Protein kinase C ε mediates up-regulation of N-type calcium channels by ethanol

T McMahon, R Andersen, P Metten, JC Crabbe… - Molecular …, 2000 - ASPET
T McMahon, R Andersen, P Metten, JC Crabbe, RO Messing
Molecular pharmacology, 2000ASPET
Brief exposure to ethanol inhibits L-type and N-type voltage-gated calcium channels in
neural cells. Although chronic ethanol exposure up-regulates the density and function of L-
type channels via a protein kinase C (PKC) δ-dependent mechanism, the effect of prolonged
ethanol exposure on N-type channels is not known. Using PC12 cells, we found that
exposure to 25 to 150 mM ethanol for 0 to 8 days produced a time-and concentration-
dependent increase in the density of binding sites for the N-type channel antagonist 125I-ω …
Brief exposure to ethanol inhibits L-type and N-type voltage-gated calcium channels in neural cells. Although chronic ethanol exposure up-regulates the density and function of L-type channels via a protein kinase C (PKC) δ-dependent mechanism, the effect of prolonged ethanol exposure on N-type channels is not known. Using PC12 cells, we found that exposure to 25 to 150 mM ethanol for 0 to 8 days produced a time- and concentration-dependent increase in the density of binding sites for the N-type channel antagonist 125I-ω-conotoxin GVIA. This was associated with an increase in ω-conotoxin GVIA-sensitive, depolarization-evoked rises in [Ca2+]i. Increases in125I-ω-conotoxin GVIA binding also were observed in the frontal cortex and the hippocampus, but not in the thalamus of mice exposed to ethanol vapor for 3 days. In PC12 cells, increases in125I-ω-conotoxin GVIA binding were blocked by the PKC inhibitor bisindolylmaleimide I and by expression of a selective peptide inhibitor of PKCε. Expression of a selective inhibitor of PKCδ did not alter ethanol-induced increases in125I-ω-conotoxin GVIA binding. These findings indicate that PKCε mediates up-regulation of N-type channels by ethanol. Because N-type channels modulate calcium-dependent neurotransmitter release, these findings suggest a mechanism that may contribute to neuronal hyperexcitability observed during alcohol withdrawal.
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