Leptin receptor expression and in vitro leptin actions on prostaglandin release and nitric oxide synthase activity in the rabbit oviduct

Abstract

In this study, we have examined the presence and the distribution of receptors for leptin (Ob-R) in the oviduct of rabbits, and the effects of leptin on the release of prostaglandin (PG) F2 and PGE2 and on the activity of nitric oxide (NO) synthase (NOS) by oviducts cultured in vitro. Rabbits were killed during the follicular phase and the oviducts were incubated in vitro with leptin, PGF2 , PGE2, NO donor and inhibitors of NOS and cyclooxigenase (COX). Using immunohistochemistry, Ob-Rlike positive reaction was observed only in the cytoplasm of secretory cells, having stronger intensity in the infundibulum and ampulla tracts than in the isthmus. Both leptin and NO donor inhibited PGE2 release, whereas they enhanced PGF2 release; NOS inhibitor alone or with leptin increased PGE2 and decreased PGF2 production; NOS activity was enhanced by leptin, while PGs did not affect this enzyme. This study suggests that the oviduct could be a potential target for endocrine regulation by leptin, whose circulating levels may act as a metabolic signal modulating oviductal PG release through mediation of the NOS/NO system.

mRNA Expression and Immunocytochemical Localization of Leptin Receptor in the Oviduct of the Laying Hen (Gallus domesticus)

“…Moreover, so far there were no reports on the detection of leptin receptor in the oviductal tissue in birds. ZERANI et al (2005) detected positive immunohistochemical staining of leptin receptor in the cytoplasm of the secretory cells of the rabbit oviduct.…”

“…To our knowledge, the present study is the first concerning mRNA expression of both long and short isoform of leptin receptor in the chicken oviduct. Previously, in mammalian oviduct, mRNA expression of long form of leptin receptor was detected (LIU et al 2003;ZERANI et al 2005), but there were no data on other isoforms of leptin receptor. Moreover, so far there were no reports on the detection of leptin receptor in the oviductal tissue in birds.…”

“…The mRNA expression of the long form of leptin receptor has been obtained in mammalian ovaries, uterus and testes (ZAMORANO et al 1997;GONZALES & LEAVIS 2003;KAWAMURA et al 2003;ZERANI et al 2004). Leptin receptor has also been detected in the oviduct of mammals (LIU et al 2003;ZERANI et al 2005), but so far it has not been shown in the avian oviduct. Therefore, the aim of the present study was to determine whether mRNA of the short and long form of leptin receptor is expressed in the oviduct of the laying hen and to ascribe their relative contributions if both isoforms are expressed.…”

Leptin induces functional activation of cyclooxygenase‐2 through JAK2/STAT3, MAPK/ERK, and PI3K/AKT pathways in human endometrial cancer cells

“…However, there has been relatively few data to date that elucidate the effect of leptin and its receptor on human endometrial cancer, and no further studies concerning leptin and COX‐2 expression and function. Leptin has been reported to increase PGF2α but inhibit PGE2 production ( 51 ) in the rabbit oviduct, while leptin has been shown to increase COX‐2 expression and PGE2 release in murine macrophage J774A.1 cells. ( 52 ) In this study, we showed that leptin stimulates COX‐2 activation dose‐ and time‐dependently which derived from leptin‐mediated COX‐2 mRNA.…”

Hormonal regulation of pregnancy and related behavioral changes in rabbits

“…Ovarian function mechanism is also dependent on leptin, a hormone produced in adipose tissue. The presence of leptin receptors on ovaries (101) and in the fallopian tubes (100) has been demonstrated in rabbits. The presence of receptors for leptin suggests its importance in the formation of preovulatory follicles and for the survival of oocyte and subsequently the blastocyst in the fallopian tube.…”