Can zebrafish solve the opioid crisis?

Aug 31 2017

Can zebrafish solve the opioid crisis?

It sounds like a headline straight out of The Onion, but researchers actually believe the small tropical fish may hold the key to new treatments for opioid addiction.

A new study published by scientists at the University of Utah looked at how zebrafish respond to opioids as a way to better understand how addiction affects the brain. They hope by better understanding the neuroscience of addiction, they can create better treatment modalities for humans.

Zebrafish might seem an odd choice, but they actually share 70 percent of the same genes as humans and have many of the same biological pathways, making them prime candidates for testing the effects of drugs and drug treatments.

The researchers set up an experiment where zebrafish could self-administer doses of hydrocodone, a common prescription painkiller. They found the fish readily became conditioned to seek the drug, displayed withdrawal symptoms, and would even brave dangerously shallow water to get their dose of the drug. Researchers say these classic signs of addiction indicate the fish could be used as a valuable model for addiction research.

“The fish needed to perform an action to get the drug rather than receiving it passively,” Dr. Gabriel Bossé, one of the study’s authors, said in a statement. “Drug-seeking has been modeled before in rodents and primates, but having a model to study this in zebrafish could move the [study of addiction] forward.”

In addition to proving the fish could be a viable model for addiction research, the team also tested opioid inhibitors. Scientists treated a group of fish with naloxone, a compound that blocks opioid receptors in the brain, and found a reduction in the animals’ drug-seeking behavior.

Researchers say using fish to test addiction treatments is a positive step because the “model is scalable and could be used to rapidly screen through thousands of compounds.” Quicker turnover in experiments could lead to faster results for human patients. They also say that because it’s easier to genetically manipulate the fish, they can more easily study specific brain pathways and pinpoint potential target treatment areas.

“We didn’t know if zebrafish would be a relevant model for opioid addiction, much less self-administer the drug,” Dr. Randall Peterson, the study’s senior author, said in a statement. “What is exciting about this work is that we see many of the hallmarks of addiction in zebrafish. This could be a useful and powerful model.”

The need for new treatment modalities has never been higher, with an estimated 144 Americans dying from drug overdoses every day. Some estimates say opioids are involved in 91 of those overdose deaths.