Heat Halts Pain Inside The Body

July 6, 2006

The old wives' tale that heat relieves abdominal pain, such as colic

or menstrual pain, has been scientifically proven by a UCL

(University College London) scientist, who will presented the

findings at the Physiological Society's annual conference hosted by

UCL.

Dr King, of the UCL Department of Physiology, led the research

that found the molecular basis for the long-standing theory that

heat, such as that from a hot-water bottle applied to the skin,

provides relief from internal pains, such as stomach aches, for up to

an hour.

Dr King said: " The pain of colic, cystitis and period pain is caused

by a temporary reduction in blood flow to or over-distension of

hollow organs such as the bowel or uterus, causing local tissue

damage and activating pain receptors.

" The heat doesn't just provide comfort and have a placebo effect - it

actually deactivates the pain at a molecular level in much the same

way as pharmaceutical painkillers work. We have discovered how this

molecular process works. "

If heat over 40 degrees Celsius is applied to the skin near to where

internal pain is felt, it switches on heat receptors located at the

site of injury. These heat receptors in turn block the effect of

chemical messengers that cause pain to be detected by the body.

The team found that the heat receptor, known as TRPV1, can block P2X3

pain receptors. These pain receptors are activated by ATP, the body's

source of energy, when it is released from damaged and dying cells.

By blocking the pain receptors, TRPV1 is able to stop the pain being

sensed by the body.

Dr King added: " The problem with heat is that it can only provide

temporary relief. The focus of future research will continue to be

the discovery and development of pain relief drugs that will block

P2X3 pain receptors. Our research adds to a body of work showing that

P2X3 receptors are key to the development of drugs that will

alleviate debilitating internal pain. "

Scientists made this discovery using recombinant DNA technology to

make both heat and pain receptor proteins in the same host cell and

watching the molecular interactions between the TRPV1 protein and the

P2X3 protein, switched on by capsaicin, the active ingredient in

chilli, and ATP, respectively.

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