GABAergic system's Injuries Induced by Sodium Sulfite in Caenorhabditis elegans Were Prevented by the Anti-Oxidative Properties of Dehydroepiandrosterone Sulfate.

Several pathophysiological processes involve Hypoxia conditions, where the nervous system is affected as well. We postulate that the GABAergic system is especially sensitive. Furthermore, drugs improving the resistance to hypoxia have been investigated, such as the neurosteroid dehydroepiandrosterone sulfate (DHEAS) which has shown beneficial effects in hypoxic processes in mammals; however, at the cellular level, its exact mechanism of action has yet to be fully elucidated. Here, we used a chemical hypoxia model through sodium sulfite (SS) exposure in Caenorhabditis elegans (C. elegans), a nematode whose response to hypoxia involves pathways and cellular processes conserved in mammals, and that allows study the direct effect of DHEAS without its conversion to sex hormones. This work aimed to determine the effect of DHEAS on damage to the GABAergic system associated with SS exposure in C. elegans. Worms were subjected to nose touch response (Not Assay) and observed in epifluorescence microscopy. DHEAS decreased the shrinkage response of Not Assay and the level of damage in GABAergic neurons on SS-exposed worms. Also, the enhanced nuclear localization of DAF-16 and consequently the overexpression of chaperone HSP-16.2 by hypoxia were significantly reduced in SS + DHEAS exposed worms. As well, DHEAS increased the survival rate of worms exposed to hydrogen peroxide. These results suggest that hypoxia-caused damage over the GABAergic system was prevented at least partially by DHEAS, probably through non-genomic mechanisms that involve its antioxidant properties related to its chemical structure.

The use of cobalt chloride as a chemical hypoxia model.

The use of hypoxia models in cell culture has allowed the characterization of the hypoxia response at the cellular, biochemical and molecular levels. Although a decrease in oxygen concentration is the optimal hypoxia model, the problem faced by many researchers is access to a hypoxia chamber or a CO2 incubator with regulated oxygen levels, which is not possible in many laboratories. Several alternative models have been used to mimic hypoxia. One of the most commonly used models is cobalt chloride-induced chemical hypoxia because it stabilizes hypoxia inducible factors 1α and 2α under normoxic conditions. This model has several advantages, and currently, there is a substantial amount of scattered information about how this model works. This review describes the characteristics of the model, as well as the biochemical and molecular bases that support it. The regulation of hypoxia inducible factors by oxygen and the role of CoCl2 are explained to understand the most accepted bases of the CoCl2 -induced hypoxia model. The different current hypotheses that explain the establishment of hypoxic conditions using CoCl2 are also described. Finally, based on the different observations reported in the literature, we provide a critical review about the scope and limitations of this widely used chemical hypoxia model to be informative to all researchers interested in the field.

Aged garlic extract and S-allylcysteine prevent apoptotic cell death in a chemical hypoxia model

BACKGROUND: Aged garlic extract (AGE) and its main constituent S-allylcysteine (SAC) are natural antioxidants with protective effects against cerebral ischemia or cancer, events that involve hypoxia stress. Cobalt chloride (CoCl2) has been used to mimic hypoxic conditions through the stabilization of the α subunit of hypoxia inducible factor (HIF-1α) and up-regulation of HIF-1α-dependent genes as well as activation of hypoxic conditions such as reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential and apoptosis. The present study was designed to assess the effect of AGE and SAC on the CoCl2-chemical hypoxia model in PC12 cells. RESULTS: We found that CoCl2 induced the stabilization of HIF-1α and its nuclear localization. CoCl2 produced ROS and apoptotic cell death that depended on hypoxia extent. The treatment with AGE and SAC decreased ROS and protected against CoCl2-induced apoptotic cell death which depended on the CoCl2 concentration and incubation time. SAC or AGE decreased the number of cells in the early and late stages of apoptosis. Interestingly, this protective effect was associated with attenuation in HIF-1α stabilization, activity not previously reported for AGE and SAC. CONCLUSIONS: Obtained results show that AGE and SAC decreased apoptotic CoCl2-induced cell death. This protection occurs by affecting the activity of HIF-1α and supports the use of these natural compounds as a therapeutic alternative for hypoxic conditions