The levels of prostaglandins in the human endometrium throughout the normal menstrual cycle were measured by bioassay. The identity of prostaglandin F2alpha and prostaglandin E2 in endometrial tissue extracts was established by combined gas chromatography/mass spectrometry. The levels of prostaglandin F2alpha and prostaglandin E2 are low during the proliferative phase of the cycle (10-25 ng/100 mg tissue). Prostaglandin F2alpha rises significantly during the luteal phase to levels of 65-75 ng/100 mg of tissue. Prostaglandin E2 levels are similar to prostaglandin F2alpha levels in the proliferative phase but remain lower during the luteal phase. The prostaglandin E2 level is highest at menstruation (52 ng/100 mg tissue). The implications of these findings are discussed in relation to the menstrual process and to the steroid hormonal changes during the cycle.
DOI 10.1113/jphysiol.1974.sp010446 10.1113/jphysiol.1974.sp010446 Downie et al. 1974, Downie 1974
Cite this article
Downie, J., Poyser, N. L., & Wunderlich, M. (1974). Levels of prostaglandins in human endometrium during the normal menstrual cycle. The Journal of Physiology. https://doi.org/10.1113/jphysiol.1974.sp010446
Downie J, Poyser NL, Wunderlich M. Levels of prostaglandins in human endometrium during the normal menstrual cycle. The Journal of Physiology. 1974. doi:10.1113/jphysiol.1974.sp010446
Downie, J., et al. "Levels of prostaglandins in human endometrium during the normal menstrual cycle." The Journal of Physiology, 1974.
1. The effect of the different phases of the menstrual cycle on skeletal muscle strength, contractile properties and fatiguability was investigated in ten young, healthy females. Results were compared with a similar group on the combined (non-phasic) oral contraceptive pill (OC). Cycle phases were divided into the early and mid-follicular, mid-cycle (ovulatory) and mid- and late luteal. Cycle phases were estimated from the first day of the menstrual bleed. 2. Subjects were studied weekly through two complete cycles. Measurements included quadriceps and handgrip maximum voluntary isometric force and the relaxation times, force-frequency relationship and fatigue index of the quadriceps during percutaneous stimulation at a range of frequencies from 1 to 100 Hz. 3. In the women not taking the OC there was a significant increase of about 11% in quadriceps and handgrip strength at mid-cycle compared with both the follicular and luteal phases. Accompanying the increases in strength there was a significant slowing of relaxation and increase in fatiguability at mid-cycle. No changes in any parameter were found in the women taking the OC. 4. The changes in muscle function at mid-cycle may be due to the increase in oestrogen that occurs prior to ovulation.
The corpus luteum is a vital yet temporary organ that plays a crucial role in fertility during the luteal phase. An endocrine structure in females exists within the ovary once the ovarian follicle releases a mature ovum during ovulation. See Image. Anatomy of the Internal Structures of the Ovary. The secretion of hormones from the corpus luteum stops within 14 days after ovulation if the oocyte is not fertilized. It then degenerates into a scar within the ovary, known as corpus albicans. The corpus luteum's role is to maintain a uterine environment that allows for implementation and pregnancy. This occurs by the release of pregnancy-related hormones and regulation of the hypothalamic-pituitary access through inhibition of gonadotropin-releasing hormone from the hypothalamus, which in turn decreases the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) released from the anterior pituitary. The primary hormone produced by the corpus luteum is progesterone, but it also produces inhibin A and estradiol. In the absence of fertilization, the corpus luteum regresses over time. A corpus luteum develops each time a woman ovulates so that she produces a corpus luteum numerous times throughout her lifetime.
Self-reported dietary intake varies across menstrual cycle phases, but objective assessments of dietary intake together with appetite and resting metabolic rate (RMR) are limited. This study aimed to assess differences in dietary intake, appetite, and RMR during two hormonally-distinct menstrual cycle phases in laboratory and free-living settings. Healthy premenopausal females with predictable normal-length menstrual cycles completed two study visits: one in the late-follicular and one in the mid-luteal phase. Menstrual cycle phases were assessed using urinary luteinizing hormone surge and prospective cycle days. Participants consumed a 2-day energyand macronutrient-balanced run-in diet prior to each visit. RMR was measured with indirect calorimetry, followed by appetite ratings before and after a standardized breakfast, and a food cravings questionnaire. Appetite was also tracked for 2.5 days post-visit in a free-living environment. Ad libitum energy and macronutrient intakes were measured using pre-weighed plus weighing of uneaten food at an in-laboratory lunch meal, as well as during the 2.5-day free-living period. Eighteen participants were included (age: 21 ± 4 years; body mass index: 21.2 ± 1.5 kg/m2). There were no differences between in-laboratory ad libitum energy or macronutrient intakes, appetite, or food cravings between phases. RMR did not differ between phases, although the mid-luteal phase RMR tended to be higher (104 ± 218 kcal/day higher; P = 0.074). No main or interaction effects for phase or time were observed for free-living dietary intake nor appetite ratings. Although RMR tended to be increased during the luteal phase, comprehensive appetite and energy intake assessments showed no significant cycle-phase differences in these 18 participants.