[Rat orbital frontal (orbital frontal cortex, OFC) GABA B receptor mechanisms in stress and depression]

Stress-induced depression is a kind of functional and structural disability of the brain and involves many neurotransmitters and regions of the brain. A number of studies suggest involvement of γ-Aminobutyric acid (GABA) in the orbital frontal cortex (OFC) in the mechanism of stress-associated depression-like behavior in rodents. However, little work has been done on the relationship between GABA and neural plasticity of the OFC under stress. Here we examine the effect of the GABA in the OFC during acute forced swim stress (FSS). We found remarkable depression-like behavior in FSS and an open field test (OFT), and we observed a marked decrease in Kalirin-7 expression and the basal dendritic spine density of layer V pyramidal neurons in OFC after FSS. GABA administration reversed these changes, which were inhibited by CGP35348, an antagonist of GABA-B receptors. These results suggest an anti-depression effect of GABA in the OFC, which may be mediated by GABA-B receptor. The anti-depression effect of GABA is related to the plasticity of the dendritic spine density. This discovery may be helpful in the development of new therapies to treat depression.