Age-Related Changes in Glucose Transporter-One mRNA Structure and Function

Abstract

To determine the molecular mechanisms of age-related changes in the expression of glucose transporter 1 (GLUT-1) mRNA in cerebral tissue, male Fischer 344 rats at 4,12, and 24 months of age were studied. The GLUT-1 mRNA in cerebral tissue was not significantly different among the various age groups. The in vitro translatability of GLUT-1 mRNA of 24-month-old rats (0.867 + 0.066 arbitrary units) was significantly lower than that in 4-month-old (1.403 + 0.153) P < 0.01 or 12-month-old rats (1.387 + 0.122) P < 0.01. The poly (A) tail length of GLUT-1 mRNA decreased from 200-350 nt in 4-month-old rats to only 50-100 nt in 24-month-old rats. Twelve-month-old rats also showed reduced poly (A) tail lengths. The poly (A) tail of G₃PDH mRNA was not altered with age. The changes in GLUT-1 mRNA translatability did not correlate with GLUT-1 content in total cerebral tissue homogenate or in isolated cerebral microvessels, suggesting that GLUT-1 protein turnover is altered with age. It is concluded that aging is associated with significant changes in the structure and function of GLUT-1 mRNA.