Effects of fluoxetine in mitigating depressive symptoms in socially isolated zebra finches

Depression, the leading cause of disability worldwide, is often associated with social isolation. To explore this relationship, we placed zebra finches (Taeniopygia guttata) in isolation. Like humans, zebra finches are gregarious. We examined how prolonged isolation influences levels of corticosterone, a stress hormone elevated during depression, as well as time spent singing and body weight. Birds were randomly selected to live in either a social colony or isolated cage. We examined how fluoxetine, a selective serotonin reuptake inhibitor (SSRI), counters the effects of isolation. SSRIs raise serotonin levels in the brain, decreasing depressive symptoms. Inconsistent with previous literature, fluoxetine and environmental condition did not lead to significant changes in weight or birdsong frequency. With this said, we did see trends in our data supporting previous findings. For instance isolated birdsong frequency decreased and social birdsong frequency increased between pre-isolation and post-isolation. Additionally, after drug administration, birds given fluoxetine saw an increase in birdsong frequency, while birds given saline saw a decrease in such. In terms of weight, isolated birds overall experienced more weight fluctuation throughout the study than that of the social birds. Also as expected, birds administered fluoxetine showed fewer weight fluctuations than did birds on saline. Unfortunately, the coronavirus pandemic prevented us from collecting corticosterone concentration measurements. Our experiment, although filled with limitations, provides insights into the development of mental illnesses in isolated individuals and explores the benefits and costs of antidepressants.