Australia - Morphine Linked To Brain Inflammation And Increased Pain Sensitivity, Study

An international team of researchers has shown for the first time how opioid drugs, such as morphine, create an inflammatory response in the brain.

AsianScientist (Apr. 4, 2012) – An international team of researchers has shown for the first time how opioid drugs, such as morphine, create an inflammatory response in the brain – by activating an immune receptor in the brain.

Morphine is an extremely important drug for pain relief, but it can lead to a range of side-effects – such as patients developing tolerance to morphine and increased sensitivity to pain. Until now, how this occurs has remained a mystery.

In this week’s Proceedings of the National Academy of Sciences, the team from the University of Adelaide and University of Colorado demonstrated how this brain immune receptor can be blocked, a major discovery that could lead to more effective treatment of severe pain using morphine.

“Because morphine is considered to be such an important drug in the management of moderate to severe pain in patients right around the world, we believe these results will have far-reaching benefits,” says study co-author Dr. Mark Hutchinson, ARC Research Fellow in the University of Adelaide’s School of Medical Sciences.

Hutchinson’s team conducted studies in mice to validate the work done at the University of Colorado by the teams of Assistant Professor Hubert Yin and Professor Linda Watkins.

“For some time it’s been assumed that the inflammatory response from morphine was being caused via the classical opioid receptors,” said Hutchinson.

“However, we found instead that morphine binds to an immune receptor complex called toll-like receptor 4 (TLR4), and importantly this occurs in a very similar way to how this receptor detects bacteria.

When the morphine-TLR4 relationship was disrupted in mice, the inflammation response was eliminated.

The results suggest that future drugs for palliative care could be developed to promote the beneficial actions of morphine while negating some of the harmful side-effects, said Hutchinson.

The article can be found at: Wang X et al. (2012) Morphine activates neuroinflammation in a manner parallel to endotoxin.

Juliana Chan

AsianScientist

Source: University of Adelaide.
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