NIH Research Festival
All organisms have evolved intrinsic biological rhythms to anticipate cyclic changes in their environment. In mammals, daily rhythmic changes in metabolism, physiology, and behavior are driven by intrinsic oscillatory mechanisms generated by the central clock located in the suprachiasmatic nucleus (SCN). To understand how an external cue shifts the central clock, we compared intrinsic gene expression in SCN neurons across the day to the change in gene expression induced by light using single nucleus RNA-sequencing. We find that the same light stimulus delivered in the early versus late night leads to divergent changes in gene expression in the mouse SCN. Changes in gene expression were not limited to clock/circadian genes in SCN neurons. Unexpectedly, the expression of genes involved in synaptic assembly and transmission also changed in response to light at night, suggesting that SCN neuron connectivity is plastic and involved in shifting the circadian clock. By measuring SCN gene expression at high depth across different times of day, we provide new insights into SCN neuron complexity and its responsiveness to light. This study is also crucial to understanding the mechanisms underlying the disruptive effects of light, such as those observed in shift work, trans meridian travel and seasonal affective disorder.
Scientific Focus Area: Neuroscience
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