Specific subcellular changes in oxidative stress in prefrontal cortex from patients with bipolar disorder

Area of Science:

• Neuroscience
• Biochemistry
• Psychiatry

Background:

• Oxidative stress is implicated in bipolar disorder (BD) and schizophrenia (SCZ).
• Previous studies indicated altered mitochondrial function and protein damage in postmortem prefrontal cortex (PFC) of BD and SCZ patients.

Purpose of the Study:

• To replicate findings of mitochondrial complex I deficits and protein oxidation/nitration in an independent BD sample.
• To specifically investigate oxidative and nitrosative damage to mitochondrial and synaptosomal proteins and lipid peroxidation in myelin.

Main Methods:

• Isolation of mitochondria, synaptosomes, and myelin from postmortem PFC using Percoll gradients.
• Assessment of mitochondrial protein levels (Complex I, III), protein oxidation (carbonylation), and nitration (3-nitrotyrosine) via immunoblotting.
• Measurement of lipid peroxidation markers (LPH, 8-isoprostane, 4-hydroxy-2-nonenal) using colorimetric/ELISA assays.

Main Results:

• Decreased mitochondrial complex I subunits in BD patients compared to controls.
• Increased protein carbonylation in synaptosomes and 3-nitrotyrosine in mitochondria from BD patients.
• Elevated lipid peroxidation markers (8-isoprostane, 4-hydroxy-2-nonenal) in BD and SCZ groups.

Conclusions:

• Mitochondrial proteins in BD may be more vulnerable to reversible nitrosative damage.
• Synaptic proteins in BD appear to sustain more persistent oxidative damage.
• Findings highlight specific molecular alterations in the brain relevant to BD and SCZ pathophysiology.