Changes of glucose metabolism and skin-collagen neogenesis in vitamin B6 deficiency.
The mechanism of pellagrous changes in skin caused by a deficiency of vitamin B6 was studied in respect to neogenesis of proline in skin collagen and glucose metabolism. In vitamin B6 deficiency the insulin/glucagon coefficient in serum decreased significantly from 3.02 to 2.32, indicating a metabolic change towards gluconeogenesis. A deficiency of vitamin B6 caused a decrease in the levels of vitamin B6-dependent enzymes, such as ornithine aminotransferase, alanine aminotransferase, and aspartate aminotransferase, which also contribute to gluconeogenesis. Because the conversion of ornithine to proline via pyrroline-5-carboxylate was suppressed due to the decrease in ornithine aminotransferase activity, the amount of proline in the skin collagen fraction also decreased significantly in vitamin B6-deficient rats compared with the pair-fed control. These results suggest that the pellagrous lesions in vitamin B6-deficiency are caused by an impaired synthesis of proline from ornithine, which results in the suppression of collagen neogenesis in the skin.
Inubushi
Tomoko
T
Tokushima Bunri University, Faculty of Life Science, Tokushima 770-8514, Japan. inutomo7@tokushima.bunri-u.ac.jp
Takasawa
Tomohiro
T
Tuboi
Yasue
Y
Watanabe
Naoko
N
Aki
Kenji
K
Katunuma
Nobuhiko
N
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001806:Blood Urea Nitrogen; D002364:Caseins / Q000008:administration & dosage; D002784:Cholesterol / Q000097:blood; D024042:Collagen Type I / Q000096:biosynthesis* / Q000737:chemistry; D004044:Dietary Proteins / Q000008:administration & dosage; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008297:Male; D011392:Proline / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000378:metabolism*; D014280:Triglycerides / Q000097:blood; D026681:Vitamin B 6 Deficiency / Q000378:metabolism*
D001786:Blood Glucose; D002364:Caseins; D024042:Collagen Type I; D004044:Dietary Proteins; D007328:Insulin; D014280:Triglycerides; D005934:Glucagon; D002784:Cholesterol; D011392:Proline; D005952:Glucose-6-Phosphatase; D005947:Glucose