Scientists say they have identified a key chemical player in the brain's control of eating, a finding that could lead to an obesity drug.
The long-sought protein lets a natural substance called neuropeptide Y tell the brain that it's time to eat.Neuropeptide Y, or NPY, powerfully stimulates feeding. Experiments about a decade ago showed that when NPY is injected into the brains of rats, it makes them greatly overeat. Giving NPY over a long period makes rats fat.
Scientists have known that NPY must bind to a particular protein structure on brain cells to deliver its time-to-eat message, and they have been trying to find this so-called feeding receptor for at least five years.
Now, scientists from Synaptic Pharmaceutical Corp. of Paramus, N.J., and Ciba-Geigy Ltd. in Basel, Switzerland, say they have succeeded.
Researchers have already capitalized on the discovery of the receptor, called Y5. They have found substances that latch onto the receptor and block NPY's access to it, reducing appetite in rats, said Synaptic researcher Christophe Gerald.
It will be at least two years before researchers can begin studies in people of the most promising receptor blockers, with an eye toward developing an obesity drug, Gerald said.
NPY is not the only natural substance that affects eating in animals and people, but it appears to be important in people, Gerald said.
He also noted that leptin, a hormone that tells the brain it's time to lose weight, reduces the output of NPY in rats from the hypothalamus, a key production center.
Another natural substance that encourages eating, called peptide YY, also exerts its message through the newfound receptor, Gerald said. Peptide YY is at least as potent as NPY, if not more so, in making rats eat, he said. The receptor blockers that work against NPY also block peptide YY's access, contributing to their appetite-reducing effect, he said.
The new work was reported in Thursday's issue of the journal Nature. Sarah Leibowitz of Rockefeller University in New York, who studies the brain's control of eating, said the report presents strong evidence that the NPY feeding receptor has at last been found.