Pain Relief
Glimpses Into the Future of Pain Relief
Scientific advances reflect a new understanding of pain as something
no longer felt or experienced, but rather something that can be
visualized as well through the structures, chemistry and
microanatomy of the nervous system. Research advances are
helping us understand pain better and select potential targets for new
therapeutic agents. Speakers at the recent "New Directions in Pain
Research" symposium outlined a number of possible sites for
advances in drug development.
- Systems and Imaging: The idea of localizing cognitive functions in
the brain dates back to phrenology, the now archaic practice of
studying bumps on the head. Positron emission tomography,
functional magnetic resonance imaging, and other imaging
technologies offer a brilliant picture of what is happening in the
brain's structures as it processes pain. Using imaging, investigators
can now see that pain activates three or four key areas of the brain's
cortex. Similarly, poststroke patients suffering from central pain
syndrome show activation of the thalamus deep within the brain.
- Channels and Transducers: Ion channels continue to represent the
frontier in the search for new drug targets. Dorsal root ganglion
cells, found within the spinal cord, show a clear, visible response
after injury. For example, after injury to nerves, sodium channels
accumulate in neurons, increasing the extent of injury. The
possibility now exists of developing new classes of drugs that would
act at the site of ion channel activity.
- Trophic Factors: A class of "rescuer" or "restorer" drugs may
emerge from our knowledge of trophic factors, natural chemical
substances found in the human body. These compounds affect the
survival and function of cells. Trophic factors can also promote cell
death, but little is known about how something beneficial can
become harmful. For example, experimental treatment with trophic
compounds can reverse changes in neurons following injury.
Conversely, investigators have observed that over-accumulations of
certain trophic factors in the nerve cells of animals result in
heightened pain sensitivity. Certain receptors found on cells respond
to trophic factors and interact with each other; these may provide
other targets for new pain therapies.
- Molecular Genetics: Certain genetic mutations can change pain
sensitivity and behavioral responses to pain. People born genetically
insensate to pain -- that is, individuals who cannot feel pain -- have a
mutation in part of a gene that plays a role in cell survival. Using
"knockout" animal models -- animals genetically engineered to lack a
certain gene -- scientists are able to visualize how mutations in
certain genes cause animals to become anxious, to make noise, rear,
freeze, and become hyper-vigilant. These genetic mutations cause a
disruption -- or alteration -- in the processing of pain information as
it leaves the spinal cord and travels to the brain. Knockout animals
offer a tool that can be used to complement efforts aimed at
developing new drugs.
- Plasticity: Following injury, the nervous system undergoes a
tremendous reorganization. This phenomenon is known as plasticity.
For example, the spinal cord is "rewired" as axons make new
contacts -- called sprouting -- which disrupts the cells' supply of
trophic factors. Scientists can now identify and study the changes
that occur during the processing of pain. For example, using a
technique called polymerase chain reaction, scientists can see the
distribution of proteins in cells and along the axons and dendrites of
the dorsal horn in the spinal cord following injury. Scientists believe
these proteins, which may be "switched on" following injury, may
play a role in cell survival and in the prevention of apoptosis or
programmed cell death. Pain, in fact, may be stored in the brain as a
molecular event, indicating the involvement of a number of
mechanisms and regions of the brain used in learning and memory.
- Transmitters: As mutations in genes may affect behavior, they
may also affect a number of neurotransmitters involved with control
of pain. Investigators can now visualize what is happening in the
spinal cord. From this, new therapies may emerge that can help
maintain pain sensibility or obliterate severe or chronic pain. For
example, investigators have isolated a tiny population of neurons,
located in the spinal cord, that together form a major portion of the
pathway responsible for carrying persistent pain signals to the brain.
When given injections of a lethal chemical cocktail, the cells, whose
sole function is communication of this type of pain, are killed off,
directly affecting the transmission of pain from the spinal cord to the
brain.
More Pain Relief Information:
Glimpses Into the Future of Pain Relief
Arthritis and Rheumatic Disease Information
Treatment and Research - Rheumatoid Arthritis
Treatment and Research - Osteoarthritis
Repetitive Motion Disorders Information
Back Pain Information Page
Low Back Pain Information
About Chiropractic and Its Use in Treating Low-Back Pain
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