CHANGES IN SYNAPTIC MEMBRANE ORDER ASSOCIATED WITH CHRONIC ETHANOL TREATMENT IN MICE

  • 1 January 1983
    • journal article
    • research article
    • Vol. 23  (1) , 86-91
Abstract
The fluidity of brain synaptosomal plasma membranes (SPM) from ethanol-treated and control mice was investigated by a sensitive EPR technique. Mice were made tolerant to and physically dependent on ethanol by 3 days of continuous exposure to ethanol vapor. Daily injections of pyrazole were used to stabilize the blood alcohol levels. At the time of withdrawal, SPM were prepared and spin-labeled with 5-, 12- or 16-doxylstearic acid. Baseline order parameters were measured in the absence of added alcohol. The chronic ethanol teatment produced a significant increase in the baseline order parameter that could be detected with the 12-doxyl probe. This indicated a more rigid membrane associated with the withdrawal hyperexcitability. Baseline order parameters measured with the 5-doxyl probe (near the bilayer surface) or with the 16-doxyl probe (near the bilayer interior) were not affected by the chronic ethanol treatment. When ethanol or tert-butanol was added in vitro to membranes labeled with the 5- or 12-doxyl probe, a membrane component of tolerance was revealed; the SPM from ethanol-treated mice required more alcohol to reduce the membrane to a given disordered state. The SPM content of cholesterol and phospholipid was not affected by chronic ethanol treatment.