Alterations in inhibitory neuron subtype-selective transcripts in the prefrontal cortex: comparisons across...

Area of Science:

• Neuroscience
• Psychiatry
• Molecular Biology

Background:

• Cognitive impairments in schizophrenia (SZ), bipolar disorder (BD), and major depression (MD) are linked to alterations in dorsolateral prefrontal cortex (DLPFC) GABA neurons.
• GABA neuron subtypes, such as parvalbumin (PV) and somatostatin (SST), show differential gene expression changes across these disorders.
• Previous studies have not directly compared GABA neuron subtype transcript alterations across SZ, BD, and MD.

Purpose of the Study:

• To compare GABA neuron subtype-selective transcript levels in the DLPFC across individuals with SZ, BD, MD, and unaffected comparisons (UC).
• To investigate the relative impact of each diagnosis on specific GABA neuron markers.

Main Methods:

• Quantitative polymerase chain reaction (qPCR) was used to analyze mRNA levels.
• Examined transcripts for GABA neuron subtypes (PV, SST, VIP, calretinin) and a pan-GABA marker (GAD67).
• Samples were obtained from DLPFC gray matter of 160 individuals (SZ, BD, MD, UC).

Main Results:

• Individuals with SZ showed significant deficits in most GABAergic transcripts, except calretinin, compared to UC.
• Individuals with BD exhibited deficits in PV mRNA, while those with MD showed deficits in SST mRNA.
• Calretinin mRNA levels were not significantly altered in any patient group compared to UC.

Conclusions:

• Broader and more severe alterations in DLPFC GABA neurons are associated with SZ.
• Specific deficits in PV and SST mRNAs in BD and MD, respectively, may underlie their distinct clinical profiles.
• Findings suggest a gradient of GABAergic dysfunction in the DLPFC correlating with cognitive deficits across SZ, BD, and MD.