Circadian clocks influence body’s response to diet

Posted May 21, 2017 by Tim Sandle
Scientists from Baylor College of Medicine have found that alterations to the circadian clock affect how the body responds to diet. In turn this influences microbes residing in the digestive tract.
The study undertaken to date relates to mouse livers. The findings indicate how a liver gene connects to the circadian system, the microbiome (totality of microorganisms in a given niche) and the mouse metabolism. In addition, these connections alter under differing dietary conditions. What is also of interest are the differences between male and female mice.
The research sowed how the circadian clock, the internal mechanism that helps orchestrate body activities such as going to sleep or when to eat, and the microbiome interact and when these go out of synchronicity this can affect metabolism, in particular how we metabolize our food. Specifically the researchers showed how changing the circadian clock affects the microbiome.
To explore the connection, Drug Store News reports that the science group genetically engineered mice so they lacked a gene involved in circadian rhythm. This gene is located in the liver and it is called the Npas2 gene. Following this the researchers determined what effect lacking the gene had in terms of a standard test for circadian genes.
The test took the form of restricted feeding. For this, in place of unrestricted amounts of food being made available to the mice for 12 hours at night (which is when mice normally feed), the mice were only given access to food for four hours. The four hours also coincided with the day time rather than night time.
As the study was run two different groups of mice were used. One group lacked the Npas2 gene and the other group did not. The two groups were subject to the same restricted diet regime. At intervals, including before, during and after the test, the scientists examined stool samples to evaluate the type of microbes present. They also assessed the amount of food the mice ate together with their weight.
The findings indicated that altering the circadian clock in the liver leads to changes in the gut microbiome. Specifically, the mice lacking the Npas2 gene had microbial communities different from those in normal mice. Of greater interest was the fact that the mice lacking the Nasp2 gene lost less weight than the normal mice. This suggests evidence of a complex interplay between the body’s circadian system, the microbiome of the gut, and the metabolism when dietary changes occur.
The implications of the findings are that they might lead to changes in dietary practice for people. This could come about through deliberate changes made to the microbial content of the gut.
The findings have been published in the American Journal of Obstetrics and Gynecology. The paper is called “Conditional postnatal deletion of the neonatal murine hepatic circadian gene, Npas2, alters the gut microbiome following restricted feeding.”