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Alterations in adipocyte response to lipolytic hormones during cold acclimation
1Department of Physiology, Faculty of Medicine, Laval University, Quebec, Canada.
The American Journal of Physiology
|May 1, 1990
Summary
Cold exposure temporarily impairs fat cell lipolysis via catecholamines. However, adipocytes adapt by increasing responsiveness to glucagon and ACTH, and reducing insulin
Area of Science:
- Metabolic Physiology
- Adipocyte Biology
- Environmental Adaptation
Background:
- Cold exposure significantly impacts metabolic regulation.
- Adipose tissue plays a crucial role in energy homeostasis during cold stress.
- Understanding lipolysis regulation is key to metabolic adaptation.
Purpose of the Study:
- To investigate the effects of cold exposure and acclimation on adipocyte lipolysis regulation in rats.
- To identify the specific steps in the lipolytic cascade affected by cold.
- To examine the compensatory mechanisms involved in maintaining energy balance during cold.
Main Methods:
- Isolation of adipocytes from rat epididymal fat pads.
- Stimulation of lipolysis using catecholamines, glucagon, ACTH, dibutyryl cAMP, and theophylline.
- Assessment of lipolytic sensitivity (1/2 Vmax) and responsiveness (Vmax).
- Evaluation of adenosine's role and insulin's antilipolytic effect.
Main Results:
- Cold exposure decreased adipocyte sensitivity and responsiveness to catecholamines.
- Lipolytic defect in cold-exposed rats was localized to a pre-cAMP step.
- Responsiveness to glucagon and ACTH increased during cold acclimation.
- Insulin's antilipolytic effect diminished during cold acclimation.
Conclusions:
- Cold exposure causes a transient impairment in catecholamine-stimulated lipolysis.
- Adipocytes compensate through enhanced responses to glucagon and ACTH.
- Reduced insulin effectiveness further contributes to lipolytic adaptation during cold acclimation.
- These findings highlight the complex adaptive strategies of adipose tissue to cold environments.