The role of ghrelin and ghrelin receptors in polycystic ovary syndrome

Background: Polycystic ovary syndrome (PCOS) is related to obesity and to major metabolic alterations including both insulin resistance and beta-cell dysfunction. Ghrelin was identified as theendogenous ligand for the growth hormone secretagogue (GHS) receptor. The actions of ghrelin are carried out through interaction with specific receptor, named GHS-R. Objective: In a case-control study, we compared the expression of ghrelin and GHS-Rs mRNA by Quantitative Real-time PCR method in studied groups in order to determine the role of ghrelin and GHS-Rs in pathogenesis of PCOS.Materials & Methods: Follicular fluid samples were obtained at oocyte collection from 22 patients undergoing IVF-ET as control and 11 patients were diagnosed as having PCOS. Total RNA wasextracted from isolated follicular fluid cells and 2μg RNA was diluted and reverses transcribed using random primers and Superscript II. Specific primers for the ghrelin, GHS-R1a and GHS-R1b were designed. Samples were run in triplicate on an ABI Geneamp 5700 sequence detection system. They were subjected to 40 cycles of amplification under condition 92°C- 20s and 62°C-1min using3μl diluted cDNA (1:7), 10μl 2X SYBR green, 3μl diluted cDNA. β-actin mRNA was assayed and then normalized to total RNA measurements for each sample. Results: Age, weight and resulting pregnancies did not vary between PCOS and non-PCOSpatients, whereas the BMI and serum testosterone level of PCOS were significantly higher thannon-PCOS patients. Quantitative real-time RT-PCR showed that mRNA for ghrelin and GHS-R 1bwere detectable in follicular fluid cells from all patients. We failed to find mRNA for GHS-R 1a in any of follicular fluid cells. There were no significant difference in ghrelin and GHS-R1b mRNA expression levels between PCOS and non-PCOS groups. Conclusion: Our findings indicate that ghrelin and ghrelin receptors may not be considered risk factors for pathogenesis of PCOS.

Keywords:

PCOS , Ghrelin , GHRs