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Regular use of antidepressants promotes the growth of new cells in the
hippocampus, an area of the brain where cells are known to waste away
in people who are depressed, new research in rats has shown.
Researchers gave the following antidepressants to rats, with each drug
representing a different class of antidepressant medication:
- tranylcypromine (Parnate)
- reboxetine (Edronax,
Vesta)
The researchers also treated rats with electroconvulsive
seizure therapy and an antipsychotic drug.
In rats treated with an antidepressant for 2 to
4 weeks, the number of brain cells in the hippocampus increased 20% to
40%. After 2 to 4 weeks of electroconvulsive seizure therapy, the
number of neurons increased by about 50%.
But it takes a while for the benefits of antidepressants
on brain cell growth to begin, the report indicates. Neuron numbers did
not increase in rats that were treated with an antidepressant for 1 to
5 days.
The antipsychotic drug
did not have any effect on neurons in the hippocampus.
"We are focusing on how antidepressants do
this," Dr. Duman said to Reuters Health, adding that if scientists
can understand how the drugs promote cell growth, they may be able to
develop new drugs that do an even better job.
The hippocampus
is a portion of the brain that plays a role in learning, memory and mood.
The Journal of Neuroscience,
December 15, 2000; 20:9104-9110
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