Like other psychiatric and neurodegenerative disorders, bipolar disorder affects nerve cells in the brain, making it difficult to study underlying neurobiological causes of the disease during its actual course.
According to senior author Nancy Rawson, PhD, a Monell cellular biologist, "Previous studies have used non-nerve cells, such as fibroblasts or red blood cells, to examine how cells function in patients with bipolar disorder. But since this is a psychiatric disorder, we need to understand what's going on in nerve cells."
Olfactory receptor neurons (ORNs), located in a small patch of epithelium inside the nose, are nerve cells that contain receptors for the thousands of odorant molecules detected by humans. Easily obtained using a simple 5-minute biopsy procedure, ORNs share many characteristics with nerve cells in the brain. These features make ORNs a useful model to study the neural effects of psychiatric disease.
Calcium is integral to properly-functioning nerves, and previous studies have implicated dysfunctions of cellular calcium metabolism as a contributing factor to bipolar disorder. Changes in how much calcium is inside ORNs and other nerve cells tell researchers how the nerves respond to stimulation.
In the study, researchers used a fluorescence imaging technique to measure basal and stimulated calcium levels in ORNs from 17 patients with bipolar disorder and age- and sex-matched healthy controls. Seven patients were medication free and 10 were being treated with mood-stabilizing drugs.