LA JOLLA, CAIf the current financial climate has taught us anything, it's that a system where over-borrowing goes unchecked eventually ends in disaster. It turns out this rule applies as much to our bodies as it does to economics. Instead of cash, our body deals in energy borrowed from muscle and given to the brain.
Unlike freewheeling financial markets, the lending process in the body is under strict regulation to ensure that more isn't lent than can be afforded. New research by scientists at the Salk Institute for Biological Studies reveals just how this process is implemented.
"We have all seen the sub-prime mortgage crisis," says Marc Montminy, M.D., Ph.D., a professor in the Clayton Foundation Laboratories for Peptide Biology who led the current study. "If you take out a loan, sooner or later you've got to pay your debt, and the same is true in fasting metabolism."
The Salk researchers' findings, which are published ahead of print in the Oct. 5 edition of the journal Nature, may pave the way for novel therapies for sufferers of metabolic diseases in whom such regulation can spiral out of control.
Most tissues in our bodies respond to fasting by switching from their usual high-octane energy sourceglucoseto burning a low-octane, cheaper alternative-fat. For our brains, however, only the high-performance fuel will do. If no food-derived glucose is available, the body must manufacture its own supply to maintain the brain in the manner to which it is accustomed. It does so by taking energy from muscle in the form of protein and converting it to glucose in the liver, a process known as gluconeogenesis. The sugar is then shipped via the bloodstream to the brain to keep it running smoothly.
Gluconeogenesis needs to be turned on rapidly in response to fasting, but shutting it off again is just as crucial. "You don't want gluconeogenesis to be prolonged," says postdoctoral researcher and co-first author Yi Liu,
|Contact: Gina Kirchweger|