First Author

At first, Thomas Hnasko's plan to look at dopamine, pain and morphine addiction in mice was met with a measure of scepticism.

A graduate student in the neurology and behaviour lab at the University of Washington in Seattle, Hnasko had trouble convincing his principal investigator, Richard Palmiter, that his project was a good idea. But when Hnasko explained that he planned to contravene conventional wisdom in the field, Palmiter was intrigued.

Hnasko suspected that release of the neurotransmitter dopamine is not absolutely essential as a ‘reward’ in mice that are addicted to morphine. Using mice that cannot produce dopamine, Hnasko tested their craving for morphine and measured their response to pain — assessed using the ‘tail flick assay’. The results, published on page 854 of this issue, show that he was right. Nature caught up with Hnasko to find out more.

How did you come up with the idea to examine this issue?

I came to the lab with a background in pharmacology and an interest in the biological processes underlying addiction. The literature suggesting a role for dopamine in response to opiate drugs, especially their rewarding aspects, was conflicting.

I decided that finding out whether a mouse that cannot produce dopamine liked morphine would be a powerful way to shed some light on the problem.

And why tail flicks?

It's about the only pain assay I could think of that wouldn't be confounded by the motor deficits of the dopamine-deficient mice.

How did Palmiter help you with this work?

He had a big influence on the experimental designs and has been tremendously inspiring to work with.

What do you think about when you're not pondering dopamine, addiction and pain?

Lately I've been anxiously thinking about the next step in my career. On more carefree days I'm plotting my next holiday — preferably somewhere near a river where I can practise my fly cast.

What's next for you?

For the project, I'm doing some experiments to see whether the conclusions we've drawn on opiates extend to other drugs of abuse that are thought to act more directly on the dopamine system, such as cocaine.

For me, I'll be defending my dissertation this spring and am currently planning my next destination.