Ovarian and Pituitary Hormones in Blood of Progestogen-Treated Ewes

Echternkamp, S. E.; Bolt, D. J.; Hawk, H. W.

doi:10.2527/jas1976.424893x

Cited by 75 publications

(24 citation statements)

References 19 publications

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“…Plasma was separated immediately and frozen at -20°C until analysis. The double antibody radioimmunoassay (RIA) method was used to determine the concentrations of plasma P 4 , E 2 [23] and LH [7]. Blood was collected every 15 min for 8 hr one day before CIDR insertion (d -1), 5 days after CIDR insertion (d 5) and 2 days after CIDR removal (d 10) to measure LH pulses.…”

Section: Animalsmentioning

confidence: 99%

GnRH Treatment at CIDR Insertion Influences Ovarian Follicular Dynamics in Japanese Black Cows

Ando

Kamimura

Hamana

et al. 2005

The Journal of Veterinary Medical Science

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ABSTRACT. Ovarian follicular dynamics and estrous synchronization after Gonadotropin-releasing hormone (GnRH) treatment at Controlled Internal Drug Releasing device (CIDR) insertion were investigated in Japanese Black cows. CIDR was inserted for eight cows at 7 days after estrus. Cows were allocated to either Group A: 8-day CIDR insertion with GnRH treatment on d 0 (n=4, d 0=CIDR insertion) or Group B: 8-day CIDR insertion (n=4). Both groups were injected with prostaglandin F 2α (PGF 2α ) on d 7. Ultrasonography and blood sampling were performed twice daily. Intensive sampling was performed every 15 min for 8 hr to determine the pulsatile release of LH on d -1, d 5 and d 10. Three of four cows showed intermediate ovulation within 2 days after GnRH treatment during CIDR insertion in Group A, whereas no ovulation was found in Group B. Three of four cows in Group A and all four cows in Group B ovulated after CIDR removal. Plasma progesterone concentrations from d 3 to d 7 in three intermediate ovulatory cows in Group A (8.4 ± 1.6 ng/ml) was significantly higher than those in Group B (4.1 ± 1.2 ng/ml; 4 cows) during CIDR insertion (P<0.01). Interval to estrus and ovulation after CIDR removal was observed at 60.0 ± 12.0 hr and 76.0 ± 6.9 hr in three cows in Group A, and 75.0 ± 15.1 hr and 93.0 ± 20.5 hr in Group B, respectively. There was a significant increase in LH pulse frequency on d 10 compared on d -1 or d 5 in both groups (P<0.05), in addition those on d 10 in Group A tended to be higher than in Group B. As a result, GnRH treatment at CIDR insertion at 7 days after estrus induced intermediate ovulation with formation of corpus luteum (CL) and rather synchronized emergence of ovulatory follicle during CIDR insertion. These induced CL increased plasma progesterone concentrations and contributed to precise synchronization.

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Section: Animalsmentioning

confidence: 99%

GnRH Treatment at CIDR Insertion Influences Ovarian Follicular Dynamics in Japanese Black Cows

Ando

Kamimura

Hamana

et al. 2005

The Journal of Veterinary Medical Science

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“…The primary antibody, rabbit anti-prolactin (DJB-7-0330) was a gift from Dr Douglas Bolt (USDA, Beltsville, MD, USA). Characterization of the antiserum and initial assay validation was reported in Echternkamp et al (1976). The assay was conducted as above for the GH assay.…”

Section: Radioimmunoassays (Ria) and Igf-i Receptor Binding Assaymentioning

confidence: 99%

Interactions between the ovary and the local IGF-I axis modulate mammary development in prepubertal heifers

