Uncoupling oxidative/energy metabolism with low sub chronic doses of 3-nitropropionic acid or iodoacetate in vivo produces striatal cell damage

Abstract

A variety of evidence suggests that the failure of cellular metabolism is one of the underlying causes of neurodegenerative diseases. For example, the inhibition of mitochondrial function produces a pattern of cellular pathology in the striatum that resembles that seen in Huntington's disease. However, neurons can also generate ATP through the glycolytic pathway. Recent work has suggested a direct interaction between mutated huntingtin and a key enzyme in the glycolytic pathway, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Yet little work has been gone into examination of the cellular pathology that results from the inhibition of this alternative energy source. Therefore, the aim of the present study is to characterize the cellular pathology that results in the striatum of mice after treatment with a toxin (iodoacete, IOA) that compromises anaerobic metabolism. This striatal pathology is compared to that produced by a widely studied blocker of mitochondrial function (3-nitropropionic acid, 3-NP).We found that low doses of either toxin resulted in significant pathology in the mouse striatum. Signs of apoptosis were observed in both experimental groups, although apoptosis triggered by IOA treatment was independent from caspase-3 activation. Importantly, each toxin appears to produce cellular damage through distinct mechanisms; only 3-NP generated clear evidence of oxidative stress as well as inhibition of endogenous antioxidants. Understanding the distinct pathological fingerprints of cell loss produced by blockade of oxidative and anaerobic metabolisms may give us insights into neurodegenerative diseases.

Naringin modulates oxidative stress and inflammation in 3-nitropropionic acid-induced neurodegeneration through the activation of nuclear factor-erythroid 2-related factor-2 signalling pathway

“…Naringin restores the level of GSH in 3-NPinduced rats and decreased the levels of ROS possibly by directly scavenging the ROS or through the transcriptional up-regulation of antioxidant genes (Jeon et al, 2001). Excessive generation of ROS by 3-NP directs mitochondrial dysfunction in ultrastructural levels with swollen and disorganised cristae and is consistent with many earlier studies (Rodrı´guez et al, 2010). However, in the naringin-treated group of animals, we observed a significant amelioration in above abnormal ultrastructures and establishing its protective efficacy against 3-NPinduced neurodegeneration.…”

3-Nitropropionic acid modifies neurotrophin mRNA expression in the mouse striatum: 18S-rRNA is a reliable control gene for studies of the striatum

“…We previously demonstrated that GAPDH levels vary with the experimental protocol [15] , therefore we evaluated β-actin and ribosomal 18S in the present study.…”

“…The assay was performed at 48 h after the last dose following the methodology in our previous report [15] using an apoptosis detection kit …”

“…This mitochondrial toxin inhibits mitochondrial complex II in the respiratory chain, reduces ATP synthesis, increases Ca 2+ influx, and activates proteases that cause cellular damage and the death of medium spiny neurons [12][13][14] . In previous experiments we showed that systemic administration of low sub-chronic doses of 3-NP to C57/BL6 mice is enough to initiate damage of calbindin-positive neurons in the striatum [15][16][17] .…”

“…To select the internal control for gene expression, we avoided GAPDH because in previous experiments, we found changes in its expression in the striatum after 3-NP treatment [15] . Instead, two genes, β-actin due to its stable expression in mouse models of neurodegeneration [18] and 18S rRNA (a gene encoding a small subunit of the 18S ribosome) due to its stability in the mouse brain and other tissues [7,19] , were tested as internal controls.…”