A study of teratological effects of intravenous, subcutaneous, and intragastric administration of delta9-tetrahydrocannabinol in mice

Maternal Delta-9-Tetrahydrocannabinol Exposure Induces Abnormalities of the Developing Heart in Mice

Introduction: Cannabis is increasingly being consumed by pregnant women for recreational purposes as well as for its antiemetic and anxiolytic effects despite limited studies on its safety during pregnancy. Importantly, phytocannabinoids found in cannabis can pass through the placenta and enter the fetal circulation. Recent reports suggest gestational cannabis use is associated with negative fetal outcomes, including fetal growth restriction and perinatal intensive care, however, the effects of delta-9-tetrahydrocannabinol (THC) on fetal heart development remains to be elucidated. Materials and Methods: We aimed to determine the outcomes of maternal THC exposure on fetal heart development in mice by administering 0, 5, or 10 mg/kg/day of THC orally to C57BL/6 dams starting at embryonic day (E)3.5. Offspring were collected at E12.5 for molecular analysis, at E17.5 to analyze cardiac morphology or at postnatal day (PND)21 to assess heart function. Results: Maternal THC exposure in E17.5 fetuses resulted in an array of cardiac abnormalities with an incidence of 44% and 55% in the 5 and 10 mg/kg treatment groups, respectively. Maternal THC exposure in offspring resulted in ventricular septal defect, higher semilunar valve volume relative to orifice ratio, and higher myocardial wall thickness. Notably, cell proliferation within the ventricular myocardium was increased, and expression of multiple cardiac transcription factors was downregulated in THC-exposed E12.5 fetuses. Furthermore, heart function was compromised with lower left ventricular ejection fraction, fractional shortening, and cardiac output in PND21 pups exposed to THC compared to controls. Discussion: The results show that maternal THC exposure during gestation induces myocardial hyperplasia and semilunar valve thickening in the fetal heart and postnatal cardiac dysfunction. Our study suggests that maternal cannabis consumption may induce abnormalities in the developing heart and cardiac dysfunction in postnatal life.

Review of Evidence for Environmental Causes of Uveal Coloboma

Uveal coloboma is a condition defined by missing ocular tissues and is a significant cause of childhood blindness. It occurs from a failure of the optic fissure to close during embryonic development,and may lead to missing parts of the iris, ciliary body, retina, choroid, and optic nerve. Because there is no treatment for coloboma, efforts have focused on prevention. While several genetic causes of coloboma have been identified, little definitive research exists regarding the environmental causes of this condition. We review the current literature on environmental factors associated with coloboma in an effort to guide future research and preventative counseling related to this condition.

Cannabis-related diagnosis in pregnancy and adverse maternal and infant outcomes

BACKGROUND

Cannabis use and cannabis use disorders are increasing in prevalence, including among pregnant women. The objective was to evaluate the association of a cannabis-related diagnosis (CRD) in pregnancy and adverse maternal and infant outcomes.

METHODS

We queried an administrative birth cohort of singleton deliveries in California between 2011-2017 linked to maternal and infant hospital discharge records. We classified pregnancies with CRD from International Classification of Disease codes. We identified nicotine and other substance-related diagnoses (SRD) in the same manner. Outcomes of interest included maternal (hypertensive disorders) and infant (prematurity, small for gestational age, NICU admission, major structural malformations) adverse outcomes.

RESULTS

From 3,067,069 pregnancies resulting in live births, 29,112 (1.0 %) had a CRD. CRD was associated with an increased risk of all outcomes studied; the strongest risks observed were for very preterm birth (aRR 1.4, 95 % CI 1.3, 1.6) and small for gestational age (aRR 1.4, 95 % CI 1.3, 1.4). When analyzed with or without co-exposure diagnoses, CRD alone conferred increased risk for all outcomes compared to no use. The strongest effects were seen for CRD with other SRD (preterm birth aRR 2.3, 95 % CI 2.2, 2.5; very preterm birth aRR 2.6, 95 % CI 2.3, 3.0; gastrointestinal malformations aRR 2.0, 95 % CI 1.6, 2.6). The findings were generally robust to unmeasured confounding and misclassification analyses.

