TY - JOUR
T1 - Biogenic amine synthesis and uptake in rodent taste buds
AU - Dvoryanchikov, Gennady
AU - Tomchik, Seth M.
AU - Chaudhari, Nirupa
PY - 2007/11/20
Y1 - 2007/11/20
N2 - Although adenosine triphosphate (ATP) is known to be an afferent transmitter in the peripheral taste system, serotonin (5-HT) and norepinephrine (NE) have also been proposed as candidate neurotransmitters and have been detected immunocytochemically in mammalian taste cells. To understand the significance of biogenic amines in taste, we evaluated the ability of taste cells to synthesize, transport, and package 5-HT and NE. We show by reverse transcriptase-polymerase chain reaction and immunofluorescence microscopy that the enzymes for 5-HT synthesis, tryptophan hydroxylase (TPH) and aromatic amino acid decarboxylase (AADC) are expressed in taste cells. In contrast, enzymes necessary for NE synthesis, tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DBH) are absent. Both TH and DBH are expressed in nerve fibers that penetrate taste buds. Taste buds also robustly express plasma membrane transporters for 5-HT and NE. Within the taste bud NET, a specific NE transporter, is expressed in some presynaptic (type III) and some glial-like (type I) cells but not in receptor (type II) cells. By using enzyme immunoassay, we show uptake of NE, probably through NET in taste epithelium. Proteins involved in inactivating and packaging NE, including catechol-O- methyltransferase (COMT), monoamine oxidase-A (MAO-A), vesicular monoamine transporter (VMAT1,2) and chromogranin A (ChrgA), are also expressed in taste buds. Within the taste bud, ChrgA is found only in presynaptic cells and may account for dense-cored vesicles previously seen in some taste cells. In summary, we postulate that aminergic presynaptic taste cells synthesize only 5-HT, whereas NE (perhaps secreted by sympathetic fibers) may be concentrated and repackaged for secretion.
AB - Although adenosine triphosphate (ATP) is known to be an afferent transmitter in the peripheral taste system, serotonin (5-HT) and norepinephrine (NE) have also been proposed as candidate neurotransmitters and have been detected immunocytochemically in mammalian taste cells. To understand the significance of biogenic amines in taste, we evaluated the ability of taste cells to synthesize, transport, and package 5-HT and NE. We show by reverse transcriptase-polymerase chain reaction and immunofluorescence microscopy that the enzymes for 5-HT synthesis, tryptophan hydroxylase (TPH) and aromatic amino acid decarboxylase (AADC) are expressed in taste cells. In contrast, enzymes necessary for NE synthesis, tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DBH) are absent. Both TH and DBH are expressed in nerve fibers that penetrate taste buds. Taste buds also robustly express plasma membrane transporters for 5-HT and NE. Within the taste bud NET, a specific NE transporter, is expressed in some presynaptic (type III) and some glial-like (type I) cells but not in receptor (type II) cells. By using enzyme immunoassay, we show uptake of NE, probably through NET in taste epithelium. Proteins involved in inactivating and packaging NE, including catechol-O- methyltransferase (COMT), monoamine oxidase-A (MAO-A), vesicular monoamine transporter (VMAT1,2) and chromogranin A (ChrgA), are also expressed in taste buds. Within the taste bud, ChrgA is found only in presynaptic cells and may account for dense-cored vesicles previously seen in some taste cells. In summary, we postulate that aminergic presynaptic taste cells synthesize only 5-HT, whereas NE (perhaps secreted by sympathetic fibers) may be concentrated and repackaged for secretion.
KW - Catecholaminergic
KW - Efferent
KW - Serotonergic
KW - Taste neurotransmitters
KW - Transporters
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U2 - 10.1002/cne.21494
DO - 10.1002/cne.21494
M3 - Article
C2 - 17879273
AN - SCOPUS:36248953770
VL - 505
SP - 302
EP - 313
JO - Journal of Comparative Neurology
JF - Journal of Comparative Neurology
SN - 0021-9967
IS - 3
ER -