16 September 2013

Analgesic mutation

The pain-free girl helped in the search for new analgesics

Copper newsSequencing of the exon – the part of the genetic set responsible for coding proteins – of a girl with congenital analgesia (pathology of the development of the central nervous system, manifested in insensitivity to physical pain) helped an international group of researchers from a number of European scientific centers to identify for the first time a key genetic mutation, due to which pain sensitivity is impaired.

The authors believe that their discovery will allow in the future to develop a fundamentally new type of analgesics. The work was published in the journal Nature Genetics (Leipold et al., A de novo gain-of-function mutation in SCN11A causes loss of pain perception).

The authors compared the genetic sequence of a girl suffering from congenital analgesia, who, due to her pathology, had serious tissue damage and even injuries, with the decoded exons of her parents, who had no such pathology, and found a de novo mutation in the SCN11A gene with the replacement of one amino acid in the DNA sequence.

The protein encoded by this gene controls the development of sodium ion channels of the same name on the surface of sensory neurons, thanks to which the pain impulse is transmitted from the peripheral nervous system to the brain. As a result of the mutation, the authors believe, there is a hyper-expression of the SCN11A protein, which eventually blocks the process of transmitting pain impulses to the brain.

To confirm their findings, the authors bred a line of mice with a mutated version of the SCN11A gene and examined their ability to feel pain. It was found that 11 percent of mice had injuries characteristic of people deprived of the ability to feel pain – bone fractures and skin wounds. In addition, mice with the mutant SCN11A gene did not respond to cauterization of the tail with a focused light beam for an average of 2.5 times longer than animals from the control group. The results obtained confirm the role of a mutation in the SCN11A gene to increase the pain threshold, however, the authors note that in humans this effect is more pronounced than it turned out in experiments on an animal model.

Currently, according to the NewScientist magazine (Girl who feels no pain could inspire new painkillers), a team led by Ingo Kurth from the clinic at the University of Jena (Germany) has begun searching for a drug capable of selectively blocking SCN11A ion channels, causing hyperactivity of the corresponding gene, which may eventually lead to the creation of fundamentally a new kind of analgesics.

Portal "Eternal youth" http://vechnayamolodost.ru16.09.2013

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