Neurons take charge to change messages

Neurons in a developing embryo respond to changes in their own electrical activity by altering the types of chemical messengers that they produce, a new study suggests. This finding counters the traditional scientific view that genes alone determine which neurotransmitters a brain cell synthesizes.

A team led by Laura N. Borodinsky and Nicholas C. Spitzer, both of the University of California, San Diego, first measured distinctive patterns of electrical activity in each of four types of embryonic neurons in the spinal cords of frogs. The researchers then changed the electrical activity in such cells in other frog embryos by genetically engineering them to pass either more or less current through their membranes.

Those alterations that led to boosts in electrical activity also led to a surge in the number of cells producing inhibitory neurotransmitters that slow down neurons . Conversely, changes that caused electrical activity to decline triggered a rise in the number of neurons generating excitatory neurotransmitters that ramp up other cells’ actions. The scientists report their findings in the June 3 Nature.

Despite undergoing these electrical and chemical changes, all the neurons retained their distinctive structures.

The study indicates that some embryonic neurons can switch the chemical signals they produce in response to changes in their own electrical activity or that of nearby cells, the investigators theorize.

It’s not yet known whether shifts in electrical activity similarly influence neurotransmitter release throughout embryonic nervous systems or in adult neurons.