12/23/2010 PERMALINK
Growth hormone appears to shorten lifespan, while growth hormone release blocker extends longevity. Scientists studying the compound MZ-5-156, a growth hormone-releasing hormone (GHRH) antagonist, have found that overall, MZ-5-156 had positive effects on oxidative stress in the brain, improving cognition, telomerase activity (the actions of an enzyme which protects DNA material) and life span, while decreasing tumor activity. The research was conducted using the SAMP8 mouse model, a strain engineered for studies of the aging process.

MZ-5-156, like many GHRH antagonists, inhibited several human cancers, including prostate, breast, brain and lung cancers. It also had positive effects on learning, and is linked to improvements in short-term memory. The antioxidant actions led to less oxidative stress, reversing cognitive impairment in the aging mouse.

"Many older people have been taking growth hormone to rejuvenate themselves," said John E. Morley, M.D., study co-investigator and director of the divisions of geriatric medicine and endocrinology at Saint Louis University School of Medicine. "These results strongly suggest that growth hormone, when given to middle aged and older people, may be hazardous." It is the antagonists of growth hormone-releasing hormone that appear to have strongly beneficial effects on aging, indicating that growth hormone does just the opposite.