Serotonin andN-Acetylserotonin Effects on Pigment Cells of the ToadBufo ictericus:Pharmacological Characterization of Melatonin Receptors

Filadelfi, Ana Maria Caliman; Castrucci, Ana Maria de Lauro

doi:10.1006/gcen.1996.0110

Cited by 5 publications

(2 citation statements)

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“…2‐Bromomelatonin, 2‐phenylmelatonin and 6‐chloromelatonin increased basal binding to the same extent as melatonin, showing full agonism at the Mel 1a receptor, while NAS behaved as a partial agonist and its effect was calculated to be around 50% of that of melatonin. NAS has already been described as a partial agonist at the Bufo ictericus melatonin receptor in a skin‐lightening test (Filadelfi & Castrucci, 1996). The ternary complex model predicts that the efficacy of a ligand is positively related to the ratio between its affinity to the low affinity ( K low ) state and to the high affinity state ( K high ) (Wreggett & De Lean 1984; Costa et al , 1992); in terms of ternary complex model interpretation of receptor‐G protein interactions GTPγS and sodium ions reduce the affinity between receptor and G protein (Costa et al , 1992), thus inducing a shift of the receptors toward the low affinity state (as seen in saturation studies with 2‐[ 125 I]‐iodomelatonin).…”

Section: Discussionmentioning

confidence: 95%

Pharmacological characterization of the human melatonin Mel_1a receptor following stable transfection into NIH3T3 cells

Nonno

Lucini

Pannacci

et al. 1998

British J Pharmacology

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1 Mouse ®broblasts (NIH3T3) transfected with the full-length coding region of the Mel 1a melatonin receptor stably expressed the receptor, coupled to a pertussis toxin-sensitive G-protein(s) and exhibiting high a nity and adequate pharmacological pro®le. 2 The receptor protein had the tendency of a strong coupling to the G-protein and therefore lowa nity state was induced by uncoupling the receptor from its G-protein in presence of high concentrations of NaCl (500 ± 700 mM) and/or GTPgS (100 mM). Thereafter, the a nity of a series of melatonin analogues was determined to both, high-and low-a nity receptor states, thus providing a basis for the prediction of their e cacy, according to the ternary complex model. 3 The cells were subsequently used to study the agonist-induced G-protein activation, determined by calculating the rate of GDP-GTP exchange measured in presence of 35 S-labelled GTPgS. The natural ligand melatonin induced a signi®cant increase in the GDP-GTP exchange rate, the presence of GDP and NaCl being necessary to observe this e ect. 4 The full agonists 2-phenylmelatonin, 2-bromomelatonin and 6-chloromelatonin equally induced an increase of the GDP-GTP exchange. 5-Hydroxy-N-acetyltryptamine activated the GTP-GDP exchange to a much lesser extent (53%) than melatonin, thus behaving as a partial agonist. As predicted by the model, the melatonin antagonist (N-[(2-phenyl-1H-indol-3-yl)ethyl]cyclobutanecarboxamide) was without e ect on basal G protein activation. Coincubation of this compound with melatonin induced a dosedependent rightward shift in the melatonin concentration-e ect curve, thus exhibiting the behaviour of a competitive and surmountable antagonist. 5 Using the equation proposed by Venter (1997) we were able to determine that there were no`spare' receptors in the system. Therefore, the approach proposed in the present work can be successfully used for the determination of`drug action' at the level of the human Mel 1a melatonin receptor and evaluation of the e cacy of new selective melatonin analogues.

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Section: Discussionmentioning

confidence: 95%

Pharmacological characterization of the human melatonin Mel_1a receptor following stable transfection into NIH3T3 cells

Nonno

Lucini

Pannacci

et al. 1998

British J Pharmacology

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“…Dihydroxyacetone (DHA) † is commonly used in skin lotions to induce a self-tanning effect in human skin (1)(2)(3)(4)(5). The tanning effect is recorded by measuring the change in light absorption with time in human skin.…”

Section: Introductionmentioning

confidence: 99%

A Sunscreen-Tanning Compromise: 3D Visualization of the Actions of Titanium Dioxide Particles and Dihydroxyacetone on Human Epiderm

Puccetti¹,

Leblanc²

2000

Photochemistry and Photobiology

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The self‐tanning agent dihydroxyacetone (DHA) was applied to human skin samples, and its effect on light absorption was followed in time to study the DHA influence inside the different layers of skin. Application of DHA shows increased light absorption in the visible light region, as evidenced by skin tanning. The tanning effect is enhanced by UV irradiation and appears localized in the near‐stratum corneum layer as revealed by depth analysis of the time signal. As a reference, application of an emulsion containing titanium dioxide particles shows clear surface stability and a screening of light penetration beyond the stratum corneum.

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Exploring the mechanisms and impacts of melatonin on fish colouration

Mubashshir,

Ahmad,

Negi

et al. 2023

Fish Physiol Biochem

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Serotonin andN-Acetylserotonin Effects on Pigment Cells of the ToadBufo ictericus:Pharmacological Characterization of Melatonin Receptors

Cited by 5 publications

References 0 publications

Pharmacological characterization of the human melatonin Mel_1a receptor following stable transfection into NIH3T3 cells

Pharmacological characterization of the human melatonin Mel_1a receptor following stable transfection into NIH3T3 cells

A Sunscreen-Tanning Compromise: 3D Visualization of the Actions of Titanium Dioxide Particles and Dihydroxyacetone on Human Epiderm

Exploring the mechanisms and impacts of melatonin on fish colouration

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Serotonin andN-Acetylserotonin Effects on Pigment Cells of the ToadBufo ictericus:Pharmacological Characterization of Melatonin Receptors

Cited by 5 publications

References 0 publications

Pharmacological characterization of the human melatonin Mel1a receptor following stable transfection into NIH3T3 cells

Pharmacological characterization of the human melatonin Mel1a receptor following stable transfection into NIH3T3 cells

A Sunscreen-Tanning Compromise: 3D Visualization of the Actions of Titanium Dioxide Particles and Dihydroxyacetone on Human Epiderm

Exploring the mechanisms and impacts of melatonin on fish colouration

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Pharmacological characterization of the human melatonin Mel_1a receptor following stable transfection into NIH3T3 cells

Pharmacological characterization of the human melatonin Mel_1a receptor following stable transfection into NIH3T3 cells