Pigment cell differentiation: the relationship between pterin content, allopurinol treatment, and the melanoid gene...

The effects of allopurinol (an inhibitor of the enzyme xanthine dehydrogenase (XDH] and the melanoid gene on pigment cell differentiation in the axolotl were examined by analyzing pigment components of the xanthophore (pterins). Pterin contents of skin extracts (70% ethanol) from wild type, allopurinol-treated and melanoid axolotls were determined by thin layer chromatography (TLC) and fluorometric scanning of TLC plates. Heights of peaks produced were used as a quantitative measure for pterin content. Results reveal that melanoid animals contain significantly reduced amounts of all seven pterins examined as compared with wild type animals. Allopurinol-treated animals have reduced levels of four pterins (xanthopterin, isoxanthopterin, biopterin and sepiapterin) as compared with the wild type. These findings suggest that the alterations in pterin biosynthetic pathways, either by drug-induced inhibition of XDH activity or by the melanoid gene, produce similar dramatic changes in pigment phenotype which are manifested by alterations in pigment cell differentiation.