A Synthetic Activation of Human Fat Cell Energy Release
—Catherine Hooke
All living cells require energy. Adipose tissue, or fat, is an efficient storehouse of energy, which can be used as fuel for cells when other energy sources run low. This energy is released from the adipose tissue through lipolysis, a process in which fat cells release their stored fat.
When the body needs energy, such as during exercise, adipose tissue lipolysis is stimulated. Likewise, when individual cells of the body need energy, an enzyme known as AMPK (AMP- activated protein kinase) is activated. Researchers seeking to better understand how cells get their energy during times of need use a synthetic stimulator of AMPK, called AICAR (5'-Aminoimidazole-4-carboxamide ribonucleoside), a chemical not normally found in the body. If a reliable synthetic stimulator of AMPK, and thereby lipolysis, could be found, this could help in the treatment of diabetes, especially type 2 (adult diabetes). Such a drug could have the same effects as exercise does in stimulating lipolysis. Previous studies using fat cells in rats showed conflicting results regarding the effects of AMPK activation on lipolysis. This study was the first to examine synthetic stimulation of AMPK and its effects on lipolysis in human fat cells.
Adipose tissue was obtained from three liposuction patients, two of normal weight and one overweight. Fat cells, isolated from this tissue, were incubated with isoproterenol (a synthetic hormone that mimics the effects of exercise and stimulates lipolysis) in the presence and absence of AICAR. Results showed that overall there was no statistically significant effect of AICAR on lipolysis. However, results differed between subjects: inner and outer thigh fat cells from the two normal weight subjects showed no change in lipolysis with the addition of AICAR compared to no addition, while bilateral hip fat cells from the overweight subject showed a decrease in lipolysis with the addition of AICAR compared to no addition.
The findings suggest that AMPK's role in lipolysis may be a function of the adipose tissue region, the weight of the subject, and/or of individual variations in metabolism. Because this is the first study to examine the effects of AMPK activation on lipolysis in freshly isolated human fat cells, further study is warranted.
The author would like to thank Dr. Gale Carey for all of her help with this project. About the author >>
