In this study, we attempted to demonstrate the expression of GHSR-1a receptor and possible effects of its activation in human, rat and boar spermatozoa. For demonstration of GHSR-1a immunocytochemical, immunofluorescence and western blotting techniques were applied. The effects of receptor activation was tested in a series of in vitro incubations of spermatozoa with or without addition of ghrelin and the effects were evaluated using confocal microscopy and flow cytometry.
GHSR-1a was shown, with both immunohistochemical and immunofluorescence techniques, in rat epididymal and boar ejaculated spermatozoa in which profiles of acrosome and head membrane was marked by the reaction and the expression was confirmed by western blotting. However, we failed to demonstrate GHSR-1a expression in human ejaculated spermatozoa neither with immunohistochemical nor western blotting techniques. In vitro ghrelin affected rat and boar spermatozoa producing a dose dependent rapid (s) and prolonged (to 20 min) increase in intracellular Ca2+ concentration, higher percentage of spermatozoa showing progressive movement and increase in number of spermatozoa with acrosome reaction induced by ionophore. Interestingly, a response of human spermatozoa to ghrelin could be recorded as a short lasting (s) increase in intracellular Ca2+ concentration and poor changes in sperm motility and acrosome reaction. It is concluded that while the effects of ghrelin in rat and boar sperms arose as a result of GHSR-1a activation those in human spermatozoa probably indicate the peptide action through different than GHSR-1a receptor(s).
Supported by Polish Ministry of Science and Higher Education (3951/P01/2006/31).
30 Apr - 04 May 2011
European Society of Endocrinology