Brain Levels of Catalase Remain Constant through Strain, Developmental, and Chronic Alcohol Challenges

Abstract

Catalase (EC 1.11.1.6) oxidizes ethanol to acetaldehyde within the brain and variations in catalase activity may underlie some consequences of ethanol consumption. The goals of this study were to measure catalase activity in subcellular fractions from rat brain and to compare the levels of this enzyme in several important settings. In the first series of studies, levels of catalase were compared between juvenile and adult rats and between the Long-Evans (LE) and Sprague-Dawley (SD) strains. Levels of catalase appear to have achieved the adult level by the preadolescent period defined by postnatal age (P, days) P25–P28, and there were no differences between strains at the developmental stages tested. Thus, variation in catalase activity is unlikely to be responsible for differences in how adolescent and adult rats respond to ethanol. In the second series of studies, periadolescent and adult rats were administered ethanol chronically through an ethanol-containing liquid diet. Diet consumption and blood ethanol concentrations were significantly higher for periadolescent rats. Catalase activities remained unchanged following ethanol consumption, with no significant differences within or between strains. Thus, the brain showed no apparent adaptive changes in levels of catalase, even when faced with the high levels of ethanol consumption characteristic of periadolescent rats.

Sequential Changes in Brain Glutamate and Adenosine A1 Receptors May Explain Severity of Adolescent Alcohol Withdrawal after Consumption of High Levels of Alcohol

“…Alcohol-containing liquid diets provided an approach leading to high levels of alcohol consumption by adolescent rats and progressively severe withdrawal symptoms over time. Alcohol consumption and severity of withdrawal reported here are consistent with our previous reports using Long-Evans adolescents and liquid diets as the source of alcohol [15, 17–19]. It is important to note that the interruptions to the alcohol administration schedule in this study to allow for withdrawal measures at 4 and 11 days had no significant impact on the final withdrawal severity compared to our previous reports with continuous uninterrupted alcohol administration for the entire period.…”

A Pattern of Adolescent Caffeine Consumption that Reduces Alcohol Withdrawal Severity

“…32 The liquid diet approach to administering alcohol to adolescent rats leads to relatively high levels of alcohol consumption and elevated blood alcohol. 31,40,41 In the present study, the adolescent LE rats showed high alcohol withdrawal severity scores after 2 weeks of alcohol consumption beginning at P25 or P35. The scores were dominated by a high frequency of convulsions as we described previously for these age groupings of the LE strain.…”

“…32 The presence of caffeine at this level (0.25 mg caffeine/mL diet) had no impact on alcohol consumption, which was in the same range [*18 g ethanol/(day$kg À1 body weight)] reported previously for adolescents of this strain. 31,40,41 This fit the design of this study, which was to have rats drinking a uniform high level of alcohol and to test the impact of adding caffeine into the mix.…”

Lipids and Oxidative Stress Associated with Ethanol‐Induced Neurological Damage

“…Catalase and CYP2E1 are the main pathways; there is evidence that they do indeed play an important role in ethanol oxidation to acetaldehyde in the brain [ 91 ]. Indeed, acetaldehyde production in the brain in vivo depends on catalase activity [ 85 , 93 ] and catalase appears to be expressed in all neural cells. Peroxisomal catalase is a tetrameric, heme-containing enzyme that, in addition to converting hydrogen peroxide (H 2 O 2 ) to water and oxygen, can also oxidize ethanol to acetaldehyde.…”