Melatonin Receptors in the Lamb Pars tuberalis/Median Eminence throughout the Day

1993 ◽  
Vol 58 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Vincent Piketty ◽  
Jean Pelletier
Keyword(s):  
Median Eminence ◽  
Melatonin Receptors ◽  
Pars Tuberalis

Characterization of melatonin receptors in the ram pars tuberalis: influence of light

1990 ◽  
Vol 123 (5) ◽  
pp. 557-562 ◽  
Author(s):  
Jean Pelletier ◽  
Bertrand Castro ◽  
Georges Roblot ◽  
Renée Wylde ◽  
Marie-Madeleine de Reviers
Keyword(s):  
Median Eminence ◽  
Binding Sites ◽  
Melatonin Receptors ◽  
Scatchard Analysis ◽  
Pars Tuberalis

Abstract. The present study was conducted to assess the binding of [125I]melatonin to frozen unfixed sections of pars tuberalis/median eminence tissue from Ile-de-France rams exposed or not exposed to light before slaughter. The specificity of [125I]melatonin binding to the pars tuberalis tissue was revealed by autoradiography and the magnitude of binding as related to the pars tuberalis area was determined after incubation and counting of pars tuberalis/median eminence sections. Subsequent studies with sections incubated with [125I]melatonin indicated that 1. the binding sites were saturable; 2. binding was stable for 24 h at 20°C, but unstable at 28 or 37°C; 3. melatonin and [12 7I]melatonin had a similar potency to compete with [125I]melatonin for binding sites, whereas other ligands such as serotonin or N-acetylserotonin were devoid of activity, and 4. by Scatchard analysis, the constant affinity Ka was found to be high in the 1010 l/mol range. Rams exposed to light throughout the night prior to slaughter presented a significant increase in the apparent number of [125I]melatonin binding sites in comparison to animals maintained under darkness (2.25±0.30 vs 1.01±0.17 fmol/mm2 pars tuberalis, p<0.01), whereas Ka values were similar in both groups. These results indicate the presence of true melatonin receptors in the pars tuberalis of the ram. Furthermore, they suggest that their apparent number is light-dependent.

scholarly journals What is the role of melatonin within the anterior pituitary?

2001 ◽  
Vol 170 (3) ◽  
pp. 493-501 ◽  
Author(s):  
DG Hazlerigg
Keyword(s):  
Anterior Pituitary ◽  
Cellular Level ◽  
Prolactin Secretion ◽  
Receptor Expression ◽  
Melatonin Receptors ◽  
Seasonal Effects ◽  
Pars Tuberalis ◽  
Melatonin Receptor ◽  
Functional Studies

The pineal hormone, melatonin, is uniquely defined by its role as hormonal time, but the processes whereby cells extract temporal information from the melatonin signal are not understood. Melatonin receptors are expressed in the pars tuberalis (PT) and, during fetal and perinatal life, in the pars distalis (PD). Functional studies suggest that the PT mediates the seasonal effects of melatonin on prolactin secretion, whilst the PD may be involved in photoperiodic programming of the developing gonadotrophic axis. To understand these effects at the cellular level we need to know the phenotype of melatonin-responsive cells. This review summarises current understanding in this area, and highlights present shortcomings. A case is presented for exploring the hypothesis that there is a functional association between melatonin receptor expression and cell differentiation in the anterior pituitary.

