150. Disruption of the gut microbiome with oral antibiotic reduces core body temperature and disrupts diurnal rhythms of locomotor activity, but not sleep, in rats

Abstract

The bidirectional communication between the gut microbiota and the brain (i.e. the gut-brain axis) can modulate behavior and neurochemical systems. Recent evidence suggests that the absence of gut microbiota can affect clock genes in peripheral tissues that could influence diurnal rhythms; and serotonin in the brain that can modulate sleep/wake behavior and temperature regulation. Thus, we hypothesized that depletion of the gut microbiota, using oral antibiotics, may disrupt diurnal rhythms, thermoregulation and sleep. Using in vivo biotelemetry, we recorded diurnal rhythms of locomotor activity (LA), core body temperature (CBT), and sleep (%REM, %NREM, %WAKE) in freely moving adult male F344 rats. Rats were given oral antibiotics (4.0 mg/ml streptomycin and 2.0 mg/ml penicillin g) in their drinking water. Total aerobic, anaerobic, Lactobacillus spp. and Bifidobacterium spp. per g of feces was determined using selective culture. After seven days of antibiotic treatment, animals had depleted gut microbiota, reduced overall CBT, and a flattened diurnal rhythm of LA when compared to baseline, while sleep architecture remained unchanged. Interestingly, five days after cessation of antibiotic, only Lactobacillus spp. remained depleted. Reduced CBT and flattened diurnal rhythm of LA also persisted. These results support a link between the gut microbiota, temperature regulation and diurnal physiology. Furthermore, they suggest that disruptions to the gut microbiota, and any resultant physiological consequences, may be long lasting even if antibiotic administration is transient.