[2][3][4][5] The Nobel Committee honored him for his work on the release and reuptake of catecholamine neurotransmitters, a class of chemicals in the brain that include epinephrine, norepinephrine, and, as was later discovered, dopamine.

While working at the Department of Health, he attended night school and received his master's in sciences degree from New York University in 1941.

He examined the mechanisms and effects of caffeine, which led him to an interest in the sympathetic nervous system and its main neurotransmitters, epinephrine and norepinephrine.

During this time, Axelrod also conducted research on codeine, morphine, methamphetamine, and ephedrine and performed some of the first experiments on LSD.

Realizing that he could not advance his career without a PhD, he took a leave of absence from the NIH in 1954 to attend George Washington University Medical School.

Axelrod received his Nobel Prize for his work on the release, reuptake, and storage of the neurotransmitters epinephrine and norepinephrine, also known as adrenaline and noradrenaline.

Axelrod and colleagues went on to show that melatonin had wide-ranging effects throughout the central nervous system, allowing the pineal gland to function as a biological clock.

[citation needed] Axelrod injured his left eye when an ammonia bottle in the lab exploded; he would wear an eyepatch for the rest of his life.

Although he became an atheist early in life and resented the strict upbringing of his parents' religion, he identified with Jewish culture and joined several international fights against anti-Semitism.

Axelrod, along with fellow Nobel-laureates Marshall W. Nirenberg and Christian Anfinsen, organized a petition by scientists opposed to the new agency, arguing that by focusing solely on cancer, public funding would not be available for research into other, more solvable, medical problems.