Antioxidant defense mechanisms in the female rat: interactions with alcohol, copper, and type of dietary carbohydrate

Fructose-enriched diet induces inflammation and reduces antioxidative defense in visceral adipose tissue of young female rats

PURPOSE

The consumption of refined, fructose-enriched food continuously increases and has been linked to development of obesity, especially in young population. Low-grade inflammation and increased oxidative stress have been implicated in the pathogenesis of obesity-related disorders including type 2 diabetes. In this study, we examined alterations in inflammation and antioxidative defense system in the visceral adipose tissue (VAT) of fructose-fed young female rats, and related them to changes in adiposity and insulin sensitivity.

METHODS

We examined the effects of 9-week fructose-enriched diet applied immediately after weaning on nuclear factor κB (NF-κB) intracellular distribution, and on the expression of pro-inflammatory cytokines (IL-1β and TNFα) and key antioxidative enzymes in the VAT of female rats. Insulin signaling in the VAT was evaluated at the level of insulin receptor substrate-1 (IRS-1) protein and its inhibitory phosphorylation on Ser³⁰⁷.

RESULTS

Fructose-fed rats had increased VAT mass along with increased NF-κB nuclear accumulation and elevated IL-1β, but not TNFα expression. The protein levels of antioxidative defense enzymes, mitochondrial manganese superoxide dismutase 2, and glutathione peroxidase, were reduced, while the protein content of IRS-1 and its inhibitory phosphorylation were not altered by fructose diet.

CONCLUSIONS

The results suggest that fructose overconsumption-related alterations in pro-inflammatory markers and antioxidative capacity in the VAT of young female rats can be implicated in the development of adiposity, but do not affect inhibitory phosphorylation of IRS-1.

Effect of copper overload together with ethanol uptake on hippocampal neurons

Copper is an essential trace element which forms an integral component of many enzymes. While trace amounts of copper are needed to sustain life, excess copper is extremely toxic in the brain. Also, ethanol intake causes morphological changes in the brain. The present study aims to investigate effects of copper overload with ethanol intake in hippocampal neuron numbers of rat brain. Control and experimental group of rats (n = 6 for each group) were fed ad libitum. Experimental group were given ethanol with copper in drinking water each day for ten days. Control group animals were given only drinking water during this period. Afterwards, animals were decapitated and their brains were removed by craniotomy. Frozen brains were cut by a cryostat. Sections collected via systematic random sampling were stained with hematoxylin and eosin. On microscopic images obtained from pyramidal cell layers in hippocampus, total neuron numbers were estimated using the optical fractionator method. We observed that pyramidal neuron numbers in the subdivisions of hippocampus were significantly lower in the experimental group than in the control group. These results suggest that copper overdose with ethanol intake can cause neuronal loss in hippocampus of rat brain.

Lipid peroxidation and antioxidant systems in rat brain: effect of chronic alcohol consumption

The effect of chronic ethanol exposure, in a liquid diet, on lipid peroxidation and some antioxidant systems of rat brain was investigated. Chronic ethanol administration induced a greater susceptibility to iron/ascorbate-induced lipid peroxidation, estimated as thiobarbituric reactive substances (TBARS) production, in the microsomal fraction, but a lower lipid peroxidation in the total homogenate. Glutathione (GSH) levels as well as GSH peroxidase and GSH reductase were unaffected, while the activity of Cu-Zn superoxide dismutase was decreased and that of catalase increased. Lipid peroxidation experiments performed in the presence of some hydroxyl radical scavengers suggested that a greater OH. generation may be responsible of the greater TBARS production in the microsomal fraction of ethanol treated rats; differently, in total homogenate of control and ethanol rats a relationship was found between the redox state of iron and TBARS production, suggesting that the lower lipid peroxidation in treated rats may depend on a different modulation of the iron redox state.