In the not-too-distant future, patients in pain may be better treated with fewer side effects using lower morphine doses combined with new painkillers already under development, according to a new study reported by researchers from the University of California San Francisco in the March 26 issue of the scientific journal Nature.
We may perceive pain as a continuum ranging from irritating to unbearable, but a UCSF research team led by Allan Basbaum, PhD, now has made the striking discovery that -- biologically -- mild pain and more intense pain are distinct and governed by different signaling molecules. Effective management of intense pain should take these distinctions into account, Basbaum says.
"Pain is not a single phenomenon that can always be attacked with one type of analgesic drug," according to Basbaum, chairman of anatomy and research scientist with the W.M. Keck Foundation Center for Integrative Neuroscience at UCSF.
Yu Qing Cao, a graduate student in Basbaum's lab, conducted key experiments on mice which revealed that two different types of signaling molecules, called neurotransmitters, are involved in mild pain and more intense pain.
For several years researchers have known that the neurotransmitter glutamate is important in signaling pain. But Cao, along with researchers in the lab of Charles Epstein, MD, UCSF professor of pediatrics, developed a "knockout" strain of mice lacking a gene for substance P and neurokinin A, two members of a different class of neurotransmitters called the tachykinins.
By measuring how long it took mice to move away from applied mechanical pressure, or how many seconds they licked skin where hot pepper extract had been applied, Cao determined that the knockout mice were as sensitive to mild pain as normal mice, but that they were much less sensitive to moderate or more intense pain.
The research team concluded that substance P or neurokinin
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Contact: Jeffery Norris
jnorris@itsa.ucsf.edu
(415) 476-2557
University of California - San Francisco
25-Mar-1998