Lacational Anovulation in Rats and Its Dependency on Progesterone

Takuya Murata, Sachiko Saito, Kunio Shiota, Michio Takahashi

研究成果: Article

3 引用 (Scopus)

抄録

The relationship between prolactin (PRL) secretion and anovulation in lactating rats was studied. Normal lactating rats and lactating rats treated with antiserum against luteinizing hormone-releasing hormone at the time of postpartal ovulation were used. Normal lactating rats were treated with either a dopamine agonist (CB-154, 150 μg/rat) on Day 10 or 13, or pups removal on Day 7 or 10, and thereafter luteolysis and inhibition on PRL secretion were assessed. With the CB-154 treatment, the incidence of luteolysis increased as the lactational period advanced (42% vs 72%), whereas it decreased (73% vs 14%) with the pups removal. Thus, dopamine effectively inhibited PRL secretion during the later lactational stage, but could not do so during the earlier stage when there were mechanisms other than dopamine stimulating PRL secretion. Following luteal regression induced by CB-154, ovulation did not occur if the rats were treated with CB-154 on Day 10, whereas 50% of the rats ovulated within 4 days if treated on Day 13. Furthermore, in the lactating rats treated with anti-luteinizing hormone-releasing hormone serum during late pregnancy, ovulation was not observed until Day 10 of lactation. Since the serum progesterone levels were low in these rats due to the absence of ovulation and lactational corpora lutea, the blockade of ovulation was not due to elevated circulating progesterone during the early lactational period. The mechanism of ovulation blockade during lactation thus seems to shift from being progesterone independent to progesterone dependent at a similar period when the neuroendocrine control of PRL secretion shifts from dopamine independent to dependent.

元の言語English
ページ(範囲)97-101
ページ数5
ジャーナルProceedings of the Society for Experimental Biology and Medicine
196
発行部数1
DOI
出版物ステータスPublished - 1991
外部発表Yes

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Anovulation
Progesterone
Rats
Ovulation
Prolactin
Bromocriptine
Luteolysis
Dopamine
Lactation
Gonadotropin-Releasing Hormone
Corpus Luteum
Dopamine Agonists
Serum
Immune Sera
Pregnancy

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

これを引用

Lacational Anovulation in Rats and Its Dependency on Progesterone. / Murata, Takuya; Saito, Sachiko; Shiota, Kunio; Takahashi, Michio.

:: Proceedings of the Society for Experimental Biology and Medicine, 巻 196, 番号 1, 1991, p. 97-101.

研究成果: Article

Murata, Takuya ; Saito, Sachiko ; Shiota, Kunio ; Takahashi, Michio. / Lacational Anovulation in Rats and Its Dependency on Progesterone. :: Proceedings of the Society for Experimental Biology and Medicine. 1991 ; 巻 196, 番号 1. pp. 97-101.
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abstract = "The relationship between prolactin (PRL) secretion and anovulation in lactating rats was studied. Normal lactating rats and lactating rats treated with antiserum against luteinizing hormone-releasing hormone at the time of postpartal ovulation were used. Normal lactating rats were treated with either a dopamine agonist (CB-154, 150 μg/rat) on Day 10 or 13, or pups removal on Day 7 or 10, and thereafter luteolysis and inhibition on PRL secretion were assessed. With the CB-154 treatment, the incidence of luteolysis increased as the lactational period advanced (42{\%} vs 72{\%}), whereas it decreased (73{\%} vs 14{\%}) with the pups removal. Thus, dopamine effectively inhibited PRL secretion during the later lactational stage, but could not do so during the earlier stage when there were mechanisms other than dopamine stimulating PRL secretion. Following luteal regression induced by CB-154, ovulation did not occur if the rats were treated with CB-154 on Day 10, whereas 50{\%} of the rats ovulated within 4 days if treated on Day 13. Furthermore, in the lactating rats treated with anti-luteinizing hormone-releasing hormone serum during late pregnancy, ovulation was not observed until Day 10 of lactation. Since the serum progesterone levels were low in these rats due to the absence of ovulation and lactational corpora lutea, the blockade of ovulation was not due to elevated circulating progesterone during the early lactational period. The mechanism of ovulation blockade during lactation thus seems to shift from being progesterone independent to progesterone dependent at a similar period when the neuroendocrine control of PRL secretion shifts from dopamine independent to dependent.",
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