Somatostatin-stimulated insulin-like growth factor binding protein-1 release is abolished by hyperinsulinemia.
It was demonstrated recently that administration of lanreotide and octreotide, two somatostatin octapeptide analogs, increased circulating insulin-like growth factor binding protein 1 (IGFBP-1) levels. The present study demonstrates that native somatostatin 14 shares this ability and that the increase in abolished by concomitant hyperinsulinemia within the physiological range. Five fasting healthy volunteers underwent a hyperinsulinemic as well as a normo-insulinemic (i.e. basal insulinemic) euglycemic clamp lasting 8 h (serum insulin levels remained constant, about 570 vs. 16 pmol/L). Immediately before the clamps, a somatostatin infusion (500 micrograms/h) was started and continued throughout. During normo-insulinemia, IGFBP-1 levels increased slowly from 6.3 +/- 6.2 to 36.1 +/- 14.8 micrograms/L (P < 0.05) reaching maximum after 7 h constant somatostatin infusion, whereas hyperinsulinemia induced a significant decrease from basal levels (from 4.7 +/- 5.4 to 1.1 +/- 1.5 micrograms/L) after 8 h (mean +/- SD, n = 5). These results may indicate hitherto unnoticed interactions of somatostatin and insulin on IGFBP-1 release with possible impact on IGF-I action at the cellular level.
Orskov
H
H
Institute of Experimental Clinical Research, University Hospital, Kommunehospitalet, Aarhus C, Denmark.
Wolthers
T
T
Grøfte
T
T
Flyvbjerg
A
A
Vilstrup
H
H
Hamberg
O
O
D000328:Adult; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000097:blood*; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood*; D018970:Insulin-Like Growth Factor Binding Protein 1; D008297:Male; D012016:Reference Values; D013002:Somatomedins / Q000378:metabolism; D013004:Somatostatin / Q000494:pharmacology*
D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D013002:Somatomedins; D013004:Somatostatin