Compound that treats chronic pain without side effects identified

Researchers have identified a compound derived from a well-known class of drugs, which gives pain relief in mice without the usual painkiller side effects of sedation, addiction or developing tolerance.

London, Jan 17 : Researchers have identified a compound derived from a well-known class of drugs, which gives pain relief in mice without the usual painkiller side effects of sedation, addiction or developing tolerance.

The researchers said that whether the compound has the same effect in people remains to be seen, but they are approaching the drug's target with "cautious optimism".

The compound is derived from Benzodiazepines, which are widely used for sedation or to treat anxiety.

Benzodiazepines act on brain pathways involved with pain perception, but have not been very effective at relieving pain, reports Nature.

Now, a team led by Hanns Ulrich Zeilhofer of the University of Zurich in Switzerland conducted a study to know why the class of drugs is not effective.

The research team first tested diazepam, commonly known as valium, by injecting it into the spines of mice. The spine is one of the body's direct pain highways, so blocking pain signals here might help avoid side effects that turn up when a drug hits the brain.

In this system the researchers found that diazepam could relieve pain - mice that either endured a painful injection or had a nerve squeezed to simulate chronic pain were less bothered if they received the spinal injections.

Researchers know that valium acts on a receptor called ?-aminobutyric acid, or GABA, in the spine, and that GABA has different parts or subunits that might be responsible for the different effects of the drug.

To investigate, the team looked at four types of mutant mouse, each of which had a different subunit of this GABA receptor rendered inactive, to see what valium would do.

The research found that two of the subunits, a2 and a3, had to be present for the drug to relieve pain. It is a different subunit, a1 that causes sleepiness when the drugs hit the brain.

The study is published in Nature 1.

ANI