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Body Composition and Metabolic Caging Analysis in High Fat Fed Mice
Published on: May 24, 2018
Hepatic mitochondrial efficiency in lines of mice differing in feed intake.
T W Murphy1, J M McDonald, M K Nielsen
1Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583-0908, USA.
Journal of Animal Science
|March 7, 2013
Summary
Mice selected for high heat loss (MH) consumed more feed, while those selected for low heat loss (ML) showed greater mitochondrial efficiency. However, mitochondrial efficiency did not explain the differences in feed intake per body weight.
Area of Science:
- Animal Genetics
- Mitochondrial Physiology
- Metabolic Efficiency
Background:
- Selection for high (MH) and low (ML) heat loss in mice over 25 generations created distinct lines.
- These lines exhibit significant differences in heat loss and feed intake per unit body weight (FI/BW) compared to a control line (MC).
- Understanding the underlying physiological mechanisms, particularly hepatic mitochondrial efficiency, is crucial for explaining these phenotypic differences.
Purpose of the Study:
- To investigate hepatic mitochondrial efficiency in genetically distinct mouse lines selected for heat loss.
- To determine the relationship between mitochondrial respiratory control and feed intake per body weight.
Main Methods:
- Direct calorimetry was used for selection of high (MH) and low (ML) heat loss lines.
- Mice were maintained for 25 generations with an unselected control (MC) line.
- Hepatic mitochondria were isolated and their oxygen consumption measured using a Clark-type oxygen electrode to assess respiratory control ratio.
Main Results:
- Mitochondria from ML mice exhibited a 22% greater respiratory control ratio compared to MH mice (P < 0.03), indicating less uncoupling during electron transport.
- MH mice showed significantly higher feed intake per body weight (FI/BW) (34%) compared to ML mice (P < 0.001).
- Regression analysis demonstrated that the respiratory control ratio explained minimal variation in FI/BW between the MH and ML lines.
Conclusions:
- Hepatic mitochondrial efficiency, as indicated by the respiratory control ratio, differs between mouse lines selected for high and low heat loss.
- Despite differences in mitochondrial function, this efficiency metric does not appear to be the primary driver of the observed variations in feed intake per body weight.
