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Assessment of the Metabolic Effects of Isocaloric 2:1 Intermittent Fasting in Mice
Published on: November 27, 2019
Food restriction and simulated microgravity: effects on bone and serum leptin
Kyunghwa Baek1, Alicia A Barlow, Matt R Allen
1Dept. of Health and Kinesiology. Texas A&M, Univ., College Station, TX 77843-4243, USA. sbloom@tamu.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 16, 2008
Summary
Spaceflight conditions, including food restriction and simulated microgravity, negatively impact bone mass. Reduced serum leptin levels correlate with decreased bone formation, suggesting leptin
Area of Science:
- Bone Metabolism and Endocrinology
- Spaceflight Physiology
Background:
- Leptin is a key hormone linking energy metabolism to bone mass regulation.
- Astronauts often experience negative energy balance during spaceflight, potentially affecting bone health.
- Understanding the interplay between nutrition, microgravity, and bone integrity is crucial for space exploration.
Purpose of the Study:
- To investigate the independent and combined effects of food restriction and simulated microgravity on bone mass.
- To assess the impact of these conditions on serum leptin levels in a rodent model.
- To explore the relationship between serum leptin and bone formation rates.
Main Methods:
- Adult male Sprague-Dawley rats were subjected to hindlimb unloading (HU) or cage-activity control (CC).
- Animals were fed either 100% or 70% of their baseline food intake for 28 days.
- Bone mass parameters, including osteoid surface and mineral apposition rate, were measured. Serum leptin levels were quantified.
Main Results:
- Food restriction and HU led to body weight loss, with the greatest loss in the combined HU and 70% food group.
- Serum leptin levels significantly decreased in restricted feeding and HU groups, becoming undetectable in the combined HU/70% food group.
- Bone formation rate was reduced in all experimental groups compared to controls, correlating significantly with changes in serum leptin.
Conclusions:
- Moderate caloric restriction can induce bone loss comparable to the effects of microgravity unloading.
- Reduced serum leptin is associated with impaired bone formation during simulated spaceflight conditions.
- Leptin may serve as a critical endocrine regulator influencing skeletal integrity under conditions of energy imbalance and unloading.
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