Body Mass and Metabolic Measurement
Objective: To determine whether a causal relationship exists between nighttime light exposure and obesity by examining effects of light at night (LAN) on body mass, glucose tolerance, and food intake timing in male mice
Gather these items before starting the experiment. Check off items as you prepare.
Equipment1
Not specified • Not specified • Not specified • Not mentioned
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Protocol Steps
Housing assignment and light exposure
Assign male mice to three housing conditions: bright light at night (LL), dim light at night (DM), or standard light/dark cycle (LD)
Note: Nocturnal rodents typically eat substantially more food at night; however, DM mice consume 55.5% of their food during the light phase, as compared with 36.5% in LD mice
View evidence from paper
“Mice housed in either bright (LL) or dim (DM) LAN have significantly increased body mass and reduced glucose tolerance compared with mice in a standard (LD) light/dark cycle”
Body mass measurement
Measure body mass in mice across the three light exposure conditions
Note: Mice in LL and DM conditions showed significantly increased body mass compared to LD controls
View evidence from paper
“Mice housed in either bright (LL) or dim (DM) LAN have significantly increased body mass and reduced glucose tolerance”
Glucose tolerance assessment
Measure glucose tolerance in mice across the three light exposure conditions
Note: Reduced glucose tolerance observed in LL and DM mice compared to LD controls
View evidence from paper
“Mice housed in either bright (LL) or dim (DM) LAN have significantly increased body mass and reduced glucose tolerance compared with mice in a standard (LD) light/dark cycle”
Caloric intake monitoring
Monitor total daily caloric intake across all three light exposure conditions
Note: Equivalent levels of caloric intake observed across all conditions despite body mass differences
View evidence from paper
“despite equivalent levels of caloric intake and total daily activity output”
Activity measurement
Measure total daily activity output in mice across the three light exposure conditions
Note: Equivalent total daily activity output observed across all conditions
View evidence from paper
“despite equivalent levels of caloric intake and total daily activity output”
Food intake timing analysis
Analyze the timing of food consumption, specifically the proportion of food consumed during light versus dark phases
Note: DM mice consume 55.5% of their food during the light phase compared with 36.5% in LD mice
View evidence from paper
“Furthermore, the timing of food consumption by DM and LL mice differs from that in LD mice. Nocturnal rodents typically eat substantially more food at night; however, DM mice consume 55.5% of their food during the light phase, as compared with 36.5% in LD mice”
Food restriction intervention
Restrict food consumption to the active phase in DM mice and assess body mass gain
Note: Restricting food consumption to the active phase prevents body mass gain in DM mice
View evidence from paper
“Restricting food consumption to the active phase in DM mice prevents body mass gain”