Role of Estradiol in the Regulation of Prolactin Secretion During Late Pregnancy

2016 ◽  
Vol 41 (12) ◽  
pp. 3344-3355 ◽  
Author(s):  
Carlos Villegas-Gabutti ◽  
Gisela E. Pennacchio ◽  
Graciela A. Jahn ◽  
Marta Soaje
Keyword(s):  
Late Pregnancy ◽  
Prolactin Secretion

Opioid modulation of prolactin secretion induced by stress during late pregnancy. Role of ovarian steroids

2014 ◽  
Vol 66 (3) ◽  
pp. 386-393 ◽  
Author(s):  
Susana R. Valdez ◽  
Gisela E. Pennacchio ◽  
Dante F. Gamboa ◽  
Elina G. de Di Nasso ◽  
Claudia Bregonzio ◽  
...  
Keyword(s):  
Late Pregnancy ◽  
Prolactin Secretion ◽  
Ovarian Steroids

Role of the placenta in the control of the ante-partum surge of prolactin in the rat

1991 ◽  
Vol 130 (3) ◽  
pp. 401-407 ◽  
Author(s):  
D. R. Grattan ◽  
R. L. W. Averill
Keyword(s):  
Early Pregnancy ◽  
Feedback Inhibition ◽  
Dark Period ◽  
Late Pregnancy ◽  
Complete Removal ◽  
Prolactin Secretion ◽  
Placental Lactogen ◽  
Surgical Removal ◽  
Plasma Prolactin

ABSTRACT A nocturnal surge of prolactin secretion occurs in the dark period preceding parturition in the rat. The aim of this study was to examine the role of the placenta in the control of this prolactin surge. Plasma prolactin and progesterone were measured by radioimmunoassay in serial blood samples collected after surgical removal of conceptuses during late pregnancy, and after intracerebroventricular (i.c.v.) injection of placental lactogen (PL) before the prolactin surge. In intact control animals, prolactin secretion remained low until a nocturnal surge of secretion occurred in the dark period preceding parturition, peaking at 269±51 (s.e.m.) μg/l at 03.00 h on day 21. Progesterone levels fell from > 200 nmol/l on day 19 to <40 nmol/l by 12.00 h on day 20 of pregnancy. PL levels during late pregnancy were modified by partial or complete removal of conceptuses at 10.00 h on day 19 of pregnancy. Removal of all but one or two conceptuses did not change the normal pattern of prolactin or progesterone secretion. Removal of all conceptuses, however, induced a large nocturnal surge of prolactin secretion, peaking at 211·7±78 μg/l at 03.00 h on day 20, 24 h earlier than the surge in intact animals. Progesterone levels after removal of all conceptuses fell to <40 nmol/l by 23.00 h on day 19, approximately 12 h before the decline in intact animals. Maintenance of increased progesterone levels after conceptus removal using silicone tubing implants significantly (P <0·05) reduced the peak of the premature prolactin surge to 79·7 ±18 μg/l at 05.00 h on day 20. To determine whether PL could act at the hypothalamic level to inhibit the prolactin surge, human PL was injected into the lateral ventricle. PL injected i.c.v. at 17.00 h on day 7 of pregnancy completely abolished both the expected diurnal and nocturnal prolactin surges in the subsequent 24 h. By contrast, the same treatment on day 20 of pregnancy had no effect on the ante-partum prolactin surge. These results demonstrate two changes in the mechanisms controlling prolactin secretion on the last day of pregnancy compared with prolactin secretion during early pregnancy. First, feedback inhibition of prolactin secretion by PL which occurs at mid-pregnancy was not functional on the last day of pregnancy. Secondly, progesterone which promotes the nocturnal prolactin surges of early pregnancy, inhibited prolactin secretion during late pregnancy. Journal of Endocrinology (1991) 130, 401–407

ROLE OF THE MEDICAL–BASAL HYPOTHALAMUS IN THE SECRETION OF GROWTH HORMONE DURING PREGNANCY AND LACTATION IN EWES

1981 ◽  
Vol 89 (3) ◽  
pp. 349-354 ◽  
Author(s):  
BARBARA WRÓBLEWSKA ◽  
E. DOMAŃSKI
Keyword(s):  
Growth Hormone ◽  
Peripheral Blood ◽  
Marked Decrease ◽  
Late Pregnancy ◽  
Peripheral Circulation ◽  
Prolactin Secretion ◽  
Medial Basal Hypothalamus ◽  
Pregnancy And Lactation

