Vascular endothelial growth factor (VEGF) is implicated as a molecular mediator for adult neurogenesis and behavioral effects of antidepressant drugs. However, these potential roles of VEGF in the CNS have not been clarified in model animals. Here we have created transgenic mice overexpressing a short active variant of VEGF-A (VEGF120) in forebrain. Expression of VEGF120 significantly enhanced cell proliferation and angiogenesis, as exemplified by the formation of an enlarged reddish brain. Adult neurogenesis in hippocampus was markedly stimulated without affecting cell differentiation of neural progenitor cells. Hippocampal neurogenesis was particularly robust in young adult animals, but it declined with age and reduced to control levels by 20 weeks under continuous expression of VEGF120. Thus, VEGF alone is not sufficient to support the long-term enhancement of adult neurogenesis, and VEGF-induced vascularization per se does not necessarily predict increased neurogenesis. In transgenic mice, we observed significant changes in affective behaviors. VEGF was found to have not only antidepressant effects but also anxiolytic effects. In addition, we found that VEGF significantly reduced fear and aggression. In contrast, basal activities under natural conditions were not affected much. Unexpectedly, these characteristic behaviors were maintained in older transgenic mice undergoing a reduced level of cell proliferation in hippocampus, suggesting that there is potential dissociation between adult neurogenesis and mood regulation. Our data indicate that VEGF exerts strong neurogenic and angiogenic effects in postnatal brain and influences different forms of affective behaviors.

Dietary fat plays an important role in higher brain functions. We aimed to assess the short and long term intake of three different types of dietary fat (soybean oil, lard, and fish oil) on anxiety-like and depression-like behavior in mice. For the short term intake assessment, a behavioral test battery for anxiety and depression was carried out for a 3-day feeding period. For the long term intake assessment, a behavioral test battery began after the 4-week feeding period. During the short term intake, the time spent in the open arms of the elevated plus-maze was the longest in the fish oil fed group, followed by the soybean oil and lard-fed groups. The elevated plus-maze is a common animal model to assess anxiety, in which an increased time spent in the open arms indicates an anxiolytic effect. The difference between the fish oil-fed group and lard-fed group was statistically significant (p < 0.01), but there was no significant difference between the soybean oil-fed group and the other two groups. Similar results were observed after a 4-week feeding period. On the other hand, there was no significant difference among the three groups in behavior tests to evaluate depression. Thus, the dietary fat types appeared to influence anxiety but not depression in mice, both in short term (3 days) and long term (4 weeks) feeding.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-165) contains supplementary material, which is available to authorized users.