Regulation of Prolactin Secretion during the Luteal Phase in the Rat

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

doi:10.1210/endo-102-4-1190

Cited by 72 publications

(52 citation statements)

References 4 publications

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“…2). These results indicate that diurnal changes of prolactin secretion depend on the circulating level of progesterone in the first spontaneous oestrous cycle as well as in the pseudopregnancy and pregnancy (de Greef & Zeilmaker, 1978;Voogt, 1980;Takahashi et ai, 1980;Gunnet & Freeman, 1983;Tomogane & Yokoyama, 1989).…”

Section: Discussionmentioning

confidence: 78%

Plasma progesterone concentrations and length of the first spontaneous oestrous cycle in pubertal rats

Tomogane

Yokoyama²

1990

Reproduction

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Section: Discussionmentioning

confidence: 78%

Plasma progesterone concentrations and length of the first spontaneous oestrous cycle in pubertal rats

Tomogane

Yokoyama²

1990

Reproduction

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“…Smith and Neill [18] have reported that the ovaries are not required for normally timed N and D surges of PRL secretion during PSP, although the magnitude of each surge is less in ovari ectomizad than in intact PSP rats [4,18] . The observations of the present study also suggest a significant role of estradiol in attenuation or termination of N PRL surges of the early and middle phases of OVX PSP.…”

Section: Discussionmentioning

confidence: 99%

“…The PRL surges is induced even in ovariectomized rats [5,7 ] . Though the ovarian steroids are not required for initiation of the PRL surges, the steroids can modify the PRL surges [4,17] . It has been thought that the N surge of PRL is essential for maintaining PSP and is stored in the hypo thalamus as memory for 6 days [4, 71.…”

mentioning

confidence: 99%

“…Though the ovarian steroids are not required for initiation of the PRL surges, the steroids can modify the PRL surges [4,17] . It has been thought that the N surge of PRL is essential for maintaining PSP and is stored in the hypo thalamus as memory for 6 days [4, 71. Gorospe and Freeman [10] have reported that at the end of PSP, estradiol plays an important role for terminating PSP in the condition of proge sterone to be decreased.…”

mentioning

confidence: 99%

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Effects of Estradiol on the Prolactin Surges and the Feedback Mechanisms of Gonadotropins in Pseudopregnant Rats

Furudate

1991

Experimental Animals

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The influences of estradiol on the prolactin (PRL) surges and on the secretion of gonadotropins (LH and FSH) were investigated in the pseudopregnancy (PSP) of acutely ovariectomized rats. The four following experimental groups were pre pared : 1) intact PSP as a control, 2) ovariectomy was performed on day 0 of PSP (OVX), 3) a Silastic tube containing estradiol was implanted for day 1-4 into the OVX rats (OVX-E 1-4), and 4) the Silastic tube was implanted for day 5-8 by the same manner into the OVX rats (OVX-E 5-8). In the OVX group nocturnal (N) PRL surges were observed at 0500 h on days 4, 8 and 12 examined, and increased secretions of LH and FSH were noted. In the OVX-E 1-4 group, the N PRL surge was suppressed on day 4, and the suppressed N PRL surge did not occur on day 8, after the removal of the implanted tubes. Diurnal (D) PRL surges with LH surges were observed at 1700 h on day 4 in these rats. Similarly, more remarkable results were obtained on days 8 and 12 in the OVX-E 5-8 group than in the OVX-E 1-4. It was concluded that : 1) PSP had the N PRL surges at least until day 12 without support of the ovary ; 2) the mechanisms for these PRL secretion have no relationship to the feedback mechanisms of gonadotropins ; 3) in acutely OVX PSP rats estradiol suppressed the N PRL surges in early and middle stages of PSP and the once suppr essed N PRL surge did not recover even after disappearance of estradiol ; and 4) estradiol stimulated the D PRL surge with LH surge, which was similar to the cycling rats.During pseudopregnancy (PSP) induced by cervical stimulation, two surges of prolactin (PRL) are observed : the nocturnal (N) surge at dawn and the diurnal (D) surge in the eve ning [1, 3, 41. PSP has functional corpora lutea with dominant progesterone secretion stimu lated with the PRL surges. The PRL surges is induced even in ovariectomized rats [5,7 ] . Though the ovarian steroids are not required for initiation of the PRL surges, the steroids can modify the PRL surges [4,17] . It has been thought that the N surge of PRL is essential for maintaining PSP and is stored in the hypo thalamus as memory for 6 days [4, 71. Gorospe and Freeman [10] have reported that at the end of PSP, estradiol plays an important role for terminating PSP in the condition of proge sterone to be decreased.Generally, a reverse relationship is observ ed between the secretion of gonadotropins and PRL in reproductive phenomenon [2,14], such as PSP, pregnancy and lactation, where PRL is secreted dominantly, whereas luteinizing hormone (LH) and follicle stimulating hormone (FSH) remain a basale level [2,19, 201. In these stage PRL probably stimulates progesterone secretion from the copora lutea, and proges terone suppresses the secretions of LH and FSH through the hypothalamus and/or pituitary. Little is still known the detail relationships between the secretion of PRL and gonadotro pins during PSP. In this study the influences of estradiol on the N surge of PRL and the feed back mechanisms of LH and FSH were studied in acutely ovariect...

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“…at about the time when plasma progesterone levels begin to decline precipitously (Smith et al 1975). Progesterone does appear to be essential for the maintenance of prolactin surges (de Greef and Zeilmaker 1978;Murakami et al 1979;Takahashi et al 1980) and may be important for the establishment of the initial mnemonic system (Everett 1963). This does not mean, however, that the other factors which have been mentioned were not implicated in the overall fail ure of response to cervical stimulation after 2400 h on D -1.…”

Section: Discussionmentioning

confidence: 99%

Critical Time Period for the Vagino-cervical Stimulus to Induce Pseudopregnancy in the Dioestrous Rat

Soares¹,

Wa²

1980

Aust. Jnl. Of Bio. Sci.

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Groups of rats experienced mechanical stimulation of the vagino-cervical region to induce pseudopregnancy at various intervals from 0900 h on dioestrus -1 (D -1) to 1800 h on D -2. Twentyfour of 26 rats which were stimulated on D -I experienced immediate pseudopregnancy whereas when the stimulus was given on D-2, 39 of 45 rats continued to cycle and the latest time when such mechanical stimulation would reliably induce immediate pseudopregnancy was

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Regulation of Prolactin Secretion during the Luteal Phase in the Rat

Cited by 72 publications

References 4 publications

Plasma progesterone concentrations and length of the first spontaneous oestrous cycle in pubertal rats

Plasma progesterone concentrations and length of the first spontaneous oestrous cycle in pubertal rats

Effects of Estradiol on the Prolactin Surges and the Feedback Mechanisms of Gonadotropins in Pseudopregnant Rats

Critical Time Period for the Vagino-cervical Stimulus to Induce Pseudopregnancy in the Dioestrous Rat

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