Characterisation of the endocannabinoid system in rat haemochorial placenta

Trophoblast cells that comprise the placenta play a crucial role in the complex cross-talk between fetus and maternal tissues. Although anandamide and 2-arachidonoylglycerol, the best studied endocannabinoids, affect trophoblast attachment and outgrowth, the functional significance of the endocannabinoid system in the development of placenta has not been established. We investigated the correlation between endocannabinoid levels and the pattern of expression of the receptors and metabolic enzymes of the endocannabinoid system during rat placental development. Here, we showed that all the endocannabinoid machinery is dynamically expressed in the functionally distinct basal and labyrinth zones of the rat placenta. Indeed, endocannabinoid levels are shown to increase with the progression of pregnancy. Together, these data support a role for the endocannabinoid system in normal placental function and evidence for a potential novel cellular target for the deleterious action of cannabis-derived compounds during the second half of pregnancy.

► All endocannabinoid elements are dynamically expressed in the functional distinct basal and labyrinth zones of the rat placenta.
► Placenta may represent a potential cellular target for the deleterious action of cannabis-derived compounds during pregnancy.
► Endocannabinoids may represent an additional prospect in the biology of trophoblast and invasion process.
► A deregulation of endocannabinoid system may be associated to placenta abnormalities.