The G Protein Linkage of Melatonin Receptors

2015 ◽  
pp. 147-153
Author(s):  
Yung H. Wong
Keyword(s):  
G Protein ◽  
Melatonin Receptors

Modulation of melatonin receptors and G-protein function by microtubules

2006 ◽  
Vol 41 (4) ◽  
pp. 324-336 ◽  
Author(s):  
Michael J. Jarzynka ◽  
Deepshikha K. Passey ◽  
Paul F. Ignatius ◽  
Melissa A. Melan ◽  
Nicholas M. Radio ◽  
...  
Keyword(s):  
G Protein ◽  
Protein Function ◽  
Melatonin Receptors

Melatonin receptors are present in adult rat Leydig cells and are coupled through a pertussis toxin-sensitive G-protein

1997 ◽  
Vol 136 (6) ◽  
pp. 633-639 ◽  
Author(s):  
Sandra Valenti ◽  
Massimo Giusti ◽  
Roberta Guido ◽  
Giulio Giordano
Keyword(s):  
G Protein ◽  
Pertussis Toxin ◽  
Binding Sites ◽  
Leydig Cells ◽  
Melatonin Receptors ◽  
Scatchard Analysis ◽  
Adult Rat ◽  
Testosterone Secretion ◽  
High Affinity Binding Site ◽  
17 Hydroxyprogesterone

Abstract Previous studies have suggested that melatonin (MLT) acts directly on rat Leydig cells by modulating androgen production. In the present study, the site of action of MLT was investigated. The binding of 2-[125I]iodomelatonin (125I-MLT; 7–240 pmol/l) to Leydig cell membrane fragments was tested in the presence or absence of guanosine 5′-O-(3-thiotriphosphate) (GTP-γ-S; 50 μmol/l). Saturation studies and Scatchard analysis revealed the existence of a high-affinity binding site with a Bmax of 46·70± 3·50 fmol/mg protein and a Kd of 88·70±6·20 pmol/l; treatment with GTP-γ-S reduced the concentration of 125I-MLT binding sites (Bmax 34·03±4·50), while increasing the Kd to 106·5± 2·61 pmol/l. Pretreatment of the cells with pertussis toxin (PTX; 10 ng/ml for 16 h) resulted in a decreased binding of I-MLT and a lack of effect of GTP-γ-S. Moreover, the effect of MLT on testosterone secretion induced by LH (30 mIU/ml), forskolin (1 μmol/l) and LHRH (100 nmol/l) was studied after 3-h incubation of cells which had been precultured with or without PTX. The inhibition of testosterone secretion due to MLT administration was eliminated by PTX pretreatment during forskolin and LH, but not during LHRH administration. However, 17-hydroxyprogesterone levels were higher in all groups incubated in the presence of MLT, irrespective of PTX pretreatment. Our data suggest that: (a) MLT receptors are present on the membranes of adult rat Leydig cells; (b) they couple through PTX-sensitive G-protein-coupled binding sites; (c) the mechanism by which MLT blocks 17–20 desmolase enzymatic activity (thus leading to increased 17-hydroxyprogesterone levels), and testosterone secretion during LHRH stimulation is likely to depend on one or more different mechanism(s) of action. European Journal of Endocrinology 136 633–639

Are G Protein‐Coupled Receptor Heterodimers of Physiological Relevance?—Focus on Melatonin Receptors

2006 ◽  
Vol 23 (1-2) ◽  
pp. 419-426 ◽  
Author(s):  
Angélique Levoye ◽  
Ralf Jockers ◽  
Mohammed A. Ayoub ◽  
Philippe Delagrange ◽  
Egemen Savaskan ◽  
...  
Keyword(s):  
G Protein ◽  
Melatonin Receptors ◽  
G Protein Coupled Receptor ◽  
Physiological Relevance ◽  
G Protein Coupled

scholarly journals Role of G Protein-Coupled Receptors in Microglial Activation: Implication in Parkinson’s Disease

2021 ◽  
Vol 13 ◽  
Author(s):  
Chao Gu ◽  
Yajing Chen ◽  
Yan Chen ◽  
Chun-Feng Liu ◽  
Zengyan Zhu ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
G Protein ◽  
Metabotropic Glutamate Receptors ◽  
Microglial Activation ◽  
G Protein Coupled Receptors ◽  
Innate Immune ◽  
Melatonin Receptors ◽  
Immune Receptors ◽  
G Protein Coupled

