A role for the endocannabinoid system in the premature luteal regression and progesterone withdrawal in a LPS-induced early pregnancy loss model

SCHANDER JULIETA; CORREA FERNANDO GABRIEL; BARIANI MARIA VICTORIA; BLANCO JULIETA; CYMERYNG CORA; CHIANELLI MONICA; WOLFSON MANUEL LUIS; FRANCHI, ANA MARIA

MOLECULAR HUMAN REPRODUCTION.

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2016

1360-9947

Study hypothesis: The aimof this study was to explore the role of the endocannabinoid system (eCS) in thealterations of the endocrine system in a murine model of lipopolysaccharide(LPS)-induced miscarriage. Study finding: We found that LPS increased the expression ofCOX-2 and the production of prostaglandin F2α (PGF2α) inthe uterus of 7-days pregnant mice, which resulted in a lower expression ofprolactin receptor in the ovary and a marked regression of corpora lutea (CL).These effects were absent in cannabinoid receptortype 1 knock-out (CB1-KO) mice, suggesting a role for the eCS as mediators of LPS-induceddeleterious effects on reproductive events. What is knownalready: Appropriate systemicprogesterone levels are critical for a successful pregnancy outcome. Precociousloss of luteal progesterone (P4) secretion leads to miscarriage in rodents. Wehave previously shown that LPS administration to pregnant mice inducesembryonic resorption accompanied by a dramatic decrease in systemicprogesterone levels in a murine model of inflammatory miscarriage, with theendocannabinoid system mediating these LPS-induced deleterious effects.Study design,samples/materials, methods: CD1 wild-type (WT) and CB1-KO mice were used in this study. Animalswere randomly allocated to Vehicle- or LPS-treated groups originating fourgroups: WT-Vehicle; WT-LPS; CB1-KO-Vehicleand CB1-KO-LPS. Vehicle consisted onsaline solution injected i.p. LPS was administered i.p. in a single dose (0.5μg/g body weight) on day 7 of pregnancy and tissues (blood, ovary, uterus) werecollected at different time-points (6, 12, 24 and 48 hours).  P4 and PGF2α plasma levels were determined byradioimmunoassay. Cyclooxygenase-2 (COX-2) mRNA (RT-PCR) and protein (Westernblot) content in uterus was assayed. COX-2 and prolactin receptor (PrlR) mRNAlevels in the ovary were assayed by RT-PCR. Tissue morphology of the CL wasassessed by haematoxylin-eosin staining. Efforts were made to minimized thenumber of animals used in each study (n=5-8). Data were analyzed by one ortwo-way ANOVA in a completely randomized design. Post-hoc comparisons wereperformed with Tukey?s test. Normality and Homoscedasticity were tested withShapiro-Wilk (modified) test and Levene test, respectively. In cases were datadid not meet the assumptions, data transformation was applied and continued aspreviously described. Mean differences were considered significant whenp<0.05.  Main results andthe role of chance: Treatment with LPSto 7-day pregnant WT mice induced a P4 withdrawal (p<0.05), increased inuterine COX-2 mRNA and protein expression (p<0.05) as well as an increase inuterine PGF2α production (p<0.05). These changes were absent inLPS-treated 7-day pregnant CB1-KOmice. In ovarian tissues, LPS treatment to 7-day pregnant WT induced adownregulation of PrlR mRNA expression (p<0.05) together with an increase inCOX-2 mRNA expression (p<0.05) and PGF2α content (p<0.05).These effects were absent in the CB1-KOmice. Collectively, our results suggest a role for the eCS mediatingLPS-induced deleterious effects on reproductive tissues.