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Arvid Carlsson

 

Arvid Carlsson made the seminal discovery in the late 1950's that dopamine is a transmitter in the mammalian brain. Dopamine was found to be located in other regions of the brain than noradrenaline, especially in the basal ganglia, which are involved in the control of movements.

 

He then made a series of experiments that became the scientific basis for the successful therapy against Parkinson's disease. By giving the drug reserpine to animals he emptied the stores of dopamine in their brains. This produced the symptoms of Parkinson's disease, especially lack of movements (akinesia) and stiffness in the muscles (rigidity).

Left picture shows rich presence of dopamine-containing nerve endings (green dots) in the basal ganglia of a rat brain, visualized by fluorescence microscopy. To the right, a close-up of one nerve ending as seen in the electron microscope. The black dots in the vesicles represent stored dopamine.

 Dopamine is synthesized from its precursor L-DOPA. Carlsson, therefore, gave L-DOPA to the reserpine-treated animals. This restored dopamine levels in the brain, and the animals recovered from their akinesia and rigidity. Inspired by Carlsson's research, studies were made in humans. This showed that dopamine neurons degenerated in Parkinson patients and, most importantly, that L-DOPA had the same effect in humans - the patients regained their ability to move. These discoveries enable millions of Parkinson patients to live a normal life for many years.

 

Dopamine, secreted from the nerve terminal, activates membrane receptors in the target cell, leading to formation of messenger molecules in the receiving cell.




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