Kisspeptin Stimulates the Pulsatile Secretion of Luteinizing Hormone (LH) during Postpartum Anestrus in Ewes Undergoing Continuous and Restricted Suckling

Abstract

This study tested whether the intravenous application of kisspeptin can stimulate the pulsatile secretion of LH in suckling ewes during postpartum anestrus. Ten days after lambing, Pelibuey ewes were allocated among two groups: (1) continuous suckling (n = 8), where the lambs remained with their mothers; and (2) restricted suckling (n = 8), where the mothers suckled their lambs twice daily for 30 min. On Day 19 postpartum, the ewes were individually penned with ad libitum access to water and feed and given an indwelling catheter in each jugular vein. On Day 20, 4 mL of blood was sampled every 15 min from 08:00 to 20:00 h to determine LH pulse frequency. At 14:00 h, four ewes in each group received 120 μg of kisspeptin diluted in 3 mL of saline as a continuous infusion for 6 h; the remaining four ewes in each group received only saline. The interaction between kisspeptin and suckling type did not affect LH pulse frequency (p > 0.05). Before kisspeptin administration, pulse frequency was similar in all groups (1.50 ± 0.40 pulses per 6 h; p > 0.05). With the application of kisspeptin, pulse frequency increased to 3.50 ± 0.43 pulses per 6 h (p ≤ 0.014), so the concentration of LH (1.11 ± 0.14 ng mL−1) was greater in kisspeptin-treated ewes than in saline-treated ewes (0.724 ± 0.07 ng mL−1; p ≤ 0.040). The frequency of LH pulses was greater with restricted suckling than with continuous suckling (2.44 ± 0.29 versus 1.69 ± 0.29 pulses per 6 h; p ≤ 0.040). We conclude that intravenous application of kisspeptin increases the pulsatile secretion of LH in suckling ewes and that suckling might reduce kisspeptin neuronal activity, perhaps explaining the suppression of ovulation. Moreover, the effects of kisspeptin and suckling on pulsatile LH secretion appear to be independent, perhaps operating through different neural pathways.

Respuesta reproductiva de ovejas multíparas postparto y nulíparas a inyecciones de GnRH y prostaglandina F2α

“…The multiparous ewes in G1 and G2 had different postpartum lengths because a differential response to hormone injection was expected (Crowder et al, 1982). Attempts to restore reproductive activity by increasing gonadotropin secretion were performed by providing external stimuli to GnRH secretion in postpartum ewes (Hernández-Hernández et al, 2021). However, there is a lack of information about the effect of GnRH on estrus response and fertility during postpartum anestrus in ewes.…”

“…A rapid resumption of reproductive activity after these periods is essential to lambing intensification. However, ewes face several physiological challenges after lambing, such as lactation and lamb suckling, which are known to delay the resumption of the reproductive axis function by suppressing the neurological network involved in the release of GnRH and gonadotropins (Hernández-Hernández et al, 2021). In addition, silent ovulations and abnormal luteal phases (short and long duration) that compromise ewe fertility are observed during the postpartum period (Ascari et al, 2013).…”

Efecto del amamantamiento restringido sobre características de crecimiento en ovinos de pelo colombiano

“…Los beneficios del DA y del AR sobre los parámetros reproductivos posparto de la oveja están bien documentados (13,14,15). Así mismo, los efectos del DA sobre el crecimiento del cordero y la funcionalidad del rumen han sido estudiados (16,17).…”

Enkephalin-δ opioid receptor signaling partly mediates suppression of LH release during early lactation in rats

“…Stimulation of the mother's nipple by suckling pups (suckling stimulus) and a negative energy balance for milk production are thought to be the main causes of gonadal dysfunction during the lactation period. Lactational suppression of gonadal function is suggested to be mainly due to the suppression of tonic (pulsatile) release of gonadotropin-releasing hormone (GnRH) and consequent gonadotropin in cows [3][4][5][6], ewes [7], sows [8], rhesus monkeys [9], mice [10], and rats [11,12].…”