Alpha-melanocyte stimulating hormone and its analogue Nle4DPhe7 alpha-MSH affect morphology, tyrosinase activity and melanogenesis in cultured human melanocytes

1994 ◽  
Vol 107 (1) ◽  
pp. 205-211 ◽  
Author(s):  
G. Hunt ◽  
C. Todd ◽  
J.E. Cresswell ◽  
A.J. Thody
Keyword(s):  
Cholera Toxin ◽  
Tyrosinase Activity ◽  
Melanin Content ◽  
Melanocyte Stimulating Hormone ◽  
Human Melanocytes ◽  
The Common ◽  
In Vitro Effects ◽  
Stimulating Hormone

Although melanocyte stimulating hormone (MSH) peptides are known to stimulate pigmentation in man, previous reports suggest that human melanocytes are relatively unresponsive to these peptides in vitro. This may be related to the conditions under which the melanocytes were cultured. Thus, we have re-investigated the in vitro effects of MSH peptides using human melanocytes cultured in the absence of artificial mitogens. Human melanocytes were incubated with alpha-MSH or its potent analogue Nle4Dphe7 alpha-MSH for 3 days. After 18 hours, melanocyte morphology had evolved from mainly bipolar to dendritic in approximately 66% of cultures. Nle4DPhe7 alpha-MSH produced dose-related increases in both tyrosinase activity and melanin content although the degree of response was variable and tyrosinase activity was the relatively more responsive to the peptide. Similar results were obtained with alpha-MSH, but, although the effect on melanin content was similar to that of Nle4DPhe7 alpha-MSH, the effect on tyrosinase activity was less marked. The preliminary EC50 values for the actions of the MSH peptides suggest that they may be equipotent in their actions on human melanocytes. In addition, we have demonstrated that the common melanocyte mitogens 12-O-tetradecanoyl phorbol-13-acetate (TPA) and cholera toxin affect basal melanogenesis and modulate the effects of the MSH peptides. However, not all melanocyte cultures showed melanogenic responses to the MSH peptides. Ability to respond was unrelated to basal levels of tyrosinase activity or melanin content. In at least some cultures, morphological and melanogenic responses appear to be independent of one another.(ABSTRACT TRUNCATED AT 250 WORDS)

An In-Vitro Assay Estimating Changes in Melanin Content of Melanoma Cells due to Ultra-Dilute, Potentized Preparations

Homeopathy ◽  
2019 ◽  
Vol 108 (03) ◽  
pp. 183-187 ◽  
Author(s):  
Renuka Munshi ◽  
Samidha Joshi ◽  
Gitanjali Talele ◽  
Rajesh Shah
Keyword(s):  
In Vitro Study ◽  
Melanoma Cells ◽  
Tyrosinase Activity ◽  
Melanin Content ◽  
B16f10 Melanoma ◽  
Vitro Assay ◽  
Melanocyte Stimulating Hormone ◽  
B16f10 Melanoma Cells ◽  
Physiological Dose

Introduction The authors had previously conducted an in-vitro study to observe the effect of homeopathic medicines on melanogenesis, demonstrating anti-vitiligo potential by increasing the melanin content in murine B16F10 melanoma cells. A similar experiment was performed using further homeopathic preparations sourced from kojic acid (KA), hydrogen peroxide (H2O2; HP), 6-biopterin (BP), and [Nle4, D-Phe7]-α-melanocyte-stimulating hormone (NLE), some of which are known to induce vitiligo or melano-destruction at physiological dose. Materials and Methods The homeopathic preparations of BP, KA, NLE, and HP were used in 30c potency. Alcohol and potentized alcohol were used as vehicle controls. Prior to starting the main experiment, the viability of B16F10 melanoma cells after treatment with study preparations was assayed. Melanin content (at 48 h and 96 h) and tyrosinase activity in melanocytes were determined. Results At the end of 48 hours, NLE and HP in 30c potency had a significantly greater melanin content (p = 0.015 and p = 0.039, respectively) compared with controls; BP and KA in 30c potency had no significant effects. No significant changes were seen at the end of 96 hours. KA, NLE, HP, and vehicle controls showed an inhibition of tyrosinase activity. Conclusion The study demonstrated melanogenic effects of two homeopathic preparations. Further research to evaluate the therapeutic efficacy of these medicines is warranted.

EFFECTS OF α-MELANOCYTE-STIMULATING HORMONE AND [8-ARGININE]-VASOTOCIN UPON MELANOGENESIS IN HAIR FOLLICLE MELANOCYTES IN VITRO

1981 ◽  
Vol 91 (3) ◽  
pp. 501-507 ◽  
Author(s):  
ANN LOGAN ◽  
BRIAN WEATHERHEAD
Keyword(s):  
Hair Follicle ◽  
Hair Follicles ◽  
Tyrosinase Activity ◽  
Arginine Vasotocin ◽  
Melanin Production ◽  
Potency Ratio ◽  
Melanin Biosynthesis ◽  
Melanocyte Stimulating Hormone ◽  
Stimulating Hormone

