Pain Response Reduced by Eating Chocolate, Drinking Water

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Researchers from the University of Chicago have found that while animals are ingesting food or liquid, their response to pain and heat is reduced even in the absence of appetite or hunger.

During the study, which was published this week in the Journal of Neuroscience, laboratory rats were given either a chocolate chip to eat or had sugar water infused directly into their mouths. The control rats were given plain water to drink. As the animal swallowed the substance, a heat stimulus was ignited under their feet. Rats that were eating or drinking were slower to raise their paws in response to the heat.

The delayed response occurred regardless of calorie intake. The rats given plain water showed the same delayed response as those given sugary substances. When the rats were given bitter-tasting quinine, their response to pain was rapid, possibly indicating that non-pleasurable foods do not trigger the same pain relief response.

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The response studied is housed in the part of the brainstem called the nucleus raphe magnus. The main function of this part of the brain is pain mediation. Neurons in this part of the brain use the neurotransmitter serotonin. Serotonin also is an important regulator for pain sensation, and abnormal levels of serotonin can contribute to painful events such as migraine headaches. Chocolate is one food that is thought to raise serotonin levels.

Previous studies have shown that children given sugar water during booster shots had improved tolerance to the sensation of pain. The March 2009 issue of Pediatrics published a study involving 240 infants that were having blood drawn for tests. The infants that were given sugar water had lower pain scores than those given a placebo.

But University of Chicago neurology professor Peggy Mason say that her recent study indicates that the pain reduction is due to the act of ingestion, not the sugar and less caloric substances can be used with the same positive effect.

Sources Include: The University of Chicago Medical Center, Atlas of Functional Neuroanatomy

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