Abstract
Neurotransmitters in vertebrate taste buds have not yet been identified with confidence. Serotonin, glutamate, and γ-aminobutyric acid (GABA) have been postulated, but the evidence is incomplete. We undertook an autoradiographic study of [3H]serotonin, [3H]glutamate, and [3H]GABA uptake in lingual epithelium from the amphibian, Necturus maculosus, to determine whether taste bud cells would accumulate and release these substances. Lingual epithelium containing taste buds was incubated in low concentrations (0.4-6 μM) of these tritiated transmitter candidates and the tissue was processed for light microscopic autoradiography. Merkel-like basal taste cells accumulated [3H]serotonin. When the tissue was treated with 40 mM K+ after incubating the tissue in [3H]serotonin, cells released the radiolabelled transmitter. Furthermore, depolarization (KCl)-induced release of [3H]serotonin was Ca-dependent: if Ca2+ was reduced to 0.4 mM and 20 mM Mg2+ added to the high K+ bathing solution, Merkel-like basal cells did not release [3H]serotonin. In contrast, [3H]glutamate was taken up by several cell types, including non-sensory epithelial cells, Schwann cells, and some taste bud cells. [3H]glutamate was not released by depolarizing the tissue with 40 mM K+. [3H]GABA uptake was also widespread, but did not occur in taste bud cells. [3H]GABA accumulated in non-sensory epithelial cells and Schwann cells. These data support the hypothesis that serotonin is a neurotransmitter or neuromodulator released by Merkel-like basal cells in Necturus taste buds. The data do not support (nor rule out) a neurotransmitter role for glutamate or GABA in taste buds.
| Original language | English |
|---|---|
| Pages (from-to) | 199-208 |
| Number of pages | 10 |
| Journal | Journal of Comparative Neurology |
| Volume | 392 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 9 1998 |
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Keywords
- Excitatory amino acids
- Gustatory
- Merkel cells
- Monoamines
- Synapses
ASJC Scopus subject areas
- Neuroscience(all)
Cite this
Uptake and release of neurotransmitter candidates, [3h]serotonin, [3H]glutamate, and [3H]γ-Aminobutyric acid, in taste buds of the mudpuppy, Necturus maculosus. / Nagai, Takatoshi; Delay, Rona J.; Welton, Joan; Roper, Stephen D.
In: Journal of Comparative Neurology, Vol. 392, No. 2, 09.03.1998, p. 199-208.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Uptake and release of neurotransmitter candidates, [3h]serotonin, [3H]glutamate, and [3H]γ-Aminobutyric acid, in taste buds of the mudpuppy, Necturus maculosus
AU - Nagai, Takatoshi
AU - Delay, Rona J.
AU - Welton, Joan
AU - Roper, Stephen D
PY - 1998/3/9
Y1 - 1998/3/9
N2 - Neurotransmitters in vertebrate taste buds have not yet been identified with confidence. Serotonin, glutamate, and γ-aminobutyric acid (GABA) have been postulated, but the evidence is incomplete. We undertook an autoradiographic study of [3H]serotonin, [3H]glutamate, and [3H]GABA uptake in lingual epithelium from the amphibian, Necturus maculosus, to determine whether taste bud cells would accumulate and release these substances. Lingual epithelium containing taste buds was incubated in low concentrations (0.4-6 μM) of these tritiated transmitter candidates and the tissue was processed for light microscopic autoradiography. Merkel-like basal taste cells accumulated [3H]serotonin. When the tissue was treated with 40 mM K+ after incubating the tissue in [3H]serotonin, cells released the radiolabelled transmitter. Furthermore, depolarization (KCl)-induced release of [3H]serotonin was Ca-dependent: if Ca2+ was reduced to 0.4 mM and 20 mM Mg2+ added to the high K+ bathing solution, Merkel-like basal cells did not release [3H]serotonin. In contrast, [3H]glutamate was taken up by several cell types, including non-sensory epithelial cells, Schwann cells, and some taste bud cells. [3H]glutamate was not released by depolarizing the tissue with 40 mM K+. [3H]GABA uptake was also widespread, but did not occur in taste bud cells. [3H]GABA accumulated in non-sensory epithelial cells and Schwann cells. These data support the hypothesis that serotonin is a neurotransmitter or neuromodulator released by Merkel-like basal cells in Necturus taste buds. The data do not support (nor rule out) a neurotransmitter role for glutamate or GABA in taste buds.
AB - Neurotransmitters in vertebrate taste buds have not yet been identified with confidence. Serotonin, glutamate, and γ-aminobutyric acid (GABA) have been postulated, but the evidence is incomplete. We undertook an autoradiographic study of [3H]serotonin, [3H]glutamate, and [3H]GABA uptake in lingual epithelium from the amphibian, Necturus maculosus, to determine whether taste bud cells would accumulate and release these substances. Lingual epithelium containing taste buds was incubated in low concentrations (0.4-6 μM) of these tritiated transmitter candidates and the tissue was processed for light microscopic autoradiography. Merkel-like basal taste cells accumulated [3H]serotonin. When the tissue was treated with 40 mM K+ after incubating the tissue in [3H]serotonin, cells released the radiolabelled transmitter. Furthermore, depolarization (KCl)-induced release of [3H]serotonin was Ca-dependent: if Ca2+ was reduced to 0.4 mM and 20 mM Mg2+ added to the high K+ bathing solution, Merkel-like basal cells did not release [3H]serotonin. In contrast, [3H]glutamate was taken up by several cell types, including non-sensory epithelial cells, Schwann cells, and some taste bud cells. [3H]glutamate was not released by depolarizing the tissue with 40 mM K+. [3H]GABA uptake was also widespread, but did not occur in taste bud cells. [3H]GABA accumulated in non-sensory epithelial cells and Schwann cells. These data support the hypothesis that serotonin is a neurotransmitter or neuromodulator released by Merkel-like basal cells in Necturus taste buds. The data do not support (nor rule out) a neurotransmitter role for glutamate or GABA in taste buds.
KW - Excitatory amino acids
KW - Gustatory
KW - Merkel cells
KW - Monoamines
KW - Synapses
UR - http://www.scopus.com/inward/record.url?scp=0032498946&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032498946&partnerID=8YFLogxK
U2 - 10.1002/(SICI)1096-9861(19980309)392:2<199::AID-CNE4>3.0.CO;2-Y
DO - 10.1002/(SICI)1096-9861(19980309)392:2<199::AID-CNE4>3.0.CO;2-Y
M3 - Article
C2 - 9512269
AN - SCOPUS:0032498946
VL - 392
SP - 199
EP - 208
JO - Journal of Comparative Neurology
JF - Journal of Comparative Neurology
SN - 0021-9967
IS - 2
ER -