Elevated anandamide and related N-acylethanolamine levels occur in the peripheral blood of women with ectopic pregnancy and are mirrored by changes in peripheral fatty acid amide hydrolase activity.
BACKGROUND
Studies from knockout mice suggest that perturbations in oviductal endocannabinoid levels, endocannabinoid receptors, or endocannabinoid degrading enzyme [fatty acid amide hydrolase (FAAH)] expression result in infertility secondary to physical trapping of embryos. Similar observations have been made in ectopic pregnant women together with a suggestion that the endocannabinoid receptor gene polymorphism 1359G/A (rs1049353) is associated with ectopic pregnancy. These observations led to the hypothesis that ectopic pregnancy is associated with a perturbation in levels of endocannabinoids and FAAH activity and that such changes are associated with impaired tubal function.


OBJECTIVE
The objective of the study was to quantify the plasma levels of endocannabinoids (anandamide, oleoylethanolamide, and palmitoylethanolamide) and evaluate blood endocannabinoid metabolizing enzyme activities FAAH and N-acyl-phosphatidyl-ethanolamine phospholipase D (NAPE-PLD) in ectopic pregnancy and normal pregnant controls and relate that to β-human chorionic gonadotropin (β-hCG) levels. Additionally, we wanted to examine the effect of endocannabinoids on cilia beat frequency in Fallopian tube epithelial cells ex vivo.


METHODS
Whole blood collected from ectopic and normal pregnancies was used for quantification of plasma endocannabinoid levels by ultra-HPLC-tandem mass spectrometry of FAAH and NAPE-PLD enzyme activities by radiometric assays, and β-hCG by immunoassay. Fallopian tube epithelial cells from healthy volunteers were treated with endocannabinoids and cilia beat frequency analyzed using a high-speed digital camera and CiliaFA software.


RESULTS
FAAH activity (P < .05) but not NAPE-PLD activity was significantly reduced in ectopic pregnancies. All 3 endocannabinoids levels were significantly higher (P < .05) in ectopic pregnancy. There was no correlation between endocannabinoids, enzyme activity, and β-hCG levels. Oleoylethanolamide (P < .05), but not methanandamide or palmitoylethanolamide, significantly decreased cilia beat frequency in Fallopian tube epithelial cells.


CONCLUSIONS
Elevated endocannabinoid levels and reduced FAAH activity are associated with ectopic pregnancy and may modulate tubal function, suggesting dysfunctional endocannabinoid action in ectopic implantation. Oleoylethanolamide may play a critical role in embryo-tubal transport.
Endocannabinoid Research Group, Reproductive Sciences Section, Department of Cancer Studies and Molecular Medicine, University of Leicester, Leicester Royal Infirmary, University of Leicester, Leicester LE2 7LX, United Kingdom.
Alpha K
AK
Gebeh
Jonathon M
JM
Willets
Monica
M
Bari
Robert A
RA
Hirst
Timothy H
TH
Marczylo
Anthony H
AH
Taylor
Mauro
M
Maccarrone
Justin C
JC
Konje
D000328:Adult; D000577:Amides; D000581:Amidohydrolases / Q000378:metabolism*; D001095:Arachidonic Acids / Q000097:blood*; D002478:Cells, Cultured; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000378:metabolism; D002923:Cilia / Q000502:physiology; D010064:Embryo Implantation / Q000502:physiology; D063388:Endocannabinoids / Q000097:blood*; D004983:Ethanolamines / Q000097:blood*; D005187:Fallopian Tubes / Q000201:enzymology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008183:Luteal Phase / Q000502:physiology; D009829:Oleic Acids / Q000097:blood; D010169:Palmitic Acids / Q000097:blood; D010739:Phospholipase D / Q000378:metabolism; D053284:Polyunsaturated Alkamides / Q000097:blood*; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000097:blood* / Q000503:physiopathology; D055815:Young Adult; D000099252:Fatty Acid Amide Hydrolases
D000577:Amides; D000581:Amidohydrolases; D001095:Arachidonic Acids; D018997:Chorionic Gonadotropin, beta Subunit, Human; D063388:Endocannabinoids; D004983:Ethanolamines; D009829:Oleic Acids; D010169:Palmitic Acids; D010739:Phospholipase D; D053284:Polyunsaturated Alkamides; D000099252:Fatty Acid Amide Hydrolases; C022203:N-acylethanolamines; C488250:oleoylethanolamide; C005958:palmidrol; C078814:anandamide