Mice Missing Cnr1 and Cnr2 Show Implantation Defects

Area of Science:

• Reproductive Biology
• Endocrinology
• Genetics

Background:

• Cannabinoid signaling, mediated by cannabinoid receptor type 1 (CB1) and type 2 (CB2), plays a role in various physiological processes.
• The specific role of CB1 and CB2 in uterine function and early pregnancy is not fully understood.

Purpose of the Study:

• To investigate the role of CB1 and CB2 in female fertility and implantation in mice.
• To elucidate the mechanisms by which cannabinoid receptors influence uterine receptivity and pregnancy outcomes.

Main Methods:

• Generation and analysis of mice lacking both Cnr1 and Cnr2 genes (Cnr1-/-Cnr2-/-).
• Histological examination of uterine implantation sites.
• Assessment of blastocyst-uterine interactions and implantation chamber morphology.
• Utilizing reporter mouse lines to track CB2 expression in uterine tissues.

Main Results:

• Cnr1-/-Cnr2-/- mice exhibit subfertility characterized by compromised embryo implantation.
• Uterine epithelium in mutant mice is ruffled, hindering proper blastocyst adhesion.
• Increased uterine edema and blood vessel leakage were observed around the implantation site in Cnr1-/-Cnr2-/- females.
• CB2 receptor expression was detected on uterine endothelial cells, and its absence correlated with vascular leakage.

Conclusions:

• Cannabinoid receptors CB1 and CB2 are crucial for successful embryo implantation in mice.
• Absence of CB1 and CB2 leads to uterine vascular dysfunction and edema, impairing implantation.
• Regulated uterine edema is essential for optimal blastocyst-uterine interactions and successful pregnancy initiation.