Leptin and reproduction

Leptin, the product of the ob gene, is a small peptide molecule synthesized by white adipocytes with an important role in the regulation of body fat a nd food intake, Leptin and leptin receptor mRNA were first detected in the brain and hypothalamus but now their ubiquitous presence has been demonstra ted. Leptin receptor signal transduction involves the activation of signal transducer and activator of transcription (STAT)-3, a member of the transcr iption family of proteins. Leptin is regulated by hormones and cytokines, i nterleukin-1, tumour necrosis factor-ex and transforming growth factor-beta , linking this molecule with the inflammatory response. In addition, emergi ng evidence has demonstrated that this molecule is related to reproductive function, This small protein is present in the ovary and decidua, in mature oocytes and during embryonic development and trophoblast invasion. Animal models have demonstrated that leptin-deficient ob/ob mice are sterile; howe ver, fertility can be restored by exogenous leptin, In addition, embryos im planted in STAT-3-deficient mice degenerate rapidly and are the target disr uption of STAT-3-provoked embryonic lethality. Leptin acts as a novel place ntal hormone participating in the control of fetal growth and development. Leptin could be a modulator for invasive features of cytotrophoblast cells. We postulate that leptin may have an autocrine/paracrine role in human imp lantation and placentation.