EN
The aim of the study was to analyze the contribution of kisspeptin-10 (KiSS-10) and peptide 234 (kisspeptin-234, potent neutral antagonist of GPR-54 receptors) to the modulation of GnRH-induced folliclestimulating hormone (FSH) secretion from anterior pituitary cells of prepubertal ram lambs in vitro. Pituitary cells were cultured in McCoy 5A medium without hormones (the negative control), with GnRH (4 × 10⁻⁹ M, the positive control), with GnRH (4 × 10⁻⁹ M) and 10⁻¹¹-10⁻⁸ M of KiSS-10 or GnRH (4 × 10⁻⁹ M), 10⁻¹¹-10⁻⁸ M of KiSS-10 and 10⁻⁷ M of peptide 234. After 6, 12 and 48 h of the experiment, the secretion of follicle-stimulating hormone was determined. The obtained results show that FSH secretion from anterior pituitary cells of ram lambs in vitro was dependent on kisspeptin-10 concentration in the culture medium. Addition of 10⁻¹¹-10⁻⁹ M of KiSS-10 caused an increase in FSH secretion (r = 0.73, 0.90, and 0.82 after 6, 12 and 48 h, respectively) compared to both the negative and positive control, whereas the highest concentration of KiSS-10 (10⁻⁸ M) suppressed the secretion of this gonadotropin. The most stimulating effect was observed under the influence of 10⁻⁹ M of KiSS-10. However, concurrent cell exposure to peptide 234 abolished the stimulating action of kisspeptin-10 on FSH secretion. The negative correlation between FSH secretion and 10⁻¹¹-10⁻⁸ M of KiSS-10 in this condition was found (r = –0.68, –0.91, and –0.81 after 6, 12 and 48 h, respectively). This confirms that the observed increase in GnRH-induced FSH secretion was a direct effect of KiSS-10 on the anterior pituitary cells of prepubertal ram lambs.