Urszula Kosior-Korzecka

Relationships between leptin, KiSS-1/GPR54 expression and TSH secretion from pituitary cells of pubertal ewes in vitro.

Kisspeptin and leptin play a crucial role in the puberty of sheep as they initiate the activity of hypothalamic-pituitary-ovarian axis. Also hormones of thyrotropic axis are probably involved in this process. The aim of study was to analyze the impact of leptin on kisspeptin-10 secretion as well as kisspeptin-1 and G protein-coupled receptor (GPR54) mRNA expression in pituitary cells of pubertal ewes in vitro. The influence of kisspeptin on TSH secretion was also examined. Cells were cultured in McCoys 5A medium without hormones; with 10(-10)-10(-5)M of leptin; with 10(-11)-10(-5)M of kisspeptin-10; with peptide 234 (10(-7)M, antagonist of GPR54) or 10(-11)-10(-5)M of kisspeptin-10 and peptide 234. Then, kisspeptin-10 and TSH secretion as well as KiSS-1 and GPR54 expression were analyzed. We found that leptin directly affected kisspeptin-10 secretion and kisspeptin-1/GPR54 expression in pituitary cells of pubertal ewes. Kisspeptin-10 did not change TSH secretion, except exerting a short-term influence after 2h.

EFFECT OF 2-METHOXYESTRADIOL ON GONADOTROPIN SECRETION AND OXIDATIVE STATUS OF PORCINE PITUITARY CELLS IN VITRO

Abstract The aim of the study was to investigate the effect of 2-methoxyestradiol (2-ME) on GnRH-induced LH and FSH secretion by porcine pituitary cells in vitro. Moreover, the concentrations of superoxide anion radical (O2-), as a possible mediator of 2-ME action, and malonyldialdehyde (MDA), as an oxidative stress indicator, were estimated. Pituitary cells were cultured in McCoy 5A medium with GnRH (positive control), with GnRH and 3.3×10-11-3.3×10-7M/L of 2-ME, or with GnRH and 2.7×10-9- 2.7×10-8 M/L of 17β-estradiol. The secretion of gonadotropins, as well as concentrations of superoxide anion and MDA were analysed after 2-72 h of the experiment. A positive correlation between 2-ME dose and FSH secretion from anterior pituitary cells (r=0.72, 0.95, 0.92, 0.90, 0.85, and 0.82 after 2, 6, 18, 24, 48, and 72 h, respectively) was demonstrated. In contrast, a negative correlation between 2-ME concentration and LH secretion was observed (r=-0.82, -0.72, -0.85, -0.89, -0.93, and -0.79 after 2, 6, 18, 24, 48, and 72 h, respectively). The concentration of O2-. was increasing under the influence of the rising doses of 2-ME, whereas the mean level of MDA was not changing significantly.