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The insulin sensitivity varies according to the night cycles, but also the organs involved. This is noted in a Geneva study encouraging diabetic patients and their doctors to consider the ideal time of using insulin.
The secretion of a number of hormones, including insulin, varies over a 24 hour period and any change in these rhythms appears to be predisposing to metabolic diseases, on Tuesday.University of Geneva (UNIGE) in a statement.
Insulin sensitivity
To synchronize, the body takes into account two essential elements: changing light and darkness, as well as the character of food and fasting. The light found by the retina neurons is therefore transferred to the brain, which in turn adapts the peripheral clocks that are located in the different parts t of the body.
"Our assumption was that insulin sensitivity varies according to the 24-hour daily cycle, but also according to the tissues," explains Roberto Coppari, UNIGE's Diabetes Center Professor, who led this work.
"As we already know that certain neurons of the hypothalamic nucleus (VMH) control the sympathetic nervous system of the skeletal muscles of the mice, we looked at these neurons – from the name VMH SF1 – by regulate an insulin action "adds the expert, quoted in the statement. t
From the brain to organs
Scientists performed a comprehensive evaluation of insulin stages in different tissues in mice (gastrocnemius muscle and muscular, both located in the paw, liver tissue and liver) and significantly fluctuations.
By keeping mice in a 12 hour cycle of light and 12 hours of darkness, insulin sensitivity was the lowest during the rest period. They then repeated the same measurements on animals where the gene SIRT1 – a gene associated with the regulation of the molecular components of the central clock – was only suspended in the thousands of VMH SF1 vets.
"We already knew that mice and the adjustment of this gene in SF1 VMH neurons have tended to withstand insulin," said Giorgio Ramadori, the first author of the study. By modulating the exposure time to light, the researchers showed that a gene SIRT1 VMH SF1 neurons played a key role in the operation of insulin in the gastrocnemius muscle, but not in other tissues.
The smallest change is adequate
According to Professor Coppari, "this teaches us two things: first, that the same time management mechanism is regulated differently by the brain according to the organs involved, but that one of the These routes regulate are sufficient to increase a person's risk of developing diabetes significantly. "
To assess the better impact of light on the insulin sensitivity of the tissues, the researchers measured the use of insulin glucose. A small disturbance to the light supply (for example an hour of light in the midst of darkness or the prevention of light for two days) appears to be enough to cause a negative effect.
The increase or decrease in light can seriously affect the sensitivity of the tissue to insulin, and even the smallest change in this mechanism is sufficient to significantly impair metabolic stability. This would explain why people exposed to light at the wrong time – for example 3×8 workers – are more likely to develop diseases such as diabetes.
Time of day
More than 450 million people worldwide are diabetic, and many need daily insulin injections. The only treatment available is not without risk, the main one being hypoglycaemia which can lead to coma and even death.
"The amount of insulin given to patients is calculated on the basis of carbohydrate intake," said Roberto Coppari: "If insulin sensitivity, as our results show, varies with the time of the t and the circadian rhythm of each, these parameters should be considered so that each patient can better manage their treatment and limit the risks. "
More generally, the influence of the time of day on the effectiveness of drug treatments deserves to be studied much wider, bringing the researcher to an end. This work is published in Cell Reports. (Ps / NXP)
Created: 21.05.2019, 16:05
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