Emotions reflect the state of the soul. Pain is a condition of the body. Pain and emotions are interconnected: bitter emotions can lead to physical pain, and pain almost always shows up in our emotions. We’ve already talked about how nature gives us regulators of emotion. Could it be that, while wiring our bodies to feel pain, nature also built “controllers” to dial that pain up or down? It did. Neurophysiologists have recently discovered that two groups of peptides—substance P and endorphins—are directly tied to pain sensations.
Substance P has been known for quite a while. American scientists W. Euler and J. Gaddum discovered it in 1931. Its name— which doesn’t reflect the peptide’s biological properties—comes from the English word “powder.” Endorphins, by contrast, were named for their function: they are endogenous morphines.
If substance P acts as a mediator and modulator of pain, then endorphins—those natural opioids inside us—blunt the pain. The more substance P present, the stronger the pain; the more endorphins, the weaker the pain.
The discovery of endorphins is credited to American researcher Eric J. Simon of New York University and Scottish scientist J. Costall of Aberdeen. Simon showed that certain brain cells have specific receptors that bind morphine. When Costall heard about Simon’s finding, he asked, “It can’t be a coincidence. Surely those receptors are designed to sense the body’s own morphine—so where is it?” Costall’s team found it. Later researchers identified related, lower-molecular-weight substances called enkephalins (named after “encephalon,” meaning brain).
Endorphins caused a real stir in medicine. Their pain-relieving power can exceed that of morphine. Unlike morphine, which can cause side effects and addiction, endorphins produced by the body don’t have those problems. That shifted pain relief from a purely medical problem into a social one: if we learn to manage endorphin levels, we might reduce or eliminate the need for morphine and other narcotics in medicine, cut production of those drugs, and help fight drug addiction, which has become a major problem in capitalist countries.
Pharmacologists and other biologists and physicians have turned their efforts in that direction. Significant progress has been made: researchers have mapped where endorphins are synthesized (in addition to nerve cells, certain APUD-system cells in the stomach, pancreas, and other organs are involved), studied their functional properties, and created substances that regulate their secretion. That last point has clinical implications already: reports describe minor surgeries where pain relief was achieved not by conventional anesthetics but by drugs that boost the body’s endorphin synthesis.
The search continues. “The discovery of endorphins,” write I. Barrer and F. Giron in the Parisian magazine “Poin,” “marks the opening of a new path toward the coveted goal—ideal pain relief.”
