Overshooting Subcellular Redox-Responses in Rett-Mouse Hippocampus during Neurotransmitter Stimulation

Area of Science:

• Neuroscience
• Cellular Biology
• Biochemistry

Background:

• Rett syndrome (RTT) is a neurodevelopmental disorder linked to neuronal dysfunction and impaired network activity.
• Mitochondrial dysfunction and compromised redox homeostasis are implicated in RTT pathogenesis.
• Previous studies noted exaggerated redox responses in MeCP2-deficient neurons under stress.

Purpose of the Study:

• To investigate the relevance of redox balance in RTT neuronal dysfunction.
• To quantify subcellular redox responses to physiological neurotransmitter stimulation in RTT models.

Main Methods:

• Utilized roGFP redox sensor in cytosol and mitochondrial matrix of cultured mouse hippocampal neurons.
• Stimulated neurons with neurotransmitters (glutamate, serotonin, dopamine, norepinephrine).
• Employed Fura-2 imaging, Ca2+ withdrawal, and chemical uncoupling to analyze contributing factors.

Main Results:

• Neurotransmitter stimulation induced stronger oxidizing responses in the cytosol of MeCP2-deficient neurons compared to wildtype.
• Mitochondrial matrix responses were more moderate and uniform across genotypes.
• Cytosolic calcium transients and NADPH/xanthine oxidases were identified as key contributors to these redox changes.

Conclusions:

• The cytosol is a significant reactive oxygen species (ROS) source and less stable redox buffer in RTT.
• Exaggerated cytosolic redox responses in MeCP2-deficient neurons, evident early in development, likely contribute to RTT's neuronal network and signaling deficits.