Sustained escitalopram administration affects glucose metabolism in the rat brain

Escitalopram is a selective serotonin reuptake inhibitor (SSRIs) antidepressant, drug that is currently used as first-line agents for the treatment of depression and it is also used in the treatment of other psychiatric disorders. The main goal of this study was to identify which brain areas are affected by escitalopram administration. This study was carried out on male Wistar rats that received escitalopram daily over 14 days and that were studied by 2-deoxy-2[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG)-PET on the last day of treatment. Computed tomography (CT) images were acquired immediately before each PET scan and the main effects of drug administration were elucidated by Statistical Parametric Mapping. The results obtained indicated that repeated exposure to escitalopram increased metabolic activity in the retrosplenial and posterior cingulate cortices, while it decreased such activity in the ventral hippocampus, cerebellum, brainstem and midbrain regions, including the raphe nuclei and ventral tegmental area. Therefore, repeated exposure to escitalopram alters the activity of several brain areas closely related to the serotonergic system, and previously identified as key regions in the antidepressant effect induced by SSRIs. Furthermore, some of the changes found, such as the dampened metabolism in the ventral tegmental area, are similar to changes that have been described after treating with other fast-acting antidepressant approaches.