α-Melanocyte-stimulating hormone (α-MSH) has been shown to act directly on the mammalian melanocyte in short-term cultures of hair follicles obtained from the Siberian hamster. Melanogenesis was stimulated through an increase in tyrosinase activity which resulted in an increase in melanin production. The response of hair follicle melanocytes to α-MSH occurred only in follicles taken from moulting animals, implying that they show a discontinuous expression of MSH receptors during the hair follicle growth cycle. Synthetic 1–24 ACTH had no effect on melanogenesis regardless of whether the follicles came from moulting or non-moulting animals. The pineal peptide, [8-arginine]-vasotocin (AVT), inhibited melanin production without a concomitant decrease in tyrosinase activity. In this respect AVT resembled melatonin, although AVT showed a potency ratio of less than half on a molar basis. The action of AVT, like that of melatonin, must ultimately be on some post-tyrosinase step in melanin biosynthesis. In these hair follicle melanocytes AVT seems to bind to specific receptors since neither of the closely related peptides, oxytocin and [8-arginine]-vasopressin, displayed any activity in our culture system.

INTERACTION OF α-MELANOCYTE-STIMULATING HORMONE, MELATONIN, CYCLIC AMP AND CYCLIC GMP IN THE CONTROL OF MELANOGENESIS IN HAIR FOLLICLE MELANOCYTES IN VITRO

1981 ◽  
Vol 90 (1) ◽  
pp. 89-96 ◽  
Author(s):  
BRIAN WEATHERHEAD ◽  
ANN LOGAN
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Phosphodiesterase Inhibitors ◽  
Hair Follicles ◽  
Tyrosinase Activity ◽  
Melanin Production ◽  
Melanocyte Stimulating Hormone ◽  
Dependent Mechanism ◽  
Stimulating Hormone

In short-term (48 h) cultures of hair follicles α-melanocyte-stimulating hormone (α-MSH) and cyclic AMP stimulated melanogenesis through an increase in tyrosinase activity. In contrast cyclic GMP mimicked the effects of melatonin by inhibiting melanin production without causing a concomitant decrease in tyrosinase activity. Both cyclic GMP and melatonin blocked the stimulatory effects of cyclic AMP and α-MSH on melanin production but they left the increased levels of tyrosinase activity unaffected. Phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine and papaverine) simultaneously stimulated tyrosinase activity and inhibited melanin production, presumably by allowing endogenous cyclic AMP and cyclic GMP to accumulate intracellularly. It is suggested that whereas MSH stimulates melanogenesis through a cyclic AMP-dependent mechanism there must also be an inhibitory cyclic GMP-dependent mechanism, perhaps activated by melatonin, which operates at some post-tyrosinase step in the melanin biosynthetic pathway.

Characterization of α-melanocyte-stimulating hormone (α-MSH)-like peptides in discrete regions of the rat brain. In vitro release of α-MSH from perifused hypothalamus and amygdala

1990 ◽  
Vol 513 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Denis Tranchand Bunel ◽  
Catherine Delbende ◽  
Catherine Blasquez ◽  
Sylvie Je´gou ◽  
Hubert Vaudry
Keyword(s):  
Rat Brain ◽  
In Vitro Release ◽  
Melanocyte Stimulating Hormone ◽  
Vitro Release ◽  
Stimulating Hormone

Effect of α-melanocyte-stimulating hormone on tyrosinase activity in hair follicular and epidermal melanocytes of the mouse

1988 ◽  
Vol 119 (3) ◽  
pp. 517-522 ◽  
Author(s):  
P. Seechurn ◽  
S. A. Burchill ◽  
A. J. Thody
Keyword(s):  
Tyrosinase Activity ◽  
In Vitro Experiments ◽  
Dorsal Skin ◽  
Wild Type ◽  
Melanocyte Stimulating Hormone ◽  
Tyrosinase Expression ◽  
In Vivo Administration ◽  
Agouti Gene

ABSTRACT In this study, the effect of α-MSH on tyrosinase activity was compared in epidermal and hair follicular melanocytes of mice. It had no effect on epidermal tyrosinase activity in dorsal skin from neonatal non-agouti black mice (C57BL/6J) in both in-vivo and in-vitro experiments. Theophylline and 8-bromocyclic (c)AMP were similarly without effect in in-vitro experiments. In-vivo administration of α-MSH and theophylline for 7 days was also without effect on epidermal tyrosinase activity in ear skin of adult non-agouti mice, and the same was true for α-MSH in wild-type agouti mice. Activation of the epidermal melanocytes in the non-agouti and wild-type agouti mice with ultraviolet radiation also failed to bring about a response to α-MSH and to theophylline in the case of the former. No tyrosinase activity was detected in the epidermis of viable yellow mice (C3H-HeAvy), but, as shown previously, tyrosinase activity was present in the hair follicle when the hair was actively growing and was increased in those mice given either α-MSH or theophylline. α-MSH and theophylline had no such effects on hair follicular tyrosinase activity in the non-agouti mice. The present results suggest that α-MSH- and cAMP-dependent mechanisms have little or no importance in the regulation of tyrosinase expression in mouse epidermal melanocytes. α-MSH may, however, regulate tyrosinase expression in hair follicular melanocytes, but even in these melanocytes its action may be restricted to mice that express the agouti gene. J. Endocr. (1988) 119, 517–522

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