Correlation between pancreatic islet uncoupling protein-2 (UCP2) mRNA concentration and insulin status in rats.
Hypothesizing that UCP2 may influence insulin secretion by modifying the ATP/ADP ratio within pancreatic islets, we have investigated the expression of intraislet UCP2 gene in rats showing insulin oversecretion (non-diabetic Zucker fa/fa obese rats, glucose-infused Wistar rats) or insulin undersecretion (fasting and mildly diabetic rats). We found that in Zucker fa/fa obese rats, hyperinsulinemia (1222+/-98 pmol/l vs. 128+/-22 pmol/l in lean Zucker rats) was accompanied by a significant increase in UCP2 mRNA levels. In rat submitted to a 5 day infusion with glucose, hyperinsulinemia (1126+/-101 pmol/l vs. 215+/-25 pmol/l in Wistar control rats), coincided with an enhanced intraislet UCP2 gene expression, whereas a 8h or a 2 day-infusion did not induce significant changes in UCP2 mRNA expression. In rats made hypoinsulinemic and mildly diabetic by the injection of a low dose of streptozotocin, and in 4-day-fasting rats (plasma insulin 28+/-5 pmol/l) UCP2 gene expression was sharply decreased. A 3-day-fast was ineffective. The data show the existence of a time-dependent correlation between islet mRNA UCP2 and insulin that may be interpreted as an adaptative response to prolonged insulin excess.
Kassis
N
N
Laboratoire de Physiopathologie de la Nutrition, CNRS ESA 7059, Université Paris 7-Denis Diderot, France.
Bernard
C
C
Pusterla
A
A
Casteilla
L
L
Pénicaud
L
L
Richard
D
D
Ricquier
D
D
Ktorza
A
A
D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005215:Fasting; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology; D015309:Glucose Clamp Technique; D006946:Hyperinsulinism / Q000503:physiopathology; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D000078790:Insulin Secretion; D007473:Ion Channels; D007515:Islets of Langerhans / Q000378:metabolism / Q000502:physiology* / Q000503:physiopathology; D007700:Kinetics; D008297:Male; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011924:Rats, Zucker; D013045:Species Specificity; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D014475:Uncoupling Agents; D000071246:Uncoupling Protein 2
D001786:Blood Glucose; D007328:Insulin; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D012333:RNA, Messenger; C000604391:Ucp2 protein, rat; D014475:Uncoupling Agents; D000071246:Uncoupling Protein 2; D005947:Glucose