Parkinson’s disease (PD) is one of the prevalent neurodegenerative diseases associated with preferential loss of dopaminergic (DA) neurons in the substantia nigra compacta (SNc) and accumulation of α-synuclein in DA neurons. Even though the precise pathogenesis of PD is not clear, a large number of studies have shown that microglia-mediated neuroinflammation plays a vital role in the process of PD development. G protein-coupled receptors (GPCRs) are widely expressed in microglia and several of them act as regulators of microglial activation upon corresponding ligands stimulations. Upon α-synuclein insults, microglia would become excessively activated through some innate immune receptors. Presently, as lack of ideal drugs for treating PD, certain GPCR which is highly expressed in microglia of PD brain and mediates neuroinflammation effectively could be a prospective source for PD therapeutic intervention. Here, six kinds of GPCRs and two types of innate immune receptors were introduced, containing adenosine receptors, purinergic receptors, metabotropic glutamate receptors, adrenergic receptors, cannabinoid receptors, and melatonin receptors and their roles in neuroinflammation; we highlighted the relationship between these six GPCRs and microglial activation in PD. Based on the existing findings, we tried to expound the implication of microglial GPCRs-regulated neuroinflammation to the pathophysiology of PD and their potential to become a new expectation for clinical therapeutics.

The development of melatonin-binding sites in the ovine fetus

1994 ◽  
Vol 142 (3) ◽  
pp. 475-484 ◽  
Author(s):  
R J A Helliwell ◽  
L M Williams
Keyword(s):  
G Protein ◽  
Binding Sites ◽  
Early Stage ◽  
Specific Binding ◽  
Melatonin Receptors ◽  
Pars Tuberalis ◽  
Dependent Manner ◽  
Pars Distalis ◽  
Specific Expression ◽  
Fetal Sheep

Abstract The pineal hormone, melatonin, is important in the timing of seasonal reproduction in the sheep. Melatonin of maternal origin readily crosses the placenta; its function in the fetal sheep is, however, unclear. To gain an insight into the role of melatonin in ovine development we have identified specific melatonin receptors throughout gestation using 2-[125I]iodomelatonin and quantitative in vitro autoradiography. Specific binding was found at the earliest time studied at 30 days of gestation, over the developing thyroid (term=145 days). At 31 days of gestation specific labelling was found over the thyroid and pituitary glands, the spinal nerves, nasal cavity and developing bronchi. This binding was diminished by over 50% in the presence of 10−4 m GTPγS (an analogue of guanosine triphosphate) indicating that the 2-[125I]iodomelatonin binding at this early stage of gestation represents a receptor coupled to a regulatory G-protein. By 40 days of gestation specific binding was found over the nasal epithelium, cochlear epithelium, regions of the brain, especially the hind brain and the vestibulocochlear and glossopharyngeal nerves, and both the pars distalis and pars tuberalis of the pituitary. As gestation proceeded, labelling over the pars distalis appeared to become more scattered in nature while that on the pars tuberalis remained consistent. Saturation studies of both the neuronal and pituitary binding sites at 121 days of gestation and in the newborn lamb revealed a single class of high-affinity binding sites with Kd values in the picomolar range. Also at 121 days of gestation, binding over the fetal pars tuberalis was diminished in a dose-dependent manner by GTPγS, again confirming that specific binding is indicative of a receptor coupled to a regulatory G-protein. These data demonstrate a potential for sensitivity to melatonin from early in gestation, as well as the developmentally specific expression of the melatonin receptor in certain tissues, and suggest a wider role for melatonin in ovine fetal development than previously considered. Journal of Endocrinology (1994) 142, 475–484

Melatonin receptors activate heteromeric G-protein coupled Kir3 channels

Neuroreport ◽  
1996 ◽  
Vol 7 (3) ◽  
pp. 717-720 ◽  
Author(s):  
Cole S. Nelson ◽  
Jennifer L. Marino ◽  
Charles N. Allen
Keyword(s):  
G Protein ◽  
Melatonin Receptors ◽  
G Protein Coupled
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