Protein kinase C epsilon mediates up-regulation of N-type calcium channels by ethanol.
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) delta-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 (125)I-omega-conotoxin GVIA. This was associated with an increase in omega-conotoxin GVIA-sensitive, depolarization-evoked rises in [Ca(2+)](i). Increases in (125)I-omega-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 in (125)I-omega-conotoxin GVIA binding were blocked by the PKC inhibitor bisindolylmaleimide I and by expression of a selective peptide inhibitor of PKCepsilon. Expression of a selective inhibitor of PKCdelta did not alter ethanol-induced increases in (125)I-omega-conotoxin GVIA binding. These findings indicate that PKCepsilon 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.
McMahon
T
T
Department of Neurology, Ernest Gallo Clinic & Research Center, San Francisco, USA.
Andersen
R
R
Metten
P
P
Crabbe
J C
JC
Messing
R O
RO
D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000378:metabolism / Q000494:pharmacology; D020864:Calcium Channels, N-Type / Q000187:drug effects / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology*; D007457:Iodine Radioisotopes; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D051379:Mice; D016716:PC12 Cells; D011493:Protein Kinase C / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D051381:Rats; D015854:Up-Regulation; D020866:omega-Conotoxin GVIA / Q000378:metabolism / Q000494:pharmacology
D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; D007457:Iodine Radioisotopes; D007527:Isoenzymes; D000431:Ethanol; D020866:omega-Conotoxin GVIA; C497256:Prkce protein, mouse; C497257:Prkce protein, rat; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D002118:Calcium