The induction of the alpha-1-adrenoceptor signal transduction system on human melanocytes.

ABSTRACT

Human melanocytes established in MCDB-153 culture medium do not express alpha 1-, beta 1-, beta-2 adrenoceptors without extracellular stimulation. The addition of 50 x 10-9 M norepinephrine to the medium causes a time-dependent induction of alpha-1-adrenoceptors with 4.278 receptors/melanocyte after 24 h. Under the same experimental conditions, the dendricity of melanocytes as well as melanogenesis was unaffected over 60 h. Since keratinocytes hold the full capacity for catecholamine biosynthesis but melanocytes lack this system, the secretion of catecholamines from keratinocytes appears to be of critical importance to the alpha-1-adrenoceptor in melanocytes, underlining the symbiosis of both cells in the epidermal unit.