Drosophila Research Leads to Light-Bulb Moment About Body Temperature Regulation
Researchers have long known that human body temperature rises when people are exposed to light during the night. Understanding the molecular mechanisms that cause such temperature changes could advance the study of sleep disorders, seasonal affective disorders and temperature regulation.
A study published in April 2015 in Current Biology reports finding important clues about the mechanisms involved in a most-unusual place: the temperature sensitivities of the tiny, cold-blooded fruit fly, Drosophila melanogaster.
A research team led by Fumika Hamada, PhD, Division of Ophthalmology, found that Drosophila exhibit light-dependent temperature preference (LDTP) in which the flies prefer a one-degree higher temperature in light than in dark. Because the flies are cold-blooded, their body temperature is also higher in light.
The team uncovered the molecular mechanisms that control LDTP in flies, and theorize that acute light on temperature regulation may be conserved evolutionarily between flies and humans. “Light affects many physiological responses, but the underlying mechanisms of it are unclear,” Hamada says.
The team also found a well-known circadian clock molecule - pigment dispersing factor receptor - in subsets of the circadian clock cells that control the flies’ LDTP. The result suggests a connection between light and circadian clock neurons. Given that LDTP occurs irrespective of the state of the circadian rhythms, the research provides new insights into how circadian clock mechanisms impact light and temperature regulation.
Heat generation is different between humans and flies, but the light/temperature connection has similarities. Eventually, this line of research could benefit people who work night shifts and are exposed to light in nighttime.
"Long-term sleep deprivation may increase the risk of obesity, diabetes and cardiovascular disease,” Hamada says. “This evening light exposure increases body temperature, which causes abnormal circadian rhythmicity.”
