title: A single administration of the GnRH antagonist acyline inhibits basal and GnRH-stimulated serum testosterone concentrations in male dogs.
abstract: The objective of this study was to describe testosterone (T) response to GnRH challenge in antagonist-treated dogs over a 30-day period. Eight mongrel dogs were randomly assigned to either the GnRH antagonist acyline 330 μg/kg sc (ACY; n = 4) or a placebo group (PLA; n = 4). The dogs were serially challenged with the GnRH agonist, buserelin 0.2 μg/kg sc on days -1, 1, 3, 7, 10, 14, 21 and 30. On these days, blood samples for T determinations were collected before (-30 min) and 60, 120 and 180 min after the agonist injection. Basal (-30 min) and post-GnRH agonist stimulation T values were compared by anova for repeated measures. Before treatments (day -1), there were no differences in basal T serum concentrations between groups (p > 0.1). After treatments, basal T showed a significant interaction between treatment and day (p < 0.05). Furthermore, when both groups were analysed independently, basal T varied in the ACY (p < 0.01) but not in the PLA group (p > 0.1). On day -1, before treatments, the stimulation tests had only a time effect (p = 0.05) although on days 1 (p < 0.01), 3 (p < 0.01), 7 (p < 0.01), 10 (p < 0.01) and 14 (p < 0.05), the response to the agonist differed between groups, becoming similar on days 21 (p > 0.05) and 30 (p > 0.05). It was concluded that, in dogs, a single administration of the GnRH antagonist prevented canine gonadal axis to physiologically respond to agonistic challenge during 14 days.
authors: Laboratory of Mineral Nutrition and Reproductive Physiology Faculty of Veterinary Medicine, National University of La Plata-CONICET, La Plata, Argentina.
authors: G
authors: G
authors: García Romero
authors: G
authors: G
authors: Mattioli
authors: D
authors: D
authors: Rosa
authors: J D
authors: JD
authors: Diaz
authors: M
authors: M
authors: Abeyá
authors: C
authors: C
authors: Gobello
mesh_terms: D000818:Animals; D002064:Buserelin / Q000494:pharmacology; D003272:Contraceptive Agents, Male / Q000008:administration & dosage / Q000494:pharmacology; D004285:Dogs; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists / Q000037:antagonists & inhibitors*; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage* / Q000494:pharmacology*; D013739:Testosterone / Q000097:blood*; D013997:Time Factors
chemical_list: D003272:Contraceptive Agents, Male; D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D002064:Buserelin; C109238:acyline