Date of Award
Background: Several lines of evidence suggest dysfunction of the Î³-aminobutyric acid (GABA)ergic system in major depressive disorder. Neuroimaging studies report reduced levels of GABA in the dorsolateral prefrontal and occipital cortex of depressed patients. Our previous postmortem study re-vealed a reduction in the density and size of calbindin-immunoreactive (CB-IR) GABAergic neurons in the prefrontal cortex in major depressive disorder. The goal of this study was to test whether the changes in CB-IR neurons can also be detected in the occipital cortex, where neuroimaging studies report a prominent GABA decrease. Methods: A three-dimensional cell counting probe was used to assess the cell-packing density and size of CB-IR neurons in layer II of the occipital cortex in 10 major depressive disorder subjects and 10 psychiatrically healthy control subjects. Results: The density of CB-IR neurons was significantly decreased by 28% in major depressive dis-order subjects compared with the control group. The size of CB-IR neurons was unchanged in major depressive disorder subjects when compared with control subjects. Conclusions: The reduction in the density of CB-IR GABAergic neurons in the occipital cortex in depression is similar to that observed previously in the prefrontal cortex. Deficits in cortical GA-BAergic interneurons may contribute to the low GABA levels detected in neuroimaging studies in major depressive disorder patients. Future Directions: Experiments are proposed to determine whether or not decreases in calbindin-immunoreactivity are due to decreases in calbindin expression. Further experiments will be designed to investigate potential involvement of calbindin interactors in MDD.
Hughes, Jonathan, "Reduced density of calbindin immunoreactive GABAergic neurons in major depressive disorder: relevance to neuroimaging studies and future directions" (2011). Honors Theses. 473.