'Un-Growth Hormone' Increases Longevity, Researchers Find

A compound which acts in the opposite way as growth hormone can reverse some of the signs of aging, a research team that includes a Saint Louis University physician has shown. The finding may be counter-intuitive to some older adults who take growth hormone, thinking it will help revitalize them.

Their research was published in the Dec. 6 online edition of the Proceedings of the National Academy of Sciences.

 The findings are significant, says 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, because people sometimes take growth hormone, believing it will be the fountain of youth.

"Many older people have been taking growth hormone to rejuvenate themselves," Morley said. "These results strongly suggest that growth hormone, when given to middle aged and older people, may be hazardous."

The scientists studied the compound MZ-5-156, a "growth hormone-releasing hormone (GHRH) antagonist." They conducted their research in the SAMP8 mouse model, a strain engineered for studies of the aging process. Overall, the researchers found that 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.

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.

William A. Banks, M.D., lead study author and professor of internal medicine and geriatrics at the University of Washington School of Medicine in Seattle, said the results lead the team "to determine that antagonists of growth hormone-releasing hormone have beneficial effects on aging."

The study team included as its corresponding author Andrew V. Schally, M.D., Ph.D., a professor in the department of pathology and division of hematology/oncology at the University of Miami Miller School of Medicine.

Child DNA donors should have their say

Biobanks should revamp how they handle DNA from healthy children, says an international team of bioethics experts. Children whose parents have signed them up for long-term studies should not have their genetic data distributed or made public until the donors consent at an older age, says the team, which publishes its recommendations today in Science.

"Children should be able to decide, when they're mature enough, about their full or fuller involvement," says Bartha Maria Knoppers, director of the Centre of Genomics and Policy at McGill University in Montreal, Canada, and an author of the paper. If implemented, the recommendation could help protect young participants' privacy, but critics say that it is arbitrary and will hamper research into children's health.

Many large biobank projects, including the US National Children's Study and the Norwegian Mother and Child Cohort Study, are now routinely collecting biological samples from healthy newborns and children. These young participants present a unique ethical challenge. They are too young to give informed consent, so authorization is needed from parents or guardians. But they will eventually become adults who may not wish to share their DNA.

David Gurwitz, director of the National Laboratory for the Genetics of Israeli Populations at Tel-Aviv University in Israel, and lead author of the study, says that the recommendations are needed to safeguard child donors from the risks associated with revealing personal genetic data. "Don't rush into distributing the DNA samples to external researchers, because DNA is a strong, unique identifier," he says. To avoid delays in paediatric research, in-house research facilities should be built so that analyses can continue without samples leaving the biobank until adult consent is obtained, Gurwitz adds.