Expression of cannabinoid receptors CB1, CB2 and GPR18 in adenomyotic lesions

The aim of this study was to assess if cannabinoid receptors CB1, CB2 and GPR18 are expressed in adenomyotic tissues. For this purpose, gene expression analysis was carried on RNA extracted from the nodular adenomyotic lesions of patients affected by adenomyosis and from healthy endometrial specimens of women without any uterine disorder. mRNA levels of CB1, CB2 and GPR18 evaluated by real-time PCR analysis resulted to be higher in adenomyotic specimens compared to healthy endometrium. In addition, the expression of cannabinoid receptors was evaluated at protein level in adenomyotic lesions and control endometrial specimens by immunohistochemistry (IHC) employing anti-CB1, anti-CB2 and anti-GPR18 antibodies. IHC analysis showed a positive staining of the analyzed cannabinoid receptors in the adenomyotic and control tissues both in stroma and in glands, without any significant difference between the groups. Thus, the increase of cannabinoid receptor expression at mRNA level was not mirrored by their protein content, stimulating further analysis. These findings suggest that cannabinoid receptors may be involved in the pathogenesis of adenomyosis and their targeting could be considered to identify innovative molecular therapeutic targets for the disease.