Antibiotic Targets Chronic Pain Memory Traces

A new study has identified a drug that controls persistent nerve pain by targeting the prefrontal cortex, the part of the brain that experiences the emotional suffering of pain.

Researchers at Northwestern University (Chicago, IL, USA) placed rats in a two-compartment chamber--one side well-lit, the other dark. When the rats were in their preferred dark side, scientists mechanically stimulated their sensitive limbs. The rats did not like that and bolted into the bright chamber, where they remained. The scientists then took the same rats and treated them with D-Cycloserine. Again, scientists stimulated the rats' sensitive limbs; this time, however, the rats remained in the dark chamber.

The results indicated that while the physical pain appeared to be reduced 30%, the rats' emotional suffering completely disappeared. The drug also had long-term benefits; animals appeared to be pain-free 30 days after the last dose of a 30-day regime of D-Cycloserine. The study was published in the online edition of Pain, the journal of the International Association for the Study of Pain (IASP).

"In some ways, you can think of chronic pain as the inability to turn off the memory of the pain,” said lead author Dr. Vania Apkarian, a professor of physiology and anesthesiology. "What's exciting is that we now may be relieving what has clinically been the most difficult to treat--the suffering or the emotional component of pain.”

D-Cycloserine, an antibiotic that is a partial agonist at the glycine modulatory site of the glutamatergic N-methyl-D-aspartate (NMDA) receptor site, has been used to treat phobic behavior over the past decade, and has also been found to control nerve pain resulting from chemotherapy.


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