Journal of Neuroscience, Vol 14, 4831-4838, Copyright © 1994 by Society for Neuroscience
Habituation of neurosecretory responses to extracellular ATP in PC12 cells
L Cheever and DE Koshland Jr
Department of Molecular and Cell Biology, University of California at Berkeley 94720.
Neuronally differentiated PC12 cells have been used as a model for
habituation. These cells secrete norepinephrine in response to
extracellular ATP, as well as other stimulants, and the response is
diminished with repetitive stimulation. This loss of neurosecretory
responsiveness displays characteristics commonly associated with
habituative learning. These include an increase in both the rate and the
relative degree of response loss with either increasing stimulation
frequency or decreasing stimulus intensity, and selective generalization of
the decreased responsiveness to heterologous stimuli. In PC12 cells, the
loss of neurosecretory responsiveness appears to be entirely caused by
stimulation-dependent inactivation of the ATP-gated cation channel. Several
unusual properties of this channel apparently allow its regulation to
produce the behaviors associated with short- term habituation. Recovery of
the ATP-gated channel requires several minutes, allowing habituation of
responses to repetitive stimuli given at intervals of several minutes.
Inactivation of the ATP-gated channel may be proportionately faster in
response to lower ligand concentrations, allowing habituation to be more
rapid in response to stimuli of weaker intensity.