Unloading does not increase brown-adipose-tissue activity in rat pups
1Department of Physiology and Biomechanics, National Institute of Fitness and Sports, Kanoya, Japan.
Research Communications in Molecular Pathology and Pharmacology
|January 14, 2000
Summary
Chronic hindlimb suspension decreases brown adipose tissue (BAT) thermogenic activity in rat pups, unlike in adults. This suggests pups are less sensitive to unloading stress, impacting their energy metabolism.
Area of Science:
- Physiology
- Developmental Biology
- Metabolism
Background:
- Previous research indicated chronic hindlimb suspension increases brown adipose tissue (BAT) thermogenic capacity in adult rats.
- The effects of unloading on BAT activity in developing animals remained unclear.
Purpose of the Study:
- To investigate whether hindlimb unloading affects BAT thermogenic activity in rat pups.
- To compare the response of BAT to unloading in pups versus adult rats.
Main Methods:
- Rat pups underwent tail suspension from postnatal day 4 to 21.
- Thermogenic activity was assessed by guanosine 5'-diphosphate binding to BAT mitochondria.
- Uncoupling protein 1 (UCP1) content and mRNA expression were measured.
Main Results:
- Suspended rat pups exhibited significantly lower BAT thermogenic activity compared to controls.
- No differences were observed in UCP1 content or mRNA expression between groups.
- Adrenal and thymus masses remained unchanged in suspended pups.
Conclusions:
- Chronic hindlimb suspension decreases BAT thermogenic activity in rat pups.
- This response contrasts with adult rats and may be due to pups' lower susceptibility to unloading stress.
- Unloading impacts thermoregulation differently during development.
