Preclinical Model of Prenatal Delta-9-Tetrahydrocannabinol Exposure to Assess Its Impact on Neurodevelopmental Outcomes

With increasing cannabinoid product legalization and more pregnant individuals using cannabinoid products, we are focused on pre-clinical models to answer questions on the impact of pre-natal cannabinoid exposure.

A major experimental challenge for us was to figure out a methodology in which voluntary consumption would occur regularly with resulting exposures similar to those in humans.

This technique is extremely translatable to the human condition. Through voluntary ingestion, we remove a lot of potential confounding factors that otherwise need to be considered.

Our findings through the use of this model will allow for a better understanding of the neurodevelopmental impacts of cannabinoid exposure during pregnancy, and could ultimately provide information on areas for interventions.

With the development of this model, others may investigate specific areas of interest to further characterize and understand the full impact of pre-natal cannabinoid exposure.

[Narrator] To begin, house the female rats individually in standard rat static micro isolator cages with bedding at 22 degrees Celsius, provide irradiated food and tap water ad libitum throughout the study. Throughout study, obtain baseline body weights for each rat. After gathering all required materials and chemicals, prepare research grade tetrahydrocannabinol or THC solutions in ethanol and keep them in vials. Proceed to prepare the THC infused cookies 30 minutes before administration at 1400 hours daily to maintain consistent feeding times. After separating the mini chocolate cookies, add approximately half a teaspoon of peanut butter to the cream. Mix the required dose of THC with the peanut butter before assembling the cookie for consumption evaluation. Remove water from the cage and administer a plain peanut butter mini chocolate cookie to each rat using forceps at 1400 hours daily. Observe until the treat is completely consumed and remove remnants if necessary. Feed plain cookies for two to four days and continue only with rats that show consistent consumption. Then administer the THC infused cookies as per the dosage mentioned, and evaluate pre-pregnancy consumption for two weeks. Assign rats with consistent ingestion randomly into two cookie groups. Allow a minimum of four days without cookies before breeding. To ensure THC clearance from their systems. Weigh the female rats to obtain a starting weight, then place them in a cage with a proven THC naive male breeder without providing any cookies. Confirm pregnancy by the presence of a vaginal plug, typically observed 24 hours after mating. Weigh the female rat again before returning it to the home cage. Marking this as gestational day or GD1. To assess maternal weight gain, weigh the dams twice a week. Next, provide a plane or THC infused cookie at a dose of three milligrams per kilogram at 1400 hours daily starting from GD1. Continue this regimen until the dam is noted to be nesting for delivery. At which point, stop the THC exposure. Once the offspring are born, record the number of live pups and designate the day of birth as postnatal day or P0. Wean the offspring at P23 and group house the weaned offspring with litter mates based on sex. Monitor pups regularly for any health or developmental issues such as abnormal body weight or developmental delays. If required, assess baseline measures such as body weight, reflexes, or other relevant developmental parameters before initiating experiments on the offspring. Litter size and maternal weight gain were similar between the control and PCE groups. The mortality rate trended higher in the PCE group and the offspring birth weight trended lower in the PCE group.