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Short-term fasting and lipolytic activity in rat adipocytes
T Szkudelski1, M Lisiecka, E Nowicka
1Department of Animal Physiology and Biochemistry, University of Agriculture, 60-637 Wolyñska 35, Poznañ, Poland. tszkudel@jay.au.poznan.pl
Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme
|November 4, 2004
Summary
Eighteen-hour food deprivation significantly enhances basal and stimulated lipolysis in rat adipocytes. This fasting-induced increase in fat breakdown occurs downstream of protein kinase A and impairs insulin
Area of Science:
- Metabolic research
- Adipocyte biology
- Endocrinology
Background:
- Food deprivation is a significant metabolic stressor.
- Adipocytes play a crucial role in energy homeostasis through lipolysis.
- Understanding lipolysis regulation is key to metabolic disease research.
Purpose of the Study:
- To investigate the impact of 18-hour food deprivation on adipocyte lipolysis in Wistar rats.
- To determine the specific pathways involved in fasting-induced lipolysis.
- To assess the effect of fasting on insulin's antilipolytic action.
Main Methods:
- Isolation of adipocytes from epididymal adipose tissue of fed and fasted Wistar rats.
- Incubation of adipocytes with various lipolytic stimulators and inhibitors.
- Measurement of glycerol and fatty acid release to quantify lipolysis.
- Assessment of protein kinase A activity and adenosine A(1) receptor agonism.
Main Results:
- Basal and stimulated lipolysis were significantly potentiated in adipocytes from fasted rats.
- Fasting-induced lipolysis occurred downstream of protein kinase A.
- Insulin's ability to suppress epinephrine-stimulated lipolysis was impaired by fasting.
- A diminished non-esterified fatty acids/glycerol molar ratio suggests increased fatty acid re-esterification in fasted rats.
Conclusions:
- Short-term food deprivation enhances adipocyte lipolysis through mechanisms primarily downstream of protein kinase A.
- Fasting significantly reduces insulin sensitivity in adipocytes.
- These findings highlight the complex metabolic adaptations to fasting at the cellular level.