups of male SD rats (N=6 in each group) were used: Group 1, control; Group 2, food restricted (20% less food than control); and Group 3, food restricted with HLS. Group 3 was suspended after one week on the HLS-restricted diet and maintained for 14 days. Tissues harvested on day 14 were measured for MDA levels.
Results:
The body weight gain of Group 2 and Group 3 was reduced as compared to that of Group 1 ( p <0.05) with no significant changes in water intakes. MDA levels in Group 2 were not different from those of the control group and were elevated only in liver tissues (p<0.05). In Group 3, MDA levels in the heart, liver, brain, and testes were significantly elevated (p<0.05) compared to the levels of Groups 1 and 2.
Conclusions:
Food restriction alleviated tissue oxidative response in all tissues except for the liver. Excessive stress resulting from HLS appeared to have been minimized by dietary restriction in all tissues except for the heart, liver, brain, and testes.
Insights
Caloric restriction mitigated oxidative stress from simulated microgravity, except in the liver. Dietary changes reduced negative impacts on tissues, but heart, liver, brain, and testes still showed elevated oxidative stress markers.
Area of Science:
- Physiology
- Biochemistry
- Space Medicine
Background:
- Oxidative stress causes physiological alterations measurable by malondialdehyde (MDA) levels.
- Simulated microgravity is known to increase oxidative stress in tissues.
Purpose of the Study:
- To investigate the effects of 20% caloric restriction on oxidative stress in rats subjected to simulated microgravity.
- To assess malondialdehyde (MDA) levels as a biomarker for oxidative stress under these conditions.
Main Methods:
- Three groups of male Sprague-Dawley rats were used: control, 20% food restricted, and food restricted with hindlimb suspension (HLS).
- Rats in the HLS group were suspended for 14 days after a one-week dietary restriction period.
- Tissue malondialdehyde (MDA) levels were measured on day 14.
Main Results:
- Body weight gain was reduced in both food-restricted groups compared to controls.
- MDA levels were elevated in liver tissues of the food-restricted group but not significantly different overall from controls.
- In the HLS group, MDA levels were significantly elevated in the heart, liver, brain, and testes compared to control and food-restricted groups.
Conclusions:
- Caloric restriction partially alleviated tissue oxidative stress, with the exception of the liver.
- Dietary restriction appeared to minimize the excessive stress from HLS in most tissues, but not the heart, liver, brain, and testes.
