Researchers of Samara University Detected How the Appetite Hormone Regulates the Biological Clock

Effect of the hormone stimulating the sense of hunger on the internal biological clock of mammals body has been established by specialists of Samara University. According to the data obtained by scientists, ghrelin synthesized in the GI tract helps body to adapt its internal sleep-wake schedule to the circadian rhythm of the outside world. Results are represented in the Russian Journal of Physiology named after I.M. Sechenov.

Ghrelin is a peptide hormone produced by the gastric mucosa membrane. It affects cognitive activity, teachability, and memory, as well as well as stimulates the sense of hunger. Its concentration in blood increases if a human sees and hears a flavor of food, thus ghrelin is called “hunger hormone” and “appetite hormone” as specialists of Samara University told us.

Scientists revealed that another function of ghrelin is the adaptation of biological clock to internal 24-hour astronomical day. So called suprachiasmatic nucleus located in the main generator of circadian rhythms (hypothalamus) is responsible for this synchronization.

“Main mechanism of the regulation of circadian rhythms is photic mechanism. It is based on what a human sees outside the window, how much light falls on the retina of the eye at certain times of the day. Some other mechanisms (non-photic) use information on dietary regimen, composition, and energy value of food,” told one of authors of the work, Associate Professor of the Department of Physiology of Animals and Human of Samara University Elena Inyushkina.

“It is by non-photic mechanism that ghrelin works,” added the researcher. The group of scientists detected that this hormone has an influence on nervous impulses transmitted from one neuron to another through synaptic connection (adhesions).

“We examined section of rat brain and established that 50 of 81 neurons had been active on response to administration of ghrelin. Detailed study showed that exposure of ghrelin on adhesion activity of neurons is performed through GHS-R1a receptors that also participate in the body anti-inflammatory response,” explained the researcher.

So during the administration of ghrelin, 32 percent of neurons enhanced activity, on the other hand, 30 percent were “suppressed.” Thus ghrelin acts mixedly,” added Inyushkina.

The work was carried out with support of the Russian Science Foundation.

Source: ria.ru