neurons give mixed signals, too

from medical news today:

when researchers at the University of Pittsburgh discovered that immature rat brain cells could fire a simultaneous three-punch salvo - three neurotransmitters bursting out of a single cell -- it was a finding they knew would excite more than just neurons.

Just as surprising, they report in the lead article of this month's Nature Neuroscience, is that by definition these three neurotransmitters are seemingly at odds with each other. One, glutamate, is a textbook excitatory neurotransmitter; while the other two, GABA and glycine, are quintessential inhibitory neurotransmitters.

this discovery may not seem like a big deal to some, but it alters the traditional conception of neuronal communication. previously, the communication rule was: one signal, one neurotransmitter, one message. although this was simplistic, it made sense - how can one neuron communicate multiple messages at once based on an all-or-nothing signal from it's partner?

with this we understand that one signal can release both excitatory and inhibitory signals, potentially all activating the same receptor (NMDA). as this sheds light on how inhibitory signals work in the brain, researchers naturally hope it will aid understanding of disorders of those signals, such as epilepsy.

reference: deda c gillespie, gunsoo kim, and karl kandler. inhibitory synapses in the developing auditory system are glutamatergic. nature neuroscience 8, 332 - 338 (2005) published online: 30 January 2005; doi:10.1038/nn1397

Labels: neuroscience