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Infant rat heads grafted onto adults' thighs

Infant rats are being decapitated and their heads grafted onto the thighs of adults by researchers in Japan.

If kept cool while the blood flow is stopped, a transplanted brain can develop as normal for at least three weeks, and the mouth of the head will move, as if it is trying to drink milk, the team reports.

The grafted heads could be "excellent models" for investigating brain function in human babies after periods of no blood flow, known as ischemia, they claim.

"Our main purpose is to investigate how the transplanted brain can develop and maintain function after prolonged total brain ischemia," researcher Nobufumi Kawai, at the Jichi Medical School in Tochigi, told New Scientist. "And we tried to investigate the effect of lowering the temperature of the brain during the grafting."

But other researchers are far from convinced by the grisly technique. Denis Azzopardi of Imperial College London, UK, who investigates brain injury in newborn babies, says many well-characterised animal models of studying brain ischemia already exist.

Public concern

"These are well established models for testing different degrees of ischemia and potential treatments. And there are plenty of studies showing experimentally that cooling during ischemia can be neuroprotective," Azzopardi says. "So I'm not sure that this complicated technique offers an advantage in any way - I can't see it being widely used."

Vivisection that provides no obvious research benefit and involves clear animal suffering will only cause public concern, adds a spokeswoman for the UK's Research Defence Society, which advocates responsible animal experimentation.

"Regulations in the UK are much stricter than in Japan. If expert opinion says there are better or other ways of doing an experiment that would cause less animal suffering, it wouldn't be licensed," she told New Scientist.

Temperature sensitive

The Japanese team removed heads from 12-day-old rats and waited 90 minutes before connecting them to the blood supply in the thigh of an adult rat recipient. "The grafted brain appeared to develop normally provided the operation was done at the low temperature of 19°C," says Kawai. But in operations conducted at 29°C, still well below body temperature, the brain was severely damaged.

In contrast, the standard animal models for studying human infant ischemia involve, for example, tying the carotid artery in rats. This halts blood flow to the brain.

About one in 500 babies suffer from a lack of oxygen during birth. This can happen if the placenta, which supplies blood from the mother, becomes detached, or a blockage forms. Azzopardi is part of a team investigating whether cooling immediately after birth can reduce subsequent brain damage.

Previous work, largely in animals, has shown that cooling after brain injury reduces damage by suppressing inflammation, for example.

Early results from the Japanese research are published in Neuroscience Letters (vol 325, p 37).



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