Cannabis is well-known for its ability to stimulate appetite, but the exact process behind this phenomenon is still unclear. A new study by researchers at Washington State University (WSU) has shed some light on how cannabis affects the brain and behavior of rodents about food.
Cannabis Increases Meal Frequency and Food-Seeking Behavior
The researchers exposed rats and mice to vaporized cannabis that contained 7.8% tetrahydrocannabinol (THC) and 0.5% cannabidiol (CBD), the main psychoactive and non-psychoactive components of cannabis, respectively. They then observed their feeding habits and other activities in different settings.
They found that cannabis exposure increased in meal frequency, meaning that the rodents ate more often, but the size of each meal decreased. They also found that cannabis increased food-seeking behavior, meaning that the rodents were more motivated to work for food rewards. These effects were not due to changes in locomotor activity, as cannabis did not alter the rodents’ movement levels.
Cannabis Activates Specific Neurons in the Brain
The researchers also used in vivo calcium imaging and electrophysiological recordings to measure the activity of neurons in the mediobasal hypothalamus (MBH), a brain region that regulates feeding behavior. They focused on two types of neurons: cannabinoid-1 receptor (CB1R)-expressing neurons, which are activated by cannabis, and Agouti-Related Peptide (AgRP) neurons, which are known to promote appetite.
They found that cannabis exposure stimulated the activity of both types of neurons, especially when the rodents anticipated or consumed food. They also found that CB1R activation reduced the inhibition of AgRP neurons, making them more active. Furthermore, they used chemogenetic techniques to manipulate the activity of AgRP neurons and showed that they were necessary for the appetite-stimulating effects of cannabis.
Cannabis Could Have Therapeutic Potential for Anorexia
The study, published in the journal Scientific Reports, is the first to provide a detailed explanation of the in vivo connection between cannabis ingestion and appetite stimulation. The researchers concluded that cannabis targets MBH neurons to increase appetite and that AgRP neurons are critical for this process.
The findings could have implications for the development of treatments for anorexia, a disorder characterized by a lack of appetite and weight loss. Cannabis could potentially be used to stimulate appetite and food intake in patients with anorexia, but further research is needed to confirm its safety and efficacy.