CONCLUSIONS

CRD in pregnancy was associated with increased risk of adverse maternal and infant outcomes. Providing education and effective treatment for women with a CRD during prenatal care may improve maternal and infant health.

Recreational use of marijuana during pregnancy and negative gestational and fetal outcomes: An experimental study in mice

The prevalence of marijuana use among pregnant women is high. However, the effects on gestation and fetal development are not well known. Epidemiological and experimental studies present conflicting results because of the route of administration, dose, time of exposure, species used, and how Cannabis toxicity is tested (prepared extracts, specific components, or by pyrolysis). In this study, we experimentally investigated the effects of maternal inhalation of Cannabis sativa smoke representing as nearly as possible real world conditions of human marijuana use. Pregnant mice (n=20) were exposed (nose-only) daily for 5min to marijuana smoke (0.2g of Cannabis) from gestational day (GD) 5.5 to GD17.5 or filtered air. Food intake and maternal weight gain were recorded. Ultrasound biomicroscopy was performed on 10.5 and 16.5dpc.On GD18.5, half of the dams were euthanized for the evaluation of term fetus, placenta, and resorptions. Gestation length, parturition, and neonatal outcomes were evaluated in the other half. Five minutes of daily (low dose) exposure during pregnancy resulted in reduced birthweight, and litter size was not altered; however, the number of male pups per litter was higher. Besides, placental wet weight was increased and fetal to placental weight ratio was decreased in male fetuses, showing a sex-specific effect. At the end of gestation, females from the Cannabis group presented reduced maternal net body weight gain, despite a slight increase in their daily food intake compared to the control group. In conclusion, our results indicate that smoking marijuana during pregnancy even at low doses can be embryotoxic and fetotoxic.

Dose-dependent teratogenicity of the synthetic cannabinoid CP-55,940 in mice

Potent synthetic cannabinoids (SCBs) are illegally distributed drugs of abuse that are frequently consumed in spite of their adverse consequences. This study was designed to determine if the toxicity observed in adults also extends to the prenatal period by examining the developmental toxicity/teratogenicity of one of these SCBs, CP-55,940, in a mammalian model. First, immunohistochemistry was employed for cannabinoid receptor 1 (CB1) localization within gestational day (GD) 8 mouse embryos; this receptor was identified in the cranial neural plate, suggesting that the endogenous cannabinoid system may be involved in normal development. Based on this information and on previous avian teratogenicity studies, the current investigation focused on cannabinoid exposure during neurulation. The treatment paradigm involved acute i.p. administration of vehicle, 0.0625, 0.125, 0.25, 0.5, 1.0, or 2.0mg/kg CP-55,940 to time-mated C57Bl/6J mice on their 8th day of pregnancy (n>10 litters per treatment group). On GD 17, litters were harvested and examined for numbers of live, dead, or resorbed fetuses, as well as for fetal weight, length, and gross morphological abnormalities. No effect on litter size, fetal weight, or crown rump length was seen at any of the CP-55,940 dosages tested. Major malformations involving the craniofacies and/or eyes were noted in all drug-treated groups. Selected fetuses with craniofacial malformations were histologically sectioned and stained, allowing investigation of brain anomalies. Observed craniofacial, ocular, and brain abnormalities in drug-treated fetuses included lateral and median facial clefts, cleft palate, microphthalmia, iridial coloboma, anophthalmia, exencephaly, holoprosencephaly, and cortical dysplasia. With the most commonly observed defects involving the eyes, the incidence and severity of readily identifiable ocular malformations were utilized as a basis for dose-response analyses. Ocular malformation ratings revealed dose-dependent CP-55,940 teratogenicity within the full range of dosages tested. While examination of additional critical periods and in depth mechanistic studies is warranted, the results of this investigation clearly show the dose-dependent teratogenicity of this SCB.

