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Sunday, 3 December, 2000, 01:19 GMT
Ovary loss 'kills brain cells in days'
When fertility ends, brain cells die
When fertility ends, brain cells die
Removing ovaries kills the brain cells that protect against Parkinson's Disease within 10 days.

That the removal of the oestrogen kills key dopamine cells was already known, but American researchers have now shown how quickly the cells die.

Researchers from the Yale School of Medicine removed the ovaries from female monkeys, depriving them of oestrogen and related hormones.

Within 10 days, the 30% of the key dopamine neurons in the brain that protect against Parkinson's Disease had disappeared. Within a month, they were permanently lost.

If oestrogen is reintroduced within 10 days, cells can regrow.

D Eugene Redmond, professor of psychiatry and neurosurgery at Yale, led the research

He said: "The results of the study shed light on why men, who have less oestrogen in their bodies and more androgen to antagonise it, are more likely to develop Parkinson's Disease than pre-menopausal women, and why post-menopausal women are more likely then to develop the disease."

Oestrogen effects

Monkeys were used in the experiments because they have menstrual cycles, like humans.

Scientists compared dopamine levels in intact male and female monkeys, and in those whose ovaries had been removed, as well as monkeys who had their ovaries removed, but were set to have oestrogen replacement therapy.

The destruction of these neurons is most closely associated with Parkinson's Disease and dementia.

The results ... shed light on why men ... are more likely to develop Parkinson's Disease than pre-menopausal women, and why post-menopausal women are more likely then to develop the disease.

Professor D Eugene Redmond

Researchers warn further studies are needed into longer-term effects of oestrogen deprivation before oestrogen therapy can be recommended.

Professor Redmond added: "It suggests a new prevention or treatment strategy for patients at risk of Parkinson's Disease and certain forms of memory-impairing disorders.

"This also provides another rationale for oestrogen replacement therapy for postmenopausal women.

"Thirty per cent is a very significant number of cells in this system. Maintenance, restoration or loss of that many cells could make the difference between severe Parkinsonism and having no symptoms at all."

Professor Adrian Williams, medical advisor to the Parkinson's Disease Society said: "This research offers interesting results with possible practical applications for Parkinson's Disease.

"I't supports a major role for hormonal influences on neural function, and bolsters the argument that oestrogen deficiency should be avoided if possible."

But Cardiff-based Professor Maurice Scanlon, who is carrying out research into oestrogen replacement therapy dopamine in relation to prolactin levels, said more work needed to be done.

"The findings are quite striking. But what they haven't shown is that the monkeys go on to get any disease."

He added scientists would then have to prove the same link in humans.

The research is published in The Journal of Neuroscience.

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