It is very well documented that plasma growth hormone (GH) levels decline with age in the human and in experimental animals, and there is considerable evidence that age-related changes in body composition may be caused by reduced function of the GH-IGF-I system. However, excessive GH levels are associated with reduced life expectancy in acromegalic patients and with symptoms of accelerated aging in GH transgenic mice. Hereditary dwarf mice deficient in GH, prolactin, and TSH live much longer than their normal siblings. Possible mechanisms of delayed aging in dwarf mice include lower core body temperature and reduced oxidative processes. It is suggested that the controversies concerning the apparent potential of GH to both prevent and accelerate aging may be reconciled by interpreting the results in light of the negative relationship between body size and life span within a species.
Bibliographical noteFunding Information:
Studies reported in this review were supported by NIH via grants HD 20001, HD 20033, AG 14193, by NSF #OSR-9452892, and by NSERC of Canada. We thank W. Croson and R. Sivanesan for their help in studies of body temperature, R. Bharadwaj for his help in the studies of inorganic peroxides, and Hua Tu for her help with the oxidative enzyme studies
- Body temperature
- Dwarf mice
- Growth hormone
- Oxidative damage
- Transgenic mice