Muscles usually contract when a neurotransmitter molecule is released from nerve cells onto muscle cells. But University of Utah scientists discovered that bare subatomic protons can act like larger, more complex neurotransmitters, making gut muscles contract in tiny round worms so the worms can poop.
There are relatively few molecules that serve as neurotransmitters to trigger electrical changes in cells. Protons are the only new members of this group in nearly 20 years, says biology Professor Erik Jorgensen, scientific director of the Brain Institute at the University of Utah and senior author of the study in the Jan. 11 issue of the journal Cell.
While conventional neurotransmitters such as serotonin, dopamine and GABA are molecules made of many atoms, the new study revealed a surprise: Protons which are single hydrogen atoms stripped of their electrons are pumped out of a round worms gut by one kind of protein and then bind to receptor proteins on neighboring muscles, making the muscles contract so the worm defecates.
Not only did the researchers show protons can act like neurotransmitters, they identified the genes and proteins involved in the process in round worms, which are about 1 millimeter (a 25th of an inch) long and also are known as nematodes.
Previous research indicated the brains of humans and mice also have proton pumps and receptors to move protons between cells. The new study raises the possibility those protons may be transmitting nerve signals in the brain, says Jorgensen and study co-author Wayne Davis, a research assistant professor of biology.
This is the first time we have found protons acting as transmitters, Davis says. It could be that these processes occur in humans. There are proton pumps present in intestinal cells and in the brain of humans and mice. Some of the pumps are thought to make acid for the gut to digest food. But why are proton pumps in the brain"
|Contact: Lee Siegel|
University of Utah