American biologists Leslie Leinwand of the University of Colorado Boulder and Jonathon Long of Stanford University have found a compound in python blood that helps the reptiles eat huge meals and then go months without food while staying healthy.
Pythons can grow as long as a telephone pole. They can swallow an antelope whole and survive months or even years without eating, all while keeping their hearts strong and maintaining their muscles.
Leinwand’s earlier research showed that after a meal, a python’s heart expands by 25 per cent and its metabolism speeds up 4,000 times to digest the massive meal.
To understand how these superpowers work, Leinwand partnered with Long, an associate professor of pathology at Stanford School of Medicine who studies metabolic by-products in blood, known as metabolites.
Long’s lab had previously studied racehorses to understand how their bodies manage energy during intense sprints, giving insight into extreme metabolism in animals.
Metabolites are small molecules produced or used during metabolism. Metabolism is the process of converting food into the energy and chemicals that are needed to power and maintain the body (see graphic).
For their new study, the researchers collected blood from ball pythons and Burmese pythons that were fed once every 28 days, sampling the blood immediately after a meal. They identified 208 metabolites that increased significantly after eating. One molecule, called para-tyramine-O-sulphate (pTOS), surged 1,000-fold.
“Obviously, we are not snakes,” Long said. “But maybe by studying these animals, we can identify molecules or metabolic pathways that also affect human metabolism.”
Further experiments, done with researchers from Baylor University, tested pTOS in mice. They found that giving high doses of pTOS to both obese and lean mice suppressed appetite by acting on the hypothalamus – the brain’s appetite centre – without causing digestive issues, muscle loss or reduced energy.
The snakes’ gut bacteria produce pTOS. The molecule does not naturally occur in mice, but it is found in humans at low levels and increases slightly after a meal.
In future studies, the team plans to explore how pTOS affects humans and to investigate the roles of other metabolites that surge after pythons eat.
Besides having a slow metabolism, how else do snakes survive when there is no food?
Unlike mammals, snakes do not generate their own body heat. By relying on heat from the environment, such as basking in the sun, they maintain a naturally low metabolism, which means they require less energy to function.
During long periods without food, snakes can further reduce their metabolic rate by up to 70 per cent. They conserve energy by shutting down several body functions, such as stopping their digestive system. To further reduce the energy needed to maintain their bodies, their internal organs actually shrink. They also stay very still to avoid burning unnecessary energy.
In addition, these animals use stored fats and nutrients from their bodies when food is unavailable. They reuse these to maintain essential functions and can even convert them into muscle and bone to continue growing while they fast for months on end.
