Poster abstracts

Poster number 84 submitted by Yasmine-marie Cisse

Early Life Exposure to Dim Light at Night Attenuates High Fat Diet Induced Weight Gain Despite Increased Daytime Food Intake

Yasmine-marie N. Cisse (Neuroscience, The Ohio State University), Randy J. Nelson (Neuroscience, The Ohio State University)

Abstract:
As one of the most potent signals to the circadian system, light exposure during the night significantly disrupts circadian rhythms. The circadian system regulates metabolism, driving physiologically relevant oscillations in gene transcription and availability of metabolic hormones and enzymes. Exposure to dim light at night (DLAN) has been associated with increased body mass and altered feeding rhythms in adult mice. High fat diet (HFD) also disrupts behavioral and molecular rhythms in adult mice. When combined with DLAN, HFD exacerbates body mass gain and impaired glucose processing. But the effect of these two factors during development remains unspecified. Early life is a critical time for the development of endogenous circadian rhythms, as well as metabolic priming. Disruption of early postnatal clock gene expression precedes an adult obesity phenotype. We predict that disruption of circadian rhythmicity through DLAN and/or HFD primes for increased adiposity in adulthood. Mice were bred in our lab and litters were normalized to 10 pups (CL) or reduced to 3 pups (SL). CL mice were weaned onto chow diet whereas SL mice were given HFD to maintain a lifelong HFD condition. Both groups were also split by light condition; half were maintained in a standard light dark (LD) cycle or exposed to nightly dim (5 lux) light (DLAN). After four weeks in respective lighting conditions, food intake and locomotor activity were assessed. At nine weeks of age mice either underwent glucose tolerance testing or hippocampal, fat, and liver tissues were collected for qPCR. Here we report that male mice exposed to lifelong HFD exhibit hyperphagia and impaired glucose tolerance. Males exposed to DLAN and HFD increased daytime food intake despite no total increase in calories consumed. Unlike reported in adults, DLAN males decreased HFD induced weight gain. Further studies are underway to elucidate the divergent weight phenotypes observed at different ages of exposure to DLAN.

Keywords: light at night, development, obesity