Role of histamine receptors in the pigmentary responses of the wall lizard, Hemidactylus flaviviridis.

Bhopal 462 001, India Effects of histamine per se along with its specific agonists and antagonists were studied on the skin melanophores of Hemidactylus flaviviridis to study the role of histamine receptors in pigmentation. Histamine and 2-methyl histamine induced powerful melanin aggregation effects, leading to paling of the skin through stimulation of H1 receptors. On the other hand, 4-methyl histamine, a specific H2 receptor antagonist caused melanin dispersion via activation of H2 receptors, making the skin appear dark. It is concluded that histaminergic compounds have a considerable role in chromatic physiology of lower vertebrates, possibly as a neurotransmitter substance in melanin dysfunctions such as hyper and hypo pigmentation. [ABSTRACT FROM AUTHOR]