Serotonin Modulates Voltage-Dependent Calcium Current in Necturus Taste
Cells.
Rona J. Delay, Sue C. Kinnamon and Stephen D. Roper.
Boston University Marine Program, Marine Biological Laboratory, Woods Hole,
MA 02543, Department of Anatomy and Neurobiology, Colorado State University,
Ft. Collins, CO 80523, Rocky Mountain Taste and Smell, University of Colorado
Heath Science Center, Denver, CO 80262, Department of Physiology and
Biophysics, University of Miami School of Medicine, Box 016430, Miami, FL
33101.
APStracts 4:0021N, 1997.
ABSTRACT
Necturus taste buds contain two primary cell types: taste receptor cells and
basal cells. Merkel-like basal cells are a subset of basal cells that form
chemical synapses with taste receptor cells and with innervating nerve fibers.
Although Merkel-like basal cells cannot interact directly with taste stimuli,
recent studies have shown that Merkel-like basal cells contain serotonin (5-
HT), which may be released onto taste receptor cells in response to taste
stimulation. Using whole-cell voltage clamp, we examined whether focal
applications of 5-HT to isolated taste receptor cells affected voltage-
activated calcium currents (ICa). Two different effects were observed. 100 M
5-HT increased ICa in 33% of taste receptor cells while it decreased ICa in
67%. Both responses used a 5-HT receptor subtype with a pharmacological
profile similar to the 5-HT1A receptor, but the potentiation and inhibition of
ICa by 5-HT were mediated by two different second messenger cascades. The
results indicate that functional subtypes of taste receptor cells, earlier
defined only by their sensitivity to taste stimuli, may also be defined by
their response to the neurotransmitter 5-HT and suggest that 5-HT released by
Merkel-like basal cells could modulate taste receptor function.
Received 2 January 1997; accepted in final form 28 October 1996.
APS Manuscript Number J852-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 24 January 1997