Increase in expression of alpha1 and alpha2/delta1 subunits of L-type high voltage-gated calcium channels after sustained ethanol exposure in cerebral cortical neurons.
Previous reports revealed up-regulation of L-type high voltage-gated calcium channels (HVCCs) in mouse brains with ethanol physical dependence. We investigated mechanisms of enhancement of L-type HVCC function using mouse cerebrocortical neurons exposed to 50 mM ethanol for 3 days and the brains of mouse physically dependent on ethanol. Ethanol facilitated 30 mM KCl-stimulated (45)Ca(2+) influx in dose- and duration-dependent manners, which was abolished by nifedipine, an inhibitor specific to L-type HVCCs, but not by inhibitors for other types of HVCCs. Increase in [(3)H]PN200-110 binding to the particulate fractions from the ethanol-treated neurons was due to increased B(max) value with no changes in K(d) value. Western blot analysis showed the increased expression of alpha1C, alpha1D, and alpha2/delta1 subunits with decreased beta4 subunit expression and no changes in expressions of alpha1A, alpha1B, alpha1F, and alpha2 subunits. A similar pattern of the changes in the expression of these subunits of L-type HVCCs were observed in the cerebral cortex from mouse with ethanol physical dependence. These results indicate that sustained ethanol exposure to the neurons induces up-regulation of L-type HVCCs, which is due to increased expressions of alpha1C, alpha1D, and alpha2/delta1 subunits, and produces no alterations in P/Q- and N-type HVCC functions.
Katsura
Masashi
M
Department of Pharmacology, Kawasaki Medical University, Japan.
Shibasaki
Masahiro
M
Hayashida
Shinsuke
S
Torigoe
Fumiko
F
Tsujimura
Atsushi
A
Ohkuma
Seitaro
S
D000437:Alcoholism / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D020864:Calcium Channels, N-Type; D020865:Calcium Channels, P-Type / Q000378:metabolism*; D020907:Calcium Channels, Q-Type / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000633:toxicity*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
D002118:Calcium; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D020864:Calcium Channels, N-Type; D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type; D000431:Ethanol; C512066:CACNA2D1 protein, mouse; C485995:Cacna1d protein, mouse