Abstract
Human growth hormone (HGH) response to arginine (25 gm IV in 30 min) and to insulin
(0.1 U/kg B.W.) was studied in 12 male patients (mean age 36 ± 2 years), with normal
glucose tolerance and normal body weight, affected with Fredrickson's Type IV primary
hyperlipemia. The patients were examined both when plasma triglycerides (TG) were
elevated and following Clofibrate (2 gm/die for 30-60 days) induced TG reduction.
No variations in glucose or FFA behaviour or in body weight were observed after Clofibrate.
HGH response to arginine was absent, while that to insulin was only inhibited, when
plasma TG were elevated. A significant increase in HGH peaks after arginine (from
1.99 ± 0.59 to 9.34 ± 1.58 ng/ml) and a slight increment in HGH peaks after insulin
(from 23.09 ± 7.19 to 31.46 ± 7.95 ng/ml) were observed following reduction in plasma
TG.
Arginine test was carried out in 7 normal subjects during saline infusion and at
the 3rd hour of lipid infusion (Intralipid 20%). HGH response to arginine was absent
in all of the subjects during lipid infusion. The HGH response to insulin test, carried
out in 9 other normal subjects during saline infusion and at the 3rd hour of lipid
infusion (Lipiphysan 15%) was significantly inhibited during lipid infusion. Since
lipid infusion provoked an increment, not only in plasma TG but also in FFA, the inhibition
of HGH release could be correlated with the elevated plasma levels of both TG and
FFA.
The results obtained in both spontaneous and experimental hyperlipemia not only confirm
the role played by FFA in the regulation of HGH secretion, but also support the hypothesis
that elevated TG levels could inhibit HGH response to some stimuli.
Key words
Human Growth Hormone - Hyperprebetalipoproteinemia - Triglycerides - Glucose - Free
Fatty Acids (FFA) - Arginine Test - Insulin Test - Clofibrate - Intralipid - Lipiphysan
1 Supported by C.N.R. (Consiglio Nationale delle Ricerche) Research grant no. 73.00507.04