Seasonality and Melatonin Receptors in the Pars tuberalis in Some Long Day Breeders

Neurosignals ◽  
1994 ◽  
Vol 3 (2) ◽  
pp. 63-70 ◽  
Author(s):  
Mireille Masson-Pévet ◽  
François Gauer
Keyword(s):  
Melatonin Receptors ◽  
Pars Tuberalis ◽  
Long Day

scholarly journals A Novel Interaction Between Inhibitory Melatonin Receptors and Protein Kinase C-Dependent Signal Transduction in Ovine Pars Tuberalis Cells*

Endocrinology ◽  
1998 ◽  
Vol 139 (4) ◽  
pp. 1723-1730 ◽  
Author(s):  
Alexander W. Ross ◽  
Catriona A. Webster ◽  
Michael Thompson ◽  
Perry Barrett ◽  
Peter J. Morgan
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Melatonin Receptors ◽  
Pars Tuberalis ◽  
Kinase C ◽  
Dependent Signal

Degranulation of mast cells located in median eminence in response to compound 48/80 evokes adrenocortical secretion via histamine and CRF in dogs

2004 ◽  
Vol 287 (4) ◽  
pp. R969-R980 ◽  
Author(s):  
Itsuro Matsumoto ◽  
Yasuhisa Inoue ◽  
Katsuhiko Tsuchiya ◽  
Toshio Shimada ◽  
Tadaomi Aikawa
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Receptor Antagonist ◽  
Median Eminence ◽  
Close Association ◽  
Portal System ◽  
Pars Tuberalis ◽  
Cortisol Secretion ◽  
Intracerebroventricular Infusion ◽  
Arterial Blood

The effect of intracerebroventricular infusion of compound 48/80 (C48/80), a mast cell secretagogue, on adrenal cortisol secretion was investigated in dogs under pentobarbital sodium anesthesia. A marked increase in adrenal cortisol secretion was elicited by C48/80 along with a concomitant increase in the plasma levels of cortisol and immunoreactive ACTH, but neither arterial blood pressure and heart rate nor the plasma histamine level altered significantly. Pretreatment with either anti-CRF antiserum or pyrilamine maleate (H1 histamine-receptor antagonist) significantly attenuated the C48/80-evoked increase in cortisol secretion, but pretreatment with metiamide (H2-receptor antagonist) significantly potentiated it. Significant attenuation of the C48/80-evoked increase in cortisol also occurred in dogs given ketotifen, a mast cell stabilizing drug, before pharmacologic challenge. In the pars tuberalis and median eminence (ME), mast cells were highly concentrated in close association with the primary plexus of the hypophysial portal system. Degranulated mast cells were extensively found in the ME of C48/80-treated animals. These results suggest that mast cells located in these regions liberated histamine within the brain as a result of degranulation induced by C48/80 and that this led to activation of the hypothalamic-pituitary-adrenocortical axis.

Daily Rhythms of Melatonin Binding Sites in the Rat Pars tuberalis and Suprachiasmatic Nuclei; Evidence for a Regulation of Melatonin Receptors by Melatonin Itself

1993 ◽  
Vol 57 (1) ◽  
pp. 120-126 ◽  
Author(s):  
François Gauer ◽  
Mireille Masson-Pévet ◽  
Debra Jean Skene ◽  
Berthe Vivien-Roels ◽  
Paul Pévet
Keyword(s):  
Binding Sites ◽  
Melatonin Receptors ◽  
Pars Tuberalis ◽  
Suprachiasmatic Nuclei ◽  
Daily Rhythms

scholarly journals Melatonin Receptors on Ovine Pars Tuberalis: Characterization and Autoradiographicai Localization

1989 ◽  
Vol 1 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Peter J. Morgan ◽  
Lynda M. Williams ◽  
Gary Davidson ◽  
Wilfred Lawson ◽  
Edward Howell
Keyword(s):  
Melatonin Receptors ◽  
Pars Tuberalis

Effects of two melatonin analogues, S-20098 and S-20928, on melatonin receptors in the pars tuberalis of the rat

1998 ◽  
Vol 25 (3) ◽  
pp. 172-176 ◽  
Author(s):  
M. Masson-Pévet ◽  
J. Recio ◽  
H. Y. Guerrero ◽  
E. Mocaer ◽  
Ph. Delagrange ◽  
...  
Keyword(s):  
Melatonin Receptors ◽  
Pars Tuberalis ◽  
Melatonin Analogues
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