The Effect of St. John’s Wort Solution on Climbing Activity Reflecting Depressive-Like Behavior in Drosophila melanogaster to Model Seasonal Depression in Low Sunlight Exposure

Although depression is a known substantial threat to public health, seasonal affective disorder (SAD) is under-researched. SAD refers to recurrent seasonal patterns of depression. This depressive disorder has few accepted treatments. The purpose of this study was to test whether St. John’s Wort (SJW), a natural supplement with researched antidepressant properties, could be a cheaper alternative with fewer limitations for treating SAD. SJW’s efficacy as a seasonal depression inhibitor was tested through a Drosophila depression-like model using climbing activity to reflect depressive behavior. It was hypothesized that as the concentration of SJW solution increases, the climbing activity of stressed Drosophila melanogaster enclosed in low sunlight exposure would increase to reach the same levels as the climbing activity of non-stressed Drosophila melanogaster, due to SJW’s ability to inhibit serotonin reuptake. The depression-like model was generated through a vibration treatment consisting of unpredictable durations of vibration. A diluted solution of SJW was made using a human-to-fruit fly ratio regarding mass and required dose. Climbing activity was measured by counting how many fruit flies passed the 100 mL mark in a graduated cylinder under one minute. Due to the high mortality rate of the fruit flies, few results were recorded. It is inferred that potential errors include difficulties with method application, specifically, handling the transfer of live organisms. Nonetheless, if this topic were researched again, then successful manipulation of the Drosophila melanogaster could result in significant data. That would expand the possibilities of treatment for this undertreated depressive disorder.