Depression is caused by decreased levels of serotonin and results in a block of new neuron growth in the hippocampus. The most effective drugs to treat depression are SSRIs or selective serotonin reuptake inhibitors. It was previously thought that these drugs only block the reuptake of serotonin therefore increasing serotonin levels in the synaptic cleft. However in recent years, chronic effects of antidepressants have been shown to increase the growth of neurons in the hippocampus. This is thought to be due to increased levels of BDNF, brain derived neurotrophic factor. BDNF has previously been shown to promote the survival of serotonin neurons. However, the mechanism behind how SSRIs increase BDNF levels is quite unclear. This project is intended to exam the levels of BDNF and serotonin after the olfactory bulbectomy, an animal model for depression in rats that includes the removal of the olfactory bulbs. By comparing animals treated with fluoxetine, an SSRI, to controls, we will clearly be able to see the effect that SSRIs have on BDNF as well as different aspects of serotonin, mainly serotonin reuptake transporters in the hippocampus.
