Faculty Mentor(s)

Dr. Leah Chase, Biology and Chemistry

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Bipolar disorder (BD) is a neuropsychological disorder that is characterized by cyclical periods of depressive and manic behaviors. The Chase lab is focused on developing a reliable animal model for BD in order to characterize the critical neurophysiological and neurochemical changes that trigger BD. Previous studies in the lab have shown that daily injection of rat pups from postnatal day 3 through 19 (P3-P19) with homocysteic acid (HCA) leads to the development of a mixed manic and depressive state after puberty. These behaviors can be reversed by treatment with lithium and involve changes in gene expression in the prefrontal cortex that are also improperly regulated in BD. Despite the reproducibility of this animal model, we observed subtle, but critical changes in the behavior of our HCA-treated rats that we analyzed during the summer of 2021, such that the animals exhibited more manic behaviors relative to depressive behaviors. Upon further analysis, we discovered that the weight of the pups in the 2021 cohort were 1.3-2.0 g heavier than previous cohorts (F1,39=17.1, p<0.001) on the first day of injection, suggesting that either the 2021 pups were about 2 days older than indicated by the vendor or the pups exhibited a faster rate of growth than the previous cohort. Our current study is focused on measuring behavior in rats given daily HCA injections beginning postnatal day 5, rather than the previous postnatal day 3, in order to determine the effects of a delayed treatment period. We hypothesize this adjusted exposure window may match that of the 2021 cohort and thus produce similar resulting behaviors. Ultimately, this work will allow us to understand how timing of HCA exposure impacts the associated behavioral changes and may provide a better understanding of the variations in behavior associated with bipolar disorder.


This project was funded by A. Paul and Carol Schaap Undergraduate Research Funds with contributions from the Biology, Chemistry and Neuroscience Programs.