Antioxidants: The New Painkiller?

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Antioxidants: The New Painkiller?

http://www.medicalnewstoday.com/medicalnews.php?newsid=56176

Antioxidant-based pain killers may one day become a viable

alternative to addictive medications such as morphine.

Researchers found that synthetic antioxidants practically eradicated

pain-like behavior in nearly three-quarters of mice with inflamed

hind paws.

" When it comes to pain killers, there aren't many choices between

over-the-counter pain relievers like ibuprofen and aspirin and

prescription opiates like morphine, " said s, a

professor of physiology and cell biology at Ohio State University.

He's the lead author of a study examining the effects of

antioxidants as pain killers.

" We need drugs that fall somewhere between these two extremes, "

s said. " Someone suffering from chronic pain can become

dependent on, or even addicted to, heavy-duty pain killers like

morphine. "

The study appears in a recent issue of the journal Behavioural Brain

Research.

Chronic pain is such a formidable problem that, in 2000, Congress

passed a bill designating January 1, 2001 as the beginning of

the " Decade of Pain Control and Research. "

Antioxidants neutralize free radicals, substances that damage cells.

While our bodies constantly produce free radicals, healthy tissues

inactivate these damaging substances and keep their levels in check.

It's when free-radical production somehow exceeds the body's natural

defenses that problems occur. Researchers have linked this excessive

production to diseases like cancer and Alzheimer's.

A handful of studies published in the last 10 years suggest that

free radicals may also contribute to chronic pain. Left unchecked,

free radicals build up in the body and can further damage already-

injured tissue.

An equally small number of studies, including those by s,

suggest that antioxidants may fight chronic pain by helping the body

to break down free radicals.

" Studying the pain-killing effects of antioxidants is an emerging

area of research, " s said. " The FDA hasn't approved

antioxidants for the treatment of chronic pain. But down the road we

may see some drugs that contain antioxidants. "

s and his colleagues first injected one of three different

synthetic antioxidants into mice. An additional group of control

mice received only saline. The antioxidants used in this study - PBN

(phenyl-N-tert-butylnitrone), TEMPOL (4-hydroxy-2,2,6,6-

tetramethylpiperidine-1-oxy) and NAC (N-acetyl-L-cysteine) - aren't

the same as those found in fruits and vegetables, and two, PBM and

TEMPOL, are currently only available for scientific purposes. NAC is

available as a dietary supplement.

" Right now we're trying to show that antioxidants are viable pain

killers, " s said. " Similar work by other researchers

suggested that these antioxidants were the best available. And while

certain foods likely contain pain-killing antioxidants, these agents

have not been systematically tested as pain relievers. "

Shortly after the antioxidant or saline injections, the researchers

injected formalin, an irritant, into the left hind paw of each

mouse. Formalin causes inflammation, which provokes pain-like

behavior in mice. Researchers then spent the next 30 minutes

studying how much time an animal spent licking and biting its

injured paw. This kind of behavior suggests that the animal is in

pain or discomfort.

The researchers divided the 30-minute observation session into three

distinct periods - a five-minute acute phase, when the body first

senses and reacts to pain, followed by a 5- to 15-minute period of

relative stillness, as the body uses its own mechanisms to try to

inhibit the pain, and ending with a 15- to 30-minute period called

the tonic phase, during which a mouse starts to again vigorously

lick or bite its irritated paw, suggesting that it still feels pain

or discomfort.

The three antioxidants significantly reduced the amount of time that

mice spent biting and licking their injured paw during both the

acute and tonic phases. The researchers reported a 70- to 90-percent

reduction in pain-related behaviors during the acute phase, and a 78-

to 98-percent reduction in such behavior during the tonic phase.

" We were surprised to see such a major decrease in pain in the mice,

particularly during the acute phase, " s said. " The

antioxidants seem to preempt pain-like behavior.

" Other investigators have given antioxidants to rodents after

experimentally inducing pain and have found that the drugs relieve

pain to a similar extent. "