Ectopic pregnancy is associated with high anandamide levels and aberrant expression of FAAH and CB1 in fallopian tubes.
BACKGROUND
Ectopic pregnancy is associated with significant morbidity and mortality, but the molecular mechanisms underlying this condition remain unclear. Although the endocannabinoids, N-arachidonoylethanolamine (anandamide), N-oleoylethanolamine, and N-palmitoylethanolamine, are thought to play a negative role in ectopic pregnancy, their precise role(s) within the fallopian tube remains unclear. Anandamide activates cannabinoid receptors (CB1 and CB2) and, together with its degrading [e.g. fatty acid amide hydrolase (FAAH)] and synthesizing enzymes (e.g. N-acyl-phosphatidylethanolamine-specific phospholipase D), forms the endocannabinoid system. High anandamide levels are associated with tubal arrest of embryos in mice and may have a similar role in women.


OBJECTIVE
The aims were to quantify the levels of the endocannabinoids and evaluate the expression of the modulating enzymes and the cannabinoid receptors in fallopian tubes of women with ectopic pregnancy compared to those of nonpregnant women.


METHODS
We conducted a prospective study at the University Hospitals of the Leicester National Health Service Trust.


METHODS
Fallopian tubes collected from women with ectopic pregnancy and nonpregnant women with regular menstrual cycles were used for quantification of endocannabinoids by ultra-HPLC tandem mass spectrometry, were fixed in formalin for immunohistochemistry, and had RNA extracted for RT-quantitative PCR or protein extracted for immunoblotting.


RESULTS
Anandamide, but not N-oleoylethanolamine and N-palmitoylethanolamine, levels were significantly higher in ectopic fallopian tubes. Endocannabinoid levels from isthmus to ampulla were not significantly different. Cannabinoid receptors and endocannabinoid modulating enzymes were localized in fallopian tube epithelium by immunohistochemistry and showed reduced CB1 and FAAH expression in ectopic pregnancy.


CONCLUSIONS
High anandamide levels and reduced expression of CB1 and FAAH may play a role in ectopic implantation.
Endocannabinoid Research Group, Reproductive Sciences Section, Department of Cancer Studies and Molecular Medicine, University of Leicester, Leicester LE2 7LX, United Kingdom.
Alpha K
AK
Gebeh
Jonathon M
JM
Willets
Emma L
EL
Marczylo
Anthony H
AH
Taylor
Justin C
JC
Konje
D000328:Adult; D000581:Amidohydrolases / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D001095:Arachidonic Acids / Q000032:analysis*; D063388:Endocannabinoids; D005187:Fallopian Tubes / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D053284:Polyunsaturated Alkamides / Q000032:analysis*; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D043884:Receptor, Cannabinoid, CB1 / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D043885:Receptor, Cannabinoid, CB2 / Q000502:physiology; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D001095:Arachidonic Acids; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; D012333:RNA, Messenger; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D000099252:Fatty Acid Amide Hydrolases; C078814:anandamide