Investigating the dose-response of prenatal-THC exposure in adolescent mice

MRC : Jessica Myatt : MC_ST_BNDU_2019

Across the world, rules regarding the legalisation of the recreational use of cannabis are changing. This is leading to a perception that cannabis is safe to use: people, therefore, remain unaware of possible consequential health risks. The concentration of delta-9-tetrahydrocannabinol (THC), often found in cannabis products, is rising - a concern as THC is known to have psychoactive effects.

This is concerning as it could mean a person may display significant disturbances in motor function, behaviour, perception or thinking, or hallucinate for example. Previous studies are now outdated as they were undertaken when the concentration of THC remained low - in the last 20-years THC concentration has risen from around 1.5-4% up to 29%. Furthermore, it has been shown that maternal and paternal cannabis use during pregnancy increases the risk of psychotic-like experiences in offspring.

Additionally, cannabis/cannabis products are being used to counteract nausea in pregnancy, therefore it is imperative that studies addressing the effect THC exposure may have on offspring are carried out sooner rather than later.

There is general acceptance for disorders such as schizophrenia, to have a substantial neurodevelopmental basis. This means evidence for both environmental and inherited risk factors that could result in a wide range of outcomes following disrupted or altered development of the brain. Taken together, the increase in the concentration of THC, alongside the substantial neurodevelopmental basis of such disorders, could, therefore, result in an emergent risk of psychotic disorders within the population.

To begin to address this, this project will investigate the dose-dependent effects of exposure to THC before birth on the neurodevelopment of adolescent offspring in rodents. Offspring will be exposed to one of two different concentrations of THC or a control substance before birth. After pups have been born and reached adolescence, they will be scanned to acquire images of the brain a week apart which will allow us to look for any structural changes across time.

The offspring will also be assessed using behavioural tasks to determine if there are any changes in their associated behaviour. Scientific data collected may provide knowledge to guide policies aimed to prevent future public health challenges that could be associated with exposure to THC before birth.