Identification of a Novel Kisspeptin with High Gonadotrophin Stimulatory Activity in the Dog

Abstract

Kisspeptin (KISS1) and its receptor (KISS1r) are essential for normal reproductive function in many species, but the role of kiss1/kiss1r signalling in the dog has not yet been elucidated. The aims of this study were to identify the canine kiss1 and kiss1r genes and to determine gonadotrophin and oestradiol stimulatory activity of KP-10, the shortest biologically active form of KISS1. Canine kiss1 and kiss1r genes were localized by comparing the reference dog genome with relevant human cDNA sequences, using BLASTn software. The amino acid sequence of canine KP-10 (YNWNVFGLRY) differs at two positions from human KP-10 (YNWNSFGLRF). A single bolus of canine KP-10 was administered intravenously to anoestrous Beagle bitches in dosages of 0, 0.1, 0.2, 0.3, 0.5, 1, 5, 10, and 30 μg/kg. Blood samples were collected before and after canine KP-10 administration for the measurement of plasma luteinizing hormone (LH, all doses), follicle-stimulating hormone (FSH) and oestradiol (1-30 μg/kg). From 0.2 μg/kg onwards, canine KP-10 resulted in a rapid and robust rise in plasma LH concentration (max. at 10 min). KP-10 also resulted in a rapid and robust rise in plasma FSH concentration (max. at 10-20 min). Plasma oestradiol concentration increased significantly after dosages of 1, 5, and 10 μg/kg and reached a maximum at 60-90 min. In conclusion, canine KP-10 is a potent kisspeptin which elicits robust gonadotrophin and oestradiol responses in anoestrous bitches, suggesting that canine kiss1/kiss1r are cogent targets for modulating reproduction in dogs.

Mechanistic insights into the more potent effect of KP-54 compared to KP-10 in vivo

“…injection of 100 μl of PBS (vehicle control; 137 mM NaCl, 2.7 mM KCl, 10 mM Na 2 HPO 4 , 1.8mM KH 2 PO 4 , pH 7.4), KP-10 (1 nmol), or KP-54 (1 nmol) in PBS and LH levels in the plasma measured at 10 min and 2 h after treatment to compare early and late responses points. We chose the 10 min point as some studies have shown that KP-10 injection results in maximal LH secretion after 10–15 min [16, 18]. 100 μl of blood was collected from a tail vein 10 min after injection, mixed with 5 μl EDTA and centrifuged at 10,000 x g for 10 min at 4°C.…”

“…This is particularly relevant for the proposed clinical use of kisspeptins, as they will most likely be administered peripherally rather than directly into the brain. Peripheral delivery of KP-54 stimulated release of LH over a sustained period of 1 to 4 hours, while KP-10 induced less sustained LH secretion between 10 min to 1 h [5, 14–18]. The reason for this difference in the potency of KP-54 and KP-10 after systemic delivery is not known.…”

Effect of kisspeptin on in vitro maturation of sheep oocytes

“…Administration of KP induces the secretion of gonadotropin hormones in many species such as pigs [9], bovines [10,11], ewes [12-14], goats [15], canines [16,17], and women [18,19]. The ability of KP to induce ovulation following intravenous administration has been demonstrated in prepubertal ewe lambs [20] and anestrous ewes [21].…”

In vitro and in vivo effects of kisspeptin antagonists p234, p271, p354, and p356 on GPR54 activation

“…Activating mutation of either of these genes is associated with precocious puberty in both man and woman [16–18]. Administration of exogenous KP results in an increase in circulating concentrations of gonadotropins and sex steroids, as has been demonstrated in many species including humans, goats, and dogs [19–22]. …”

“…These peptides are therefore interesting targets for therapeutic interventions concerning the endocrinological control of reproductive function in mammals. As female dogs exhibit a robust rise in plasma LH, FSH, and estradiol concentrations after peripheral administration of KP10 [22], they represent a good model in which to explore the in vivo effects of potential KP agonists and antagonists.…”