Resumen

ALAMILLA RODRIGUEZ, Mónica et al. Kisspeptin in prepubertal heifers. I Effects of age on the response of LH, FSH and GH to kisspeptin-10 and its association with IGF-I, leptin and estradiol. Rev. mex. de cienc. pecuarias [online]. 2017, vol.8, n.4, pp.375-385. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v8i4.4644.

To evaluate effects of age on the response of LH, FSH and GH to kisspeptin-10 (KISS) in prepubertal heifers and its association with circulating levels of IGF-I, estradiol (E2) and leptin, 21 heifer calves that were 4, 7 or 11 mo old, received an iv injection of KISS (5 μg/kg). LH, FSH and GH were quantified in blood serum taken every 15 min (4 h pre- and 4 h post-KISS-10). In three pre- and six post-KISS samples, IGF-I, leptin and E2 were determined. All heifers responded to KISS with an LH increment but the response magnitude differed among groups since maximum value was higher (P<0.05) in 11 mo (11.6+1.3 ng/ml) than in 7 mo (7.2±1.3 ng/ml) and 4 mo (6.1±1.3 ng/ml) old calves. Duration of response differed (P<0.05) among ages (11 mo=132.9+20 mina; 7 mo=92±20 mina,b; 4 mo=64.3±20 minb). For FSH, all and 11 mo calves responded to KISS but only 71.4 % of 4 mo did. In GH, 71.4 % of 4 mo and 85.7 % of 7 mo calves responded to KISS whereas 100 % of 11 mo animals responded. FSH and GH did not differ among age groups. The 11 mo heifers had the highest IGF-I and E2 but the lowest leptin levels. In conclusion, KISS evokes LH increments in all calves 4 to 11 mo old, but the response increases with age in association with high circulating IGF-I and E2 and low leptin. The response of FSH and GH to KISS is not influenced by age or variations in circulating IGF-I, E2 or leptin.

Palabras llave : Kisspeptin; Prepubertal heifers; LH; FSH; GH.