Arvid Carlsson Biography

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World of Genetics on Arvid Carlsson

On October 9, 2000, Arvid Carlsson, along with Paul Greengard and Eric Kandel, received the Nobel Prize in Medicine or Physiology for work concerning signal transduction in the nervous system. The three scientists have enhanced the understanding of normal brain function by discovering slow synaptic transmission, one type of signal transduction between nerve cells. In addition, their work establishes a basis for the evaluation of receptor genes and the genetic control of signal transmission.

The human brain has billions of nerve cells, or neurons. The junction between neurons is the synapse, the precise point of the transmission of information, or signal transduction, from the brain. Neurotransmitters are formed from chemical compounds, or precursors, and are released by the presynaptic cell into the synapse. There the neurotransmitters combine with protein molecules (receptors) from the postsynaptic cell to regulate electrical signal transmission between neurons.

Arvid Carlsson received the Nobel Prize for his discovery that dopamine is a neurotransmitter. Paul Greengard then discovered how dopamine and other neurotransmitters interact with the nervous system, and Eric Kandel determined that the synapse is the location of short-term and long-term memory in the sea slug. The research of the three Nobel laureates has led to a better understanding of how the brain functions and how neurological and psychiatric diseases can be caused by disturbances in signal transduction. Because of the findings of Carlsson, and the further research of Greengard and Kandel, scientists are able to understand the molecular mechanisms involved in certain neuropsychiatric diseases.

Arvid Carlsson's groundbreaking research in the 1950's established the relationship between neurotransmitters and diseases of the central nervous system when he discovered that a depleted neurotransmitter causes Parkinson's disease, a debilitating brain condition named after the English doctor who first described it in 1817. Carlsson moreover established that Parkinson's and other diseases caused by neurotransmitter dysregulation could be treated with drugs that regulate the governing neurotransmitters.

Born in Uppsala, Sweden, Arvid Carlsson received his medical degree from the University of Lund, Sweden, in 1951. He became professor of pharmacology at the University of Göteborg, Sweden, in 1959, and Professor Emeritus in 1989. A member of the Swedish Academy of Sciences and a foreign affiliate of the U.S. National Academy of Sciences, Professor Carlsson has authored several hundred peer-reviewed journal articles and received almost twenty prestigious awards before winning the Nobel Prize in 2000.

While conducting research at the University of Lund on how neurons transmit signals, Carlsson discovered that dopamine is a neurotransmitter. Scientists had previously believed that dopamine was only a precursor of noradrenaline, another neurotransmitter. Carlsson, however, was able to measure levels of dopamine in different brain tissue. Finding that dopamine existed in areas where there was no noradrenaline, he concluded that dopamine itself was a transmitter. He also discovered that dopamine was especially concentrated in the basal ganglia, the portion of the brain that controls motor behavior.

When Carlsson conducted several experiments with animals to deplete them of some of their neurotransmitters, he observed that the animals lost the ability for spontaneous movement. After he administered a precursor of dopamine called levodopa to the animals, they regained normal motor function. Carlsson then made a comparable experiment using the precursor of another transmitter, serotonin, but the animals did not regain their motor ability.

Recognizing the similarity between the impaired motor functioning in his animals and the symptoms (involuntary, uncontrollable tremors and increasing muscle rigidity) of Parkinson's disease in humans, Carlsson concluded that patients with Parkinson's must have a dopamine deficiency. His work led to the drug L-dopa being developed and used to treat Parkinson's, the first disease treated by drugs that replaced abnormally functioning neurotransmitters.

Carlsson's research led to an important discovery about schizophrenia, a hereditary mental illness. He found that the reuptake of dopamine by the receptors in the basal ganglia is much higher than normal in schizophrenics. Drugs that block dopamine receptors, therefore, are now prescribed for schizophrenia.

Carlsson also discovered that the dysregulation of another neurotransmitter, serotonin, causes clinical depression and several other behavioral disorders, including OCD (Obsessive- Compulsive Disorder), obesity, violent and aggressive behaviors, and suicide, one of the ten leading causes of death in the United States. His work led to the development of anti-depressive drugs called selective serotonin reuptake inhibitors (SSRIs, such as Prozac and Paxil) to treat the various illnesses caused by low levels of serotonin.

The drugs that emerged from Carlsson's research, however, are not cure-alls. L-dopa helps temporarily to alleviate some symptoms of Parkinson's, but it does not cure the disease; moreover, people who take L-dopa often suffer several unpleasant side effects, including nausea and cardiac irregularities. Patients who use SSRIs also complain of complications, including unwanted weight gain and some loss of sexual functioning. Nevertheless, Carlsson's research led to the understanding and treatment of serious neurological and psychiatric diseases.