Leptin and its receptors in the course of pregnancy in the rat

Abstract

Control of processes responsible for food intake and regulation of energy homeostasis during pregnancy is crucial for mother as well as for fetus development. Leptin is one of the main hormonal factors involved in regulation these processes in organisms. During pregnancy leptin regulates mother's energy balance and may also affect fetus growth and development, particularly via receptors in hypothalamus arcuate nuclei (ARC), pituitary and placenta. In the present study, serum leptin levels and expression of both short (ObRs) and long (ObRb) form of leptin receptor in the hypothalamus, pituitary and placenta were measured in the course of pregnancy. The results of these studies indicate that leptin concentration in serum increases during pregnancy and decreases 24 h after the delivery. The expression of both short and long forms of the leptin receptor in the hypothalamus decreases in the course of pregnancy and increases after the delivery. In the pituitary, however, a decrease of leptin receptor mRNA during pregnancy was observed only for ObRb. Analysis of placental leptin receptor expression demonstrated an increase of ObRb and constant high levels of ObRs mRNA. Our results suggest that changes in leptin level and its receptor expression may influence the energy homeostasis during pregnancy. In addition, changes in ObR expression are suggestive for: i) leptin resistance in the hypothalamus and pituitary; and ii) an increased leptin-dependent signaling in the placenta.

Maternal adaptations to pregnancy in spontaneously hypertensive rats: leptin and ghrelin evaluation

“…However, the possible involvement or alteration of other peptides or peripheral hormones, which regulate food intake, cannot be excluded. No significant modification of hypothalamic Ob-Rb expression was seen at day 20 of pregnancy in WKY, even if previous data are suggestive for leptin resistance in the hypothalamus and pituitary (Szczepankiewicz et al 2006). Moreover, in our conditions, no significant modification of Ob-Rb expression was seen in adipose tissues either in normotensive or in hypertensive animals.…”

Changes of agouti-related protein in hypothalamus, placenta, and serum during pregnancy in the rat

“…During pregnancy, leptin level increased in the serum; however, mRNA level for the leptin receptor, both short and long forms, decreased (Amico et al 1998, Garcia et al 2000, Szczepankiewicz et al 2006. These data may partly explain the increase of mRNA level for Agrp in the hypothalamus.…”

“…The presence of sperm was defined as the first day of pregnancy. After fertilization, pregnant rats were kept under conditions described previously (Szczepankiewicz et al 2006). Experimental rats were analyzed on day 4 (before implantation and placenta development, group B), day 13 (embryonic period, group C), day 18 (fetal period, group D) and one day after parturition (group E), as suggested by Witschi (1962).…”

Saturated fat-rich diet increases fetal lipids and modulates LPL and leptin receptor expression in rat placentas

“…Indeed, Lepra induces the expression of transcription factors in vitro and a reduction in body weight in vivo (Murakami et al 1997, Grasso et al 1999. The a and b isoforms are expressed in the rat placenta, showing an increment in their expression at term gestation, suggesting an important role of leptin during gestation and at term pregnancy (Smith & Waddell 2002, Szczepankiewicz et al 2006.…”