Professor Shinobu Yasuo Fukuoka, Japan \u2013 Jet lag is one of the worst parts of long-distance traveling or shift work\u2014it makes us tired and cranky, and also plays havoc with our metabolism (and therefore our weight). Now, new research on mice suggests that the way jet lag impacts our metabolism may depend on our sex.<\/p>\n Frequent shifts in light-dark cycles\u2014inducing a state of chronic jet lag\u2014cause drastically different effects on male and female metabolism in mice, say researchers from Kyushu University. The study, published in the journal, Biology of Sex Differences, found that the body clocks of female mice are more easily disrupted than the clocks of male mice, and revealed opposing metabolic effects; jet-lagged male mice gained weight and developed glucose intolerance, while jet-lagged females lost weight compared to female mice without jet lag. The findings imply that metabolism is not only influenced by jet lag, but also by a complex interplay of insulin and sex hormones, leading to different effects in each sex.<\/p>\n \u201cChronic jet lag, where a person\u2019s body clock is consistently out of sync with natural day-night cycles, is a condition that affects many people, such as shift workers,\u201d says senior author Professor Shinobu Yasuo from Kyushu University\u2019s Faculty of Agriculture. \u201cChronic jet lag increases the risk of metabolic disorders, like obesity and diabetes, so understanding the biological effects of jet lag is very important.\u201d<\/p>\n However, studies on humans can be limited as other confounding factors affect metabolism, such as diet, stress, exercise, and genetics. By studying animals like mice under controlled conditions, it is easier to identify the direct effects of jet lag itself.<\/p>\n \u201cThe biggest issue so far is that animal studies have typically focused only on males, yet over half of all shift workers, such as nurses, are women,\u201d says Yasuo. \u201cSo for me, it was important to look at female mice too.\u201d<\/p>\n The body clock, or circadian clock, runs on a roughly 24-hour cycle that is kept in sync, or regulated, by light. In these experiments, the researchers manipulated the mice\u2019s body clocks by changing the timing of the overhead room lights. For the mice under control conditions, the lights were switched on and off every 12 hours, while for the mice under chronic jet lag conditions, the timing of the lights shifted forward by six hours every two days.<\/p>\n Over a period of eight weeks, researchers measured the body weight of the mice under control and chronic jet lag conditions and found that jet-lagged male mice gained weight and developed glucose intolerance, a condition which increases the risk of developing diabetes. However, the jet-lagged female mice lost weight, compared to controls.<\/p>\n \u201cThe outcome was very surprising. We expected both male and female mice to gain weight under chronic jet lag, just to varying degrees,\u201d says Yasuo.<\/p>\n To determine what impact chronic jet lag was having on the mice\u2019s body clock, Yasuo and her colleagues measured the activity of clock genes in the liver and adrenal glands. They also monitored changes in the mice\u2019s deep body temperature, which acts as a marker of body clock activity, peaking during the day and dropping at night.<\/p>\n They found that under chronic jet lag conditions, female mice showed greater disturbance in clock gene activity and a weakened rhythm for deep body temperature, while male mice showed very little change.<\/p>\n In a later experiment, when male mice that had been castrated were put under chronic jet lag conditions, they responded similarly to female mice, showing perturbed body temperature and clock gene activity, and also losing weight. These changes were then able to be reversed when castrated mice received testosterone injections.<\/p>\n \u201cTestosterone is therefore key to a resilient body clock in male mice. It also significantly impacts metabolism and how the body responds to glucose,\u201d says Yasuo. \u201cThis finding underscores the importance of taking sex into account when looking at jet lag\u2019s impact on metabolism.\u201d<\/p>\n In future studies, the researchers hope to unpick exactly why the male mice gain weight and develop glucose intolerance, despite little obvious change in clock gene activity. They also plan to examine the effect of the female sex hormone, estrogen, on the resilience of the body clock.<\/p>\n The weight loss seen in female mice also raises questions on the common perception that jet lag promotes weight gain.<\/p>\n \u201cIt could be that jet-lagged female mice are more sensitive to stress and anxiety,\u201d suggests Yasuo. \u201cWe also plan to research further into the effect of sex on appetite and food preference under chronic jet lag.<\/p>\n \u201cOf course, human lifestyles are much more complicated. Different people respond to stress in different ways, or have different dietary or exercise habits,\u201d continues Yasuo. \u201cBut overall, this study highlights the need to take gender differences into account when recommending appropriate health strategies to people living irregular hours, like shift workers.\u201d<\/p>\n Shinobu Yasuo, Professor<\/a>
\nFaculty of Agriculture<\/span><\/strong><\/p>\nResearch-related inquiries<\/h4>\n
\nFaculty of Agriculture<\/a>
\nContact information can also be found in the full release<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Sex hormones, like estrogen and testosterone, could play a critical role in how metabolism is impacted by an out-of-sync body clock. Professor Shinobu Yasuo Faculty of Agriculture Fukuoka, Japan \u2013 Jet lag is one of the worst parts of long-distance traveling or shift work\u2014it makes us tired and cranky, and also plays havoc with our […]","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[23],"tags":[43],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/posts\/25109"}],"collection":[{"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/comments?post=25109"}],"version-history":[{"count":2,"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/posts\/25109\/revisions"}],"predecessor-version":[{"id":25111,"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/posts\/25109\/revisions\/25111"}],"wp:attachment":[{"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/media?parent=25109"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/categories?post=25109"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sdgs.kyushu-u.ac.jp\/en\/wp-json\/wp\/v2\/tags?post=25109"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}