Serum adiponectin is reduced in acromegaly and normalized after correction of growth hormone excess.
Adiponectin, an adipocyte-derived hormone, possesses insulin-sensitizing, antiinflammatory, and antiatherogenic properties. We hypothesized that hypoadiponectinemia was present in acromegaly, as in other conditions with increased insulin resistance and cardiovascular risk. Using an in-house RIA, serum adiponectin was determined in 35 patients with active acromegaly and 35 age-, sex-, and body mass index-matched healthy controls. Twenty-five patients were restudied after GH-lowering therapies. Serum adiponectin was significantly reduced in the acromegalic patients (4.3 +/- 1.8 vs. 6.7 +/- 1.8 microg/ml in controls; P < 0.001), but was increased after treatment with Sandostatin LAR, a long-acting somatostatin analog (5.8 +/- 2.6 vs. 3.8 +/- 1.6 microg/ml pretreatment; P < 0.001; n = 15) or transsphenoidal surgery (6.5 +/- 2.7 vs. 3.9 +/- 1.5 microg/ml preoperation; P < 0.01; n = 10). Fasting insulin was an independent determinant of serum adiponectin levels (P < 0.01) in control subjects, contributing to 11.7% of the variance in circulating adiponectin. In cultured 3T3-L1 adipocytes, adiponectin mRNA levels were decreased by insulin (1.5 microm; P < 0.005) or IGF-I (1 microg/ml; P < 0.05), but not by GH (1 microm) or somatostatin (1 microm). In conclusion, hypoadiponectinemia is present in active acromegaly, probably secondary to the inhibitory effect of high circulating insulin levels. Hypoadiponectinemia, reversible with GH-lowering therapies, may contribute to the increased insulin resistance and cardiovascular risk in patients with acromegaly.
Lam
Karen Siu-Ling
KS
Department of Medicine, University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong. ksllam@hkucc.hku.hk.
Xu
Aimin
A
Tan
Kathryn Choon-Beng
KC
Wong
Lai-Ching
LC
Tiu
Sau-Cheung
SC
Tam
Sidney
S
D041721:3T3-L1 Cells; D000172:Acromegaly / Q000097:blood*; D052242:Adiponectin; D000328:Adult; D000368:Aged; D000818:Animals; D005260:Female; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000097:blood; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008297:Male; D051379:Mice; D008875:Middle Aged
D052242:Adiponectin; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; D019382:Human Growth Hormone