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Thermal preference behavior in preweaning genetically obese (ob/ob) and lean (+/?, +/+) mice
L M Wilson1, P J Currie, T L Gilson
1Department of Psychology, University of Manitoba, Winnipeg, Canada.
Physiology & Behavior
|July 1, 1991
Summary
Genetically obese mouse pups exhibit impaired thermoregulation, leading to lower body temperatures. They compensate by seeking warmer environments, demonstrating an age-dependent effect of the obesity gene on thermal preference.
Area of Science:
- Physiology
- Genetics
- Developmental Biology
Background:
- Genetically obese (ob/ob) mice show early postnatal impairments in nonshivering thermogenesis and lowered rectal temperatures (Tre).
- Adult obese mice behaviorally compensate for thermoregulatory deficits, failing to defend low Tres.
- Young mammals rely heavily on behavioral thermoregulation for thermal homeostasis during preweaning development.
Purpose of the Study:
- To investigate the impact of the obesity gene on the development of behavioral thermoregulation in preweaning mouse pups.
- To determine if thermoregulatory impairments in obese pups enhance their reliance on behavioral thermoregulation compared to lean littermates.
- To assess age-dependent changes in thermal preference and rectal temperatures in obese and lean mouse pups.
Main Methods:
- Testing of intact litters from heterozygous lean (ob/+) and homozygous lean (+/+) matings at 6, 12, and 18 days postpartum.
- Utilizing a thermal gradient (14–44°C) to assess behavioral thermoregulation and thermal preference.
- Measuring pretest and posttest rectal temperatures (Tre) to evaluate thermoregulatory capacity.
Main Results:
- Obese pups exhibited lower pretest Tres than lean littermates at all tested ages (6, 12, and 18 days postpartum).
- Exposure to the thermal gradient equalized Tre differences among phenotypes post-exposure.
- Obese pups preferred warmer locations on the gradient compared to +/+ lean controls, with this difference becoming more pronounced at 18 days.
Conclusions:
- The findings support the hypothesis that early thermoregulatory impairments in obese mouse pups promote increased reliance on behavioral thermoregulation.
- The study highlights the age-dependent influence of the obesity gene (ob) on altering thermal preferences in developing mouse pups.
- Behavioral thermoregulation plays a crucial role in maintaining thermal homeostasis in young mice with genetic predispositions to obesity.