Search

Background: In vitro data have shown conflicting results in terms of the effect of leptin on granulosa cells steroidogenesis., Aim: The aim of the present study was to investigate the effect of low and high doses of leptin on basal and FSH-induced steroids secretion by human luteinized granulosa cells in culture., Materials and Methods: Granulosa cells were obtained from normal women undergoing in vitro fertilization (IVF) treatment and were cultured in serum-free conditions for 72 h. A one-way analysis of variance design was set to study the effect of leptin on basal and FSH-induced steroidogenesis., Results: Leptin affected basal estradiol and progesterone secretion in a dose-related manner. In particular, leptin at low concentrations stimulated the secretion of estradiol (1 and 10 ng/ml) and progesterone (10 ng/ml), while at a high concentration (100 ng/ml) it suppressed the secretion of both steroids. A dose-related effect of leptin on FSH-induced steroidogenesis was not evident, since only the suppressive effect of the high concentration of leptin (100 ng/ml) reached statistical significance for both steroids., Conclusions: These results demonstrate that leptin affects the secretion of steroids in luteinized granulosa cells in a dose-dependent manner. Although a physiological role for leptin is possible, it is suggested that this protein is a mediator of negative rather than positive influential interactions on ovarian function that may compromise fertility.

Objective: To investigate the effect of leptin on the actions of growth hormone (GH) and insulin-like growth factor-I (IGF-I) in ovarian steroidogenesis in vitro., Design: In vitro cell culture study., Setting: Research laboratory of a university hospital., Patient(s): Luteinized granulosa cells (GC) were obtained from 20 healthy women undergoing ovarian stimulation for IVF treatment., Intervention(s): Granulosa cells were cultured in serum free conditions for 72 hours with either GH or IGF-I, or their combination, in the absence or presence of leptin (1, 10, and 100 ng/mL)., Main Outcome Measure(s): At 24 and 72 hours of the culture estradiol (E(2)) and progesterone (P) concentrations were measured in culture supernatants by enzyme immunoassays., Result(s): Leptin at the doses of 1 and 10 ng/mL significantly stimulated, whereas at the dose of 100 ng/mL it significantly suppressed E(2) and P production as compared to control. Estradiol production was significantly stimulated by both GH (72 hours) and IGF-I (24 and 72 hours) and that of P only by IGF-I (72 hours). Leptin at the low doses enhanced, whereas at the high dose it suppressed the effect of GH or IGF-I on E(2) and P synthesis., Conclusion(s): These results demonstrate for the first time that leptin can modulate the effect of GH on steroids production by human luteinized GC in culture.

Whether leptin is secreted by the human ovary is not known. The available data on leptin gene (ob gene) expression by human granulosa cells are conflicting. The aim of the present study was first to re-examine the expression of leptin messenger RNA (mRNA) by human granulosa cells and second to investigate if these cells have the ability to secrete leptin in cultures. Human luteinized granulosa cells were obtained from normal women undergoing in vitro fertilisation treatment after ovarian stimulation and follicle aspiration. The expression of ob gene was studied by Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR) both in primary granulosa cells treated immediately after oocyte recovery and in cells cultured up to 24 h under baseline and hormonally stimulated conditions (FSH: 100 ng/ml, LH: 100 ng/ml). ob mRNA transcripts were not detected in luteinized granulosa cells, while they were present in adipose tIssue cDNA. Actin gene expression was detected in all studied samples. Using a sensitive radioimmunoassay (lower limit of detection 0.05 ng/ml), leptin was undetectable in the culture media at all points during the 72 h cultures, while at the same time significant amounts of oestradiol and progesterone were produced particularly after the addition of androstendione (1 microM) to the incubation media. These results demonstrate for the first time that leptin is not secreted by human luteinized granulosa cells in cultures. From a physiological point of view, this may contribute to the development of the optimal follicular environment for oocyte maturation during the preovulatory period.