The publication of the gate control theory and the founding of the IASP (International Association for the Study of Pain) attracted many young researchers to the field and sparked an explosion in pain research in the 1970s and 1980s. Among the most important developments from this period was the discovery of the opiate receptors in the brain.

	John Liebeskind

In 1971, John C. Liebeskind (1935-1997) and his lab associates at UCLA described an odd phenomenon in Science: stimulation of the midbrain area called the periaqueductal gray (PAG) produced pain in animals, but stopping or reducing stimulation produced an analgesic effect. In the discussion section, they suggested that this effect was analogous to the analgesic action of opiate drugs. The following year, Liebeskind, David Mayer, and Huda Akil reported that this Stimulation-Produced Analgesia (SPA) was blocked by the opiate antagonist, naloxone.

	Map to the Franz Hall "C" Floor Lab, prepared for John Liebeskind by his students

Liebeskind had a close relationship with his students and fellows. Although his offices were eleven floors removed from the laboratory, he worked with students and postdocs intensively on developing ideas and presenting them for publication.

Stimulation-Produced Analgesia

"We were very aware that this was a fascinating phenomenon, a very powerful phenomenon; we felt that we understood something about it and understood it in a way that itself was as important as the phenomenon. That by the way we understood it, it would lead to other things, would lead to other kinds of experiments and applications. So that, for example, one of the things we said in the article, we drew some fascinating parallels between how brain stimulation produced analgesia and where in the nervous system it produced analgesia, and how and where opiate drugs worked. . . So kind of the word spread, as it were, and people caught on to these concepts and pursued them; they were interested by them." (From the Oral History of John C. Liebeskind, 1995)

	Portrai of Kosterlitz

The work of the Liebeskind lab suggested that the brain itself produced opiate-like substances which acted to modulate the perception of pain. Building on this work, Solomon Snyder, Candace Pert, and Lars Terenius identified specific opiate receptor cells in the brain. In 1977, Hans Kosterlitz and his associates discovered enkephalin, the first known opioid produced by the human body.

Kosterlitz on enkephalins (1980): his discovery illuminated the brain's role in pain modulation and had direct clinical implications.

"Scientists can map brain structures that contain opiate receptors and are responsible for opiate drug effects on the body. This positron emission tomography (PET) scan of mu opiate receptors in the human brain shows the highest concentrations in the thalamus (red) which is involved in pain; intermediate concentrations in the cerebral cortex (green) and basal ganglia (yellow and green) which plays an important role in movement and emotions; and low levels in the visual cortex (violet)." (Brain Briefings ©1994 Society for Neuroscience, reproduced with permission.)

"Pain Can Kill!"

Liebeskind's lab remained in the forefront of the field for more than twenty years. In the 1980s, he and his team demonstrated that pain repressed the body's immune system and could indirectly promote tumor growth, or in Liebeskind's stark phrase, "Pain Can Kill!"

Liebeskind's editorial in the APS Bulletin (1983) was a forceful expression of his lifelong view that the ultimate purpose of pain research was to provide better care for pain patients and to ensure that no patient should have to suffer the debilitating and dangerous condition of chronic pain.