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

Summary

As legislative restrictions change, resulting in increased accessibility of cannabinoid products, it is critically important to develop models to study the impact of these exposures, particularly during pregnancy. A preclinical model of moderate prenatal cannabinoid exposure through voluntary ingestion has been developed, enabling more in-depth investigations.

Abstract

Prenatal cannabinoid exposure (PCE) is becoming increasingly frequent as more states across the United States legalize recreational marijuana (cannabinoids). The consumption of cannabinoid products during pregnancy has been associated with various abnormal outcomes, although historical studies were conducted during a time when the potency of these products was approximately 300% lower than that of current products. Given the rising use of cannabinoids, it is essential to understand the potential impacts PCE may have on fetal neurodevelopment and subsequent infant and child development. Previous studies have demonstrated that PCE negatively affects learning and memory, behavioral skills, sleep, and attention in offspring. The aim of this study is to recapitulate PCE through voluntary ingestion of delta-9-tetrahydrocannabinol (THC), the psychoactive component of cannabinoid products, during pregnancy in a preclinical model. This article outlines the procedure for achieving moderate PCE throughout gestation. In this model, the control group consumes plain mini-chocolate/peanut butter cookies, while the PCE group consumes THC mixed into peanut butter paired with mini-chocolate cookies. This approach enables further investigation into the impact of PCE on developmental outcomes.

Introduction

As rates of prenatal cannabinoid product use increase¹, likely influenced by the growing legalization of cannabinoid products across the United States, studies are needed to better understand their impact on fetal development. Delta-9-tetrahydrocannabinol (THC), the psychoactive component of cannabinoid products, readily crosses the placenta and interacts with the endogenous endocannabinoid system^2,3. The endogenous endocannabinoid system plays a critical role in neural development and may be a pathway through which developmental alterations occur. Cannabinoid use during pregnancy has b....

Protocol

All procedures described here were approved by the University of New Mexico Health Sciences Center (UNM HSC) Institutional Animal Care and Use Committee (IACUC). All experiments were conducted in compliance with the ARRIVE guidelines. Long-Evans (Blue Spruce, HsdBlu: LE) rats were obtained from a commercial source. The males used were proven adult breeder rats, 12 weeks old upon arrival and 15-16 weeks old at the start of the breeding protocol. The females weighed 125-150 g and were approximately 6-7 weeks old upon arrival. At the time of breeding, the females were approximately 9-10 weeks old. It is critical to ensure that all prospective dams have no prior history o....

Results

To establish voluntary consumption of THC, numerous treats were trialed to determine which ones were palatable to the rats and would be consumed quickly and consistently.

Initially, sugar-free strawberry-flavored gelatin cubes (1 cubic mL size), both with and without THC, were trialed. The amount of strawberry syrup flavoring was increased, and THC was trialed at three different concentrations (2 mg/kg/dose, 3 mg/kg/dose, and 5 mg/kg/dose). The rats did not consistently consume the cubes and w.......

Discussion

The PCE paradigm outlined here involves voluntary THC consumption by pregnant rat dams. This is the first study to explore THC administration to pregnant rat dams via voluntary ingestion in a preclinical model. Both groups of rat dams consumed the same rat chow diet, minimizing potential variability in nutrition and caloric intake between groups. Animal models offer the advantage of controlling the timing and dosage of PCE for study purposes.

Pre-pregnancy consumption is assessed to identify r.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
5L0D PicoLab Laboratory Rodent Diet, irradiated	Purina LabDiet	5L0D
Cellulose/paper bedding BioFresh Comfort Bedding	BioFresh Vet	NA	https://biofreshvet.com/products/
Digital Kitchen Scale	Etekcity	EK4150
Female rats, 125-150 g	Inotiv	14005F
Long-Evans rats (Blue Spruce, HsdBlu: LE)	Inotiv	14016M
N10 Rodent Plastic Cage Bottoms	Ancare	N10PLF
N10 Rodent Wire Lids	Ancare	N10SS
Narrow Pattern Forceps	Fine Science tools (FST)	11002-14
OREO mini chocolate Sandwich cookies, Go Paks, 12-3.5 oz cups	Amazon	B0198TUO7W
proven adult breeder males	Inotiv	14016M
Rat static polysulfone microisolator cages (R20):
Research Grade THC  (only available with a DEA license, Schedule I drug)	NIDA	NA	https://nida.nih.gov/research/research-data-measures-resources/nida-drug-supply-program
SKIPPY Creamy Peanut Butter spread	Amazon	B0C75KZ28C
THC Consumption Supplies: