Parallel pathways for habituation in repetitively stimulated PC12 cells.

Habituation was investigated in neuronally differentiated PC12 cells by measuring the decrease in cellular secretion of norepinephrine with repetitive stimulation by either membrane depolarization or acetylcholine. When these two types of repetitive stimulation were applied to the same cells, habituation occurred independently to each, showing that two pathways for habituation can be utilized simultaneously in single cells. The two pathways apparently process stimuli in parallel, without competition between common intermediates.