New Mechanism Found That May Underlie Neuropathic Pain

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New Mechanism Found That May Underlie Neuropathic Pain

http://www.medicalnewstoday.com/medicalnews.php?newsid=54280

Researchers at & Pharmaceutical Research &

Development (J & JPRD) announced on 15 October 2006 that they have

discovered a new molecular mechanism that may underlie neuropathic

pain. The clearer understanding of the root-cause of chronic

neuropathic pain, and the preclinical validation of new targets for

pharmaceutical therapies shown in this research, together present an

opportunity for the development of new ways to treat the severe pain

associated with such common conditions or diseases as sciatica,

diabetic neuropathy and shingles.

This research was presented at Neuroscience 2006, the annual meeting

of the Society for Neuroscience.

Neuropathic pain, or the spontaneous pain and abnormal sensitivity

following a nerve injury, typically results from a traumatic injury,

an infection or disease, or surgery, and can persist long after the

initial injury has healed. Millions of people worldwide suffer some

form of neuropathic pain, and the current treatment options are

limited or inadequate for many people. The research presented today

suggests that the persistent pain may be caused by specific types of

ion channels, called " pacemaker channels, " which initiate a constant

and rhythmic transmission of pain signals to the brain, rhythmically

similar to those generated by pacemaker cells that regulate one's

heart rate.

" What we have shown in our early preclinical research is that we can

inhibit the inappropriate neuronal activity and resulting

sensitivity that follows nerve injury, " said Alan Wickenden, Ph.D.,

Research Fellow in the Pain and Related Disorders Team at

J & JPRD. " Trauma to nerves and the tissues that surround them seems

to trigger a complicated cascade of events that results in an

increase in the activity of these pacemaker ion channels and the

resulting transmission of pain signals to the brain. We are

encouraged by early evaluations of certain chemical structures that

seem to disrupt this rhythmic transmission. "

Ion channels are openings that exist within a cell that allow the

passage of certain ions into a cell to regulate activity. It is

believed that hundreds of different types of ion channels exist in

the body, each with a distinct responsibility for sending a specific

message, and that specific pacemaker channels exist in peripheral

nerves as well as in the heart and the central nervous system. In

the heart, for instance, signals generated by pacemaker channels

stimulate the heart muscle to contract, and in the brain, they

control sleep and waking. Made up of glycoproteins, or proteins with

sugar molecules attached, pacemaker channels -- also known as HCN

channels (Hyperpolarization activated, Cyclic Nucleotide-gated

cation channels) -- allow the entrance of sodium ions into the cell

based on the configuration of the protein. Entry of sodium ions can

trigger electrical activity in both cardiac cells and neurons.

" We think we have only scratched the surface in this area, as

pacemaker channels may also play a role in inflammatory pain as well

as other types, " said Dr. Wickenden. " More research is needed

before this will translate to patient benefit, but the better

understanding we've gained of the mechanism can enable us to narrow

our focus. "