[Alcohol, tobacco and cannabis: Review of teratogenicity studies in animals]

Despite an intensive national campaign of information, the drugs most frequently consumed by young adults undoubtedly continue to be alcohol, tobacco and cannabis. If the impact of these drugs on the health of the consumers can be evaluated in conjunction with the clinical and epidemiologic data, the consequences on the embryo due to their consumption by the pregnant women can be appreciated thanks to the abundant literature describing their effects in the gravid animal. Taking into account the abundant literature available in multiple animal species, the zero drug recommendation should be widely diffused to pregnant women.

The effect of intragastric administration of delta 9-tetrahydrocannabinol on the growth and development of fetal mice of the A/J strain

Pregnant A/J mice were intubated with vehicle (sesame oil:Tween 80:water) or 60, 120, or 240 mg/kg of delta 9-tetrahydrocannabinol on Days 11 and 12, 12 and 13, or 13 and 14 (vehicle and 240 mg doses only) of gestation. Mice were killed on Day 20 of gestation, and examined for number of corpora lutea and live and resorbed fetuses. Fetuses were weighed and examined for gross external and internal malformations. Each treatment group consisted of a minimum of 10 litters with about 10 pups per litter. In a few groups the effects of feed deprivation on Day 12 or of glucocorticoid administration on Days 12 and 13 (positive control) were assessed. Intubation with vehicle or delta 9-tetrahydrocannabinol, or feed deprivation did not affect number of live fetuses, incidence of resorption, fetal weights, or gross malformations other than cleft palate. Intubation of delta 9-tetrahydrocannabinol on gestational Days 12 and 13 or 13 and 14 increased the mean frequency of cleft palate formation. The increase was 2- to 2.5-fold at the 240-mg dose, being significant (p = 0.05) in the Days 12 and 13 group. Cortisone acetate and corticosterone injection induced both resorption and cleft palate formation. Other developmental or reproductive parameters were not influenced by delta 9-tetrahydrocannabinol treatment. We conclude that delta 9-tetrahydrocannabinol administered by gavage during Days 12 and 13 of gestation retards normal palatal development.

Maternal toxicity--a possible factor in fetal malformations in mice

The assumption that major fetal malformations are indicative of a chemical's teratogenic potential was not supported by a literature review of teratology studies conducted in mice. In these studies, dose levels of test agents that manifested maternal toxicity as suggested by reduction in dam's body weight, clinical signs of toxicity, or deaths, also invariably caused reduction in fetal body weight, increased resorptions, and rarely fetal deaths. In several such studies, conducted with maternotoxic doses of structurally unrelated test agents, a consistent pattern of fetal defects was discovered. These defects included exencephaly, open eyes, hemivertebrae, fused arches or centra of lumbar or thoracic vertebrae, fused, missing or supernumerary ribs, and fused or scrambled sternebrae. These defects were absent at drug dosages that were distinctly nontoxic for the mother. In a few studies conducted at two or more maternally toxic doses, the degree and severity of maternal toxicity showed a positive correlation with the incidence and severity of above fetal defects. It is hypothesized that maternal toxicity, on its own, may have an etiologic role in these fetal defects.

Interactive effects of nutrition and cannabis upon rat perinatal development

In order to examine the effects of cannabinoids, malnutrition, and their possible interaction upon the developing rat fetus, female Wistar rats were exposed to cannabis smoke, placebo smoke, or no smoke while concurrently consuming 1 of 3 diets differing in protein concentration (8%, 24%, 64%). Both the diet and drug treatments were administered 20 days prior to and throughout gestation. Of the 12 variables affected by the low-protein diet, 8 were significantly potentiated when undernutrition was combined with cannabis treatment. Some dependent variables that were not altered either by the low-protein diet or by cannabis inhalation were affected by the combination of treatments. These included a lengthened gestation period, an increase in occurrence of stillbirths and litter destruction, and decreased activity in the rat pups. Cannabis coupled with a standard protein diet resulted in a number of developmental indices being delayed but combining the drug with an enriched protein diet ameliorated these effects. The evidence also suggests that the administration of cannabis both before and during gestation resulted in a degree of tolerance to some aspects of the drug effects.