The main aim of this study was to examine the role of the hypothalamus in controlling the secretion of GH in the ewe. This was evaluated by studying the effect of lesions placed either in the anterior or the posterior medial–basal hypothalamus (MBH) on the concentration of GH in the peripheral circulation during pregnancy and lactation, i.e. when the levels would be high in normal ewes. Simultaneously, the level of prolactin in the peripheral blood of these animals was followed. Lesions of the MBH resulted in a marked decrease in circulating GH as well as disturbances in the mammogenic and lactogenic processes during the periods of periparturition and lactation respectively. The changes were particularly evident if the anterior MBH was lesioned. The present experiments confirm our previous findings that a stimulatory centre is localized in the anterior MBH of sheep whilst in the caudal MBH there is an inhibitory centre regulating the release of prolactin. The results also confirm the important role of GH during lactation in ewes, especially during lactogenesis. The results indicate a differentiated but synchronizing and synergistic role of the MBH regulating the patterns of GH and prolactin secretion in late pregnancy and lactation.

Role of Oxytocin in Prolactin Secretion during Late Pregnancy

2017 ◽  
Vol 106 (4) ◽  
pp. 324-334 ◽  
Author(s):  
Carlos M. Villegas-Gabutti ◽  
Gisela E. Pennacchio ◽  
Laura Vivas ◽  
Graciela A. Jahn ◽  
Marta Soaje
Keyword(s):  
Elevated Serum ◽  
Late Pregnancy ◽  
Prolactin Secretion ◽  
Rt Pcr ◽  
Stimulatory Action ◽  
Paraventricular Nuclei ◽  
Dopaminergic Tone ◽  
Pituitary Prolactin ◽  
Supraoptic Nuclei

Background/Aims: During late pregnancy, the blockade of progesterone action by mifepristone (Mp) treatment induces a dopaminergic tone fall that enables naloxone (NAL) administration to release pituitary prolactin (PRL). We determined whether oxytocin (OT), which stimulates PRL secretion acting directly on anterior pituitary lactotrophs, mediates the stimulatory action of Mp and NAL on PRL secretion during late pregnancy. Methods: On day 19 of pregnancy, circulating and pituitary OT and PRL levels were measured by radioimmunoassay, 10, 20, and 30 min after NAL (given at 17:30 h) in rats pretreated with Mp (at 08:00 h). Pituitary OT receptor (OTR) expression in Mp-treated rats was evaluated by RT-PCR. Activation of OT neurons in Mp-NAL-treated rats was measured counting double immunoreactive neurons for Fos and OT (Fos-OT-ir) in supraoptic nuclei (SON), and medial (PaMM) and lateral magnocellular divisions of paraventricular nuclei. Results: Elevated serum OT and decreased pituitary OT were observed 10 min after NAL administration in both vehicle- and Mp-treated rats. This PRL increase was prevented by previous i.p. administration of an OTR antagonist, but intracerebroventricular OT administration was ineffective. Mp increased pituitary OTR expression at 18:00 h. Only Mp-NAL increased Fos-OT-ir neurons in the PaMM and SON. Conclusions: These findings suggest that PRL secretion induced by Mp-NAL treatment is preceded by OT release. These results, together with the activation of hypothalamic OT neurons and the higher expression of pituitary OTR, support the hypothesis that, during late pregnancy, OT may act at the pituitary level to facilitate PRL secretion if the inhibitory action of progesterone is blocked.

Pineal denervation by cervical sympathetic ganglionectomy suppresses the role of photoperiod on pregnancy or pseudopregnancy, body weight and moulting periods in the mink (Mustela vison)

1985 ◽  
Vol 107 (1) ◽  
pp. 31-39 ◽  
Author(s):  
L. Martinet ◽  
D. Allain ◽  
Y. Chabi
Keyword(s):  
Body Weight ◽  
Environmental Factors ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Progesterone Secretion ◽  
Cervical Ganglion ◽  
Cervical Sympathetic ◽  
Implantation Period ◽  
Short Days

