Candace B. Pert, a noted neuroscientist, died Sept. 12 at her home in Potomac. She was 67. (Michael Ruff)

Candace B. Pert, a neuroscientist and pharmacologist who was credited with unlocking a chemical mystery of the brain while in graduate school and later became a noted researcher in the field of mind-body medicine, died Sept. 12 at her home in Potomac. She was 67.

The cause was apparent cardiovascular arrest, said her sister, Deane Beebe.

Dr. Pert rose to prominence in the early 1970s as a graduate pharmacology student at Johns Hopkins University in Baltimore. Working with neuroscientist Solomon H. Snyder, she discovered what became known as the opiate receptor — the first verified receptor in the brain and the one responsive to painkillers such as morphine and drugs such as opium.

Receptors, which are found in the brain and throughout the body, are often compared to locks. Each receptor has corresponding chemicals that fit the receptor in the way that a key fits a lock.

“Any way you can make love, somebody’s already thought of,” Dr. Pert told The Washington Post years later. “Any crazy caper you can get up to, any great meal you can think of, any combination of children or idea of how to raise them — somebody’s already thought of. But nobody’s ever discovered an opiate receptor before.”

To make their discovery, Dr. Pert and her colleagues introduced radioactively tagged drugs to brain material and observed where the drugs bonded with the tissue. Their findings, published in the journal Science in 1973, raised beguiling questions about the neurological system.

“God presumably did not put an opiate receptor in our brains so that we could eventually discover how to get high with opium,” Smithsonian magazine later quoted Dr. Pert as saying.

Scientists reasoned that the opiate receptor existed because the body produced a natural painkiller similar to analgesic drugs. In 1975, two researchers in Scotland, Hans W. Kosterlitz and John Hughes, identified enkephalins — naturally occurring substances in the body that can relieve pain or create feelings of euphoria.

Kosterlitz, Hughes and Snyder shared the 1978 Lasker Award for basic medical research, which is often regarded as a precursor to the Nobel Prize. Dr. Pert attracted media attention by protesting her omission from the award.

By her account, Dr. Pert had continued the research after Snyder ordered her to move on to other projects. Some observers suggested that she had been excluded because she was a woman, The Post reported.

On the other hand, young researchers are generally expected to stand aside when more-senior colleagues take credit for group achievements, with the understanding that they will receive the same privileges later in their own careers.

Because of her protestations, Dr. Pert became, according to Smithsonian, “something of a pariah to the establishment.” Years after the incident, she told the Denver Post that she had been “naive” and “stepped too far over the line.”

After receiving her PhD from Johns Hopkins in 1974, Dr. Pert joined the National Institute of Mental Health in Bethesda and deepened her research to include neuropeptides — chemicals used by the brain for communication. In 1982, she became the NIMH’s section chief for brain biochemistry. She was credited with leading the team that discovered Peptide T, a chemical thought to be potentially capable of impeding the HIV virus.

In 1987, Dr. Pert left NIMH and co-founded Peptide Design, a company based in Germantown that continued research into the use of Peptide T for HIV/AIDS and other conditions, said her husband, immunologist-virologist Michael Ruff. He was co-founder of Peptide Design.

After working at Georgetown University as a research professor for more than a decade, Dr. Pert co-founded Rapid Pharmaceuticals with Ruff and another colleague in 2007. The Rockville-based company develops experimental treatments for HIV/AIDS, autism, Alzheimer’s disease and pain management, Ruff said.

Candace Dorinda Beebe was born June 26, 1946, in New York City. She entered Bryn Mawr College in Pennsylvania as an English major and began studying science on the suggestion of her first husband, Agu Pert, a future scientific collaborator.

She received a bachelor’s degree in biology in 1970 and became fascinated by analgesics in part because of her injury in a horseback-riding accident shortly before she entered Johns Hopkins.

In the later years of her career, Dr. Pert became an outspoken advocate for the scientific research behind the mind-body connection, a line of medical inquiry founded on the notion that the two realms are inextricably linked. She was credited with adhering strictly to scientific standards even as she pursued un­or­tho­dox ideas.

Miles Herkenham, chief of the NIMH’s section on functional neuroanatomy and a former colleague of Dr. Pert’s, said in an interview that she “represented legitimate science in a crowd of people who are not legitimate scientists.”

In addition to her more specialized publications, she wrote two books for general readers, “Molecules of Emotion” (1997) and “Everything You Need to Know to Feel Go(o)d” (2006). She also appeared on television programs such as PBS’s “NewsHour” and in Bill Moyers’s “Healing and the Mind” (1993).

Dr. Pert’s first marriage ended in divorce. Besides her sister, survivors include her husband of 27 years, Michael Ruff of Potomac; three children from her first marriage, Evan Pert of Fredericksburg, Vanessa Pert Haneberg of Arnold and Brandon Pert of Los Angeles; and a grandson.

Dr. Pert was an advocate for women in science, once remarking that “it’s very difficult to climb up the bureaucratic ladder if you’re a female.” Her awards included a 1978 Arthur S. Flemming Award for exceptional service by a government employee.

Dr. Pert seemed to embrace her reputation as an independent-minded scientist. She kept in her office a sign that read: “If you are getting run out of town, get in front of the crowd and make it look like a parade.”