Prolactin Secretion in Female Siberian Hamsters following Hypothalamic Deafferentation Role of Photoperiod and Dopamine

1994 ◽  
Vol 59 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Lori L. Badura ◽  
Bruce D. Goldman
Keyword(s):  
Prolactin Secretion ◽  
Hypothalamic Deafferentation ◽  
Siberian Hamsters

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

Serotoninergic control of prolactin secretion in prepubertal male rats

1994 ◽  
Vol 131 (5) ◽  
pp. 547-554 ◽  
Author(s):  
Enrique Aguilar ◽  
Antonio Ranchal ◽  
Manuel Tena-Sempere ◽  
Leonor Pinilla
Keyword(s):  
Specific Inhibitor ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Serotoninergic System ◽  
Selective Agonist ◽  
5 Ht Uptake ◽  
Releasing Effect

Aguilar E, Ranchal A, Tena-Sempere M, Pinilla L. Serotoninergic control of prolactin secretion in prepubertal male rats. Eur J Endocrinol 1994;131:547–54. ISSN 0804–4643 The role of the serotoninergic system in the control of prolactin (PRL) secretion has been studied in prepubertal male rats. Serum PRL concentration was measured in 16-day-old male rats at different times after the administration of 5-hydroxytryptophan (5-HTP), a precursor of serotonin (5-HT) synthesis, alone or in combination with fluoxetine, a specific inhibitor of 5-HT uptake; dl-p-parachlorophenylalanine (PCPA), an inhibitor of 5-HT synthesis; and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a selective agonist of 5-HT1A receptors. Also, serum PRL concentration and pituitary content were measured after 5-HTP administration in castrated males implanted with silastic capsules containing testosterone or 5α-androstane-3α,17β-diol (α-diol). We found that: the reduction in serotoninergic activity after PCPA administration did not modify serum PRL concentrations; the stimulatory effect of 5-HTP on PRL secretion was not observed before day 16; the effects of 5-HTP or 5-HTP and fluoxetine were similar in intact and orchidectomized males; a significant increase in PRL secretion took place after 8-OH-DPAT administration; the duration of the stimulatory effect of 5-HTP increased after α-diol treatment; and pituitary PRL content increased after 5-HTP injection in intact males and decreased in castrated males treated with testosterone or α-diol. Therefore, we conclude that: the PRL-releasing effect of 5-HTP remains after orchidectomy; activation of 5-HT1A receptors may mediate, at least partially, the effect of 5-HTP; testosterone and α-diol affect the duration of PRL release after 5-HTP administration differently; and testicular factors other than androgens might be involved in the effects of 5-HTP on PRL pituitary accumulation. Enrique Aguilar, Department of Physiology, Faculty of Medicine, Córdoba University, 14004 Córdoba, Spain

OPIOID REGULATION OF PROLACTIN SECRETION: EVIDENCE FOR A SPECIFIC ROLE OF β-ENDORPHIN

Endocrinology ◽  
1981 ◽  
Vol 109 (5) ◽  
pp. 1769-1771 ◽  
Author(s):  
VANAJA V. RAGAVAN ◽  
ANDREW G. FRANTZ
Keyword(s):  
Prolactin Secretion ◽  
Specific Role

scholarly journals Regulation of prolactin secretion during the estrus in rats: possible role of glucocorticoids

Reproduction ◽  
2011 ◽  
Vol 142 (3) ◽  
pp. 477-485 ◽  
Author(s):  
Constanza M López-Fontana ◽  
María E Maselli ◽  
Florencia E G de Di Nasso ◽  
Carlos M Telleria ◽  
Rubén W Carón
Keyword(s):  
Glucocorticoid Receptor ◽  
Inhibitory Action ◽  
Neutralizing Antibody ◽  
Prolactin Secretion ◽  
Receptor Antagonists ◽  
Steroid Synthesis

