Individual differences in animal models: an approach to study neurobiological factors related to depression

The study of individual differences in the forced swimming test (FST) in rats allows the identification of either susceptibility or resilience factors in the development of depression- related behaviors. In order to study these differences several rat groups were subjected to the FST. Afterward, animals with low and high immobility were compared, which allowed us to identify a number of features that could function as risk or protection factors. Thus, neurobiological factors such as the expression levels of the corticotropin-releasing factor receptor 1 (CRFR1) in the nucleus accumbens, a differential accumbal dopamine turnover and the differential expression kinetics of the brain- derived neurotrophic factor (BDNF) in the prefrontal cortex, could play an important role in the modulation of depressive behaviors. The current review summarizes our key results in such research line.