Figure 1

Fluoxetine increases breast tumor metastasis to the brain. Nu/Nu mice were treated with fluoxetine and injected with 231BR cells as described. A) Representative images of micrometastases (upper panel) and a macrometastasis (lower panel) in the brain of Nu/Nu mice 3 weeks after cell injection. Metastases were visualized in brain tissue by fluorescent microscopy. Note that the cells exhibited a tendency to localize perivascularly and form “sleeves” around blood vessels. Fluoxetine treatment increased the total number of metastases observed within the brain (B) as well as the number of brain micrometastases (C), p < 0.05, t-test. D) While there was a trend towards an increase in the number of macrometastases, it did not reach statistical significance, p = 0.08, t-test. E) The diameter of macrometastases did not differ between the fluoxetine and control group. n = 11-12 per group. Scale bar: 50 μm.