Kiss1 expression in the hypothalamic arcuate nucleus is lower in dairy cows of reduced fertility

Abstract

We tested the hypothesis that divergent genetic merit for fertility of dairy cows is due to aberrant reproductive neuroendocrine function. The kisspeptin status of non-pregnant cows of either positive (POS) or negative (NEG) breeding values for fertility was studied in 3 groups (n = 8), based on their previous post-partum period: POS cows which had spontaneous ovarian cycles (POS-CYC) and NEG cows which either cycled (NEG-CYC) or did not cycle (NEG-NONCYC). Ovarian cycles were synchronized, blood samples were taken to define endocrine status and the animals were slaughtered in an artificial follicular phase. The brains and the pituitary glands were collected for quantitative polymerase chain reaction (qPCR) and in situ hybridisation (ISH) of hypothalamic GNRH1, Kiss1, TAC3 and PDYN and pituitary expression of LHB and FSHB. Gonadotropin releasing hormone (GnRH) and kisspeptin levels were quantified in snap frozen median eminentes (ME). GNRH1 expression and GnRH levels in the ME were similar across groups. Kiss1 expression in the preoptic area of the hypothalamus was also similar across groups, but Kiss1 in the arcuate nucleus was almost 2-fold higher in POS-CYC cows than in NEG groups. TAC3 expression was higher in POS-CYC cows. The number of pituitary gonadotropes and the level of expression of LHB and FSHB was similar across groups. We conclude that the lower levels of Kiss1 and TAC3 in NEG cows with low fertility status, and may lead to deficient GnRH and gonadotropin secretion.

The Emerging Therapeutic Potential of Kisspeptin and Neurokinin B

“…In male castrated sheep with reduced food intake, mean serum LH and hypothalamic ARC Kiss1 mRNA expression were decreased ( 164 ). Cows with nonovulatory cycles have a 2-fold reduction in ARC Kiss1 expression compared to controls ( 165 ). Stress induced by lipopolysaccharide administration also decreased hypothalamic Kiss1 mRNA expression and serum LH levels in female rats ( 166 ).…”

THE INFLUENCE OF VARIOUS KISSPEPTINS ON THE REPRODUCTIVE FUNCTION OF Bos taurus (review)

“…(37) косвенно подтверждают, что в ARC нейроны, продуцирующие кисспептин, более активные. У коров со спонтанными овариальными циклами экспрессия kiss1 в аркуатном ядре почти в 2 раза выше по сравнению с коровами, у которых фиксируются различные проблемы в проявлении цикличности (37).…”