The achievement, using rat and mouse cells, provides the first clear evidence that signals from fat cells can directly influence neurons outside of the brain, the researchers say, with implications for understanding the storage and burning of fat, obesity and related disorders, such as diabetes.
"It's been known for a long time that neurons outside of the brain communicate to fat cells, but no one has thought much about whether fat cells can signal back to the neurons," says first author Christine Turtzo, an M.D.-Ph.D. candidate at The Johns Hopkins University School of Medicine. "We now have evidence that fat cells directly signal neurons and influence their behavior. Unless you had both types of cells growing together, you would not know."
Previously, fat cells were only known to influence the brain by producing substances that would be carried through the blood stream. The brain was known to control the burning of fat and to respond to its signals by sending messages through the spinal cord and out to nerves located in and around the fat deposits. The study shows that fat and nerve cells can influence each other without direction from the brain.
The research, reported in the Oct. 16 online version of the Proceedings of the National Academy of Sciences, used nerve cells from rats, and grew them with fat cells from mice. The fat cells are similar to those from deposits known as "white adipose tissue," the body's primary energy-producing fat store.
The experiments showed that fat cells affect nerve cells' production of a messenger called neuropeptide Y (NPY). Also, the fat cells produce an as-yet-unidentified factor that influences the nerve cells, says the study's principal investigator, Daniel Lane, Ph.D., professor of biological ch
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Contact: Joanna Downer
jdowner1@jhmi.edu
410-614-5105
Johns Hopkins Medical Institutions
16-Oct-2001