Constant Light Disrupts the Developing Mouse Biological Clock

Abstract

ABSTRACT:The central biological clock of the brain, contained within the suprachiasmatic nuclei (SCN) of mammals, orchestrates an orderly "internal day" of physiology and behavior. The developing biological clock begins to respond to light at an early stage and a particular concern in humans is whether light exposure has disruptive effects on the developing biological clock of infants exposed to constant lighting conditions in neonatal intensive care units (NICUs). Worldwide, eighteen million, or 14%, of newborns estimated to be of low birth weight, are exposed to artificial lighting environments in hospital nurseries annually. Here, we have tested whether constant light (LL) exposure disrupts the developing biological clock of mice, using a circadian reporter transgenic mouse model in which the organization of the central biological clock can be assayed by real-time gene expression imaging. We now find that LL has both acute and long-term disruptive effects on developing biological clocks and that cyclic lighting conditions are critical for developing circadian clocks to coordinate their molecular circadian mechanisms. This suggests that, from the perspective of developing circadian organization in humans, cyclic light conditions in NICUs are likely to be most appropriate for infants. (Pediatr Res 60: 304-308, 2006)

The Uterus Sustains Stable Biological Clock during Pregnancy

“…The present study further supports this idea particularly by first proving the existence of stable circadian clocks in the pregnant uterus and the decidua at the molecular level. Our study gives a basis to explore the molecular connections between circadian clocks in pregnant reproduction organs and their physiological functions and also suggests an importance of circadian environments for developing organisms to achieve their sound physiology (Mann et al 1986;Miller et al 1995;Mirmiran and Ariagno 2000;Brandon et al 2002;Rivkees et al 2004;Miller et al 2004;Ohta et al 2006Ohta et al , 2008.…”

Influence of light exposure during early life on the age of onset of bipolar disorder

“…However, this analysis cannot determine threshold values for too little or too much sunlight in early life, and too much or constant light exposure in early life may also disrupt the developing circadian clock (Mann et al, 1986;Ohta et al, 2006). The time of day of light exposure may also impact circadian development (Harrison, 2004;Rivkees 2003).…”

Perinatal light imprinting of circadian clocks and systems (PLICCS): A signature of photoperiod around birth on circadian system stability and association with cancer

“…Behavioural differences in mice induced by postnatal (P0-P20) LL alone appear to be rescuable by LD (Ohta et al, 2006). Interestingly, perinatal exposure to abnormal light can aid in susceptibility to adverse effects of abnormal light in later life.…”

“…The circadian clocks and systems are potentially very susceptible to environmental factors in perinatal life (for a comprehensive review of circadian development with regard to postnatal light, see the 2013 publication by Brooks & Canal (Brooks & Canal, 2013)). Given recent findings in animal models regarding developmental sensitivity to photoperiod and photoperiod changes (Ciarleglio et al, 2011;Green et al, 2015;Ohta et al, 2006), plasticity of human circadian clocks and systems may be differentially affected by different paradigms of perinatal photoperiod exposure to the detriment of health in later life (Bauer et al, 2015;Ciarleglio et al, 2011;Erren et al, 2011aErren et al, , 2011bErren et al, , 2012b.…”