Pythons build up brains after digesting dinner

Abstract

If the bulk of your life is spent sitting around waiting for a dish to amble past – and you never know when that could be – it makes sense to cut back on the non-essentials. For ball pythons, this can mean reducing the size of pretty much all of the digestive system and the heart. However, when a python's luck is in, the race is on to build up these organs as rapidly as possible in a bid to make the most of dinner. Christine Strand from California Polytechnic State University (Cal. Poly.), USA, explains that many people have studied how the reptiles swiftly soup up their heart and digestive organs after consuming a meal: ‘But no one had looked into how feeding affects the brain’, she says.Intrigued by the possibility that feasting pythons may grow new brain cells that could eventually go on to form new neurons, Strand, Stacy Habroun (now at University of California San Diego, USA) and Emily Taylor decided to monitor the brains of adolescent pythons after feeding. ‘We weren't sure if the brain would respond to feeding by increasing cell proliferation’, Strand admits. However, she reasoned that if the brain did grow, there were two possible time points when it could occur: while the snake was digesting its meal and building up its other organs, or after digestion was complete, when the snake's system was full of fresh nutrients and it had energy to spare.Having convinced ball pythons, which are notoriously fussy eaters, to consume a substantial meal of mice, Habroun and Strand allowed some of the snakes 2 days to begin digesting their meal while the remaining snakes were allowed 6 days to complete digestion before the pair collected samples from the animals’ brains. However, a day before taking the samples, Habroun injected the snakes with a tracer that would only be incorporated into newly born cells, in the hope that it would reveal whether, and when, the brains of the satisfied snakes had grown. Then, Habroun and Strand worked with Andrew Schaffner, also from Cal. Poly., to compare the pythons’ brains and the results were impressive. ‘We found a huge increase in cell proliferation in the brain 6 days after feeding, compared to the group that was fed 2 days before’, says Strand. So, the snakes were investing energy in building up their brains when they had energy to spare after the exertions of digestion. And, while the growth occurred throughout the brain, some was concentrated in specific regions with different functions, including spatial memory, sensory processing and controlling feeding and drinking.Ultimately, Strand would like to know the fate of the new-born brain cells, and she says, ‘We would like to look at the survival of the new cells and track where they go in the brain and whether or not they become neurons’. She also suspects that the well-fed snakes may be making hay while the sun shines. ‘The snakes in this study were juvenile, so they were definitely still growing. The increase in new cell growth after eating may occur because they have extra energy available for growth’, she says.