TY - JOUR

T1 - The effect of recombinant human growth hormone and resistance training on IGF-I mRNA expression in the muscles of elderly men

AU - Hameed, M

AU - Lange, K H W

AU - Andersen, J L

AU - Schjerling, P

AU - Kjaer, M

AU - Harridge, S D R

AU - Goldspink, G

PY - 2004/2/15

Y1 - 2004/2/15

N2 - The expression of two isoforms of insulin-like growth factor-I (IGF-I): mechano growth factor (MGF) and IGF-IEa were studied in muscle in response to growth hormone (GH) administration with and without resistance training in healthy elderly men. A third isoform, IGF-IEb was also investigated in response to resistance training only. The subjects (age 74 +/- 1 years, mean +/- S.E.M) were assigned to either resistance training with placebo, resistance training combined with GH administration or GH administration alone. Real-time quantitative RT-PCR was used to determine mRNA levels in biopsies from the vastus lateralis muscle at baseline, after 5 and 12 weeks in the three groups. GH administration did not change MGF mRNA at 5 weeks, but significantly increased IGF-IEa mRNA (237%). After 12 weeks, MGF mRNA was significantly increased (80%) compared to baseline. Five weeks of resistance training significantly increased the mRNA expression of MGF (163%), IGF-IEa (68%) and IGF-IEb (75%). No further changes were observed after 12 weeks. However, after 5 weeks of training combined with GH treatment, MGF mRNA increased significantly (456%) and IGF-IEa mRNA by (167%). No further significant changes were noted at 12 weeks. The data suggest that when mechanical loading in the form of resistance training is combined with GH, MGF mRNA levels are enhanced. This may reflect an overall up-regulation of transcription of the IGF-I gene prior to splicing.

AB - The expression of two isoforms of insulin-like growth factor-I (IGF-I): mechano growth factor (MGF) and IGF-IEa were studied in muscle in response to growth hormone (GH) administration with and without resistance training in healthy elderly men. A third isoform, IGF-IEb was also investigated in response to resistance training only. The subjects (age 74 +/- 1 years, mean +/- S.E.M) were assigned to either resistance training with placebo, resistance training combined with GH administration or GH administration alone. Real-time quantitative RT-PCR was used to determine mRNA levels in biopsies from the vastus lateralis muscle at baseline, after 5 and 12 weeks in the three groups. GH administration did not change MGF mRNA at 5 weeks, but significantly increased IGF-IEa mRNA (237%). After 12 weeks, MGF mRNA was significantly increased (80%) compared to baseline. Five weeks of resistance training significantly increased the mRNA expression of MGF (163%), IGF-IEa (68%) and IGF-IEb (75%). No further changes were observed after 12 weeks. However, after 5 weeks of training combined with GH treatment, MGF mRNA increased significantly (456%) and IGF-IEa mRNA by (167%). No further significant changes were noted at 12 weeks. The data suggest that when mechanical loading in the form of resistance training is combined with GH, MGF mRNA levels are enhanced. This may reflect an overall up-regulation of transcription of the IGF-I gene prior to splicing.

KW - Aged

KW - Aged, 80 and over

KW - Aging/drug effects

KW - Analysis of Variance

KW - Double-Blind Method

KW - Exercise/physiology

KW - Gene Expression Regulation/drug effects

KW - Human Growth Hormone/pharmacology

KW - Humans

KW - Insulin-Like Growth Factor I/biosynthesis

KW - Male

KW - Muscle, Skeletal/drug effects

KW - Protein Isoforms/biosynthesis

KW - RNA, Messenger/biosynthesis

KW - Recombinant Proteins/pharmacology

KW - Weight Lifting/physiology

U2 - 10.1113/jphysiol.2003.051722

DO - 10.1113/jphysiol.2003.051722

M3 - Journal article

C2 - 14565994

VL - 555

SP - 231

EP - 240

JO - The Journal of Physiology

JF - The Journal of Physiology

SN - 0022-3751

IS - Pt 1

ER -