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.