Comparing Ames Dwarfism and Calorie Restriction
Ames dwarf mice are among the longest lived longevity mutants so far created. They lack growth hormone, and this has a large effect on their metabolism, size, and pace of aging. Here researchers compare this extension of life with that produced by calorie restriction in mice:
Since 1996, aging studies using several strains of long-lived mutant mice have been conducted. Among these studies, Ames dwarf mice have been extensively examined to seek clues regarding the role of the growth hormone/insulin-like growth factor-1 axis in the aging process. Interestingly, these projects demonstrate that Ames dwarf mice have physiological characteristics that are similar to those seen with calorie restriction, which has been the most effective experimental manipulation capable of extending lifespan in various species. However, this introduces the question of whether Ames dwarf and calorie-restricted (CR) mice have an extended lifespan through common or independent pathways.To answer this question, we compared the disease profiles of Ames dwarf mice to their normal siblings fed either ad libitum (AL) or a CR diet. Our findings show that the changes in age-related diseases between AL-fed Ames dwarf mice and CR wild-type siblings were similar but not identical. Moreover, the effects of CR on age-related pathology showed similarities and differences between Ames dwarf mice and their normal siblings, indicating that calorie restriction and Ames dwarf mice exhibit their anti-aging effects through both independent and common mechanisms.
It is worth noting that a similar mutant, in which growth hormone receptor is removed rather than growth hormone, has a corresponding small human population in which this mutation occurred naturally, a condition known as Laron syndrome. While the mice are exceedingly long-lived in comparison to their peers, people with Laron syndrome do not appear to exhibit significantly extended lives. They are, however, somewhat resistant to diabetes and cancer.
There is also a human population with a mutation in the same gene responsible for Ames dwarfism. See here: http://www.ncbi.nlm.nih.gov/m/pubmed/20679996/
"It is concluded that despite the long lasting GH and sex hormone deficiencies and irregular thyroid hormone ingestion, patients with congenital MPHD due to Prop-1 gene defects can live a long life."
Note that Laron is an author on this study.