ABSTRACT
Dopamine (DA) receptors (DAR) are detected in all layers of the skin: epidermis, dermis and hypodermis. Several lines of evidence indicate that DA is involved in major cutaneous functions, including wound healing, pigmentation, sweating, and hair growth. In wound healing, DA has direct interactions with platelets, keratinocytes, and endothelial cells. In pigmentation, the biosynthetic pathways for the production of DA and melanin share the same precursors (tyrosine and L-Dopa). Thus, DA is associated with disorders of pigmentation such as albinism and vitiligo. The innervation deficit of sweat glands and their dysfunction in patients with Parkinson's disease support the notion that DA contributes to the function of sweat glands. Both direct and indirect (via the suppression of prolactin release) roles for DA on normal and defective (i.e., alopecia) hair growth have been demonstrated in several studies. Studies with DA transporter (DAT)-deficient mice and other evidence indicate that DA affects bone metabolism and is also involved in synovial joint disorders as well as several muscular dysfunctions such as rheumatoid arthritis.
