Disruptions to the brain's stress-response system can make opiate withdrawal symptoms worse, researchers say, but animal studies show that administering the hormone corticosterone can ease symptoms like pain, nausea, and agitation, Medical News Today reported Feb. 20.

French researchers used mice deficient in a stress-related brain receptor called CRF1 (corticotrophin-releasing factor-1) to study withdrawal. They found that the CRF1 mice had more severe withdrawal symptoms than other mice; moreover, when drugs were given to normal mice to block CRF1, they also had worse withdrawal symptoms.

Genetic changes in the brains of the mice indicated that their stress-response system was impaired, the researchers said. However, when mice were given the steroid hormone corticosterone, the differences in severity of withdrawal between the CRF1-deficient mice and the normal mice disappeared, and the genetic variances vanished as well.

"The findings of the present study demonstrate that, like hyperactive stress systems, severe deficiencies in major components of the stress-responsive system may worsen the somatic reactions to drug withdrawal," the authors wrote.

The research was published in the Feb. 15, 2007 issue of the journal Neuron.