Increased number of IGF-I receptors on erythrocytes of women with polycystic ovarian syndrome.
OBJECTIVE
To test the hypothesis that insulin acts though ovarian IGF-I receptors to produce excessive amounts of androgens in polycystic ovarian syndrome (PCOS), by measuring the binding capacity of IGF-I receptors on erythrocytes and relating the findings to the degree of hyperandrogenism and hyperinsulinaemia.


METHODS
A case-control study of IGF-I receptors on erythrocytes of women with PCOS and age- and weight-matched controls.


METHODS
IGF-I receptors on erythrocytes, serum levels of androgens, IGF-I, GH, basal insulin and insulin response during oral glucose tolerance test (oGTT) were measured after induced or spontaneous withdrawal bleeding in 10 women with PCOS and eight normo-ovulatory women.


RESULTS
An increased number of IGF-I receptors was found on erythrocytes of patients with PCOS compared with the controls (P < 0.01), irrespective of their body mass index. Serum IGF-I levels were similar in both groups. The degree of hyperinsulinaemia, provoked by oGTT, correlated positively with basal insulin (r = 0.69; P = 0.003), but not with the number of IGF-I receptors. However, the number of IGF-I receptors correlated positively with androstenedione (r = 0.54, P = 0.0018).


CONCLUSIONS
The findings in the present study that the number of IGF-I receptors and not the insulin levels correlate with serum androstenedione support the theory that the hyperandrogenism in PCOS is not a direct effect of the hyperinsulinaemia, but IGF-I mediated.
Gdansky
E
E
Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Jerusalem, Israel.
Diamant
Y Z
YZ
Laron
Z
Z
Silbergeld
A
A
Kaplan
B
B
Eshet
R
R
D000293:Adolescent; D000328:Adult; D000735:Androstenedione / Q000097:blood; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D005951:Glucose Tolerance Test; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D011085:Polycystic Ovary Syndrome / Q000378:metabolism*; D017526:Receptor, IGF Type 1 / Q000378:metabolism*
D007328:Insulin; D000735:Androstenedione; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D017526:Receptor, IGF Type 1