Biologists Have Clarified The Role Of Adrenaline In The Transmission Of Nerve Impulses
It turned out that this hormone changes the nature of how neurons secrete acetylcholine molecules, one of the main chemical signals of these nerve cells.
By observing the effect of adrenaline on rat muscles, Russian scientists have learned how this hormone affects the transmission of signals from the nerve to the muscles. This is reported by the press service of the Russian Science Foundation (RSF) with reference to the scientific journal Cellular and Molecular Neurobiology.
"We found that the effectiveness, direction, and mechanisms of action of epinephrine and norepinephrine depend on the type of animal, the type of muscle, and its functional activity. This may be due to the existence of different types of epinephrine receptors, and the processes that develop in a living cell after their activation," said Ella Bukharayeva, a Professor at the Kazan Institute of Biochemistry and Biophysics of Kaznc RAS and one of the authors of the work.
The hormones epinephrine and norepinephrine are not only responsible for the response to fear or aggression but also participate in many important processes in the human nervous system. In particular, as neurophysiologists have recently noticed, their presence or absence greatly changes the way nerve cells secrete and absorb acetylcholine molecules, one of the main chemical signals exchanged by neurons when transmitting impulses between themselves and interacting with muscles.
In recent years, doctors have created several experimental drugs based on epinephrine to combat disorders in the acetylcholine cycle. They work quite effectively, but the principles of action of such drugs on the brain and nervous system are still a mystery to biologists. Professor Bukharaeva and her colleague Venera Khuzyakhmetova tried to find the answer to this question in experiments on fragments of the leg muscles of rats.
By connecting a set of electrodes to the nerves in these tissue samples, scientists injected them with epinephrine or norepinephrine and observed how the electrical activity of neurons changed, the concentration of acetylcholine in their vicinity, and how this all affected muscle contractions.
It turned out that epinephrine changes the way neurons secrete acetylcholine molecules. Its appearance in the vicinity of nerve cells contributes to the fact that they will be produced in portions, which increases the probability of transmitting a signal to the muscles. Interestingly, norepinephrine, a kind of antipode of adrenaline, did not affect the nature of the work of nerve cells and muscles.
In this regard, the scientists note, the discovery came as a surprise to them since in past experiments they found that small amounts of this hormone significantly affected the way the neurons of two other animals, frogs, and mice, released acetylcholine. Why this is so is still unclear, but scientists plan to find out the reasons for this in the course of a more detailed study of the relationships between different types of adrenaline receptors and the characteristics of neurons.