Understanding the pathophysiology of affective disorders and their treatment relies on the availability of experimental models that mimic aspects of the disease. Most of the studies on depressive disorders are conducted with male rodents, mostly because including females in protocols is more difficult. Indeed, there is a complex series of changes in the brain of females due to the estrous cycle, adding an important variability factor to the disease. However, twice as many women as men have a lifetime diagnosis of major depressive disorder (MDD), so we need to develop reliable female models of depression to improve our understanding of this disease. Here, we describe the effects of chronic corticosterone administration (CORT) on female mice, a procedure known to enhance behavioral emotionality in male mice. A dose-response study showed that 4 weeks of CORT exposure at 35 μg/ml in the drinking water enhanced the emotionality score of female mice, but with a very small size effect. Tests of longer treatment duration failed to potentiate the behavioral effects of CORT. As some steps of adult hippocampal neurogenesis are known to be sensitive to chronic CORT exposure, cell proliferation and survival, as well as neuronal maturation in the dentate gyrus of the hippocampus, analyses revealed no effect of chronic CORT exposure in female mice. Overall, this study showed that female C57BL6 mice are insensitive to chronic CORT as a way to model anxio-depressive-like behavior. (PsycINFO Database Record

Strategies designed to increase adult hippocampal neurogenesis (AHN) may have therapeutic potential for reversing memory impairments. H3 receptor antagonists/inverse agonists also may be useful for treating cognitive deficits. However, it remains unclear whether these ligands have effects on AHN. The present study aimed to investigate the effects of a 28-day treatment with S 38093, a novel brain-penetrant antagonist/inverse agonist of H3 receptors, on AHN (proliferation, maturation and survival) in 3-month-old and in aged 16-month-old mice. In addition, the effects of S 38093 treatment on 7-month-old APPSWE Tg2576 transgenic mice, a model of Alzheimer’s disease, were also assessed. In all tested models, chronic treatment with S 38093 stimulated all steps of AHN. In aged animals, S 38093 induced a reversal of age-dependent effects on hippocampal brain-derived neurotrophic factor (BDNF) BDNF-IX, BDNF-IV and BDNF-I transcripts and increased vascular endothelial growth factor (VEGF) expression. Finally, the effects of chronic administration of S 38093 were assessed on a neurogenesis-dependent “context discrimination (CS) test” in aged mice. While ageing altered mouse CS, chronic S 38093 treatment significantly improved CS. Taken together, these results provide evidence that chronic S 38093 treatment increases adult hippocampal neurogenesis and may provide an innovative strategy to improve age-associated cognitive deficits.