Effects of an LHRH antagonist on gonadotrophin and oestradiol secretion, follicular development, oestrus and ovulation in Holstein heifers

Rieger, D.; Roberge, S.; Coy, D. H.; Rawlings, N. C.

doi:10.1530/jrf.0.0860157

Cited by 9 publications

(3 citation statements)

References 23 publications

(24 reference statements)

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“…Therefore, we decided to use a higher dose administered as a single injection or a multiple injection over 5 d. Treatment with a 100-µg/kg BW dose abolished LH pulse frequency for at least 7 d and reduced mean serum LH concentration. Suppression of serum LH pulse numbers and mean LH concentrations by the LHRH antagonist has been documented in cows by Rieger et al (1989), Peters et al (1994), and Madill et al (1994). We could not detect any LH pulses on d 1 of the cycle.…”

Section: Discussioncontrasting

confidence: 57%

“…Suppression of E 2 production during the follicular (Campbell et al, 1990) or midluteal phases (Brooks and McNeilly, 1994) was demonstrated in sheep. Rieger et al (1989) also delayed the preovulatory E 2 peak when an LHRH antagonist was administered during the late follicular phase. Similarly, E 2 concentrations were suppressed in a dose-dependent manner in superstimulated heifers (Madill et al, 1994).…”

Section: Discussionmentioning

confidence: 93%

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LHRH antagonist decreases LH and progesterone secretion but does not alter length of estrous cycle in heifers.

Ülker

Gant²,

Avila³

et al. 2001

Journal of Animal Science

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The objective of this study was to evaluate the suppressive effect of an LHRH antagonist, Cetrorelix SB-75 (SB-75), on secretion of LH, FSH and ovarian function in beef heifers. In Exp. 1, heifers were treated with a single dose of 10 microg/kg body weight intramuscularly on d 3 of the estrous cycle. In Exp. 2, heifers received either a single injection (100 microg/kg) of SB-75 on d 3 of the estrous cycle or multiple injections of 20 microg/kg on d 3, 4, 5, 6, and 7. Serum LH, but not FSH, was suppressed from one to several days. However, neither FSH nor progesterone was significantly altered. In Exp. 3, heifers received an injection vehicle (5% mannitol) or 100 microg/kg BW of SB-75 on d 1 of the estrous cycle (30 h after first observed standing estrus). Injection of SB-75 suppressed LH pulse frequency on d 3, 5, and 7 (P < 0.001). The mean LH concentrations in the SB-75 treatment groups were lower on d 3 (P < 0.01) and 5 (P < 0.05). There were no differences (P > 0.1) between the two groups in the mean concentrations of LH on d 1, 7, or 14. Treatment did not affect the secretion pattern or concentration of FSH. Injection of SB-75 did not alter estradiol-173 concentrations (P > 0.1). Treatment reduced corpus luteum (CL) function as indicated by lower progesterone production. However, the length of the estrous cycle was not shortened. These data show that the CL can form and survive in the face of depressed LH concentrations during the early stages of the estrous cycle.

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Section: Discussioncontrasting

confidence: 57%

Section: Discussionmentioning

confidence: 93%

LHRH antagonist decreases LH and progesterone secretion but does not alter length of estrous cycle in heifers.

Ülker

Gant²,

Avila³

et al. 2001

Journal of Animal Science

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“…B r e a k d o w n o f t h e b a s e m e n t m e m b r a n e accompanied by follicle rupture permits invasion of theca cells and thecal microcapillary into the avascular granulosa layer, contributing to structural and functional parts in CL formation [1,2]. Several studies indicate that blocking the endogenous LH surge using GnRH antagonist resulted in delay or suppression of ovulation and CL formation in various species [3][4][5]. …”

mentioning

confidence: 99%

Effect of the Dominant Follicle Aspiration before or after Luteinizing Hormone Surge on the Corpus Luteum Formation in the Cow

Hayashi

Matsui

Acosta

et al. 2006

Journal of Reproduction and Development

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Abstract. Luteinizing hormone (LH) surge and follicle rupture act as trigger to start corpus luteum (CL) formation. Thus, we aimed to investigate whether a dominant follicle that has not been exposed to an LH surge can become a functional CL. For this purpose, follicular fluid from the dominant follicles (DF) of cows was aspirated before or after a GnRH-induced LH surge, and subsequent CL formation was observed. Holstein cows were divided into four groups as follows: Luteal phase, a DF was aspirated 7 days after GnRH injection; Pre-LH surge, a DF was aspirated 42 h after PGF2α injection during the mid luteal phase; Post-LH surge, a DF was aspirated 24 h after GnRH injection following PGF2α; and Intact follicle, ovulation was induced by GnRH injection after PGF2α. Observation of morphological changes in the aspirated follicle using color Doppler ultrasonography and blood sampling was performed on Days 0, 3, 6, and 9 (Day 0=follicle aspiration). CL formation following DF aspiration was observed only in the Post-LH surge group. In both the Luteal phase and Pre-LH surge groups, however, none of the cows showed local blood flow at the aspirated site or CL formation. Luteal blood flow area, CL volume, and plasma progesterone concentration in the Post-LH surge group were no different from those in the Intact follicle group. The present results clearly demonstrate that rather than follicle rupture, it is the LH surge that is essential for CL formation in cows. Key words: Corpus luteum formation, Cow, Follicle aspiration, LH surge (J. Reprod. Dev. 52: [129][130][131][132][133][134][135] 2006) t is w ell established that preovulatory luteinizing hormone (LH) surge acts as a trigger f o r t h e s u c c e s s i v e p r o c e s s e s o f f o l l i c u l a r luteinization, ovulation, and corpus luteum (CL) f o r m a t i o n b y i n d u c i n g m o r p h o l o g i c a l , endocrinological, and biochemical changes in the preovulatory follicle [1]. One of the most important events of the ovulatory process is follicle rupture. B r e a k d o w n o f t h e b a s e m e n t m e m b r a n e accompanied by follicle rupture permits invasion of theca cells and thecal microcapillary into the avascular granulosa layer, contributing to structural and functional parts in CL formation [1,2]. Several studies indicate that blocking the endogenous LH surge using GnRH antagonist resulted in delay or suppression of ovulation and CL formation in various species [3][4][5].

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Effects of an LHRH antagonist on the time of occurrence and amplitude of the preovulatory LH surge, progesterone and estradiol secretion, and ovulation in superovulated Holstein heifers

et al. 1994

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Effects of an LHRH antagonist on gonadotrophin and oestradiol secretion, follicular development, oestrus and ovulation in Holstein heifers

Cited by 9 publications

References 23 publications

LHRH antagonist decreases LH and progesterone secretion but does not alter length of estrous cycle in heifers.

LHRH antagonist decreases LH and progesterone secretion but does not alter length of estrous cycle in heifers.

Effect of the Dominant Follicle Aspiration before or after Luteinizing Hormone Surge on the Corpus Luteum Formation in the Cow

Effects of an LHRH antagonist on the time of occurrence and amplitude of the preovulatory LH surge, progesterone and estradiol secretion, and ovulation in superovulated Holstein heifers

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