Effects of Cannabis on the Brain: Evidence from Experiments with Mice and Brain Activities

2024-01-31 19:25:14

Science already knows a lot about the effects of cannabis on the mind and body. For example, in the case of certain illnesses and symptoms of illness, doctors recommend therapy with cannabis if other medicines do not achieve the desired effect. During chemotherapy, for example, attempts are made to use cannabis to combat nausea and to stimulate patients’ appetite.

However, ordinary consumers are also aware of the various aspects that can accompany the use of intoxicating hemp products. Almost every consumer will have experienced the feeling of cravings after consuming cannabis. Researchers have now been able to find out exactly why this happens in experiments with mice to which cannabis was administered in vaporized form and their brain activities were then observed. It was found that cannabis activates specific hunger neurons in the brain.

Of Mice and Munchies

It has long been known that cannabis can trigger a feeling of cravings, but only now, thanks to a series of animal studies, researchers at Washington State University have discovered the mechanism in the brain responsible for promoting appetite. They used calcium imaging technology – similar to a brain MRI – to determine how the animals’ brain cells responded to vaporized cannabis sativa. The researchers were able to observe that cannabis activated a number of cells in the hypothalamus when the rodents expected and consumed tasty food. However, this did not happen in the experimental animals that were not exposed to cannabis sativa vapor. Jon Davis, assistant professor of neuroscience at WSU and corresponding author of the study, says of the discovery that something important happens in the hypothalamus after consuming cannabis.

“When mice are given cannabis, neurons that are not normally active are activated,” says Davis. While calcium imaging technology has been used by other researchers to study the brain’s responses to food, this appears to be the first time it has been used to understand these functions following cannabis exposure. The results of the study, published in Scientific Reports, could pave the way for improved therapeutics to treat appetite disorders in cancer patients, as well as anorexia and even possibly obesity.

Cannabinoid 1 receptor control

As part of this research, the scientists also found that the cannabinoid-1 receptor, occupied by cannabinoids, controls the activity of a known group of “phagocytes” in the hypothalamus. The so-called “Agouti Related Protein Neurons” – neuropeptides that are formed in the arcuate nucleus of the hypothalamus. With this information, the researchers used a chemogenetic technique that acts like a molecular light switch to control these neurons when the animals were exposed to cannabis. When these neurons were switched off, cannabis no longer stimulated the mice’s appetite.

We now know that one of the responses – when the brain responds to recreational cannabis – would be to increase appetite, Davis said of the findings. The current work builds on previous research from his laboratory on cannabis and appetite. It was among the first to use completely vaporized cannabis plants instead of injected THC in its animal studies. The aim was to better imitate the usual cannabis consumption of people in the laboratory.

In previous work, researchers had already identified genetic changes in the hypothalamus in response to cannabis, so in this study, Davis and his colleagues focused on this area to learn something new about cannabis’ effects on appetite.