Julius Axelrod, a pharmacologist and neuroscientist who shared the 1970 Nobel Prize in medicine for his insights into how human brain cells communicate with each other, died last December 29 at the age of 92. Axelrod’s findings about the behavior of neurotransmitters – the chemical messengers of the brain – drew a clear connection between the physiology of the brain and emotional moods. His discoveries paved the way for the multibillion-dollar ­antidepressant drug industry, and in so doing helped give rise to what was later called by some “Prozac Nation.”

Axelrod, who was known as ­”Julie,” focused on how the neurotransmitters secreted by a brain cell travel across a synapse (the space between nerves) and are then picked up by a receptor on the surface of another cell. Before Axelrod’s research in the late 1950s, scientists believed that neurotransmitters were broken down by enzymes in the brain after they crossed a synapse. But Axelrod’s findings suggested that, instead, they were retrieved by the very cells that released them, in a process called “reuptake.”

The identification of this process allowed drug researchers to pinpoint areas where they might boost or lower ­chemi­cal levels in the nervous system. For example, selective serotonin reuptake inhibitors, the class of antidepressants that includes Prozac, work by blocking the reuptake process that Axelrod identified.

Born on Manhattan’s Lower East Side in 1912, Axelrod was the first to describe his origins as humble, even inauspicious. The son of a Jewish basket maker who emigrated from Polish Galicia, Axelrod fortified his undistinguished early edu­cation by spending most of his time at the ­library reading Upton Sinclair, H. L. Mencken, and Leo Tolstoy.

After attending New York University for one year, Axelrod ran out of money, which forced him to transfer to City College of New York. Although he showed a greater aptitude for history, philosophy, and literature, he decided to apply to medi­cal school; but he was rejected everywhere. He completed his undergraduate studies in 1933 at the height of the Depression and managed to find a job paying $25 a month at an NYU lab.

Axelrod soon took a research job at the New York City Department of Health’s Laboratory of Industrial Hygiene, where he remained until 1946, taking night classes and earning a master’s in chemistry along the way. In 1949, he joined the National Heart Institute and briefly returned to school in 1954 to earn his PhD from George Washington University.

In 1955, Axelrod joined the National Institute of Mental Health (NIMH), where he established his famed laboratory. He remained at NIMH until his retirement in 1984 and presided over a cadre of postdoctoral students, many of whom would become distinguished researchers themselves. He also became a vocal advocate for the preservation of basic research in the sciences and took up various political causes.

Axelrod was happiest, however, away from the spotlight, acknowledging his accomplishments with modesty and even a touch of self-deprecation. As he liked to recount, he was notified of his Nobel Prize while on his annual trip to the dentist. He was speechless, he said, but only because his mouth was stuffed with cotton.