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Endocrine/Metabolic Function/Body Composition

Body Composition

qMRI-bar-shop

Rationale: Measures of whole body fat mass, lean tissue mass and free water.

Instrument: Quantitative magnetic resonance imaging (qMRI) instrument by EchoMRI.

Measures: Exact measures of total body fat, lean mass, and free water are obtained by ascertaining how protons contained in the lean and fat mass perturb a magnetic field. Measures are performed without the need for sedation, in less than one minute.

Data Inference: Data are QMR fat mass (grams), QMR lean mass, QMR free water and QMR body weight calculated by adding fat mass, lean mass, and free water together.

Controls: All animals are tested individually.


Clamp Studies for Sensitivity and β-cell Function

clamp

Hyperinsulinemic euglycemic clamps are performed in conscious unrestrained rodents to assess whole body glucose turnover and insulin sensitivity. Hyperglycemic clamps are performed to evaluate beta cell function.


Circulating Lipids, Glucose, and Insulin Concentration


Exercise Tolerance and Performance

treadmill

Exercise tolerance testing is performed following a ramped protocol using a treadmill for rodents (Columbus Instruments).


HbA1c Levels


Indirect Calorimetry

MARS System to be replaced with CLAMS system

Rationale: Measures of metabolism (oxygen consumption, carbon dioxide production, respiratory quotient, heat) in a 48 h period.

Instrument: Oxymax-CLAMS (Comprehensive Lab Animal Monitoring System) from Columbus Instruments.

Measures: Animals are placed in cages for 48 hours. The difference between the concentrations of oxygen and carbon dioxide in a sealed cage at baseline is compared to the amounts present after the mouse has breathed the air during the testing period in an open circuit.

Data Inference: Oxygen consumption, carbon dioxide production and respiratory quotient are analyzed through Oxymax software.

Controls: Care is taken to acclimatize animals and ensure that room is secluded and not accessed during testing.


Thyroid Hormone, Cortisol, and Sex Steroid Levels


Voluntary Activity/Mobility

general-locomotor-test

Rationale: Measures of circadian activity in rodents.

Instrument: SmartFrameTM High Density Cage Rack 8 unit system (Hamilton-Kinder, Inc.).

Measures: Interruptions of high-density infrared photo-beams mounted in large, high cages similar to home cages with food and water available ad libitum are recorded during a 24 of 48 hour period.

Data Inference: Measures of circadian activity including fine movements, time, distance traveled, rest time, active time and number of rears are obtained for a 24 or 48 hour period.

Controls: Care is taken to acclimatize animals and ensure that room is secluded and not accessed during testing.


Voluntary Activity/Mobility

Rationale: Measures of circadian activity in rodents.

Instrument: Opto-Varimex-5 8 unit system (Columbus Instruments).

Measures: Interruptions of high-density infrared photo-beams mounted in large, high cages similar to home cages with food and water available ad libitum are recorded during a 24 or 48 hour period.

Data Inference: Measures of circadian activity including fine movements, time, distance traveled, rest time, active time and number of rears are obtained for a 24 or 48 hour period and analyzed with Auto-Track software.

Controls: Care is taken to acclimatize animals and ensure that room is secluded and not accessed during testing.