Regulation of glucose transporter messenger RNA levels in rat adipose tissue by insulin.
Analysis of glucose transporter mRNA levels in adipose tissue from streptozotocin (STZ)-induced diabetic rats demonstrated a specific decrease (10-fold) in adipose tissue GLUT-4 mRNA with no significant effect on GLUT-1 mRNA levels. Treatment of STZ-diabetic rats with twice daily injections of insulin for 1-3 days resulted in a 16-fold increase in the relative amount of GLUT-4 mRNA to levels approximately 2-fold greater than those in control animals. However, after 7 days of insulin therapy the amount of GLUT-4 mRNA decreased approximately 2-fold back to the levels in the control animals. Normalization of the STZ-induced serum hyperglycemia by phlorizin treatment, which inhibits renal tubular reabsorption of glucose, had no effect on GLUT-4 mRNA in the absence of insulin. Similar to STZ-diabetes, fasting for 48 h also reduced adipose GLUT-4 mRNA levels. Parenteral administration of insulin with glucose over 7.5 h, but not glucose alone, increased the levels of the GLUT-4 mRNA 3- to 4-fold. These studies demonstrate that the relative glycemic state does not influence GLUT-4 glucose transporter mRNA expression in vivo and strongly suggests that insulin is a major factor regulating the levels of GLUT-4 mRNA in adipose tissue.
Sivitz
W I
WI
Department of Medicine, University of Iowa, Iowa City 52242.
DeSautel
S L
SL
Kayano
T
T
Bell
G I
GI
Pessin
J E
JE
D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004822:Epididymis; D005215:Fasting; D005786:Gene Expression Regulation / Q000187:drug effects*; D006943:Hyperglycemia / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis* / Q000235:genetics; D010695:Phlorhizin / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013311:Streptozocin
D001786:Blood Glucose; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D013311:Streptozocin; D010695:Phlorhizin