Dopamine controls formation of new brain cells

A study of the salamander brain has led researchers at Karolinska Institutet to discover a hitherto unknown function of the neurotransmitter dopamine. In an article published in the prestigious scientific journal Cell Stem Cell they show how in acting as a kind of switch for stem cells, dopamine controls the formation of new neurons in the adult brain. Their findings may one day contribute to new treatments for neurodegenerative diseases, such as Parkinson's.

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 salamnder brain detects the absence of these cells. This question is a fundamental one since it has not been known what causes the new formation of nerve cells and why the process ceases when the correct number have been made.

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.

"The medicine often given to Parkinson's patients is L-dopa, which is converted into dopamine in the brain," says Dr Andras Simon, who led the study at the Department of Cell and Molecular Biology. "When the salamanders were treated with L-dopa, the production of new dopamine-producing neurons was almost completely inhibited and the animals were unable to recover. However, the converse also applies. If dopamine signalling is blocked, new neurons are born unnecessarily."

I was pretty upset about it but considering I saved them from being carelessly crushed by drivers who just can’t seem to notice *hundreds* of them plodding across the road on the mountain top, en mass, during mating season [as if they ‘dart out so fast you can’t avoid them’] they had long, happy lives here.

They’re savage little beasts and contrary to popular belief, they do have teeth...LOL

http://wiki.answers.com/Q/Will_a_spotted_salamander_bite_your_child

“salamanders do bite but they wont if you dont make them mad”

Words to the wise.

Most folks would never guess just how personable something with no eyebrows can be, do they?

“Sal” was a trip.

She was very interactive and loved it when I dipped a soft Kolinsky sable watercolor brush into warm water and gently stroked her back and head with it.
[for potential salamander keepers, it’s not good to handle them too much because their skin is fragile and its slime coat is easily damaged, plus, they secrete a mild toxin that is not much fun if you get it in your eyes]

The little boys never came out much.

I never pushed the issue...I assumed if they were scared of her they probably knew more than I did.

Gosh.

I haven’t thought of them in a long time.

Yep, they do have their own personalities. Badass had no fear of me but no aggression either. The little one was afraid of the grasshoppers. I only had them a couple of weeks and decided I didn't want them to end up like so many of my childhood pets. I wasn't sure I could keep them alive.

I don't think their teeth could break the skin. Not on mine but even Tiger Salamanders get bigger. Badass must have been about 7"-8"s long. He/she was about 2"s bigger around the belly when I let them go. :-)

Really cool critters. I'd love to see some of the bigger species that live in the mid-west and southern states. AFAIK Tigers are the only species in CO. When I lived in VT I got out of my truck in the woods, walked about fifty feet down a trail and there were two red efts walking away from each other. I left them alone but it was great to see them. I had seen them in books since I was a kid and always thought they were interesting and mysterious. And so they were!

That's cool about stroking them with a sable brush. I never got poisoned by their toxin. My great aunt lived on a farm in Iowa and had a toad in the root cellar that she brought flies regularly. There was a shelf or something it would get up on to be fed by her. It's hard not to like amphibians.

Possibly because grasshoppers aren’t their usual diet.

They prefer soft-bodied prey and the chitin in the exoskeletons of “hard” bugs can amass in their intestines and kill them.

I used blood worms which were small, very nutritious and not so cute that guilt overwhelmed me for feeding them to the ‘phibs.

Tigers are actually part of the “Mole” salamander family and spend most of their time under cover.

We have Eastern Spotteds here but you hardly ever see them.

Late Feb/early march is their breeding season and they cross roads following ancestral breeding paths, usually to their detriment because drivers just disregard them and run them down.
[hence my many years of standing alone on the cold, rainy mountain top with a flashlight and a bucket, trying to save as many as possible]

Later in the summer, if I’m really lucky, I’ll see the ‘toddlers’ who emerge from the ponds after spending the last 2 years in an aquatic form.

Red backs are really common and often I see them running _across the snow_ in the middle of winter.

Crazy, huh?

These are the ones we have here:

http://www.fish.state.pa.us/salamander.htm
[I know it’s PA but they’re all in MD, too]

The Jeffersons tend to cross the road when the Spotteds do but I gave up trying to save them.

The Spotteds are slow and lumbering but the Jeffersons are little turbo-manders.
I sure can’t out-run ‘em and they had a much better time dodging cars....:)

I’d love to see one of these but they’re west coast/Pacific critters.

http://www.californiaherps.com/salamanders/images/dtenebrosusneomemr083.jpg

*Huge*!

The only thing we have really big here is Hellbenders and finding them in a stream or crick is nearly impossible.

Little Bronze Frogs and Spring Peepers hang out near the motorcycle shop door waiting for the bugs who fry themselves on the security light to hit the ground.

[work smarter, not harder]....;D

We had a “Guard toad” who challenged anybody who came to our gate.
The stupid UPS driver [who knew the toad was always there and to stay at least 5 feet from the gate] pulled in too far and ran over it one day.

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