A Swede and two U.S. researchers won the Nobel Prize in medicine Monday for discoveries about how messages are transmitted between brain cells, work that has paid off for treating Parkinson's disease and depression.
Arvid Carlsson, Paul Greengard and Eric Kandel will share $915,000 prize for their pioneering discoveries concerning one way brain cells send messages to each other, called "slow synaptic transmission."
These discoveries have been crucial for understanding how the brain normally works. In addition, the work laid the groundwork for developing the standard treatment for Parkinson's disease and contributed to the development of a class of antidepressants that includes Prozac, the Nobel Assembly at Karolinska Institute said.
Carlsson, 77, is with the University of Goteborg in Sweden, Greengard, 74, is with Rockefeller University in New York and Kandel, 70, is an Austrian-born U.S. citizen with Columbia University in New York.
The medicine prize was the first announced in a week of awards. The winners of the prizes for physics and chemistry will be announced Tuesday and for economics -- the only one not established in Nobel's will -- on Wednesday in Stockholm.
The awards culminate Friday with the coveted peace prize in Oslo, Norway. The date for the literature prize, also announced in Stockholm, has not yet been set.
Carlsson said he was thrilled to learn Monday morning that he had won.
"What shall I say, you get glad of course, overwhelmed," he said in an interview with Swedish radio.
Carlsson's studies during the late 1950s led to the development of the drug L-dopa, still the most important treatment for the disease, the committee said.
His research also shed light on how other drugs work, especially antipsychotic drugs used against schizophrenia.
Carlsson's work has contributed strongly to the development of a generation of anti-depression drugs called SSRIs (selective serotonin reuptake inhibitors), which includes Prozac, the Nobel committee said.
"The discoveries of Arvid Carlsson have had great importance for the treatment of depression, which is one of our most common diseases," the citation said.
Greengard was awarded for showing how brain cells respond to dopamine and other chemical messengers.
Kandel was cited for his research on the biology of memory, showing the importance of changes in the synapse, the place where chemical messages pass from one brain cell to another.
Tim Bliss, head of neuroscience at the National Institute for Medical Research in London, said Kandel's work -- ongoing since the 1960s -- could someday lead to new treatments for Alzheimer's disease and other conditions involving memory loss.
"It's a very major piece of work and he's been an outstanding leader in the field for many years," Bliss said. "He identified the physical embodiment of learning and memory in the brain."
This year's award for medicine was bumped to the top slot after the academy failed to reach a decision last week on the literature prize -- usually the first announced
The Swedish Academy, which traditionally keeps the date of the literature prize secret until a couple days before it announces the winner, has not set a time yet, but it is always a Thursday, usually in October.
The suspense for the literature award was heightened last week when the academy failed to reach a decision.
Alfred Nobel, the Swedish industrialist and inventor of dynamite, left only vague guidelines in his will establishing the prizes. The selection committees deliberate in strict secrecy.
The only public hints available are for the peace prize. The five-member awards committee never reveals the candidates, but sometimes those making the nominations announce their favorites.
This year that includes President Clinton and former President Jimmy Carter for wide-ranging peace efforts, as well as former U.S. Sen. George Mitchell for his efforts to resolve conflict in Northern Ireland.
As for the first announcement, Nobel's direction that a prize be awarded to the person who made "the most important discovery within the domain of physiology or medicine" is interpreted by a committee of 50 professors from the world-renowned Karolinska Institute in the Swedish capital.
The Nobel Assembly at Karolinska invites nominations from previous recipients, professors of medicine and other professionals worldwide before whittling down its choices in the fall, as do the other selection committees.
Last year's winner was Dr. Guenter Blobel, 64, a German native and U.S. citizen who discovered how proteins find their rightful places in cells -- a process that goes awry in diseases like cystic fibrosis and plays a key role in the manufacture of some medicines.
The awards always are presented Dec. 10, the anniversary of Nobel's death in 1896.