Detection of obestatin in seminal plasma and its relationship with ghrelin and semen parameters

Objective: To investigate the occurrence of ghrelin and obestatin in human semen. Design: Prospective study. Setting: University, center for research and therapy of male infertility. Patient(s): 112 consecutively selected men. Intervention(s): Family history, clinical and physical examination, radioimmunoassay for ghrelin and obestatin determinations, semen analysis, annexinV/propidium iodide assay. Main Outcome Measure(s): Ghrelin and obestatin detected in the semen and relationships with semen parameters and conditions influencing semen quality (smoking, varicocele, ex varicocele, leukocytospermia). Result(s): The levels of both peptides in semen were higher versus serum. Linear correlations between ghrelin and obestatin levels in serum and in semen were observed. Serum ghrelin levels were negatively correlated with the men's ages. Semen obestatin levels were positively correlated with sperm concentration and motility. Obestatin levels were decreased in the semen of smokers and in the presence of leukocytospermia. Conclusion(s): This is the first study on the presence of obestatin in human semen and its relationship with sperm concentration and motility, suggesting a possible role of the peptide in controlling cell proliferation and survival. Further investigations are required to explore the exact role of obestatin and ghrelin in human semen. (Fertil Steril (R) 2011; 95: 2303-9. (C) 2011 by American Society for Reproductive Medicine.)