Student Name: Rachel Backstrom
Advisor: Dr. Amy Jo Stavnezer
Major depressive disorder (MDD) affects a wide range of people and, within that population, some have drug-resistant depression. Previous rodent and human research demonstrates that sleep deprivation chronotherapy may provide antidepressant effects. Sex differences of these effects have not been previously investigated, despite the prevalent sex differences within MDD populations. Using a rodent model, this study aimed to (1) investigate the positive effects of sleep deprivation chronotherapy by assessing learned helplessness behavior in the forced swim test and to (2) identify any significant sex differences of these antidepressant-like effects. We hypothesized that rats treated with sleep deprivation chronotherapy would demonstrate less learned helplessness behavior (decreased immobility), female rats would show more learned helplessness overall, and females would demonstrate greater antidepressant effects of the treatment than males. The experimental rats were sleep deprived for 24 hours via the flowerpot method between days in the standard 2-day forced swim test. Immobility, swimming, and climbing were scored as measures of depressive-like behavior. Males who underwent sleep deprivation showed significantly less immobility than control males. We did not support our predicted sex difference, however, at least for males, sleep deprivation chronotherapy may be a beneficial rapid antidepressant treatment. Sleep deprived males also showed significantly more climbing behavior, which is associated with the noradrenergic systems of the brain. This may indicate that common antidepressant treatments that target serotonergic systems would not be effective for some people suffering from MDD, and that a noradrenergic targeted treatment (possibly sleep deprivation chronotherapy) would be a more effective treatment.
Rachel will be online to field comments on April 16: Noon-2 pm EDT (PST 9am-11am, Africa/Europe: early evening).