Rat synaptic membrane fluidity parameters after intermittent exposures to ethanol in vivo.

Differentiated membrane alterations correlate with the development of functional tolerance or dependence during chronic alcohol intoxication in humans as well as in animals. In animal studies, a single period of continuous exposure was generally used. In humans, the consumption can be more episodic with heavier weekend drinking. How a heavy but intermittent alcohol exposure over 4 weeks affects the synaptic membrane fluidity and sensitivity was examined in male and female adult rats. No differences were seen between membranes from males and females. Alterations were found in the negative polar membrane region probed by TMA-DPH and the sensitivity to acute ethanol was significantly reduced in the DPH (lipid core) and TMA-DPH probed membrane regions. Tolerance to the hypothermic effect of ethanol has developed and could be correlated with the resistance of the membrane lipid core to ethanol. Intermittent exposures to ethanol, as continuous ones, can result in development of functional and membrane tolerance and in specific alterations in the fluidity of the polar part of the membrane, probably in relation with dependence.