UCSF in The News: Huff Post article There's So Much We Still Don't Know about Pain..Featuring Dr. David Julius, Professor and Chair of Physiology

Why Pain Is So Hard To Treat 

“We use ‘pain’ as one word, but I think it reflects a panoply of different disorders,” says David Julius, chair of physiology at the University of California, San Francisco, School of Medicine, who has spent decades trying to understand how humans perceive pain.

Pain can be recovery from a broken ankle or a pulled wisdom tooth. It can be migraines, or backaches, or the burning of chemotherapy-induced neuropathy, or debilitating sickle cell episodes. Pain can be in muscles, bones, nerves. 

Pain has long been treated with a very limited arsenal of drugs that don’t precisely distinguish between one type of pain and another. The biggest reason is that scientists don’t yet understand all the mechanisms that cause pain, Julius says. “You got to understand how things work before you can fix them. Otherwise you’re taking potshots in the dark.”

The path of pain starts with sensory neurons that activate in response to a stimulus. From there, the neural signal travels to the spinal cord and up into the brain. It’s a chain that gets more complicated the further up you go, and there are mysteries at every step that scientists are still trying to unravel. 

Julius’ work focuses on the first step: what is happening on a cellular level when you feel pain. In the late 1990s, he figured out that the reason we get a burning sensation from chili peppers — or, more specifically, the capsaicin that gives them their kick — is that they activate receptors in nerve cells that also respond to painfully high heat. Julius’ lab also discovered the so-called wasabi receptor, which responds to both its pungent namesake and inflammation in the body. 

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