Brain marker protein changes after short- and long-term ethanol intoxication and withdrawal in the rat

The brain marker proteins, D1, D2, and D3, localised to neuronal membranes, and mitochondrial and cytoplasmic marker proteins (MM and CM), were studied during 1-6 days (short term) intragastrically-induced severe ethanol intoxication and during 1 month (long-term) ethanol intoxication established by a liquid diet regimen. The concentrations of the same brain proteins were also measured during withdrawal from the ethanol intoxication periods. Three categories of effect were encountered: decreased concentration of brain marker proteins during severe short-term intoxication the effect being most marked for D3, possibly indicating degradation of mature synapses; increased concentration of proteins D2 and MM during withdrawal, the D2 changes possibly indicating formation of new synapses; increased concentration of D1 protein and MM during long-term intoxication. We suggest that the changes in brain marker proteins reflect dynamic changes of subcellular neuronal structures which may form a part of the basis of functional tolerance to and physical dependence upon ethanol or the reversion of these states after withdrawal of ethanol.