Affiliations: Department of Pediatrics, Osaka Medical College,
Osaka, Japan
Note: [] Address for correspondence: Kimitaka Takitani, Department of
Pediatrics, Osaka Medical College, 2-7 Daigakumachi, Takatsuki, Osaka, Japan,
569-8686. Tel.: +81 72 683 1221; Fax: +81 72 684 6554; E-mail:
ped016@poh.osaka-med.ac.jp
Abstract: The vitamin A status has been studied in type 2 diabetes and it is
known that plasma retinol levels of patients with type 2 diabetes are elevated.
However, the details of vitamin A metabolism in type 2 diabetes are unclear.
β-Carotene exhibits biological activity as provitamin A
and β-carotene 15,15'-monooxygenase (BCM) cleaves
β-carotene to form retinal. We studied BCM gene
expression in type 2 diabetic Goto-Kakizaki (GK) rats. BCM gene expression was analyzed in the liver, intestine, and
testis of 8- and 13-week-old GK rats and Wistar rats (control). The plasma and
liver retinol levels were measured, and plasma retinol-binding protein (RBP)
was detected. BCM gene expression in the liver, intestine and testis of GK rats
was increased compared with that in controls. Plasma retinol levels and RBP
levels were increased in GK rats, but hepatic retinol levels did not differ
between GK rats and controls. BCM gene expression in the liver and intestine
might affect retinol levels in type 2 diabetes. Conversion of β-carotene
to retinal might be accelerated in the presence of insulin
resistance status, so that plasma retinol levels are increased in type 2
diabetes.
