The relationship between plasma levels of the endocannabinoid, anandamide, sex steroids, and gonadotrophins during the menstrual cycle

Objective: To further investigate the relationship between plasma anandamide (AEA), sex steroids, and gonadotrophins to improve our understanding of how AEA may be involved in human fertility. Design: Cross-sectional and longitudinal study. Setting: University Hospital of Leicester NHS Trust, Leicester Royal Infirmary. Patient(s): Healthy premenopausal and postmenopausal volunteers. Intervention(s): UPLC-MS/MS-measured plasma AEA and ELISA-measured serum FSH, LH, estradiol, and progesterone levels at five different phases of the menstrual cycle and postmenopause. Main Outcome Measure(s): Plasma AEA, serum steroids and gonadotrophins. Result(s): Changes in AEA levels were similar in the two cohorts. The mean +/- SEM levels in the early follicular phase (0.89 +/- 0.06) for the cross-sectional cohort and the longitudinal cohort (0.73 +/- 0.03) were higher than those in the late follicular phase (0.77 +/- 0.09 cross-sectional; 0.63 +/- 0.08 longitudinal). The highest AEA levels were measured at ovulation (1.38 +/- 0.14 and 1.33 +/- 0.16) and the lowest level was measured in the late luteal phase (0.66 +/- 0.07 and 0.56 +/- 0.06). There was a statistically significant positive correlation between AEA, estradiol (P=0.0015), LH (P<0.0001) and FSH levels but not progesterone (P=0.022). Conclusion(s): Peak plasma AEA occurred at ovulation and positively correlated with estradiol and gonadotrophin levels suggesting that these may be involved in the regulation of AEA levels. (Fertil Steril (R) 2010;93:1989-96. (C)2010 by American Society for Reproductive Medicine.)