Mifepristone (MIF) administration to cycling rats at proestrus induces hypersecretion of prolactin (PRL) at the following estrus. We aimed to assess whether this effect is due to the antiprogesterone or antiglucocorticoid action of MIF and to help underscore the nature of the circulating hormone(s) regulating PRL secretion at estrus. Female cycling rats in proestrus were treated with vehicle; the progesterone (Pg) and glucocorticoid receptor antagonists, MIF (5 mg/kg) or ORG-33628 (5 mg/kg); the glucocorticoid agonist dexamethasone (DEX; 27 mg/kg)±MIF; or the inhibitor of steroid synthesis aminoglutethimide (AG; 150 mg/kg)±MIF. The animals' blood was sampled the same day at 1800 h and at 1800 h of the following day to assess for circulating PRL and Pg levels. To distinguish antiglucocorticoid from antiprogesterone effects of MIF, we administered a highly specific neutralizing antibody against Pg. None of the antagonists modified serum PRL values at proestrus but increased PRL levels at estrus. DEX decreased the secretion of PRL at proestrus, yet the effect was entirely blocked by MIF. Furthermore, DEX decreased PRL at estrus in a MIF-reversible manner, suggesting that adrenal corticoids during proestrous may regulate PRL secretion at estrus. AG increased PRL secretion at estrus, whereas its association with MIF produced an even higher response. PRL concentration at estrus was not modified by the antiprogesterone antibody, suggesting that the effect of MIF is a consequence of its antiglucocorticoid effect and not due to its antiprogesterone properties. In conclusion, PRL secretion in the afternoon of the estrus is most likely regulated by glucocorticoids through an inhibitory action.

Dual Role of Glucocorticoids in Suckling-Induced Prolactin Secretion

Endocrine ◽  
2001 ◽  
Vol 15 (3) ◽  
pp. 287-290 ◽  
Author(s):  
Katalin M Horváth ◽  
Zsuzsanna Bánky ◽  
Béla E Tóth ◽  
György M Nagy ◽  
Béla Halász
Keyword(s):  
Prolactin Secretion ◽  
Dual Role

Regulation of the photoperiod-induced cycle in the peripheral blood concentrations of β-endorphin and prolactin in the ram: role of dopamine and endogenous opioids

1990 ◽  
Vol 127 (3) ◽  
pp. 461-469 ◽  
Author(s):  
E. Ssewannyana ◽  
G. A. Lincoln
Keyword(s):  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Endogenous Opioids ◽  
Fold Change ◽  
Opioid Antagonist ◽  
Light Cycle ◽  
Blood Concentrations ◽  
The Mean ◽  
Short Days

ABSTRACT In a group of adult Soay rams housed indoors under an artificial light cycle of alternating 16-week periods of long and short days, there was a conspicuous longterm cycle in the peripheral plasma concentrations of β-endorphin and prolactin. The levels of β-endorphin were highest under short days and lowest under long days (15-fold change), and inversely related to the changes in the plasma levels of prolactin (120-fold change). The role of dopamine in the control of β-endorphin and prolactin was investigated in a series of experiments, conducted under both long and short days, in which rams were treated with dopamine receptor agonists (dopamine and bromocriptine) and antagonists (pimozide and sulpiride). Naloxone (opioid antagonist) was also administered to assess the additional involvement of endogenous opioids. Dopamine injected i.v. (6·6 mg/kg every 10 min) did not significantly affect the mean plasma concentrations of β-endorphin and prolactin under either long or short days. Pimozide (0·08 mg/kg i.m. every 2 h) caused a large increase in the mean plasma concentrations of β-endorphin and prolactin under long days but not short days. Naloxone (1·6 mg/kg, i.v.), administered alone or in combination with dopamine or pimozide, had no effect on the mean plasma concentrations of β-endorphin and prolactin, except under short days when, combined with pimozide, it induced an increase in the plasma concentrations of the two polypeptides. Bromocriptine (0·06 mg/kg, s.c.) caused a significant decrease in the plasma concentrations of both β-endorphin and prolactin; this effect was most marked at the times of increased secretion (under short days for β-endorphin and under long days for prolactin). Sulpiride (0·59 mg/kg, s.c.) produced the converse effect and caused an increase in the plasma concentrations of β-endorphin and prolactin with the amplitude and duration of the effect varying with the stage of the photoperiod-induced cycle. From these results in the Soay ram, we conclude that dopamine inhibits β-endorphin and prolactin secretion by way of D2 receptors under both long and short days. Endogenous opioids interact with dopamine, augmenting this inhibition under short days. Differences in the acute responses in the secretion of β-endorphin and prolactin, and the inverse relationship between β-endorphin and prolactin during the cycle, indicate that different regulatory systems involving dopamine influence the two pituitary polypeptides. Journal of Endocrinology (1990) 127, 461–469

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