Senile snails give insight into human ageing
Scientists are using the common pond snail to look for treatments for senility.
Researchers at the University of Brighton have discovered that snails suffer the same kind of memory loss that humans experience as they get older.
Professor Richard Faragher said: “One of the things you have to remember if you are a snail or, indeed, a person, is where you have left your food.
“As these little chaps get older, they forget where their lettuce is. I think all of us humans have been there and can sympathise with them.
“These poor animals get forgetful – there are such things as senile snails.”
By studying the snail’s nervous system scientists are understanding how the more complex human brain functions and that could help in developing treatments for conditions such as dementia.
Professor Faragher, professor of biological gerontology and chair of the British Society for Research on Ageing, said: “This research will help us understand the root causes before you start to see the serious problems with learning and memory.
“The human brain is the Rolls Royce of brains and the snail’s is the Mini Metro but the mechanisms involved are the same.
“By understanding how the snail’s brain changes we can understand how to make it work normally and, by analogy, we can do the same with humans.”
Professor Faragher’s colleague Dr Mark Yeoman is looking at what might cause our brains to age, a process that seems to involve the connections between some nerve cells losing their efficiency over time.
This is the reason that we may not be able to learn things as easily and forget them more often and more quickly than before. This is not the same as degenerative disease like Alzheimer’s, where nerve cells actually die in large numbers, but a more subtle process that we think of as natural to getting older. But even apparently natural things like becoming absent minded have a physical cause, and Dr Yeoman thinks that snails might shed some light on this.
He said the giant pond snail, Lymnaea stagnalis, has two advantages for researchers – its brain system is simple, and its nerve cells are differently coloured, both making studying their brains easy.
Dr Yeoman has found that some of the older snails – those more than a year old – become forgetful. He tests this by giving snails a sugar solution as food at the same time as spraying a neutral chemical smell of pear drops round them. The snails associate the food and the smell.
Days later he simply sprays the pear drop solution round them; although there is no sugar for them to eat, the snails begin trying to chew, as if the food was there too, a sign that they remembered the smell went with the food. A younger snail can keep this memory for a month, but older ones only for a week, because their brain cells have lost efficiency.
Older snails also begin not to be able to swallow leaves properly, an indication that some part of the brain or nervous system that controls muscles has begun not to work properly.
Dr Yeoman can find out which nerves in the snails’ brains are still sending electrical signals as normal and which are failing to do so because age has caused them to malfunction.
He can then examine the difference on a molecular scale to see which proteins in the malfunctioning nerve cell have changed and try to establish what caused them to alter.
He said there were similarities between snail brains and human ones – the nerve cells are similar and the chemicals that move between one brain cell and another, such as serotonin and dopamine, are also the same.
So what causes ageing in a snail’s brain could well be similar to what ages the human brain – it may not be a coincidence that older people can also have difficulty in swallowing, just as snails do, as well as problems remembering.
Dr Yeoman, whose research is funded by the Engineering and Physical Sciences Research Council and the Biotechnology and Biological Sciences Research Council, hopes his research will find out the cause.
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