Mode of Action of Oestrogen in Maintaining the Functional Life of Corpora Lutea in Sheep

Denamur, R; Martinet, J.; Short, R. V.

doi:10.1530/jrf.0.0230109

Cited by 14 publications

(3 citation statements)

References 11 publications

(10 reference statements)

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“…Some recent studies, however, present a different view. For instance, experiments in hypophysectomized or stalksectioned sheep show that only prolactin can maintain the secretory activity of the CL (Denamur, Martinet & Short, 1970Bryant, Greenwood, Kann, Martinet & Denamur, 1971; Kann & Denamur, 1974) and are in accord with the findings of Domanski, Skrzeczkowski, Stupnicka, Fitko & Dobrowolski (1967) that LTH in sheep stimulates the secretion of progesterone by the perfused ovary on the 7th and 8th days of the oestrous cycle. Measurements of serum prolactin levels by radioimmunoassay throughout the oestrous cycle in sheep have indicated marked changes with release at a very high rate just before ovulation, and with the peak preceding that of LH (Reeves, Arimura & Schally, 1970;Bryant et al, 1971;Davis, Reichert & Niswender, 1971; Cumming, Brown, Goding, Bryant & Greenwood, 1972).…”

Section: Introductionsupporting

confidence: 67%

Cyclic activity of the pituitary prolactin cells and plasma prolactin levels in the oestrous cycle of the ewe

Polkowska¹,

Wolińska²,

Domański³

1976

Reproduction

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The relative proportions of prolactin cells, somatotrophs and gonadotrophs were determined in the adenohypophyses of 28 Merino ewes on selected days during the oestrous cycle. Plasma prolactin levels were measured in 16 of the animals at 3-hr intervals during the 24 hr before autopsy. From Days 1 to 5 of the cycle (Day 0=day of ovulation), plasma prolactin levels were 20-40 ng/ml and the prolactin cells were filled with granules. Plasma levels increased to 168 ng/ml between Days 6 and 9, and marked degranulation of the prolactin cells occurred. The greatest degranulation was found on Days 16 and 0, and was associated with a prolactin surge to a concentration of 610 ng/ml. The rise in plasma prolactin and intensive degranulation of prolactin cells at the time of ovulation and formation of the CL suggest that prolactin is important at this stage of the oestrous cycle.

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Section: Introductionsupporting

confidence: 67%

Cyclic activity of the pituitary prolactin cells and plasma prolactin levels in the oestrous cycle of the ewe

Polkowska¹,

Wolińska²,

Domański³

1976

Reproduction

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“…The corpus luteum which results from the ovulation preceding the beginning of treatment does not disappear more quickly after the large drop in plasma prolactin concentration. Thus, while this hormone is necessary for the maintenance of normal luteal structure (Denamur et al, 1970 there seems to be an excess of it during the cycle. Also, as Niswender (1972) indicates, the rôle of prolactin during ovulation does not appear to be fundamental since normal ovulation occurs in the absence of the pre-ovulatory prolactin surge.…”

Section: Prolactin During the Oestrous Cyclementioning

confidence: 99%

Possible Role of Prolactin During the Oestrous Cycle and Gestation in the Ewe

Kann¹,

Denamur²

1974

Reproduction

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“…In the sheep, the antiluteolytic effect of oestradiol (Piper & Foote, 1970) is associated with decreased progesterone production by the CL. This effect has not been seen by Denamur, Martinet & Short (1970). They showed that twice-daily injections of oestradiol benzoate from Days 2 to 30 maintained the CL, and that progesterone secretion on Day 20 was not significantly different from that on Day 12 of the cycle.…”

Section: Discussionmentioning

confidence: 97%

Effects of Oestrogen, Administered Early or Late in the Oestrous Cycle, Upon the Survival and Regression of the Corpus Luteum of the Guinea-Pig

Illingworth¹,

Perry²

1973

Reproduction

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The lytic effect of oestrogen administered within the first 5 days of ovulation in the guinea-pig can be abolished by hysterectomy and is greatly reduced by hypophysectomy. After Day 9 of the cycle, large doses of oestrogen resulted in the maintenance of the CL for at least 3 weeks after ovulation, and in many instances for more than 4 weeks, and their further growth to sizes seen after hysterectomy or during pregnancy (3\ m=. \ 2 \ m=+-\ 0\m=.\3 mm3). These large CL contained and secreted more progesterone than those of the normal cycle. Hypophysectomy did not abolish the antiluteolytic effect of oestrogen. A luteotrophic, not solely an antiluteolytic, effect of the hormone could be demonstrated. The luteolytic or luteotrophic action of oestrogen did not depend upon the age of the CL but upon pituitary and/or uterine factors. The study used mainly stilboestrol, but similar results were obtained with oestradiol compounds.

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Mode of Action of Oestrogen in Maintaining the Functional Life of Corpora Lutea in Sheep

Cited by 14 publications

References 11 publications

Cyclic activity of the pituitary prolactin cells and plasma prolactin levels in the oestrous cycle of the ewe

Cyclic activity of the pituitary prolactin cells and plasma prolactin levels in the oestrous cycle of the ewe

Possible Role of Prolactin During the Oestrous Cycle and Gestation in the Ewe

Effects of Oestrogen, Administered Early or Late in the Oestrous Cycle, Upon the Survival and Regression of the Corpus Luteum of the Guinea-Pig

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