The influence of exogenous progestin on the occurrence of proestrous or estrous signs, plasma concentrations of luteinizing hormone and estradiol in deslorelin (GnRH agonist) treated anestrous bitches.
Theriogenology
; 66(6-7): 1513-7, 2006 Oct.
Article
em En
| MEDLINE
| ID: mdl-16488001
ABSTRACT
UNLABELLED The objectives of this study were to confirm (i) whether progestin treatment suppressed GnRH agonist-induced estrus in anestrous greyhound bitches; and (ii) the site of progestin action (i.e. pituitary, ovary). All bitches received a deslorelin implant on Day 0 and blood samples were taken from -1 h to +6 h. Five bitches were treated with megestrol acetate (2 mg/kg orally once daily) from -7 d to +6 d (Group 1) and 10 bitches were untreated controls (Group 2). Proestrous or estrous signs were observed in 4 of 5 bitches in Group 1, and 4 of 10 bitches in Group 2 (P = 0.28). The plasma LH responses (area under the curve from 0 to 6h after implantation) were higher (P = 0.008) in Group 2 than in Group 1. Plasma LH responses were similar (P = 0.59) in bitches showing signs of proestrus or estrus (responders) and in non-responders. The plasma estradiol responses (calculated as for LH response) were greater in Group 1 than in Group 2 (P = 0.048), and in responders than in non-responders (P = 0.02). IN CONCLUSION:
(i) progestin treatment (a) did not suppress the incidence of bitches showing deslorelin-induced proestrus or estrus, and (b) was associated with a reduced pituitary responsiveness and an increased ovarian responsiveness to deslorelin treatment; (ii) the occurrence of proestrous or estrous signs reflected increased ovarian responsiveness to induced gonadotrophin secretion and not increased pituitary responsiveness to deslorelin.
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Bases de dados:
MEDLINE
Assunto principal:
Progestinas
/
Anestro
/
Hormônio Luteinizante
/
Pamoato de Triptorrelina
/
Cães
/
Estradiol
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Theriogenology
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Austrália