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Chronic depolarization stimulates norepinephrine transporter expression via catecholamines
Author(s) -
Habecker Beth A.,
Willison Breanne D.,
Shi Xiao,
Woodward William R.
Publication year - 2006
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.03792.x
Subject(s) - depolarization , tyrosine hydroxylase , norepinephrine transporter , medicine , endocrinology , catecholamine , norepinephrine , tyrosine 3 monooxygenase , chemistry , sympathetic ganglion , biology , dopamine
Chronic depolarization increases norepinephrine (NE) uptake and expression of the norepinephrine transporter (NET) in sympathetic neurons, but the mechanisms are unknown. Depolarization of sympathetic neurons stimulates catecholamine synthesis, and several studies suggest that NET can be regulated by catecholamines. It is not clear if the depolarization‐induced increase in NET is because of nerve activity per se, or is secondary to elevated catecholamines. To determine if induction of NET mRNA was a result of increased catecholamines, we used pharmacological manipulations to (i) inhibit tyrosine hydroxylase activity in neurons depolarized with 30 m m KCl, thereby preventing increased catecholamines, or (ii) stimulate tyrosine hydroxylase activity in the absence of depolarization. Inhibiting the depolarization‐induced increase in catecholamines prevented the up‐regulation of NET mRNA, but did not block the increase in tyrosine hydroxylase (TH) mRNA. Furthermore, stimulating catecholamine production in the absence of depolarization elevated NE uptake, NET protein, and NET mRNA in sympathetic neurons. Similarly, elevating endogenous catecholamines in SK‐N‐BE(2)M17 neuroblastoma cells increased NE uptake and NET expression. These data suggest that chronic depolarization of sympathetic neurons induces NET expression through increasing catecholamines, and that M17 neuroblastoma cells provide a model system in which to investigate catechol regulation of NET expression.