Berry

Howard²,

Jobst³

et al. 2003

Journal of Endocrinology

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The objective was to determine the effects of ovariectomy and epithelial-stromal interactions on mammary development and local expression of IGF-I and IGF-binding protein (IGFBP) mRNA in prepubertal heifers. An epithelium-free ('cleared') fat pad (CFP) was prepared in two glands in each of 14 Holstein heifers, aged 1-3 months. Eight of the calves were also ovariectomized. Serum concentrations of GH, IGF-I and prolactin were not affected by ovariectomy. At 6 months of age, calves were killed to provide mammary samples of parenchyma, CFP and intact fat pad (MFP). Total mammary mass was reduced in ovariectomized calves (130 21 g vs 304 25 g; P<0·001), and in several cases parenchymal tissue was essentially absent. Uterus weight was also reduced by ovariectomy (14·5 3·8 g vs 30·4 4·5 g; P<0·05). In support of our hypothesis that local IGF-I mediates prepubertal mammary development, mRNA expression of IGF-I was lower in ovariectomized than in control calves (62·1 7·8 vs 91·6 7·8 arbitrary units; P<0·05). Specific binding of IGF-I to mammary parenchymal microsomes was also reduced by ovariectomy (377 142 vs 868 82 c.p.m.; P<0·01), suggesting decreased sensitivity to IGF-I. Expression of IGFBP-3 and IGFBP-5 mRNA were not influenced by ovariectomy. Expression of IGF-I, IGFBP-3 and IGFBP-5 mRNA did not differ between CFP and MFP, suggesting that expression of these factors was not influenced by interactions between stroma and developing epithelium. Overall, the data suggested that interactions between the ovary and the local IGF-I axis act to optimize the availability and effectiveness of IGF-I within the gland to stimulate mammary growth.

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“…Plasma progesterone, estradiol-17β, LH and FSH c o n c e n tr a t i o n s w e r e d e t e r m i n e d b y radioimmunoassay [16][17][18]. The intra-and interassay coefficients of variation were, 9.3% and 7.6% for progesterone, 7.0% and 12.7% for estradiol-17β, 7.1% and 12.2% for LH, and 5.9% and 10.7% for FSH, respectively.…”

Section: Hormone Assaysmentioning

confidence: 99%

Comparison of the Effectiveness of Ovulation Synchronization Protocol in Anestrous and Cycling Beef Cows

Osawa

Morishige

Ohta

et al. 2003

Journal of Reproduction and Development

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Abstract. Applicability of ovulation synchronization protocol using GnRH and PGF2α (PGF) injection to anestrous beef cows remains controversial. We compared the effectiveness of the protocol in the anestrous stage of the beef cow with that in the cycling stage using the same animals. Ovaries of five Japanese Black and three Japanese Shorthorn cows were ultrasonographically examined, and blood samples were collected daily for hormonal analyses. Each animal received the protocol twice (Day -6 to -8: GnRH, Day 0: PGF, Day 2: GnRH). Additional blood samples were taken before and after GnRH injection for LH and FSH measurements to evaluate the pituitary function. For the ovarian status at the onset of the protocol cows were divided into anestrous (n=8) and cycling (n=8) stages. There was no significant difference in size of the dominant follicle at the first and second GnRH injections, and in the magnitude of the pituitary response to GnRH between the two stages. However, the size of the corpus luteum and progesterone concentrations at the PGF injection in the anestrous stage were significantly smaller and lower (P<0.01), respectively, and ovulation synchronization rate in the anestrous stage was significantly lower (P<0.05) than in the cycling stage. In conclusion, ovulation synchronization protocol in anestrous beef cows has limited effectiveness.

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Ovarian and Pituitary Hormones in Blood of Progestogen-Treated Ewes

Cited by 75 publications

References 19 publications

GnRH Treatment at CIDR Insertion Influences Ovarian Follicular Dynamics in Japanese Black Cows

GnRH Treatment at CIDR Insertion Influences Ovarian Follicular Dynamics in Japanese Black Cows

Interactions between the ovary and the local IGF-I axis modulate mammary development in prepubertal heifers

Comparison of the Effectiveness of Ovulation Synchronization Protocol in Anestrous and Cycling Beef Cows

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