CHEMICAL STUDIES ON MELANOGENESIS IN NORMAL AND ADRENALECTOMIZED RATS1

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Abstract
Black rats of the Long-Evans strain, beginning at 35 days of age, were fed on a diet deficient in the filtrate factors of vit. B which cause achromotrichia. Some were adrenalectomized after 28-30 days on the diet. These survived 12-15 days, weighed 70-100 gms. (approx. the normal wt. of 37-47 days old rats), and were about 70-75 days old at death. Hides of normal rats (37, 47, and 70 days old), of "deficient-diet" rats, of "deficient-diet" adrenalectomized rats, and of adrenalectomized deficient-diet" rats given doses of adrenal cortical extract, (0.4 ml./rat/day) or of desoxycorticosterone acetate (0.5 mg./ rat/day) were analyzed for water soluble non-protein components containing precursors to melanin, for water soluble protein components containing enzymatic activities associated with melanogenesis, tissue lipid, and melanin. Analyses of skins of normal rats, "deficient-diet" rats and adrenalectomized "deficient-diet" rats given 1% NaCl, 2% NaCl, tap water or deprived of water were also made. The filtrate-factor-deficient diet caused both achromotrichia and a decrease in extractable melanin in the skins. The effects of dehydration (by 2% NaCl or water deprivation) caused chemical changes somewhat similar to those following filtrate-factor deficiency. After adrenalec-tomy in "deficient-diet" rats, the extractable melanin of the skin was increased, but it was less if such rats were given desoxycorticosterone acetate. Skins of adrenalectomized rats deprived of salt but given a normal diet contained no more melanin than those of normal rats. The results indicate that both adrenal cortex and NaCl are concerned in melanin metabolism.

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