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Determination of Mitochondrial Membrane Potential and Reactive Oxygen Species in Live Rat Cortical Neurons
Published on: May 23, 2011
Age-Dependent Vulnerability to Oxidative Stress of Postnatal Rat Pyramidal Motor Cortex Neurons
Livia Carrascal1,2, Ella Gorton1, Ricardo Pardillo-Díaz3,2
1Departament of Physiology, Pharmacy School, University of Seville, 41012 Seville, Spain.
Insights
Newborn rats resist oxidative stress better than older rats due to higher antioxidant levels. Motor cortex neurons become more vulnerable to oxidative damage with age during postnatal development.
Area of Science:
- Neuroscience
- Developmental Biology
- Oxidative Stress Research
Background:
- Oxidative stress is a key factor in neuronal degeneration.
- Understanding its impact on developing neurons is crucial for identifying therapeutic targets.
Purpose of the Study:
- To investigate the effects of oxidative stress on motor cortex pyramidal neurons during rat postnatal development.
- To compare the neuroprotective mechanisms across different developmental stages.
Main Methods:
- Whole-cell patch-clamp technique on rat brain slices.
- Induction of oxidative stress using cumene hydroperoxide (CH).
- Biochemical analysis of lipid peroxidation markers (4-HNE) and antioxidant levels (glutathione, thiols).
Main Results:
- Newborn rats exhibited enhanced antioxidant defenses (glutathione, thiols, reductase activity), resisting CH-induced damage.
- Infantile rats showed increased neuronal excitability (input resistance, decreased rheobase) due to impaired GABAergic conductance.
- Lipid peroxidation markers increased in infantile and young adult rats, indicating heightened vulnerability with age.
Conclusions:
- Rat motor cortex neurons increase in vulnerability to oxidative stress as they mature.
- Newborn rats possess a robust endogenous antioxidant system providing significant neuroprotection.
- Targeted neuroprotection, like with glutathione monoethyl ester, can mitigate oxidative stress effects in developing neurons.
Abstract:
Oxidative stress is one of the main proposed mechanisms involved in neuronal degeneration. To evaluate the consequences of oxidative stress on motor cortex pyramidal neurons during postnatal development, rats were classified into three groups: Newborn (P2-P7); infantile (P11-P15); and young adult (P20-P40). Oxidative stress was induced by 10 µM of cumene hydroperoxide (CH) application. In newborn rats, using the whole cell patch-clamp technique in brain slices, no significant modifications in membrane excitability were found. In infantile rats, the input resistance increased and rheobase decreased due to the blockage of GABAergic tonic conductance. Lipid peroxidation induced by CH resulted in a noticeable increase in protein-bound 4-hidroxynonenal in homogenates in only infantile and young adult rat slices. Interestingly, homogenates of newborn rat brain slices showed the highest capacity to respond to oxidative stress by dramatically increasing their glutathione and free thiol content. This increase correlated with a time-dependent increase in the glutathione reductase activity, suggesting a greater buffering capacity of newborn rats to resist oxidative stress. Furthermore, pre-treatment of the slices with glutathione monoethyl ester acted as a neuroprotector in pyramidal neurons of infantile rats. We conclude that during maturation, the vulnerability to oxidative stress in rat motor neurons increases with age.
