Auditory Cortical Plasticity Induced By Chronic Fluoxetine Administration In Adult Rats

How to modulate the adult brain plasticity is one of the important topics in the neuroscience research.It has been shown that the antidepressant fluoxetine-the selective serotonin reuptake inhibitor fluoxetine was approved for treating major depression and obsessive-compulsive disorder-can induce plasticity in the adult visual cortex.However,whether fluoxetine can induce plasticity in the adult auditory cortex is not yet clear.In this study,we investigate the behavior and electrophysiological effects of fluoxetine on plasticity in the adult auditory cortex,by using rats as experimental models.We found that: 1)Chronic administration of fluoxetine in adulthood did not significantly alter spontaneous activities and exploratory behaviors of rats;2)While fluoxetine had little effect on the tonotopic map of frequency in the auditory cortex,it degraded frequency tuning of individual cortical neuron.3)The short-term pure tone exposure with specific frequency after fluoxetine administration significantly increased the representation area of the tonal frequency in the auditory cortex,a phenomenon that we did not observe in normal adults;4)The transient exposure to enriched acoustic environment after fluoxetine administration significantly reversed the drug-induced degradation in cortical frequency tuning.The following behavior test also observed an improvement in individual’s ability in sound frequency discrimination.These results indicate that chronic administration of fluoxetine induces the critical period-like plasticity in the adult auditory cortex without affecting the cortical tonotopy.Therefore,transient exposure to enriched acoustic environment significantly sharpens cortical frequency selectivity in adult rats,affecting individual’s sound frequency discrimination ability.