| Popis: |
The importance of genetic factors in obesity is under investigation. During the last few years, our understanding of the regulation of body weight in mammals has broadened to include several new proteins based on the cloning of genes from rodent mutants and characterization of their effects on energy stores and metabolism. Since its discovery in 1994, leptin has been acknowledged as an adipocyte-derived signal molecule, able to limit food intake and increase energy expenditure by interacting with specific leptin receptors located in the central nervous system and in peripheral tissues. Leptin is also important for growth, reproduction and neuroendocrine signalling. Although leptin is mainly synthesized in adipocytes, it is also expressed in the placenta, epithelium of the stomach and breast glands and, under certain conditions, in skeletal muscles. The importance of leptin is demonstrated by the discovery of mutations in the genes encoding leptin and its receptor among some subjects with morbid obesity and infertility. Plasma concentration of leptin should be measured in obese infertile adolescents since replacement could be curative among individuals with leptin deficiency. |
