Humanin (HN) is a mitochondrial peptide* that in some research has shown the ability to protect against the death of neurons, the devastating consequence of diseases like Alzheimer’s. According to the leader of a research team at the Albert Einstein College of Medicine at Yeshiva University in the Bronx, however, it also significantly improves the insulin sensitivity of diabetic rats and sharply drops their glucose levels.
In short, says Dr. Nir Barzilai, the Ingeborg and Ira Leon Rennert Chair of Aging Research and Director of the Institute for Aging Research at the college, HN is the most powerful insulin metabolism regulator his team has ever seen.
Dr. Barzilai’s research into HN is an outgrowth of his study of longevity among several hundred Ashkenazi Jews, aged 95 to 112, and their offspring. In his study, he found that although production of HN decreases in people as they age, it decreased less in the Azhkenazi group. Their children also had high levels of HN, a genetic endowment.
The ultimate controllable effects of HN on insulin metabolism, says Dr. Barzilai, will probably be intertwined with two genes: one for insulin-like growth factor (IGF-1) and the other for insulin-like growth factor binding protein-3 (IGFBP-3). Dr. Barzilai had previously found that some of the oldest of his Ashkenazi patients had a mutation in the IGF-1 gene that has been shown in other life forms, including mammals, to prolong life span.
In the current study involving HN, his team found that IGFBP-3 inhibited HN’s effect on insulin action and that when the gene was inhibited, HN’s potency increased.
All of this points to a possible new drug therapy, obviously several years down the road as scientists cautiously move from laboratory experiments to experiments with human test subjects. In the meantime, the results of the study considerably advance the notion that the brain is far more associated with diabetic processes than was believed even a few years ago.
* A peptide is a molecule consisting of two or more amino acids. They are like proteins, which are also extended chains of amino acids, but smaller.