LEPTIN AND LEPTIN RECEPTOR MESSENGER-RNA AND PROTEIN EXPRESSION IN THE MURINE FETUS AND PLACENTA

Leptin is a 167-aa protein that is secreted from adipose tissue and is important in the regulation of energy balance, It also functions in h ematopoiesis and reproduction, To assess whether leptin is involved in fetal growth and development we have examined the distribution of mRN As encoding leptin and the leptin receptor (which has at least six spl ice variants) in the 14.5-day postcoitus mouse fetus and in the placen ta using reverse transcription-PCR and in situ hybridization, High lev els of gene expression for leptin, the leptin receptor, and the long s plice variant of the leptin receptor with an intracellular signaling d omain were observed in the placenta, fetal cartilage/bone, and hair fo llicles, Receptor expression also was detected in the lung, as well as the leptomeninges and choroid plexus of the fetal brain, Western blot ting and immunocytochemistry, using specific antibodies, demonstrated the presence of leptin and leptin receptor protein in these tissues, T hese results suggest that leptin may play a role in the growth and dev elopment of the fetus, both through placental and fetal expression of the leptin and leptin receptor genes, In the fetus, leptin may be mult ifunctional and have both paracrine and endocrine effects.