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Changes in hepatic metabolism through simulated weightlessness: decrease of glycogen and increase of lipids following
T Goda1, S Takase, H Yokogoshi
1Department of Nutrition, School of Food and Nutritional Sciences, University of Shizuoka, Japan.
Research in Experimental Medicine. Zeitschrift Fur Die Gesamte Experimentelle Medizin Einschliesslich Experimenteller Chirurgie
|January 1, 1991
Summary
Simulated weightlessness in rats caused significant changes in liver metabolism. Immobilization led to decreased glycogen and increased lipids, suggesting impaired fat processing during spaceflight conditions.
Area of Science:
- Physiology
- Space Medicine
- Metabolic Research
Background:
- Simulated weightlessness is a key challenge in space exploration.
- Understanding its impact on organ systems is crucial for astronaut health.
- Hepatic (liver) metabolism plays a vital role in energy balance.
Purpose of the Study:
- To investigate the effects of simulated weightlessness on carbohydrate and lipid metabolism in the liver.
- To determine how chronic immobilization impacts hepatic cellular processes.
Main Methods:
- Rats were chronically immobilized using a suspension harness for 10 days.
- Nutrient intake was controlled via force-feeding in some animals.
- Hepatic glycogen, total lipids, and triglyceride content were measured.
- Glucose-6-phosphatase activity and lipogenic enzyme activities were assessed.
Main Results:
- Immobilized rats showed decreased hepatic glycogen and markedly elevated hepatic total lipids.
- Hepatic parenchymal cells accumulated large fat droplets and elevated triglycerides.
- Glucose-6-phosphatase activity increased, suggesting enhanced glycogenolysis.
- Lipogenic enzyme activities remained unchanged, indicating no increased fat synthesis.
Conclusions:
- Prolonged immobilization leads to hepatic lipid accumulation.
- This accumulation is likely due to reduced lipolysis and/or impaired lipoprotein mobilization.
- Findings suggest potential metabolic disturbances relevant to spaceflight.