Learning from the Salamander Brain
Salamanders can regenerate more than just limbs: "A study of the salamander brain has led [researchers] to discover a hitherto unknown function of the neurotransmitter dopamine. ... The study was conducted using salamanders which unlike mammals recover fully from a Parkinson's-like condition within a four week period. Parkinson's disease is a neurodegenerative disease characterised by the death of dopamine-producing cells in the mid-brain. As the salamander re-builds all lost dopamine-producing neurons, the researchers examined how the salamander brain detects the absence of these cells. ... What they found out was that the salamander's stem cells are automatically activated when the dopamine concentration drops as a result of the death of dopamine-producing neurons, meaning that the neurotransmitter acts as a constant handbrake on stem cell activity. ... As in mammals, the formation of neurons in the salamander mid-brain is virtually non-existent under normal circumstances. Therefore by studying the salamander, scientists can understand how the production of new nerve cells can be resumed once it has stopped, and how it can be stopped when no more neurons are needed. It is precisely in this regulation that dopamine seems to play a vital part. Many observations also suggest that similar mechanisms are active in other animal species too. Further comparative studies can shed light on how neurotransmitters control stem cells in the brain, knowledge that is of potential use in the development of therapies for neurodegenerative diseases."
Link: http://ki.se/ki/jsp/polopoly.jsp?l=en&d=130&a=120420&newsdep=130