What if the sensation of hunger, that gnawing feeling in the pit of our stomachs, could be the key to slowing down the aging process? It may sound like science fiction, but a team of researchers at the University of Michigan has been delving into this very possibility, with some intriguing results.
The Science of Hunger and Aging
The study, initially inspired by previous findings showing that even the taste and smell of food can counteract the life-extending effects of dietary restriction, wanted to explore if the brain’s response to hunger could be the secret ingredient to longevity. In the words of Scott Pletcher, Ph.D., one of the study’s principal investigators, the team aimed to “divorce the life-extending effects of diet restriction from all of the nutritional manipulations of the diet,” to see if the mere perception of food scarcity could be enough.
Experimenting with Fruit Flies
To investigate this, the researchers induced hunger in fruit flies in two main ways. First, they altered the levels of branched-chain amino acids (BCAAs) in the flies’ food, creating a low-BCAA snack. After consuming this, the flies were allowed to freely feast on a buffet of yeast or sugar food. Interestingly, the flies that consumed the low-BCAA snack showed a clear preference for yeast over sugar, indicative of need-based hunger. The research team observed that these flies consumed more food and more total calories, suggesting that the behavior wasn’t due to the calorie content of the snack. Most importantly, these flies lived significantly longer when they consumed a low-BCAA diet for life.
Optogenetics and Longevity
In a separate line of investigation, the researchers used a technique called optogenetics, which involved activating neurons associated with the hunger drive in the flies using exposure to red light. The optogenetically stimulated flies ate twice as much as their non-stimulated counterparts and, just like the low-BCAA-fed flies, they also lived significantly longer.
Beyond these fascinating observations, the researchers were able to link the molecular mechanics of hunger to changes in the epigenome of the involved neurons. They discovered that the presence or absence of a specific amino acid in the diet affected how much of specific genes were expressed in the flies’ brains, which in turn influenced their feeding behavior and aging. While the authors caution against directly applying these findings to humans, they believe there’s a good chance that the mechanisms discovered could affect hunger drives in other species as well.
Looking forward, the team plans to investigate whether the drive to eat for pleasure, a phenomenon seen in both flies and humans, may also be linked to lifespan. Who knows, the future of aging research might just be tied to our stomachs in ways we never imagined.