Effects of triiodothyronine and bovine growth hormone on glucose transporter isoform-2 (GLUT-2) and glucokinase (GK) gene expression in pancreatic islets of fetal and adult rats.
This study was conducted to determine the effects of triiodothyronine (T3) and bovine growth hormone (bGH) on the expression of glucose transporter-2 (GLUT-2) and of glucokinase (GK) from pancreatic islets of fetal and adult rats. Incubation of both sets of pancreatic islets with T3 did not modify GLUT-2 mRNA levels, but did reduce the content of GLUT-2 protein, while it reduced the expression of GK mRNAs in fetal and adult pancreatic islets. Treatment of fetal and adult pancreatic islets with 1 microg/ml bGH did not alter the expression of GLUT-2 mRNAs, but significantly increased GLUT-2 protein levels in adult islets by 50%. Also, bGH had no effect on the GK mRNA content of fetal and adult pancreatic islets whereas, in contrast, there was a significant reduction in the amount of GK protein in fetal islets cultured with that hormone but not in those corresponding to adult rats. These findings suggest that T3 and bGH are able to modulate the expression of GLUT-2 and GK mRNAs and proteins in pancreatic islets in a manner different from that in the liver, as previously reported by others. In addition, both hormones produced different responses in fetal and in adult pancreatic islets.
García-Flores
M
M
Department of Biochemistry and Molecular Biology, Faculty of Medicine, Complutense University, 28040-Madrid, Spain.
Blázquez
E
E
Zueco
J A
JA
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D046508:Culture Techniques; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D005941:Glucokinase / Q000235:genetics* / Q000378:metabolism; D051273:Glucose Transporter Type 2; D013006:Growth Hormone / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000196:embryology / Q000502:physiology*; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014284:Triiodothyronine / Q000494:pharmacology*
D051273:Glucose Transporter Type 2; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D014284:Triiodothyronine; D013006:Growth Hormone; D005941:Glucokinase