In the human body, biological rhythms are in motion every day. It’s how the body adapts. Physiological processes and behaviors are regulated within a 24 hour circadian clock. This internal clock allows our bodies to prepare for the changes that come with day and night, sleep and wakefulness, activity and non-activity. These rhythms are affected by light and energy input; therefore, sleep, waking patterns, and dietary habits influence this tedious circadian clock.
Disruptions occur to this internal rhythm. Working late into the night and peering into screens of artificial light can change how the body perceives day and night, confusing the natural rhythm of biological processes. Eating at unpredictable times can affect this process too.
Hormones release in anticipation of feeding and resting cycles
The endocrine system of the body, which governs the release of key hormones, operates in biological rhythm. Scientists at the University of Geneva studied the internal clocks governing hormone secretion for two types of pancreatic cells. These cells, in charge of insulin and glucagon production, operate at specific times that are influenced by the anticipation of feeding-fasting cycles and resting-activity cycles. If activity and eating times are unpredictable, then the orchestrated release of these crucial hormones is misaligned and thrown off rhythm.
The researchers found that metabolic problems explode when the circadian rhythm of the individual is misaligned. Resetting this internal clock is key to living a healthier, more disease-free life. Many cases of Type-2 diabetes can be traced back to abnormal rhythm of metabolic processes.
A number of factors can affect biological rhythms, including time changes, shift changes at work, long flights, and sleepless nights of study or partying. Ancestors understood the importance of sleeping when the sun was down and waking with the sunrise. This study shows the importance of eating and being active at regular times during the day.
This does not mean that every cell is on the same clock, but it does indicate that the body coordinates metabolic processes in rhythm. Not all cellular processes occur at the same time; therefore, the body must optimize energy levels for sleep and wake cycles to best distribute energy for periods of activity and inactivity. As the researchers have found, timely insulin secretion is part of this process.
Type-II diabetes and metabolic issues may be caused by misaligned biological clocks
The researchers studied the rhythms and interactions of insulin-producing α-cells and glucagon-producing β-cells, in vivo and in vitro.
“Contrary to what we thought, these cellular clocks appear to be slightly distinct, which helps fine-tune the secretion of insulin and glucagon, and thus maintains glucose homeostasis,” says Dr. Charna Dibner of the UNIGE Faculty of Medicine. He says both of these cellular clocks coordinate to adapt to the feeding and fasting state of the individual. “Misalignments of these cell clocks may therefore lead to the disruption of hormone secretion and glucose homeostasis, and to the development of metabolic diseases such as obesity and diabetes,” he said.
To test the rhythmic activity of the islet cells, the Geneva scientists conducted parallel high-throughput RNA sequencing on the cells at multiple times within a 24 hour period. After recording 19,000 transcripts of the gene expression, they were able to identify functional genes in the pancreas and exactly how their temporal regulation process occurs. This cellular rhythm was then compared to the cellular rhythm that occurs in mouse cells. “The mice whose pancreatic islets lack cellular clocks do develop type 2 diabetes, indicating that the disruption of cell rhythms is sufficient to perturb normal hormonal secretion and regulation of glucose homeostasis,” says Charna Dibner.
The researchers concluded that metabolic imbalances can occur when internal clocks are misaligned and adversely affected by the lifestyle choices of an individual in relation to the light of day and the darkness of night. This research suggests the importance of setting and maintaining circadian rhythm for healthy metabolic processes. (RELATED: For more news on prevention, check out Prevention.News.)