Body Chemicals Involved in Fibro Pain
In people who have fibromyalgia, certain body chemicals are altered, which can affect the degree of their pain. In addition to central sensitization and wind-up phenomenon, changes in the levels of certain neurochemicals in your body can exaggerate your sensitivity. Some of the neurochemicals involved in fibromyalgia include substance P, serotonin, endorphins, and growth hormone.
People who have FMS have higher-than-normal levels of substance P, a chemical that makes pain nerves much more sensitive. High levels of substance P make a person quicker to feel pain than someone with lower levels. Studies show that people with fibromyalgia have, on average, about three times the normal level of substance P.
Research has also shown that simply applying pressure to bring on pain does not appear to increase substance P levels. This finding suggests that elevated levels of substance P aren't brought on by something external but rather that something internal is raising the levels.
Serotonin is a neurotransmitter found in unusually low levels in people with fibromyalgia. Neurotransmitters are chemical messengers that transmit messages through nerve cells. Serotonin has numerous roles in the body. It regulates mood and alleviates depression, promotes sound sleep, and relieves pain. It also regulates the immune system and promotes smooth muscle function.
Most times when you get hurt, emotionally or physically, your body doesn't sit by idly and absorb the assault. It launches its own defense. One way that it does that is by releasing natural opiates called endorphins. These feel-good substances are also responsible for the high that some people experience from exercise, sex, addictive drugs, and certain foods, such as chocolate.
Endorphins block the transmission of pain within the nervous system by binding to the same receptor sites that pain signals use. But in people who have chronic pain like fibromyalgia, endorphins offer little respite. After a while, enzymes called endorphinase devour the endorphins, rendering them ineffective.
Low levels of serotonin and other hormones, a lack of deep sleep, and overproduction of a compound called somatostatin cause many fibro patients to have abnormally low levels of growth hormone, a substance essential to normal muscle metabolism and repair. A reduction in growth hormone occurs in about a third of fibromyalgia patients.
Researchers at the University of Michigan have found that women are better able to tolerate pain when estrogen levels are high by releasing endorphins that soften the signals. Unfortunately, a dip in estrogen, which occurs just before your period, reduces the system's effectiveness, which may explain why women say their FMS symptoms are worse during their periods.
As much as 80 percent of growth hormone is secreted when we are in the deepest stages of sleep. If we are deprived of deep sleep — which is what happens in fibromyalgia patients — the muscles go unrepaired. Even tiny microtraumas go unrestored and are subject to further damage.
Low levels of growth hormone usually also result in low levels of insulin-like growth factor (Ig-4), another hormone. While some studies have shown that giving growth hormone to correct the deficiency can reduce fibro symptoms, the treatment costs almost $80,000 a year, and most insurance plans won't pay for it.