Is Hydrocodone Addictive? Absolutely, Confirms Zebrafish Study
A recent study published in the journal Behavioral Brain Research found that in less than a week of self-administration, zebrafish were exhibiting signs of drug-seeking behavior and withdrawals.
Zebrafish as a population addition to home aquariums, and are relevant to such research because they share about 70% of our genes, and have similar biological addiction pathways. Also like humans, they have an opioid receptor and two neurotransmitters, dopamine and glutamate, which affect the brain’s reward system in the brain.
For the investigation, researchers from the University of Utah developing an automated opioid self-administration device for zebrafish, which enabled them to “…measure drug seeking and gain insight into the underlying biological pathways.”
Moreover, the zebrafish trained in the study for five days “exhibited robust self-administration” and “conditioned fish continued to seek the drug despite an adverse consequence and showed signs of stress and anxiety upon withdrawal of the drug.”
The system was set up in a tank with a food dispenser equipped with a motion detector that was trigged by fish swimming nearby. Fish quickly learned how to obtain the food. Next, researchers replaced the food dispenser with one that infused the water with small doses of hydrocodone when fish swam close by.
A continual flow of water flushed the tank, which encouraged the fish to trigger the dispensing to obtain more hydrocodone. In just five days, the fish figured out how to self-administer the drug.
Also, drug seeking behavior increased when the fish were forced to obtain the opioid in progressively shallower water, which is a stressful environment that the fish would otherwise avoid. In other words, the fish were willing to do more work to receive the hydrocodone – a true example of drug-seeking behavior.
Next, the researchers went a step further by exposing the fish to naloxone, a medication that blocks opioid receptors and reverses overdoses. As expected, the naloxone seemed to lessen the zebrafishes’ drug-seeking.
Study researchers posit that their zebrafish model can be used to test thousands of different compounds quickly, thus effectively leading to new addiction treatments. Also, their genetics can be changed to explore the biological pathways linked to drug addiction.
~ G. Nathalee Serrels, M.A., Psychology
https://www.sciencedirect.com/science/article/pii/S016643281730801X Is Hydrocodone Addictive?