ABSTRACT In mink, termination of the delayed implantation period, following reactivation of the corpora lutea, and onset of the spring moult are associated with a rise in prolactin secretion triggered by increasing daylength, while decreasing daylength induces the autumn moult. To establish whether suppression of the function of the pineal rendered the mink unresponsive to daylength changes, the superior cervical ganglion was removed bilaterally 2–4 weeks before mating. Intact and operated females were then left outdoors or were put under a lighting regime of either 15 h light: 9 h darkness (15L: 9D) or 8L: 16D. In July, at the end of the spring moult, the 15L: 9D lighting regime was changed to one of 8L: 16D. Under artificial photoperiods ganglionectomy suppressed the stimulatory role of long days and the inhibitory role of short days on prolactin secretion, and consequently on progesterone secretion and spring moult. Neither was the autumn moult, induced early in intact females by the change to a short photoperiod, advanced in ganglionectomized females, showing that the latter were unresponsive to the artificial modification of the photoperiod. However, in animals kept outdoors, prolactin and progesterone secretion and spring moult were not changed by ganglionectomy. Increase in body weight and autumn moult were only slightly delayed by the operation suggesting that other environmental factors had replaced the synchronizing effect of the daylength changes. Alternatively the desynchronization between intact females responsive to photoperiodism and those rendered unresponsive may be too slow to be observed soon after ganglionectomy. J. Endocr. (1985) 107, 31–39

Role of extracellular calcium and calmodulin in prolactin secretion induced by hyposmolarity, thyrotropin-releasing hormone, and high K+ in GH4C1 cells

1990 ◽  
Vol 123 (2) ◽  
pp. 218-224 ◽  
Author(s):  
Xiangbing Wang ◽  
Noriyuki Sato ◽  
Monte A. Greer ◽  
Susan E. Greer ◽  
Staci McAdams
Keyword(s):  
Smooth Muscle ◽  
Muscle Relaxant ◽  
Prolactin Secretion ◽  
Thyrotropin Releasing Hormone ◽  
Dependent Manner ◽  
Cell Toxicity ◽  
High K ◽  
Dose Dependent ◽  
Smooth Muscle Relaxant

Abstract. The mechanism by which 30% medium hyposmolarity induces PRL secretion by GH4C1 cells was compared with that induced by 100 nmol/l TRH or 30 mmol/l K+. Removing medium Ca2+, blocking Ca2+ channels with 50 μmol/l verapamil, or inhibiting calmodulin activation with 20 μmol/l trifluoperazine, 10 μmol/l chlorpromazine or 10 μmol/l pimozide almost completely blocked hyposmolarity-induced secretion. The smooth muscle relaxant, W-7, which is believed relatively specific in inhibiting the Ca2+-calmodulin interaction, depressed hyposmolarity-induced PRL secretion in a dose-dependent manner (r = −0.991, p<0.01 ). The above drugs also blocked or decreased high K+-induced secretion, but had much less effect on TRH-induced secretion. Secretion induced by TRH, hyposmolarity, or high K+ was optimal at pH 7.3-7.65 and was significantly depressed at pH 6.0 or 8.0, indicating that release of hormone induced by all 3 stimuli is due to an active cell process requiring a physiologic extracellular pH and is not produced by nonspecific cell toxicity. The data suggest hyposmolarity and high K+ may share some similarities in their mechanism of stimulating secretion, which is different from that of TRH.

Role of Hypothalamic Catecholamines in the Regulation of Luteinizing Hormone and Prolactin Secretion in the Ewe during Seasonal Anestrus

1989 ◽  
Vol 49 (1) ◽  
pp. 80-87 ◽  
Author(s):  
Jean-Claude Thiéry ◽  
Graeme B. Martin ◽  
Yves Tillet ◽  
Martine Caldani ◽  
Monique Quentin ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Prolactin Secretion

scholarly journals The Physiological Role of Thyrotropin-Releasing Hormone in the Regulation of Thyroid-Stimulating Hormone and Prolactin Secretion in the Rat

1978 ◽  
Vol 61 (2) ◽  
pp. 441-448 ◽  
Author(s):  
Arthur R. C. Harris ◽  
Dana Christianson ◽  
M. Susan Smith ◽  
Shih-Lieh Fang ◽  
Lewis E. Braverman ◽  
...  
Keyword(s):  
Physiological Role ◽  
Thyroid Stimulating Hormone ◽  
Prolactin Secretion ◽  
Thyrotropin Releasing Hormone ◽  
Releasing Hormone ◽  
Stimulating Hormone

Maternal prolactin secretion during labor. The role of dopamine

2001 ◽  
Vol 80 (1) ◽  
pp. 34-38 ◽  
Author(s):  
Theodor Stefos ◽  
Alexandros Sotiriadis ◽  
Panagiotis Tsirkas ◽  
Ioannis Messinis ◽  
Dimitrios Lolis
Keyword(s):  
Prolactin Secretion
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