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Consider what happens inside your body when it is subjected to intense pain. Say, for example, you're on your way to work when a runaway car jumps the curb and crushes your left leg. First, your mangled limb lets loose a flood of chemicals, called prostaglandins, that trigger swelling and activate the nerves that stretch from leg to spine. As soon as the nerve signals reach the spinal column, another group of nerves takes over and passes the message on to the brain. It is only after the brain gets in on the act that you can "feel" your own pain.
Scientists have long known that morphine blunts that chain of pain reactions by preventing the spinal nerves from signaling the brain. But what they didn't know until the late 1980s is that these nerves are more than just glorified gatekeepers. They actually "remember" the body's past travails, causing permanent changes that are recorded in their molecular structure. "Think of the spinal cord as a voice-mail system," says neurobiologist Allan Basbaum of the University of California, San Francisco. "A message comes in and leaves something behind." The longer the injury persists, the more sensitive the spinal nerves become to painful stimuli--and the more intensely they signal the brain that something is wrong.
When Basbaum and his colleagues stumbled on this mailbox effect, they quickly realized that it could revolutionize surgery. In the past, most patients were put to sleep with a general anesthetic, which dulls the brain's memory of what has happened but does nothing to stop the spinal nerves from reacting. In the early 1990s, Basbaum's team showed that the spinal cord triggers a cascade of chemical and electrical signals during an operation. Once the brain comes out of its anesthesia-induced fog, it translates all this electrochemical activity into sheer agony.
Physicians have since learned how to short-circuit that chain reaction. By numbing the surgical site with a separate injection of a local anesthetic, they can prevent many of the pain signals from ever reaching the spinal cord. Then, by administering small amounts of morphine to the spinal cord once the operation is over, they can significantly reduce any pain that occurs after the local anesthetic wears off.
Basbaum's work proved that morphine not only relieves pain but prevents it from occurring in the first place. Building on his insights, other researchers determined that morphine and pre-emptive anesthesia given to patients undergoing abdominal surgery reduced their pain so effectively that they left the hospital, on average, more than a day ahead of schedule.
But doctors were not entirely comfortable putting these ideas into practice. There is an ingrained prejudice within the medical community against using narcotics--even when they are indicated. Everybody seems to be concerned about possibly turning thousands of sober, law- abiding patient into morphine addicts.
That's nonsense, says Robert Raffa, a pharmacology professor at Temple University in Philadelphia. "Clearly there is potential for abuse," he admits. "But the idea that your mom will go into a hospital, be exposed to morphine and automatically become an addict is just plain wrong."