Do Rats Get the Munchies?

Well, do they? Do rats get high? How can rat medical studies be applied to humans? Find out here.

In an age where countries and states are legalising weed at a rate of knots, there has been an increase in scientific testing to further understand the short and long term effects of cannabis in its whole state, and as isolated CBD and THC. Due to its legal status, there has been minimal research in these areas, so it's exciting to see reports with new knowledge starting to come through.

In a recent study from Washington State University's Integrative Physiology and Neuroscience department, it was found that lab rats exhibit cannabis-seeking behaviours and even get the munchies. This means big things for the future of cannabis research, and the practicality of using rats in these studies.

The full study has been published in The Journal of Neuroscience.

Why do we use rats?

Why does it matter what happens to rats in the lab? How can that be used to model for humans? 

According to the Foundation for Biomedical Research, almost 95% of all U.S. lab animals are rats and mice – for a number of reasons. Practically speaking, mice and rats are cheap to obtain and house. They are small enough to be handled easily by scientists, and their reproduction rate is very high, allowing for large numbers or trials in a short time frame. Genetically, rats and mice which have been bred in captivity are genetically very consistent, ensuring more accurate data.

Another key reason rodents are so commonly used is that their biological, genetic and even behavioural characteristics closely resemble those of humans. Rats and mice have shown symptoms of human conditions in testing, allowing for various conditions to be replicated consistently.Due to their likeness to humans, rodents are examined to create a wide variety of medical testing models including aging, sensory and nutrition studies – including research into anti-craving medication which could be used to aid in ending drug addiction.

What was the study?

In this study by Washington State University, rats were divided into three groups. Each group was placed into a specially-designed Plexiglass chamber for one hour a day over 21 days. The groups had access to either THC-rich vapour, CBD-rich vapour or regular air.

Each chamber contained two spigots which were only activated by the insertion of a rat's nose. The first group's chamber had access to a THC-rich vapour from one spigot, and a burst of regular air from the other. The second group received either CBD-rich vapour or regular air, and the third control group had two spigots delivering regular air.

The spigots which released CBD-rich and THC-rich vapours also illuminated a cue light with the activation of the spigot, creating a visual signal the rats would come to associate with the delivery of the cannabis vapours.

Over the 21 days, the rats' behaviour was recorded including frequency of seeking delivery, and associations between the spigots and a drug-influenced state. On the 22nd day, the rats were returned to their chambers for their one hour session, but all spigots only activated regular air.

What did they find?

By the third day, the rats had made associations between their nose-pokes and the delivery of the cannabis vapours. The rats in groups one and two were already self-administering their cannabis vapours more often than the control group. These three days were considered 'training days' for the purpose of the study.

On the fourth day, it was observed that the rats in the THC-rich vapour group would self-administer their cannabis spigots far more often than the other two groups. On some days, this group would self-administer more than twice as often as the other groups.

This is considered the most significant finding of the study – that these rats exhibited clear drug-seeking behaviour which is comparable to humans.

"It's always difficult to establish reliable cannabis-seeking behavior using animal models. In this study, we have a clear and reliable response for cannabis by utilizing the very first self-administration model involving on-demand delivery of whole-plant cannabis vapor."— Prof. Ryan J. McLaughlin, senior author

After the 21 day study ended, the rats were returned to their chambers for their regular one hour daily session, but all spigots released regular air only. Our friends from the THC-rich vapour group increased their activity in attempting to access the cannabis vapour. During the release of THC-rich vapour, the rats were self-administering 17-18 times a day on average. When they were cut off, this increased to 70-80 times a day.

This clearly shows that the rats who had access to THC were actively seeking it out and were trying to understand how to access it again, even when the spigot stopped producing it. These rats were then shown the visual light cue and this stimulated more nose-pokes, highlighting the association the rats had made between the visual cue and the self-administration of the cannabis vapour.

Do rats get high?

Interestingly, the rats with access to THC-rich vapour showed many human characteristics while they were under the influence – which suggests rats do get high.

These rats consumed far more food after self-administering cannabis – yes, rats get the munchies, too! They also displayed far lower physical activity levels after self-administering, but still burned more calories than their CBD and control counterparts.

They experienced a lot of the same effects people would experience. And that is very important when you're trying to validate a model and then extend it to a human population.

— Tim Freels, first author

This study represents a positive step forward in the world of cannabis research. This study clearly found that rats exhibit familiar human characteristics when under the influence of cannabis. In the future, similar studies can be used to further understand the impact cannabis use has on a variety of human states, including adolescence and pregnancy.

To continue cannabis testing is to move toward a safer experience for anyone who chooses to consume cannabis or CBD products. With thorough research, people will be able to make informed choices and understand the way cannabis interacts with the body without the fear-mongering from the long-standing War on Drugs.

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Laura Desmond
Laura Desmond

Laura Desmond is an Adelaide-based writer with a keen interest in the arts, gender politics and social change. She is currently working to obtain a Master in Writing through Swinburne University.

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