Estradiol effects on the growth hormone/insulin-like growth factor-1 axis in amenorrheic athletes.
Disruption of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis has been reported and studied in menopause, hypothalamic amenorrhea, and anorexia nervosa, but not in weight-stable amenorrheic athletes. We investigated the effects of short-term transdermal estradiol on basal and exercise-stimulated serum GH, IGF-1, and associated binding proteins (IGFBP-1 and IGFBP-3) in seven weight-stable female amenorrheic athletes with percentage body fats greater that 12%. Each subject received a 72 h placebo patch followed by 144 h of transdermal estradiol. Serum samples for GH, IGF-1, IGFBP-1, and IGFBP-3 were obtained at baseline (t1), 72 hr (t2), 144 hr (t3), and during three 90-minute trials of aerobic exercise. Basal, and exercise GH, IGF-1, and IGFBP-1 were not different between trials. Baseline IGFBP-3 decreased from t1 to t2 (p = 0.04) and serum free fatty acids increased from t1 to t2, and t1 to t3 (p = 0.04, and 0.02 respectively). These findings differ from postmenopausal women, and women having weightloss-associated amenorrhea, suggesting that estrogen, exercise, and nutritional deficiencies may have independent effects on the GH/IGF-1 axis.
Waters
Debra L
DL
School of Medicine, Department of Internal Medicine, University of New Mexico, Albuquerque, NM, USA.
Dorin
Richard I
RI
Qualls
Clifford R
CR
Ruby
Brent C
BC
Baumgartner
Richard N
RN
Robergs
Robert A
RA
D000279:Administration, Cutaneous; D000568:Amenorrhea / Q000097:blood*; D000704:Analysis of Variance; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*
D005230:Fatty Acids, Nonesterified; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone