# GROWTH HORMONE & SEX STEROID EFFECTS ON SKELETAL MUSCLE

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 1992 · $260,045

## Abstract

Human aging is generally accompanied by a gradual decline in various
physiological functions, which in some people results in physical
impairments, and ultimately may cause disabilities which worsen the
quality of life and limit the independence of the individual.  It now
appears that age-related disturbances in muscle strength, gait, and
balance are at least partly reversible.  Three well-documented
accompaniments of the aging process are: (a) decreased circulating growth
hormone (GH) and insulin-like growth factor-I (IGF-I), (b) reduced plasma
sex steroid hormone levels; and (c) altered body composition, with
decreased muscle mass and increased body fat.  Recent evidence suggests
that treatment with either recombinant human GH (rhGH) or sex steroids
can improve body composition in some older persons, but the effects of
such hormonal treatment (singly or in combination) on various
physiological functions are unknown.  We hypothesize that: (a) the
decreases in GH, IGF-I and sex steroids that occur with aging, separately
and interactively contribute to diminished skeletal muscle mass and
strength, increased body fat, and reduced aerobic capacity in older women
and men; and that (b) restitution of normal GH, IGF-I and sex steroid
status by combined hormone therapy will exert additive or synergistic
effects to increase muscle mass, strength, and aerobic capacity, and
decrease body fat.  We therefore propose to demonstrate, in a population
of ambulatory, community-dwelling, sedentary women and men beyond the age
of 65, with low IGF-I and sex steroid levels, and reduced mobility, that
6-months of hormonal treatment with rhGH, sex steroid hormones
(estrogen/progestin in women and testosterone in men), or combined rhGH
plus sex steroids will, singly or together, result in improvements in
certain physiological variables such as skeletal muscle mass and
strength, total body protein synthesis, aerobic capacity and myocardial
function.  Additionally, we propose to examine (1) molecular mechanisms
by which the hormonal interventions may exert their effects, using the
quantitative RNA template-specific polymerase chain reaction technique to
quantify mRNAs for IGF-I, IGF-I receptors and IGF-I binding proteins in
skeletal muscle biopsy specimens; and (2) the relationships between the
latter molecular events and the physiological outcome variables.  Should
the proposed study reveal beneficial effects of hormone replacement, then
longer-term investigations will be warranted to examine the interactions
of hormone treatment with other interventions (e.g. exercise
conditioning), and their effects on functional status measurements, in
additional populations of older people.

## Key facts

- **NIH application ID:** 3122978
- **Project number:** 1R01AG011002-01
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **SAM.gov UEI:** FTMTDMBR29C7
- **Principal Investigator:** Marc Roy Blackman
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $260,045
- **Award type:** 1
- **Project period:** 1992-09-01 → 1997-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3122978

## Citation

> US National Institutes of Health, RePORTER application 3122978, GROWTH HORMONE & SEX STEROID EFFECTS ON SKELETAL MUSCLE (1R01AG011002-01). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3122978. Licensed CC0.

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