Jet lag impacts male and female mice's metabolism differently

New research from Kyushu University shows that chronic jet lag affects male and female mice differently. The study found that male mice gain weight and become less tolerant to glucose when exposed to jet lag, while female mice actually lose weight compared to those without jet lag. The study highlights that female mice's body clocks are more easily disturbed than those of males. This suggests that metabolism is influenced not only by jet lag but also by a mix of hormones and insulin, creating differing effects based on sex. Senior author Professor Shinobu Yasuo emphasized the relevance of this research for people with irregular schedules, such as shift workers. Understanding these biological impacts is crucial because chronic jet lag can increase the risk of conditions like obesity and diabetes. Researchers manipulated lighting to create jet lag in mice, adjusting light cycles every two days. Over eight weeks, they monitored the mice's weight, glucose tolerance, and clock gene activity in the liver and adrenal glands. Male mice showed little change in their biological clock, while female mice experienced significant disruptions. Interestingly, when male mice were castrated and placed under jet lag, they reacted like females, demonstrating the role of testosterone in maintaining a strong body clock and metabolism. The study raises questions about the reasons behind these differences, particularly why females lose weight under jet lag. Professor Yasuo suggests that stress and anxiety responses may vary between sexes. Future studies aim to explore the role of estrogen in female mice and further investigate appetite and food preferences under chronic jet lag. Overall, the findings stress the importance of considering gender differences when addressing health issues faced by those living irregular hours.