Suppression of STAT3 Signaling by Δ9-Tetrahydrocannabinol (THC) Induces Trophoblast Dysfunction

Abstract

Aims: Marijuana is a widely used illicit drug and its consumption during pregnancy has been associated with adverse reproductive outcomes. The purpose of this study was to determine the effects of chronic intake of Δ⁹-tetrahydrocannabinol (THC), the major component of marijuana, on trophoblast function, placental development, and birth outcomes. Methods: The pathological characteristics and distribution of cannabinoid receptors in placenta were observed by immunohistochemical (IHC) staining. Cell migration in response to THC was measured by transwell assays. The levels of cannabinoid receptors and Signal Transducer and Activator of Transcription 3 (STAT3) were detected by western blot. Results: We found the placenta expressed two main cannabinoid receptors, suggesting that THC induced biological responses in placental cells. Supporting this hypothesis, we observed dramatic alterations of placental morphology in marijuana users. Using THC and inhibitors of cannabinoid receptors, we demonstrated that THC impaired trophoblast cell migration and invasion partly via cannabinoid receptors. Additionally, pregnant mice injected with THC showed adverse reproductive events including reduced number of fetuses, lower maternal and placental weights. Mechanistically, STAT3 signaling pathway was involved in the THC-induced suppression of trophoblast cell motility and pregnancy outcomes. Conclusion: Our study indicates that the STAT3 signaling pathway plays a critical role in THC-induced trophoblast dysfunction.

Δ9-tetrahydrocannabinol exposure during rat pregnancy leads to symmetrical fetal growth restriction and labyrinth-specific vascular defects in the placenta

“…Based on the results in this study, the reduction in fetal growth are likely attributable to impaired placental function, however, as Δ9-THC has been shown to cross the placenta, it is worth considering that Δ9-THC binding to the CB1R/CB2R in the fetal liver and brain may also have an impact 12,82,100,108 . The current study is limited in its scope and independent studies will need to be conducted to evaluate the post-natal onset of MetS along with an in-depth evaluation of the placenta vascular pathology.…”

“…Thus BeWo cells were cultured with and without 15 µM Δ9-THC or its inactive metabolite, 11-COOH-THC, to explore the direct effects of Δ9-THC on GLUT1 expression. 15 µM www.nature.com/scientificreports www.nature.com/scientificreports/ was chosen as the experimental dose based on studies, which determined equivalent doses to those found in the serum of cannabis users and did not affect cellular viability in BeWo cells 12,80,82,83 . Treatment with Δ9-THC led to decreases in the steady-state mRNA levels of GLUT1 and GR (p < 0.05), while the metabolite (11-COOH-THC) at an equimolar concentration, had no effect (Fig.…”

“…Increased placental weight has been observed in cannabis users and in mice exposed to cannabis smoke during pregnancy 53,89 , therefore it is possible that it is the Δ9-THC in cannabis that contributes to this reported increase, though it is worth noting that 5 mg/kg Δ9-THC i.p. led to decreased placental weights in the mouse 12 . This could be attributed to the noted loss of junctional zone trophoblast subtypes at that dose and may identify a population of trophoblast that are more susceptible to Δ9-THC.…”

“…The decreased fetal blood space and increased maternal blood space created a 60% higher maternal to fetal blood space ratio in the placentae from Δ9-THC exposed pregnancies, suggestive of impaired nutrient transport 91 . The changes in the ratio of maternal to fetal vascularity could be attributed to an overall defect in blood vessel formation given pregnant women who used cannabis at least once per month exhibited less expression of CD31 in the placenta, a marker of endothelial cells and thereby, indirectly, angiogenesis 12,91 . Moreover, treatment of pregnant mouse dams with 5 mg/kg i.p.…”

“…in the rat did not alter these populations, in mice, pregnancy exposure of 5 mg/kg Δ9-THC i.p. reported junctional zone disorganization with reduced glycogen trophoblast and the spongiotrophoblast populations 12 . It is possible that the higher dose of Δ9-THC may be more toxic to the junctional zone trophoblast and that 3 mg/kg allows for junctional zone specific trophoblast survival, though it must be considered that it could be a difference between species.…”