Meeting Abstract
Seasonal affective disorder (SAD) is a recurrent depression triggered by short photoperiod exposure. In addition to being a major mental health issue, SAD has been linked to circadian dysfunction and weight gain, both of which have important implications for susceptibility to cardiovascular disease, type II diabetes, and metabolic syndrome. We use a diurnal rodent model, the Nile grass rat (Arvicanthis niloticus), to examine the effect of photoperiod (short 4:20 LD vs. neutral 12:12 LD) on sleep and activity patterns, sucrose consumption, and gut microbiome changes. We tracked individual sleep patterns in 45 grass rats and assessed reward-seeking behavior by measuring their consumption of high-concentration (8%) sucrose (HCS) solution. We collected liver (to diagnose fatty liver disease), cecum, large intestine, and periodic fecal samples (to characterize the diversity and functional profile of the gut microbiome). We found that animals on short photoperiods showed disrupted activity and sleep patterns, but maintained strong diurnal rhythms and similar subjective day lengths. We found no effect of photoperiod on sucrose consumption, but short photoperiod individuals had marginally higher liver fat content, and those with access to high sucrose had higher liver fat across both photoperiod treatments. Our study highlights the potential for metabolic effects of exposure to short photoperiods. Completion of sequencing will allow us to assess whether these effects are associated with shifts in the gut microbiome diversity or functional profile.
