Undergraduate Honors Theses

Thesis Defended

Spring 2019

Document Type


Type of Thesis

Departmental Honors


Molecular, Cellular, & Developmental Biology

First Advisor

Dr. Christopher Lowry

Second Advisor

Dr. Pamela Harvey

Third Advisor

Dr. Jennifer Martin


Major depression is one of the most prevalent mental illnesses in the United States, with approximately 16.1 million people suffering from a depressive episode every year. Colorado, Utah, Wyoming, and other states at altitude report a higher prevalence of depression and suicide, pointing to a possible link between low oxygen pressure at high altitude and increased prevalence of depression. Additionally, females report higher rates of depression compared to males, indicating a possible sex difference in vulnerability to depression. Serotonin, a neurotransmitter responsible for regulating mood and emotion, has been implicated in depression and also responds to changes in oxygen. Thus, serotonin dysregulation may contribute to increased prevalence of depression at high altitude. However, little is known about the effects of acute vs chronic altitude exposure on depression or the effects of varying acclimation durations on behavioral changes. Furthermore, there is no established scientific protocol specifying appropriate acclimation periods for rodent testing at elevation, despite the fact that low oxygen pressure may introduce variability in animal research. In this study, we examined the effect of altitude and acclimation duration on the depressive-like behavior and hematology of male and female rats in Boulder, CO (5,430ft elevation) or San Diego, CA (633ft elevation). A sucrose preference test (SPT), which measures anhedonia in rodent models, was performed to examine behavioral changes. Here, we show that altitude did have an effect on anhedonia in a sex- and acclimation-dependent manner. These data show that exposure to altitude increased depressive-like behaviors in rats during behavioral testing.

Available for download on Friday, April 09, 2021