ABSTRACT
In times of excess caloric intake, adipose tissue serves as an energy buffer. Superfluous calories are stored as triglycerides (TGs), ready to satisfy future needs. To perform this seemingly simple task, the adipose tissue needs to be well connected. It needs to know the general energy status of the organism, including present demand, storage capacity, size of present energy store, etc. At yet another level of integration, energy, in the form of free fatty acids (FFA), can be redistributed, for example, from adipose tissue to meet the demands of other cell types (e.g., myocytes). An elaborate system of endocrine and paracrine functions as well as neuronal signaling makes sure that the adipose tissue is well integrated into the general energy network described in greater detail elsewhere in this book. The importance of adipose tissue in this context is illustrated by the dramatic metabolic consequences that are induced by lack of it. Lipodystrophy both in man and mouse leads to, among other things, steatosis, hepatomegaly, and insulin resistance. In mice, transplanting adipose tissue back to lipodystrophic mice has been used as a way to treat this condition (1). This approach leads to a more or less complete reversal of the metabolic disturbances. Thus, supplying ample TG storage capacity to mice that lack it can cure many obesitylinked symptoms such as fatty liver and insulin resistance.
