Exploring Mouse Models and Optogenetics to Probe Bipolar Disorder

Bipolar disorder is a neuropsychiatric disease affecting 1-4% of the worldwide population; characterized by spontaneous depressive and manic episodes, very little is known about the pathology of bipolar disorder, and there is no known cure. Theorized pathologies of bipolar disorder include genetic and environmental factors, the dopamine hypothesis, and the role of gut microbiota. This paper reviews several pieces of scientific literature pertaining to these theories, integrating optogenetics as a research tool to more accurately examine and manipulate relevant cellular activity. The reviewed literature draws clear connections from the HPA axis, gut microbiota, circadian rhythms, and dopaminergic expression to the pathology and manifestation of bipolar disorder. However, despite this, there is simply not enough information about the disease itself for researchers to come to a sound conclusion. The disparity is mentioned at least once in each piece of literature and is attributed to both the ambiguity of the disease, and the variability in symptoms between patients. Not only does this affect the current theories surrounding bipolar disorder, but also makes studying the disease incredibly difficult, as without a pathology, ideal animal models are nearly impossible to identify. Literature rooted in the use of optogenetics present results which express increased specificity in both data and conclusions, cementing its potential in future studies concerning bipolar disorder. From this, this paper proposes a new behavioral experimental design in mouse models, integrating optogenetics with the most prevalent theories of the pathology of bipolar disorder.