Transgenic animal models have influenced and challenged our understanding of adipose tissue biology remarkably. In the past years, many genetically modified animal models have revealed further insights into the role of adipose tissue in energy homeostasis, in endocrine function and in relation to other physiological systems. Continued generation and characterization of transgenic animal models will add pieces to the puzzle for a better understanding of the pathophysiology of adipose tissue, including obesity, lipodystrophy and insulin resistance. Transgenic animal models are valuable tools for the functional characterization of single genes in vivo, and for the search of unknown genes or unrecognized functions of genes.
Nevertheless, transgenic animal models have limitations and the study of single genes independently through the generation of genetically modified animals only provides a fragmented view on complex physiological processes. The major limitations in studying transgenic animal models are that a phenotype can be masked by compensatory mechanisms for the loss or overexpression of individual proteins, and that it may be difficult to distinguish phenotypes arising from developmental defects from those resulting from gene targeting.
Taken together, transgenic animal models with single genetic defects can yield important information on adipose tissue biology and pathophysiological states, but may not always match the human disease. Thus, it is important that new relevant animal models employing more sophisticated strategies for gene inactivation or overexpression are developed to extend our understanding of the mechanisms underlying obesity and its metabolic consequences. Finally, a better understanding of the function of adipose tissue biology will likely permit more rational approaches in the prevention and treatment of excess and deficiency of adipose tissue(