Recent evidence suggests that an oxygen free radical/oxidative damage etiology induced by ethanol, or its principal metabolite, acetaldehyde, is important in its toxic actions. While many laboratories have demonstrated significant neurochemical perturbations due to ethanol exposure, there is a paucity of data correlating the neurochemistry to the changes in functional behavior of intact organisms. We recently have made the novel observation of a significant correlation between the presence of salicylate-trapped hydroxyl radical adducts and the expression of spontaneous seizure activity in brain homogenates extracted from recently ethanol-withdrawn rats. While auditory evoked seizures were induced in all ethanol-treated rats, the r-point biserial correlation was most significant (rbs=82) between the expression of spontaneous seizures and the metabolic correlate of oxidative stress. It is not clear whether athe hydroxyl radical production is/was induced by ethanol intoxication, chronic exposure, or withdrawal phenomenon. The current proposal will examine the temporal relationship between behavioral markers of ethanol intoxication and the progression of withdrawal symptomatology and the production of free radical-induced brain injury/damage. Using the temporal and quantitative dimension of the ethanol withdrawal syndrome in the rat previously detailed by Majchrowicz (1975, 1977), we propose to correlate the temporal change in the behavioral markers of intoxication and withdrawal with the neurochemical markers of free radical production. In a 2 x 6 (treatment x time) design, twelve groups of rate will be chronically exposed to either ethanol (N=24/group) or water (N=12/group) vapor in standard vapor chambers. Exposure will be for 14 days with a terminal BAC of more 300 mg/dl for the last three consecutive days in the ethanol treated rats. Observations will be scored using a complex set of behavioral and neurological ratings scales (Lal et all., 1988; Colombo et al., 1995) at 6 timepoints proceeding from the initial re-exposure to fresh air (0, 2, 12, 24, 36, and 48 hrs post withdrawal). These timepoints correspond to the full spectrum of behaviors indicative of ethanol intoxication and withdrawal. At the end of a 1 hr. observation period, the brain of each rat will be harvested, frozen in liquid nitrogen, and later assayed for the following salicylate-adducts, glutamate concentrations, glutamine synthetase activity, protein oxidation, mitochondria respiratory function, hydroxyl radical formation in synaptosomes, mobile free iron, aldehyde oxidase function, and cytochrome P450 (CYP2E1). A Multiple Correlation Statistical Analysis, robust for violations of unequal N, will be completed to find the best behavioral predictor of free radical production.
| Vallett, M; Tabatabaie, T; Briscoe, R J et al. (1997) Free radical production during ethanol intoxication, dependence, and withdrawal. Alcohol Clin Exp Res 21:275-85 |
