The Relationship Between Plasma Levels Of The 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.Methods:This study was undertaken in two parts.The first part was cross-sectional and designed to examine in greater detail plasma AEA changes during the menstrual cycle;the second part was longitudinally designed with the volunteers acting as their own controls to allow for further investigation of whether the changes in AEA levels observed cross-sectionally were mirrored in the same individuals.A prospective trial was performed on 89 patients hospitalized in the Assisted Reproductive Center,Second Hospital of Hebei Medical University from May 2014 to October 2014.All the volunteers included in the study were selected with the following criteria: Age 20-38years;menstruating in regular cycles(defined as occurring every 26~32 days)for 6 months before entry into the study,spontaneously ovulation;laparoscope or HSG prompt oviduct obstruction or male factor infertility;excluded polycystic ovary syndrome,significant uterine,endocrine,immune infertility,no endometriosis symptom on clinical;BMI 19-25kg/m~2;have not used hormone drugs for nearly three months.not taking any medication or hormonal contraception for at least three months before recruitment into the studies,and nonsmokers.In both parts of the study,the menstrual cycle was divided into four phases based on their self-reported last menstrual period and vaginal ultrasound: early follicular(days 2~6),late follicular(days 8~12),ovulatory(days 13~16),and early luteal(days 18~23).In order to confirm the phase,both of the two groups accepted ovulation detection by vaginal ultrasound.All samples were collected between 10:00 and 12:00 AM to avoid any diurnal variation.The 79 volunteers in the cross-sectional study divided into 4 groups and was respectively in 4 phases collected 5 mL of blood obtained for plasma AEA,whereas 10 volunteers in the longitudinal study had 10 mL of blood collected for AEA、sex steroids and andgonadotrophins in each phases.To observe the changes of plasma AEA,and investigate the relationship between plasma anandamide(AEA),sex steroids,and gonadotrophins to improve our understanding of how AEA may be involved in human fertility.Result: There was no difference between two groups in the BMI,age(P>0.05).There was no significant difference between the two groups in the dosage of AEA in each phases(P>0.05).Plasma AEA levels in the cross-sectional and longitudinal arms of the study were comparable.Plasma AEA levels in each phases of the menstrual cycle were no significantly different(P>0.05).In the cross-sectional arm of the study,the plasma AEA level(9.71±0.86ng/mL)in the early follicular phase(day 2~6)of the menstrual cycle were lower than those(10.61±1.05 ng/mL)in the late follicular(day 8~12)phase,but this was not statistically significant(P>0.05).Plasma AEA level measured at the time of ovulation(days 13~16)was the highest and compared with the level observed in the early follicular phase and luteal(day 18-23)phase(7.46±0.71ng/m L),there was a statistically significant difference(P<0.0001).The lowest plasma AEA level was observed in the luteal phase and was significantly lower(P<0.05)than that of other three phases by multiple compared.In the longitudinal arm of the study,there was a rise in plasma AEA level from 8.76±0.91ng/mL in the early follicular(day 2~6)phase to 11.61±1.28ng/mL at the time of late follicular(day 8~12)phase.The highest plasma AEA level(13.85±1.18ng/mL)measured at the time of ovulation(days 13~16)is followed by a statistically significant(P<0.05)decrease to 8.50±1.08ng/mL in the early luteal(day18~23)phase.Serum levels of E2,P4,LH and FSH were in keeping with the classically described patterns for these hormones in premenopausal ovulating women.There were highly statistically significant positive correlations between plasma AEA levels and serum LH(P<0.001),FSH(P<0.001)and E2 levels(P=0.003),but not with serum P4 levels(P>0.05).Conclusion: There was a rise in plasma AEA level from early follicular(day 2~6)phase to ovulation(days 13~16).The highest plasma AEA level measured at the time of ovulation(days 13~16)is followed by a statistically significant decrease to the early luteal(day18~23)phase.There were highly statistically significant positive correlations between plasma AEA levels and serum LH,FSH and E2 levels,but not with serum P4 levels.Our observations suggests that AEA may be controlled by either gonadotrophins or most probably by estradiol,or by both during the menstrual cycle,and are important to further our understanding of the role of endocannabinoids(especially AEA)in human fertility and will form the basis for further studies investigating the precise controlling mechanisms that influence successful implantation and other facets of human reproduction.