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Indian J Dermatol Venereol Leprol. 2012 Jan-Feb;78(1):64-7. doi: 10.4103/0378-6323.90948.

The effect of H₁ and H₂ receptor antagonists on melanogenesis.

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Department of Dermatology, Al-Minya University, Al-Minya, Egypt.



Histamine was found to stimulate melanogenesis in cultured human melanocytes specifically mediated by histamine H 2 receptors via protein kinase A activation. Based on this finding, the effect of topically applied H 2 antagonist on UVB-irradiated Guinea pigs' skin was examined and found to be suppressive on the post-irradiation melanogenesis.


In this study, we tried to explore the role of topically applied H 1 and H 2 receptor antagonists, in inhibition of UVB-induced melanization.


The effect of topically applied H 1 and H 2 receptor antagonists in inhibition of melanization was done clinically and histochemically using Fontana Masson and DOPA reactions compared with placebo.


The post-irradiation pigmentation was found to be brownish/black instead of the original light brown color. This color change occurred below the shaved orange-red fur suggesting a switch of melanogenesis from pheomelanin to eumelanin. The induced pigmentation was suppressed by topically applied H 2 antagonist while both H 1 antagonist and vehicle had no effect. The microscopic examination showed that the keratinocytes in the H 2 antagonist-treated areas contained few melanosomes while the nearby dendrites are full of them.


H 2 antagonists' inhibition of UVB-induced pigmentation is not only due to suppression of melanization but also due to a specific action on melanosomes' transfer.

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