New Mechanism Improves Chronic Pain Management

A previously unknown mechanism which offers a new potential target for increasing the therapeutic effect of drugs for chronic pain was discovered by researchers in Japan. This involves a newly identified group of cells in the spinal cord which plays a role in pain control. Glial (Greek word for glue) cells a type of non-neuronal cell are important for regulating neuronal development and function in the central nervous system. There are different types of glial cells out of which astrocytes are present in abundance in the CNS. However researchers still have to develop a detailed understanding of these astrocytes.

Researchers at Kyushu University's Graduate School of Pharmaceutical Sciences led by professor Makoto Tsuda have discovered a special population of astrocytes in the spinal cord which has a key role in producing pain hypersensitivity.

Astrocytes are found in the outer layers of gray matter near the back of the spinal cord. They are present in the region which carry out general sensory information such as pressure, heat and pain from all over the body to the brain.

In mice it was observed that by stimulating noradrenergic (NAergic) neurons which use noradrenaline as the neurotransmitter, the signal is carried from the locus coeruleus in the brain down the spinal cord resulting in the activation of astrocytes which leads to pain hypersensitivity.

Tsuda said,“ The discovery of this new population of astrocytes reveals a new role of descending LC-NAergic neurons in facilitating spinal pain transmission."

According to the findings, if we suppress the signals of these astrocytes by noradrenaline, it will increase the effect of drugs for chronic pain.

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To test this, the researchers administered duloxetine which is an analgesic drug to genetically engineered mice in which the response of astrocytes to noradrenaline was inhibited selectively. The drug duloxetine is thought to increase the levels of noradrenaline in the spinal cord by preventing uptake by the descending LC-NAergic neurons.

In the genetically engineered mice there was decrease in chronic pain after duloxetine administration, which further supported the researcher’s proposed role of the astrocytes in chronic pain.

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Tsuda said,“ Although we still need more studies with different drugs, this astrocyte population appears to be a very promising target for enhancing the therapeutic potential of drugs for chronic pain.”

Source-Medindia