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Titolo:
INDUCTION OF OVULATION IN THE ACYCLIC POSTPARTUM EWE FOLLOWING CONTINUOUS, LOW-DOSE SUBCUTANEOUS INFUSION OF GNRH
Autore:
FRAY MD; LAMMING GE; HARESIGN W;
Indirizzi:
AFRC,INST ANIM HLTH,DEPT PATHOL & IMMUNOL NEWBURY RG16 0NN BERKS ENGLAND UNIV NOTTINGHAM,AFRC,HORMONES & FARM ANIM REPROD RES GRP SUTTON LE12 5RD LEICS ENGLAND
Titolo Testata:
Theriogenology
fascicolo: 6, volume: 43, anno: 1995,
pagine: 1019 - 1030
SICI:
0093-691X(1995)43:6<1019:IOOITA>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
GONADOTROPIN-RELEASING-HORMONE; SEASONALLY ANESTROUS EWES; PITUITARY-RESPONSIVENESS; LUTEINIZING-HORMONE; POST-PARTUM; PROGESTERONE PRETREATMENT; ENDOMETRIAL FUNCTION; OVARIECTOMIZED EWES; MULTIPLE INJECTIONS; LUTEAL FUNCTION;
Keywords:
EWE; GNRH; POSTPARTUM; OVULATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
36
Recensione:
Indirizzi per estratti:
Citazione:
M.D. Fray et al., "INDUCTION OF OVULATION IN THE ACYCLIC POSTPARTUM EWE FOLLOWING CONTINUOUS, LOW-DOSE SUBCUTANEOUS INFUSION OF GNRH", Theriogenology, 43(6), 1995, pp. 1019-1030

Abstract

Pituitary and ovarian responses to subcutaneous infusion of GnRH wereinvestigated in acyclic, lactating Mule ewes during the breeding season. Thirty postpartum ewes were split into 3 equal groups; Group G received GnRH (250 ng/h) for 96 h; Group P+G was primed with progestagen for 10 d then received GnRH (250 ng/h) for 96 h; and Group P received progestagen priming and saline vehicle only. The infusions were delivered via osmotic minipumps inserted 26.6+/-0.45 d post partum (Day 0 ofthe study). Blood samples were collected for LH analysis every 15 minfrom 12 h before until 8 h after minipump insertion, then every 2 h for a further 112 h. Daily blood samples were collected for progesterone analysis on Days 1 to 10 following minipump insertion, then every third day for a further 25 d. Tn addition, the reproductive tract was examined by laparoscopy on Day -5 and Day +7, and estrous behavior was monitored between Day -4 and Day +7. Progestagen priming suppressed (P<0.05) plasma LH levels (0.27+/-0.03 vs 0.46+/-0.06 ng/ml) during the preinfusion period, but the GnRH-induced LH release was similar for Group G and Group P+G. The LH surge began significantly (P<0.05) earlier (32.0+/-3.0 vs 56.3+/-4.1 h) and was of greater magnitude (32.15+/-3.56 vs 18.84+/-4.13 ng/ml) in the unprimed than the primed ewes. None ofthe ewes infused with saline produced a preovulatory LH surge. The GnRH infusion induced ovulation in 10/10 unprimed and 7/9 progestagen-primed ewes, with no significant difference in ovulation rate (1.78+/-0.15 and 1.33+/-0.21,respectively). Ovulation was followed by normal luteal function in 4/10 Group-G ewes, while the remaining 6 ewes had short luteal phases. In contrast, each of the 7 Group-P+G ewes that ovulated secreted progesterone for at least 10 d, although elevated plasma progesterone levels were maintained in 3/7 unmated ewes for > 35 d. Throughout the study only 2 ewes (both from Group P+G) displayed estrus. These data demonstrate that although a low dose, continuous infusion of GnRH can increase tonic LH concentrations sufficient to promote a preovulatory LH surge and induce ovulation, behavioral estrus and normalluteal function do not consistently follow ovulation in the progestagen-primed, postpartum ewe.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 17:32:10