Resumo

SANTOS ECHEVERRIA, Rubén et al. Luteinizing hormone and ovarian activity in response to kisspeptin-10 and its association with IGF-1 and leptin in prepubertal heifers. Rev. mex. de cienc. pecuarias [online]. 2014, vol.5, n.2, pp.181-200. ISSN 2448-6698.

We evaluated the effect of kisspeptin-10 (Kiss-10) administered repeatedly on the release of LH and ovarian activity in prepubertal heifers. We also assessed the association of serum IGF-1 and leptin with these effects. Fourteen Holstein or Brown Swiss by Zebu female calves (11.2 ± 0.2 mo old, 187.4 ± 6.3 kg) were randomly assigned to receive every 2 h for three days an i.v. application of Kiss-10 (Kisspeptin-10; 5 pg/kg of body weight, n= 7) or saline solution (control, n= 7). Blood was collected every 15 min for 0-6, 24-30 and 72-78 h, and every 2 h until 84 h. Each application of Kiss-10 was followed by an increase of LH whose magnitude (area under the curve) decreased (P<0.05) over time. Kiss-10 induced a preovulatory surge of LH and corpus luteum formation in 28.5 % of the calves. Ovulating calves had the highest (P<0.05) serum concentrations of 1Gf-1 and the lowest (P<0.05) leptin. During 63 post-treatment days, no changes were detected in follicular waves attributable to treatments (P>0.05) and heifers did not show cyclic ovarian activity. The conclusion is that Kiss-10 given repeatedly to prepubertal heifers is sufficient to evoke consistent increases of LH, to induce ovulation and luteal activity in animals with high IGF-1 and low leptin in peripheral blood but it is insufficient to establish regular estrous cyclicity.

Palavras-chave : Prepubertal heifers; Kisspeptin; IGF-1; Leptin; Luteinizing hormone.