Gene expression of GABA and glutamate pathway markers in the prefrontal cortex of non-suicidal elderly depressed patients.

BACKGROUND

The prefrontal cortex (PFC) is presumed to be involved in the pathogenesis of depression.

METHODS

We determined the gene expression of 32 markers of the pathways of the two main neurotransmitters of the PFC, gamma-aminobutyric acid (GABA) and l-glutamic acid (glutamate), by real-time quantitative PCR in human postmortem anterior cingulate cortex (ACC) and dorsolateral PFC (DLPFC) in elderly non-suicidal patients with major depressive disorder (MDD) or bipolar disorder (BD).

RESULTS

We found the transcript levels of GABA(A) receptor beta 2 (GABRB2) and post-synaptic density-95 (PSD-95) to be significantly decreased in the ACC in mood disorder. DLPFC mRNA expression of all the detected genes in the mood disorder group did not differ significantly from that of the non-psychiatric controls.

LIMITATIONS

Several inherent and potentially confounding factors of a postmortem study, such as medication and cause of death, did not seem to affect the conclusions. The group size was relatively small but well documented, both clinically and neuropathologically.

CONCLUSIONS

The observed alterations in the GABAergic and glutamatergic pathways indicate a diminished activity. These alterations were only present in the ACC and not in the DLPFC.