Health effects of eating marijuana is subject of a new study

Summary: Mice exposed to dough containing THC were less active and had lower body temperature after consumption. The effects were more pronounced in males than females.

Source: Indiana University

Researchers have conducted a study in which mice voluntarily ate a dough containing THC, the primary psychoactive component in marijuana. That opens the door to additional studies that will help shed light on behavioral and physiological effects that occur in people when they eat food infused with marijuana.

The study is among the first to report on voluntary oral THC consumption in animals, a method of consumption that is similar to the way humans take the drug.

In a recently published paper in Drug and Alcohol Dependence, researchers at IUPUI and Indiana University Bloomington said they found the mice were less active, and their body temperatures were lower, after consuming the edible THC.

The researchers also noted that the effects of edible THC varied based on the subject’s sex, said Michael Smoker, first author of the paper and an addiction neuroscience Ph.D. candidate in the lab of professor Stephen Boehm in the psychology department at IUPUI. The addiction neuroscience graduate program is a Purdue University program at IUPUI.

The study showed that mice will self-administer — or voluntarily choose to consume — behavioral-effective doses of edible THC, and do so repeatedly, Smoker said. The mice were given gradually increasing doses in a dough made from flour, sugar, salt, glycerol and THC.

Understanding the health effects of eating marijuana edibles is important, given the growing popularity of that method of consumption in states where marijuana has been legalized, Smoker said.

“People can buy cookies, candies and all sorts of things with THC in them. Back in the day, you had to make your own brownies, or something like that, and now they are becoming more widely available and increasing in popularity,” he said.

Marijuana edibles can elicit extreme, adverse reactions, Smoker said. Many of the commercially made marijuana-based products have a relatively higher concentration of THC than does marijuana plant material. In some cases, people are unsure how much of a marijuana edible they should eat and end up eating more than they should.

Questions researchers want to answer include the impact of edibles on people’s ability to think, whether there are any long-term consequences for someone who has been eating edibles repeatedly and then stops, and what the consequences are, if any, of a child accidentally eating a marijuana edible, Smoker said.

This shows a smiley face cookie
The study is among the first to report on voluntary oral THC consumption in animals, a method of consumption that is similar to the way humans take the drug. The image is in the public domain.

Researchers turned to mice to answer questions about edible forms of THC due to ethical barriers involving use of humans in studies and the lack of control over human subjects’ prior exposure to THC and other drugs.

Mice have been used in studies previously to study the effects of marijuana, but figuring out a way for them to self-administer the drug, as humans do, has been notoriously difficult, Smoker said.

Co-authors of the paper are Ken Mackie, with the Department of Psychological and Brain Sciences and the Gill Center at IU Bloomington; Christopher Lapish, with the Department of Psychology and the Indiana Alcohol Research Center at IUPUI; and Stephen Boehm II, with the Department of Psychology and the Indiana Alcohol Research Center at IUPUI. Boehm is also a funded investigator with the IU Addictions Grand Challenge initiative.

About this neuroscience research article

Indiana University
Media Contacts:
Rich Schneider – Indiana University
Image Source:
The image is in the public domain.

Original Research: Closed access
“Self-administration of edible Δ9-tetrahydrocannabinol and associated behavioral effects in mice”. Michael P. Smoker, Ken Mackie, Christopher C. Lapish, Stephen L. BoehmII.
Drug and Alcohol Dependence. doi:10.1016/j.drugalcdep.2019.02.020


Self-administration of edible Δ9-tetrahydrocannabinol and associated behavioral effects in mice

With increasing access to legal cannabis across the globe, it is imperative to more closely study its behavioral and physiological effects. Furthermore, with the proliferation of cannabis use, modes of consumption are changing, with edible formulations becoming increasingly popular. Nevertheless, there are relatively few animal models of self-administration of the primary psychoactive component of cannabis, Δ9-tetrahydrocannabinol (THC), and almost all incorporate routes of administration other than those used by humans. The aim of the current study was to develop a model of edible THC self-administration and assess its impact on CB1 receptor-mediated behaviors in female and male mice.

Mice were given limited access to a palatable dough which occasionally contained THC in doses ranging from 1 to 10 mg/kg. Following dough consumption, mice were assessed for home cage locomotor activity, body temperature, or analgesia. Locomotor activity was also assessed in conjunction with the CB1 receptor antagonist SR141716A.

Dough was well-consumed, but consumption decreased at the highest THC concentrations. Edible THC produced dose-dependent decreases in locomotor activity and body temperature in both sexes, and these effects were more pronounced in male mice. Hypolocomotion induced by edible THC was attenuated by SR141716A, indicating mediation by CB1 receptor activation.

In contrast to other cannabinoid self-administration models, edible THC is relatively low in stress and uses a route of administration analogous to one used by humans. Potential applications include chronic THC self-administration, determining THC reward/reinforcement, and investigating consequences of oral THC use.

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