Leptin receptor transcripts are constitutively expressed in placenta and adipose tissue with advancing baboon pregnancy.

The baboon (Papio sp.) is an accepted nonhuman primate model for the study of the endocrinology of human pregnancy. To further characterize this model with regard to leptin function, messenger RNA transcripts for both long (Ob-RL) and short (Ob-RS) leptin receptor isoforms were identified in maternal tissues at various stages of gestation. Thus, placental villous, subcutaneous and omental adipose tissues were collected upon cesarean delivery at early (Days 60-62), mid (Days 98-102) and late (Days 159-164) pregnancy (term approximately 184 days). Additionally, amniochorion, decidua, and corpus luteum were collected in late gestation. Expression of Ob-RL and Ob-RS transcripts was determined in relation to constitutively expressed glyceraldehyde-3-phosphate dehydrogenase via reverse transcriptase-polymerase chain reaction, and transcripts were localized within specific placental cell types by in situ hybridization. Ob-RL and Ob-RS transcripts were present in amniochorion, decidua, and corpus luteum at term and appeared constitutively expressed throughout gestation in placenta and adipose tissues. Ob-RS was expressed in greater (P < 0.02) abundance than Ob-RL in all tissues. Within the placenta, receptor isoforms were localized predominantly to the syncytiotrophoblast. The expression of leptin receptor transcripts in maternal adipose tissues, as well as in the syncytiotrophoblast, amniochorion, decidua, and corpus luteum, suggests the potential for autocrine/paracrine roles for the polypeptide in the endocrinology of primate pregnancy. These are the first such observations in a nonhuman primate and support the use of the baboon as a model for the study of leptin in human pregnancy.