Effects of abnormal cannabidiol on oxytocin-induced myometrial contractility

Considerations and Implications of Cannabidiol Use During Pregnancy

PURPOSE OF REVIEW

Cannabis is a naturally occurring plant that is composed of over sixty phytocannabinoids, of which cannabidiol (CBD) has been recently identified as having therapeutic potential.

RECENT FINDINGS

Although not clearly understood in its mechanism of action, CBD contains potent anti-inflammatory, anti-hyperalgesia, and analgesic qualities now being further analyzed for its use in the treatment of a plethora of diseases. Related to its large safety profile and lack of psychoactive effects typically associated with cannabis and tetrahydrocannabinol (THC), CBD is being used more frequently for self-treatment of chronic pain, anxiety, and depression. With the help of broad marketing, CBD is being used by numerous people, including pregnant women who use CBD as an anti-emetic. Since marijuana is legalized in many states in the USA, the use of CBD has increased not only in the general population but also in specific groups such as pregnant women with chronic pain. Despite CBD's accessibility, there are limited studies showing its safety during pregnancy. While the use of cannabis has been well explored in terms of the effects on pregnancy, the use of CBD during pregnancy thus far has limited literature. The goal of this investigation is to impart the current understanding of CBD and its effects of pregnancy.

Metformin attenuates susceptibility to inflammation-induced preterm birth in mice with higher endocannabinoid levels

Premature decidual senescence is a contributing factor to preterm birth. Fatty acid amide hydrolase mutant females (Faah-/-) with higher endocannabinoid levels are also more susceptible to preterm birth upon lipopolysaccharide (LPS) challenge due to enhanced decidual senescence; this is associated with mitogen-activated protein kinase p38 activation. Previous studies have shown that mechanistic target of rapamycin complex 1 (mTORC1) contributes to decidual senescence and promotes the incidence of preterm birth. In this study, we sought to attenuate premature decidual aging in Faah-/- females by targeting mTORC1 and p38 signaling pathways. Because metformin is known to inhibit mTOR and p38 signaling pathways, Faah-/- females were treated with metformin. These mice had a significantly lower preterm birth incidence with a higher rate of live birth after an LPS challenge on day 16 of pregnancy; metformin treatment did not affect placentation or neonatal birth weight. These results were associated with decreased levels of p38, as well as pS6, a downstream mediator of mTORC1 activity, in day 16 Faah-/-decidual tissues. Since metformin treatment attenuates premature decidual senescence with limited side effects during pregnancy, careful use of this drug may be effective in ameliorating specific adverse pregnancy events.

Role of the endocannabinoid system in the control of mouse myometrium contractility during the menstrual cycle

Cannabis and cannabinoids are known to affect female reproduction. However, the role of the endocannabinoid system in mouse uterine contractility in the dioestrus and oestrus phases has not been previously investigated. The present study aimed at filling this gap. Endocannabinoid (anandamide and 2-arachidonoylglycerol) levels were measured in mouse uterus at dioestrus and oestrus phases by liquid chromatography-mass spectrometry; quantitative reverse transcription-PCR and western blot were used to measured the expression of cannabinoid receptors and enzymes involved in the metabolism of endocannabinoids. Contractility was evaluated in vitro either on the spontaneous contractions or by stimulating the isolated uterus with exogenous spasmogens. The tissue concentrations of anandamide and 2-AG were reduced in the oestrus phase, compared to dioestrus. Uteri obtained in the dioestrus, but not oestrus, phase showed spontaneous phasic prostaglandin-mediated contractions that were reduced by ACEA (CB₁ receptor agonist) and to a lower extent by JWH133 (CB₂ receptor agonist). These inhibitory effects were counteracted by the corresponding selective antagonists. Neither ACEA nor JWH133 did affect the contractions induced by exogenous PGE₂ in the uterus from the oestrus phase. The FAAH inhibitor JNJ1661010 and, to a lower extent, the MAGL inhibitor JZL184 also reduced spontaneous contractions. It is concluded that the endocannabinoid system undergoes to adaptive changes between the oestrus and dioestrus phases. CB₁ and, to a lower extent, CB₂ receptor activation results in selective inhibition of myometrial contractility, without un-specific relaxing effects on the smooth muscle. These results might be of interest for female marijuana smokers as well as for the design of novel tocolytic agents.

Sustained Endocannabinoid Signaling Compromises Decidual Function and Promotes Inflammation-induced Preterm Birth

Recent studies provide evidence that premature maternal decidual senescence resulting from heightened mTORC1 signaling is a cause of preterm birth (PTB). We show here that mice devoid of fatty acid amide hydrolase (FAAH) with elevated levels ofN-arachidonyl ethanolamide (anandamide), a major endocannabinoid lipid mediator, were more susceptible to PTB upon lipopolysaccharide (LPS) challenge. Anandamide is degraded by FAAH and primarily works by activating two G-protein-coupled receptors CB1 and CB2, encoded by Cnr1 and Cnr2, respectively. We found thatFaah(-/-)decidual cells progressively underwent premature senescence as marked by increased senescence-associated β-galactosidase (SA-β-Gal) staining and γH2AX-positive decidual cells. Interestingly, increased endocannabinoid signaling activated MAPK p38, but not p42/44 or mTORC1 signaling, inFaah(-/-)deciduae, and inhibition of p38 halted premature decidual senescence. We further showed that treatment of a long-acting anandamide in wild-type mice at midgestation triggered premature decidual senescence utilizing CB1, since administration of a CB1 antagonist greatly reduced the rate of PTB inFaah(-/-)females exposed to LPS. These results provide evidence that endocannabinoid signaling is critical in regulating decidual senescence and parturition timing. This study identifies a previously unidentified pathway in decidual senescence, which is independent of mTORC1 signaling.

Lipid regulation of BK channel function

This mini-review focuses on lipid modulation of BK (MaxiK, BK_Ca) current by a direct interaction between lipid and the BK subunits and/or their immediate lipid environment. Direct lipid-BK protein interactions have been proposed for fatty and epoxyeicosatrienoic acids, phosphoinositides and cholesterol, evidence for such action being less clear for other lipids. BK α (slo1) subunits are sufficient to support current perturbation by fatty and epoxyeicosatrienoic acids, glycerophospholipids and cholesterol, while distinct BK β subunits seem necessary for current modulation by most steroids. Subunit domains or amino acids that participate in lipid action have been identified in a few cases: hslo1 Y318, cerebral artery smooth muscle (cbv1) R334,K335,K336, cbv1 seven cytosolic CRAC domains, slo1 STREX and β1 T169,L172,L173 for docosahexaenoic acid, PIP₂, cholesterol, sulfatides, and cholane steroids, respectively. Whether these protein motifs directly bind lipids or rather transmit the energy of lipid binding to other areas and trigger protein conformation change remains unresolved. The impact of direct lipid-BK interaction on physiology is briefly discussed.