Hippocampal and striated skeletal muscle changes in fatty acid composition induced by ethanol in alcohol-preferring rats

Rat strain differences in brain structure and neurochemistry in response to binge alcohol

RATIONALE

Ventricular enlargement is a robust phenotype of the chronically dependent alcoholic human brain, yet the mechanism of ventriculomegaly is unestablished. Heterogeneous stock Wistar rats administered binge EtOH (3 g/kg intragastrically every 8 h for 4 days to average blood alcohol levels (BALs) of 250 mg/dL) demonstrate profound but reversible ventricular enlargement and changes in brain metabolites (e.g., N-acetylaspartate (NAA) and choline-containing compounds (Cho)).

OBJECTIVES

Here, alcohol-preferring (P) and alcohol-nonpreferring (NP) rats systematically bred from heterogeneous stock Wistar rats for differential alcohol drinking behavior were compared with Wistar rats to determine whether genetic divergence and consequent morphological and neurochemical variation affect the brain's response to binge EtOH treatment.

METHODS

The three rat lines were dosed equivalently and approached similar BALs. Magnetic resonance imaging and spectroscopy evaluated the effects of binge EtOH on brain.

RESULTS

As observed in Wistar rats, P and NP rats showed decreases in NAA. Neither P nor NP rats, however, responded to EtOH intoxication with ventricular expansion or increases in Cho levels as previously noted in Wistar rats. Increases in ventricular volume correlated with increases in Cho in Wistar rats.

CONCLUSIONS

The latter finding suggests that ventricular volume expansion is related to adaptive changes in brain cell membranes in response to binge EtOH. That P and NP rats responded differently to EtOH argues for intrinsic differences in their brain cell membrane composition. Further, differential metabolite responses to EtOH administration by rat strain implicate selective genetic variation as underlying heterogeneous effects of chronic alcoholism in the human condition.

Elevation of GM2 ganglioside during ethanol-induced apoptotic neurodegeneration in the developing mouse brain

GM2 ganglioside in the brain increased during ethanol-induced acute apoptotic neurodegeneration in 7-day-old mice. A small but a significant increase observed 2 h after ethanol exposure was followed by a marked increase around 24 h. Subcellular fractionation of the brain 24 h after ethanol treatment indicated that GM2 increased in synaptic and non-synaptic mitochondrial fractions as well as in a lysosome-enriched fraction characteristic to the ethanol-exposed brain. Immunohistochemical staining of GM2 in the ethanol-treated brain showed strong punctate staining mainly in activated microglia, in which it partially overlapped with staining for LAMP1, a late endosomal/lysosomal marker. Also, there was weaker neuronal staining, which partially co-localized with complex IV, a mitochondrial marker, and was augmented in cleaved caspase 3-positive neurons. In contrast, the control brain showed only faint and diffuse GM2 staining in neurons. Incubation of isolated brain mitochondria with GM2 in vitro induced cytochrome c release in a manner similar to that of GD3 ganglioside. Because ethanol is known to trigger mitochondria-mediated apoptosis with cytochrome c release and caspase 3 activation in the 7-day-old mouse brain, the GM2 elevation in mitochondria may be relevant to neuroapoptosis. Subsequently, activated microglia accumulated GM2, indicating a close relationship between GM2 and ethanol-induced neurodegeneration.

Oxidative damage in rat erythrocyte membranes following ethanol intake: effect of ethyl pyruvate

Alcoholic patients and experimental animals exposed to ethanol display biochemical signs of oxidative damage, suggesting a possible role of free radicals in causing some of the toxic effects of alcohol. The ester derivative, ethyl pyruvate (EP) is stable in solution and should function as an antioxidant and energy precursor. In the present study, the effect of ethanol intake on plasma membrane fluidity, lipid oxidation and antioxidant enzyme activities (GPx, CAT and SOD) were first evaluated. Secondly, the consequences of ethyl pyruvate treatment on the physico-chemical properties of erythrocyte plasma membranes were investigated. The results obtained demonstrate that ethanol induces an increase in lipid peroxidation, a reduction of GPx activity and fluidity in the hydrophilic-hydrophobic region of the bilayer, moreover an increase of fluidity in hydrophobic part of the plasma membrane was measured. When rats were treated with ethyl pyruvate a partially protective effect can be observed for the hydrophilic-hydrophobic region tested by Laurdan, while EP cannot restore the DPH anisotropy values to the control values. In summary, our data indicate that treatment with EP can only partially reduce ethanol plasma membrane perturbation. Since this study shows an ethyl pyruvate dose-dependent effect, it is important to consider the amount of EP required to maintain the right level of membrane fluidity and polarity. These results could be interesting in order to investigate if EP, due to its radical scavenging effect, can prevent oxidative damage induced by ethanol intake and can protect against injure related with ethanol intake.

Protective effect of ethyl pyruvate on msP rat leukocytes damaged by alcohol intake

Alcohol consumption for long periods negatively influences physiological functions of many cells, and leads to organ damage. Reactive oxygen and nitrogen species produced by ethanol metabolism cause adverse effects that might be alleviated by simultaneous treatment with various antioxidants. Here, the ability of ethyl pyruvate (EP) to reduce ethanol-induced oxidative stress was evaluated. Chemiluminescence studies show that EP has a higher capacity than pyruvate to scavenge hydrogen peroxide and superoxide anions. In order to evaluate whether EP can exert a protective effect against ethanol, rats were offered 10% ethanol in drinking burettes, containing or not different concentrations of EP (0.3%, 1% and 3%). The comet assay was employed to quantify the alcohol-induced DNA damage in rat lymphocytes. This test is a promising tool for the estimation of DNA damage at the single cell level. A significant protective effect of EP was observed in rat groups treated with this antioxidant, compared with those drinking only ethanol. Since EP has been shown to decrease the expression of numerous pro-inflammatory mediators, the monocyte respiratory burst was evaluated. The activation of monocyte NADPH oxidase by phorbol esters (PMA) showed that superoxide anion production was higher in the ethanol group than in the control group. The presence of EP considerably reduced superoxide anion production. In conclusion, hypotheses on possible mechanisms of action of EP on rat white blood cells are proposed.