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Monkeys allowed to self-administer 'Ecstasy' do not show brain damage (4/3/04)
What happens when you give a group of monkeys a pile of MDMA and a year and a half to use it? Binging, but no obvious brain damage, say researchers at the University of Michigan Medical School.
The monkeys were given the ability to self-dose with MDMA at various times by pressing a button connected to an IV pump. Typically, the monkeys would self-administer 2-3 mg/kg of MDMA per session when given unrestricted access (comparable to many human users), but binges of as much as 15 mg/kg were also recorded (equivalent to a 145 pound human taking about 14 average 'ecstasy' tablets in a single session.) Total MDMA consumption over the 18 month period was in the range of 120-250 mg/kg (roughly equivalent to a 145 pound person taking 110-235 'ecstasy' tablets.)
When the period of self-administration was over, the monkey's brains were analyzed for levels of serotonin, dopamine, and a protein found in serotonin and dopamine neurons. In every test, the MDMA-using monkey's brains were indistinguishable from those of monkeys that did not receive drugs, suggesting that little or no neurotoxic damage occurred.
The study was limited in that it had a rather small sample size (only three monkeys in the MDMA-using group.) There is a possibility that damage did occur but was too minor to be distinguished from random variations in such a small group. In some ways this research raises more questions than it answers, such as why the monkeys did not suffer harm at doses similar to those that have been reported to cause extensive damage in other animal experiments. The stress of being forcibly injected with drugs may itself increase the toxicity of MDMA, perhaps by adrenaline increasing body temperature.