Neutralizing a substance that increases sensitivity to pain will allow the administration of morphine in low doses and over time and will reduce the side effects
One of the limitations of long-term treatment with morphine for pain relief is the rapid development of tolerance to the drug. The effectiveness of morphine decreases rapidly with long-term use and it is necessary to increase the dose to maintain its effectiveness, which increases the side effects. A study by Prof. Yehuda Shavit and research student Gili Wolf from the Department of Psychology at the Hebrew University found that the administration of morphine causes the release of a substance called "interleukin-1" in the body that increases the sensitivity to pain and decreases the effectiveness of morphine as a pain reliever. The study found that administering morphine together with drugs that block the activity of interleukin-1 may result in more effective pain relief over time.
Pain sensitivity is determined at any given moment as a balance between internal physical processes that increase sensitivity and processes that decrease it. Among the substances that increase the sensitivity to pain in our body is the substance interleukin-1 that is released by the immune system and plays an important role in the inflammatory process. This substance is also released from nerve cells and glial cells (cells that are around the nerve cells and support them) in the central nervous system, and is critical in regulating pain processes.
Prof. Shavit and Wolff's research, which will be presented next week at the conference of the Pain Research Center at the Hebrew University, found that the action of the interleukin-1 molecule increases the sensitivity to pain in normal conditions and especially in inflammatory conditions. In cases of tissue damage, nerve damage, or an inflammatory process, interleukin-1 is released and activates processes that increase pain sensitivity in the affected area. Pain plays an important survival role because it signals to the body the existence of a problem, but sometimes it becomes chronic and pathological and requires prolonged treatment.
The study shows that prolonged use of morphine gradually increases the level of interleukin-1 in the body which in turn acts as a counter-reaction to the pain-relieving effect of morphine. In this way, the substance contributes to the development of tolerance to morphine and to the reduction of its effectiveness.
"Giving morphine together with substances that block interleukin-1 may result in effective pain relief at lower doses of morphine, thus reducing the side effects it causes," says Prof. Shavit and adds that "the research may also contribute to finding a way to minimize the development of tolerance to morphine so that Morphine will be used clinically for a long time."
The study will be presented at a conference of the Pain Research Center at the Hebrew University on May 3, 2009 at the Mount Scopus campus of the Hebrew University. The convention is open to journalists and pain professionals.
