title: Age-related decrease in plasma growth hormone: response to growth hormone-releasing hormone, arginine, and L-dopa in obesity.
abstract: Aging is associated with a reduction in plasma growth hormone (GH) secretion in non-obese subjects. To determine whether or not age-related changes in plasma GH secretion exist in obese subjects, we measured (a) plasma GH response to growth hormone-releasing hormone (GRH; 1 microgram/kg body wt), arginine (0.5 g/kg body wt), L-dopa (500 mg), and (b) plasma glucose, insulin, and free fatty acids (FFAs) in 26 fasted obese subjects of various ages ranging from 16 to 71 years. Only subjects with a body mass index (BMI; kg/m2) between 30.0 and 39.0 were studied. Six subjects were adolescents, 9 were in their 20s, and 11 were 30 years or older. The mean peak levels of plasma GH in response to GRH, arginine, and L-dopa in obese subjects were 11.3 +/- 2.1, 21.9 +/- 4.4, and 5.2 +/- 0.3 ng/mL in adolescents, 8.2 +/- 1.6, 9.1 +/- 1.5, and 3.1 +/- 0.6 ng/mL in those in their 20s, and 4.5 +/- 0.4, 7.3 +/- 1.4, and 2.8 +/- 0.3 ng/mL in those 30 years or older, respectively, showing a significant decrease in peak GH level with advancing age (P less than .05 to P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Third Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: S
authors.initials: S
authors.lastname: Inoue
authors.forename: J
authors.initials: J
authors.lastname: Shiraki
authors.forename: T
authors.initials: T
authors.lastname: Shishido
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.forename: K
authors.initials: K
authors.lastname: Numata
authors.forename: Y
authors.initials: Y
authors.lastname: Takamura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood*; D001120:Arginine / Q000494:pharmacology*; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*
chemical_list: D007980:Levodopa; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine