Secretion of Prolactin and Luteinizing Hormone at Oestrus in the Ewe

Cumming, I. A.; Brown, Joan M.; Goding, J. R.; Bryant, Gillian D.; Greenwood, F. C.

doi:10.1677/joe.0.0540207

Cited by 27 publications

(20 citation statements)

References 8 publications

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“…Saji (1967) who used the haemagglutination-inhibition assay for measuring prolactin. These results differ substantially from those reported by Arai & Lee (1967) (Johke, 1970) and hand milking in the goat (Hart, 1972) (Bryant & Greenwood, 1968;Davis et al, 1971;Cumming, Brown, Goding, Bryant & Greenwood, 1972) Prolactin levels are expressed in ng/ml plasma. 1965; Bryant, Linzell & Greenwood, 1970;Johke, 1970;Neill, 1970;Butler, 1971;Raud, Kiddy & Odell, 1971;Cumming et al, 1972;Frantz, Kleinberg & Noel, 1972;Fell, Findlay, Cumming & Goding, 1973 (1971) and Fell et al (1972).…”

contrasting

confidence: 97%

“…These results differ substantially from those reported by Arai & Lee (1967) (Johke, 1970) and hand milking in the goat (Hart, 1972) (Bryant & Greenwood, 1968;Davis et al, 1971;Cumming, Brown, Goding, Bryant & Greenwood, 1972) Prolactin levels are expressed in ng/ml plasma. 1965; Bryant, Linzell & Greenwood, 1970;Johke, 1970;Neill, 1970;Butler, 1971;Raud, Kiddy & Odell, 1971;Cumming et al, 1972;Frantz, Kleinberg & Noel, 1972;Fell, Findlay, Cumming & Goding, 1973 (1971) and Fell et al (1972). It is tempting to associate this with the rapid rise in free circulating oestrogens and the decrease in progesterone that takes place at this time (Challis, 1971;Obst & Seamark, 1972;Chamley & co-authors, 1973;Robertson & Smeaton, 1973), but a careful study of the time sequence of these events is necessary before any more definite conclusions can be drawn.…”

contrasting

confidence: 97%

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Prolactin Release in the Sheep

Ge¹,

Moseley²,

McNeilly³

1974

Reproduction

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The recent development of radioimmunoassay for prolactin has extended the depth and extent of studies of factors affecting prolactin levels in mammals and has permitted long-term studies to be made of changes in blood prolactin levels in individual animals. Although ovine prolactin has been widely studied in relation to its structure (Li, 1972) and biological activity (see Wolstenholme & Knight, 1972) and has been extensively used as a reference material, the serum prolactin levels of the sheep have not been widely investigated. Many of the early studies involved measurements of single samples obtained by venepuncture, a stressful procedure now known to affect prolactin release in the

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contrasting

confidence: 97%

contrasting

confidence: 97%

Prolactin Release in the Sheep

Ge¹,

Moseley²,

McNeilly³

1974

Reproduction

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“…Specifically, all breeding season ewes received an initial synchronizing injection and were left for 10 days. Following a second cloprostenol injection, groups of ewes were treated 24 h later (mid-follicular phase), 40 h later (late-follicular phase), and on day 10 of the ensuing estrous cycle (luteal phase) [20,21]. The experiments were carried out according to the guidelines established by the Australian Prevention of Cruelty to Animals Act 1986 and were approved by the Monash University, School of Biomedical Sciences, Animal Ethics Committee.…”

Section: Methodsmentioning

confidence: 99%

Seasonal and Cyclical Change in the Luteinizing Hormone Response to Kisspeptin in the Ewe

Smith

Saleh

Clarke³

2009

Neuroendocrinology

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Background: Kisspeptins are recognized as important stimulators of gonadotropin-releasing hormone (GnRH) and gonadotropin secretion. In sheep, the nonbreeding (anestrous) period is characterized by reduced Kiss1 mRNA expression in the hypothalamus. The aim of the present study was to determine whether the response to kisspeptin treatment varies between the breeding and nonbreeding seasons. Methods: Corriedale ewes were treated intravenously with murine kisspeptin-10 (submaximal dose: 20 μg or maximal dose: 250 μg) or GnRH (250 ng) during either the anestrous period or during the breeding season at the luteal, mid-follicular, or late-follicular phase of the estrous cycle. Results: Kisspeptin treatment increased the concentration of luteinizing hormone (LH) in all animals. We found the LH response to kisspeptin (20 μg) was greater in ewes during the anestrous period, being 4-fold that seen during the luteal phase of the estrous cycle. Within the breeding season, kisspeptin (20 μg) was most effective during the late-follicular phase of the estrous cycle. Kisspeptin treatment (both 20 and 250 μg) had no effect on plasma levels of growth hormone, prolactin or cortisol. The variable effect of kisspeptin (20 μg) on LH secretion appeared to mirror that of GnRH treatment indicating that the effect may be mediated by a change in the pituitary response to GnRH. Conclusion: We conclude that the gonadotropic response to kisspeptin depends upon the reproductive status of the female.

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“…Oocytes were immediately recovered from 3 to 5 mm follicles using the optical system already described. The incubation systems were the same as described above and harvests were made after 23 to 31 hr (i) or 45 to 48 hr (ii) previously shown (Jagiello, Ducayen, Miller, Lin & Fang, 1973) Goding, Bryant & Greenwood (1972) and Goding & co-authors (1973); for the monkey from Hotchkiss, Atkinson & Knobil (1971) and Yamaji, Peckham, Atkinson, Dierschke & Knobil (1973); for the cow from Nancarrow & co-authors (1973) and for the human from Gay, Midgley & Niswender (1970), Vande Wiele & co-authors (1970), Korenman & Sherman (1973), Shaaban & Klopper (1973), Snyder, Jaffe, Midgley & Bolte (1973), Jaffe, Yuen, Keye & Midgley (1973) and Fournier, Desjardins & Friesen (1974). Values for peripheral plasma levels were used or, when available, ovarian venous blood levels.…”

Section: Introductionmentioning

confidence: 99%