Serum Prolactin Concentrations during Hormonally Induced Pseudopregnancy in the Rat

Greef, W. J. De; Zeilmaker, G. H.

doi:10.1210/endo-105-1-195

Cited by 29 publications

(12 citation statements)

References 27 publications

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“…4). This fact is consistent with results in adult rats in which a single injection of progesterone at the same time as ovariectomy performed on the day of oestrus induces nocturnal prolactin surges (de Greef & Zeilmaker, 1979;Murakami et ai, 1980). On the other hand, nocturnal prolactin surges during the pubertal stage could be induced by progesterone administration even at 6 days after the ovariectomy (Fig.…”

Section: Discussionsupporting

confidence: 90%

Development of progesterone dependency in the appearance of the nocturnal prolactin surge in immature rats

Tomogane

Yokoyama²

1989

Reproduction

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Section: Discussionsupporting

confidence: 90%

Development of progesterone dependency in the appearance of the nocturnal prolactin surge in immature rats

Tomogane

Yokoyama²

1989

Reproduction

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“…It has been reported by our (Murakami et al, 1980) and other (de Greef and Zeilmaker, 1979) groups that the single injection of progesterone to the estrous rats induces pseudopregnancy with daily PRL surges beginning two days after the injection. In these rats, the plasma level of PRL rose immediately after the injection to nearly the peak of the PRL surge, and the level remained high for1or2days.…”

Section: Discussionsupporting

confidence: 50%

“…Though it is known that the daily PRL surges can be induced by a single treatment with an extremely high dosage of progesterone (de Greef and Zeilmaker, 1979;Murakami et al, 1980), the effectiveness of a continuously maintained high, but not pharmacologically high, plasma progesterone level on the initiation of PRL surges has not been investigated.…”

mentioning

confidence: 99%

Induction of Daily PRL Surges in Rats by Chronic Treatment with Progesterone

Kawaminami

Takahashi

1987

Endocrinol Japon

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The effect of a high plasma progesterone level on the PRL releasing mechanism was investigated in rats of both sexes. Progesterone levels were maintained by implanting silicone tubes filled with the steroid. In the intact female, 6progesterone tubes (inner diameter2mm; outer diameter3mm; length40mm) were implanted subcutaneously on the estrous day. With2-to5-day latent periods, the daily rise in the plasma PRL level was observed coincident with the time of nocturnal surge in the pseudopregnant rats induced by cervical stimulation.The same treatment applied to ovariectomized rats induced diurnal and nocturnal surges. The peak height was lower in ovariectomized rats than that in intact or normal pseudopregnant rats, and was restored to almost the normal range by concomitant implantation of estradiol with progesterone. This latter protocol, however, did not induce any PRL surge in chronically orchidectomized rats. These results suggest that1) chronically elevated progesterone levels can induce such PRL surges as are observed in pseudopregnant rats, 2) estradiol enhances the magnitude of the PRL surge, and3) the progesterone sensitive central mechanism, controlling the PRL surge, does not exist in adult male rats.

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“…It has been demonstrated that the effect of estrogen on the diurnal PRL surge is similar to its effect on the proestrous afternoon surge of PRL [40]. Treatment with estrogen or progesterone on the day of estrous induced twice daily PRL surges as seen in mated animals [41]. The present study, for the first time, demonstrated that neuronal activity changed in the mPOA, mAMYG and VMH both during the proestrous PRL surge and following mating, suggesting that both hormonal and vaginocervical stimuli are processed and possibly integrated in these brain regions.…”

Section: Discussionmentioning

confidence: 99%

Fos Expression in the Female Rat Brain during the Proestrous Prolactin Surge and following Mating

Yang

Lee²,

Voogt³

1999

Neuroendocrinology

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A prolactin (PRL) surge occurs in the female rat during proestrus in response to elevated estradiol levels. The elevated release of ovarian steroids on the day of proestrus is also associated with sexual receptivity. Mating triggers twice-daily PRL surges that supplant the proestrous PRL surge and are responsible for maintaining luteal function during the first half of pregnancy. In order to understand the neuronal mechanisms controlling the proestrous- and mating-induced PRL surges, we examined patterns of Fos expression by immunocytochemistry in specific brain regions as a measure of neuronal activity. Intact female rats were sacrificed at 09.00, 15.00, and 18.00 h on the day of proestrus and the day of diestrus. Brain tissues were also collected at 21.00 h on the day of proestrus from rats receiving intromissions or mounts from males or taken directly from their homecage. On the day of proestrus, the number of neurons expressing Fos in the medial preoptic area (mPOA), medial amygdaloid nucleus (mAMYG), and ventromedial nucleus of the hypothalamus (VMH) was few and was associated with low plasma PRL levels at 09.00 h; however, the number of Fos-positive cells in these brain regions significantly increased at 15.00 and 18.00 h when the proestrous PRL surge occurred. Mating during the evening of proestrus resulted in a dramatic increase in the number of Fos-positive cells in the mPOA, mAMYG, and VMH as well as in the arcuate nucleus (ARC). Nonmated animals in diestrus showed low and unchanged PRL levels and Fos expression in all the brain areas throughout the day. These results suggest that the mPOA, mAMYG, VMH and ARC may be important brain sites for the integration of stimuli associated with proestrous- and mating-induced PRL surges.

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Serum Prolactin Concentrations during Hormonally Induced Pseudopregnancy in the Rat

Cited by 29 publications

References 27 publications

Development of progesterone dependency in the appearance of the nocturnal prolactin surge in immature rats

Development of progesterone dependency in the appearance of the nocturnal prolactin surge in immature rats

Induction of Daily PRL Surges in Rats by Chronic Treatment with Progesterone

Fos Expression in the Female Rat Brain during the Proestrous Prolactin Surge and following Mating

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