Mini mitter

Single-housed mice were exposed to the T24 and/or T7 cycles, and light intensity was kept ~500 lux (provided by Philips Daylight deluxe fluorescent lamps), measured using a light meter (EXTECH Foot Candle/Lux Light Meter, 401025). The general activity of mice was monitored using infrared motion detectors from Mini Mitter (Respironics) mounted to the top of the cages. Data was collected in 10-min bins using VitalView software (Mini Mitter, OR). The total activity and period lengths were calculated using ClockLab (Actimetrics, IL).

Mice were housed individually in cages with a 4.5 inch wheel and their activity was measured by wheel rotations collected in 5-min bins with VitalView software (MiniMitter; Respironics). Mice were placed in 12 h light – 12 h dark (12:12 LD) cycles at ~700 lux for at least 2 weeks, followed by darkness (DD) for 2–3 weeks, and placed in 12:12 LD again for 2 weeks. Custom MATLAB scripts were used to generate actograms and measure activity onset to calculate period lengths. The wheel running activity of mice exposed to changing light paradigms is recorded in 5-min bins double plotted.

Indirect Calorimetry (Oxymax/ CLAMS, Columbus Instruments, Columbus, OH) was used to measure energy expenditure, respiratory exchange ratio (RER), and physical activity in mice at 22°C and 30°C. The core body temperature was continuously monitored by Telemetry (Mini Mitter/Philips Respironics, Bend, OR; ER4000 energizer/receivers, G2 E-mitters implanted intraperitoneally). Rectal temperature was monitored in some mice subjected to acute cold exposure using Thermalert TH-5 device (Physitemp). Food intake was measured in metabolic chambers. Body composition was determined by using by EchoMRI-100H Body Composition Analyzer (EchoMRI LLC). We allowed 2-4 days of acclimation to different housing environment and temperature conditions.

Sixteen male Sprague-Dawley (Harlan, Frederick, MD) rats weighing 250-275 g upon arrival were the subjects of this experiment. The rats were housed in a climate-controlled vivarium with a 12 h on//off light (0100)/dark (1300) cycle. Rats were individually housed either in metal wire-meshed hanging cages (the sedentary, Sed group) or conventional tubs equipped with a locked wheel (Mini Mitter, Philips Respironics, OR, USA; the wheel running, WR group). Due to limited number of running wheel cages, the Sed controls were housed in metal wire-meshed hanging cages. A standard chow diet (Harlan 2018, 3.1 kcal/g, 58% carbohydrate, 24% protein and 18% fat; Harlan Laboratories, USA) and tap water were available ad libitum. All animal procedures were approved by the Institutional Animal Care and Use Committee at Johns Hopkins University and conformed to the guidelines of the National Institutes of Health.

We studied healthy females and males (N=17 [3 females]) aged 31.7 ± 6.1 (Mean ± SD). Participants gave written informed consent and the Partners Health Care (Boston, MA) and the University of Colorado Boulder Institutional Review Boards approved the procedures and/or analyses for the protocol. Data collection was conducted at the Brigham and Women's Hospital. All participants were determined to be healthy after passing a rigorous health screening, including medical history, physical exam, electrocardiogram, blood and urine chemistries, a toxicology screen for drug use, psychological tests and an interview with a clinical psychologist. None reported regular night work or rotating shift work within the past three years or crossing more than one time zone in the previous three months. Participants maintained a regular routine of 8-h scheduled sleep and 16-h scheduled wakefulness for a minimum of three weeks while living at home before the in-laboratory protocol, as verified by sleep logs, call-in times to a time stamped voice recorder and wrist actigraphy recordings for at least one week prior to laboratory admission (Philips Respironics, Mini Mitter, Bend OR).