Submission Number: MIC-4-24-2
Abstract Number: 232
REGULATION OF SOLUBLE LEPTIN RECEPTOR PROTEIN IN BABOON PREGNANCY: EFFECTS OF GESTATIONAL AGE AND FETECTOMY.
Deborah E Edwards* 1,2, Jennifer S O'Neil* 1,2, Amy E Green* 1,2, Terry Gimpel 4, V Daniel Castracane* 4 and Michael C Henson* 1,2,3
Tulane University School of Medicine, Department of Ob/Gyn, New Orleans, LA 1
Interdisciplinary Program in Molecular and Cellular Biology, New Orleans, LA 2
Tulane Regional Primate Research Center, Covington, LA 3
Texas Tech University Health Sciences Center, Department of Ob/Gyn, Amarillo, TX 4
Abstract:
Maternal serum leptin levels in both the human and nonhuman primate increase with advancing gestation. We have proposed that circulating soluble leptin receptor, originating in tissues unique to gestation, may act to modulate serum leptin concentrations by inhibiting clearance. In order to more fully explore this role, leptin receptor was assessed by immunoblot in maternal serum, placenta, decidua, and amniochorion with advancing pregnancy in the baboon (Papio sp.), a recognized nonhuman primate model for human pregnancy. Additionally, the effects of estrogen, which increases in the maternal periphery with advancing pregnancy due to fetal production of androgen precursors, were assessed by removal of the fetus at midgestation (fetectomy) to eliminate these precursors. Serum samples were obtained from nonpregnant cycling baboons (n = 5); pregnant baboons at early (day 60, n = 5), mid (day 100, n = 5), and late (day 160, n = 5) gestation; postpartum (day +20, n = 5); and 30 days following fetectomy (day 130, n = 5). Normal term in the baboon is approximately 184 days. Placental villous tissue, decidua, and amniochorion were collected from pregnant baboons at progressive gestational stages and from fetectomized baboons, 60 days following the procedure. Soluble receptor levels in serum increased approximately 60% (P < 0.003) between early and late normal pregnancy, but was undetectable in nonpregnant cycling animals and only minimally detectable postpartum. Estradiol levels near term were 7-fold lower (P < 0.001) and leptin receptor protein 40% lower (P < 0.018) in fetectomized baboons than in intact controls. Two isoforms (130 kD, >130 kD) of the leptin receptor were present in placental villous tissue. Levels of the smaller isoform increased 3-fold (P < 0.025) in placental villous tissue from early to late normal gestation. Following fetectomy, the larger isoform declined 50% (P < 0.008) from midgestation. Leptin receptor protein in decidua increased 3-fold (P < 0.0003) and in amniochorion increased 13-fold (P < 0.024) from early to late gestation. Collectively, our results suggest that increasing soluble leptin receptor concentrations could play a role in the modulation of serum leptin levels in primate pregnancy and that estrogen may serve to regulate receptor abundance.
Keywords: Leptin, Leptin Receptor, pregnancy, primate
This abstract is being presented at: 2:30 PM in session:
SESSION 10: BIOLOGY OF PREGNANCY