Glucose-dependent insulinotropic polypeptide may enhance fatty acid re-esterification in subcutaneous abdominal adipose tissue in lean humans.
OBJECTIVE
Glucose-dependent insulinotropic polypeptide (GIP) has been implicated in lipid metabolism in animals. In humans, however, there is no clear evidence of GIP effecting lipid metabolism. The present experiments were performed in order to elucidate the effects of GIP on regional adipose tissue metabolism.


METHODS
Eight healthy subjects were studied on four different occasions. Abdominal subcutaneous adipose tissue metabolism was assessed by measuring arterio-venous concentration differences and regional adipose tissue blood flow during GIP (1.5 pmol/kg/min) or saline infused intravenously alone or in combination with a hyperinsulinemic-hyperglycemic (HI-HG) clamp.


RESULTS
During GIP and HI-HG clamp, abdominal subcutaneous adipose tissue blood flow, hydrolysis of circulating triacylglycerol (TAG) (P = 0.009), and glucose uptake (P = 0.03) increased significantly while free fatty acid (FFA) output (P = 0.04) and FFA/glycerol release ratio (P = 0.02) decreased compared with saline and HI-HG clamp.


CONCLUSIONS
In conclusion, GIP in combination with hyperinsulinemia and slight hyperglycemia increased adipose tissue blood flow, glucose uptake, and FFA re-esterification, thus resulting in increased TAG deposition in abdominal subcutaneous adipose tissue.
Asmar
Meena
M
1Department of Clinical Physiology/Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark.
Simonsen
Lene
L
Madsbad
Sten
S
Stallknecht
Bente
B
Holst
Jens Juul
JJ
Bülow
Jens
J
D000328:Adult; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D002096:C-Peptide / Q000097:blood / Q000187:drug effects; D005227:Fatty Acids / Q000378:metabolism*; D005749:Gastric Inhibitory Polypeptide / Q000097:blood / Q000494:pharmacology*; D015309:Glucose Clamp Technique / Q000379:methods; D005990:Glycerol / Q000097:blood / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia; D006946:Hyperinsulinism; D008297:Male; D050507:Subcutaneous Fat, Abdominal / Q000187:drug effects / Q000378:metabolism*; D013851:Thinness / Q000378:metabolism*; D014280:Triglycerides / Q000097:blood / Q000378:metabolism
D001786:Blood Glucose; D002096:C-Peptide; D005227:Fatty Acids; D014280:Triglycerides; D005749:Gastric Inhibitory Polypeptide; D005990:Glycerol