Kumar S, Lane B M, Morrow A L
Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7178, USA.
J Pharmacol Exp Ther. 2006 Dec;319(3):1366-75. doi: 10.1124/jpet.106.110890. Epub 2006 Sep 22.
Systemic ethanol administration alters protein kinase C (PKC) activity in brain, but the effects of ethanol on the expression and translocation of specific isoforms are unknown. Rats were administered ethanol (2 g/kg i.p.) or saline and PKC levels were measured in the cytosolic and membrane fractions by Western blot analysis. PKCepsilon expression was increased in the cytosol and decreased in the membrane (P2) fraction of cerebral cortex at 10 min. At 60 min, expression of PKCepsilon in the P2 fraction was increased by 42.2 +/- 12%, but cytosolic levels were unchanged. In contrast, PKCgamma in the P2 fraction was decreased 32.7 +/- 7% at 60 min but not at 10 min post-ethanol administration. PKCgamma levels in the cytosol were reduced at 10 min post-ethanol administration and unchanged at 60 min. PKCbeta expression was increased 36 +/- 10 and 144 +/- 52% in the P2 fraction both at 10 and 60 min post-ethanol administration, whereas cytosolic levels were unchanged. Serine phosphorylation of GABA(A) receptor beta-chain was reduced, and phosphorylation of N-methyl-d-aspartate receptor NR1 subunit was increased 60 min following ethanol administration. There was no effect of acute ethanol administration on PKC isoform levels in the hippocampus. Ethanol challenge did not alter PKC isoform expression in the P2 fraction of cerebral cortex following chronic ethanol administration. These findings suggest that acute ethanol administration alters PKC synthesis and translocation in an isoform and brain region specific manner that leads to alterations in serine phosphorylation of receptors. Furthermore, chronic ethanol administration prevents ethanol-induced alterations in PKC expression in the P2 fraction, where PKC interacts with ethanol-responsive ion channels.
全身性给予乙醇会改变大脑中的蛋白激酶C（PKC）活性，但乙醇对特定亚型的表达和转位的影响尚不清楚。给大鼠腹腔注射乙醇（2 g/kg）或生理盐水，通过蛋白质印迹分析测量细胞溶质和膜部分中的PKC水平。10分钟时，大脑皮层细胞溶质中的PKCε表达增加，而膜（P2）部分中的表达减少。60分钟时，P2部分中PKCε的表达增加了42.2±12%，但细胞溶质水平未改变。相比之下，乙醇给药后60分钟时，P2部分中的PKCγ减少了32.7±7%，但10分钟时未减少。乙醇给药后10分钟时，细胞溶质中的PKCγ水平降低，60分钟时未改变。乙醇给药后10分钟和60分钟时，P2部分中的PKCβ表达分别增加了36±10%和144±52%，而细胞溶质水平未改变。乙醇给药60分钟后，GABA（A）受体β链的丝氨酸磷酸化减少，N-甲基-D-天冬氨酸受体NR1亚基的磷酸化增加。急性给予乙醇对海马体中的PKC亚型水平没有影响。慢性给予乙醇后，乙醇激发并未改变大脑皮层P2部分中的PKC亚型表达。这些发现表明，急性给予乙醇以亚型和脑区特异性方式改变PKC的合成和转位，从而导致受体丝氨酸磷酸化的改变。此外，慢性给予乙醇可防止乙醇诱导的P2部分中PKC表达的改变，PKC在该部分与乙醇反应性离子通道相互作用。
