Related Experiment Video
Updated: Jun 5, 2026
Remote Neuronal Activation Coupled with Automated Blood Sampling to Induce and Measure Circulating Luteinizing Hormone in Mice
Published on: August 25, 2023
Luteal blood flow in patients undergoing GnRH agonist long protocol
Akihisa Takasaki1, Isao Tamura, Fumie Kizuka
1Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan. sugino@yamaguchi-u.ac.jp.
Insights
Luteal blood flow impedance is high in women undergoing GnRH agonist long protocol due to low LH. Human chorionic gonadotropin (HCG) and vitamin E treatments improved luteal blood flow, suggesting LH regulates it.
Area of Science:
- Reproductive endocrinology
- Vascular biology
Background:
- Corpus luteum (CL) blood flow is vital for luteal function, but its regulation is not fully understood.
- The gonadotropin-releasing hormone agonist (GnRHa) long protocol suppresses luteinizing hormone (LH), potentially causing luteal phase defects.
- Investigating CL blood flow during this protocol may elucidate LH's regulatory role.
Purpose of the Study:
- To examine the impact of luteal support on corpus luteum blood flow impedance in women undergoing a GnRH agonist long protocol.
- To determine if luteinizing hormone (LH) regulates luteal blood flow.
Main Methods:
- Twenty-four infertile women on a GnRHa long protocol were divided into control, human chorionic gonadotropin (HCG), and vitamin E groups.
- Luteal phase support varied: control (ethinylestradiol plus norgestrel), HCG group (HCG plus ethinylestradiol/norgestrel), and vitamin E group (vitamin E plus ethinylestradiol/norgestrel).
- Transvaginal color-pulsed-Doppler-ultrasonography measured corpus luteum resistance index (CL-RI) during the mid-luteal phase.
Main Results:
- Serum LH levels were significantly suppressed in all groups.
- The control group exhibited high CL-RI (>0.51), indicating poor luteal blood flow.
- Both HCG and vitamin E treatments significantly reduced CL-RI (<0.51), improving luteal blood flow impedance.
Conclusions:
- Women undergoing GnRHa long protocol experience high luteal blood flow impedance associated with low LH levels.
- HCG administration effectively improved luteal blood flow impedance.
- These findings suggest that luteinizing hormone (LH) plays a crucial role in regulating corpus luteum blood flow.
Background:
Blood flow in the corpus luteum (CL) is closely related to luteal function. It is unclear how luteal blood flow is regulated. Standardized ovarian-stimulation protocol with a gonadotropin-releasing hormone agonist (GnRHa long protocol) causes luteal phase defect because it drastically suppresses serum LH levels. Examining luteal blood flow in the patient undergoing GnRHa long protocol may be useful to know whether luteal blood flow is regulated by LH.
Methods:
Twenty-four infertile women undergoing GnRHa long protocol were divided into 3 groups dependent on luteal supports; 9 women were given ethinylestradiol plus norgestrel (Planovar) orally throughout the luteal phase (control group); 8 women were given HCG 2,000 IU on days 2 and 4 day after ovulation induction in addition to Planovar (HCG group); 7 women were given vitamin E (600 mg/day) orally throughout the luteal phase in addition to Planovar (vitamin E group). Blood flow impedance was measured in each CL during the mid-luteal phase by transvaginal color-pulsed-Doppler-ultrasonography and was expressed as a CL-resistance index (CL-RI).
Results:
Serum LH levels were remarkably suppressed in all the groups. CL-RI in the control group was more than the cutoff value (0.51), and only 2 out of 9 women had CL-RI values < 0.51. Treatments with HCG or vitamin E significantly improved the CL-RI to less than 0.51. Seven of the 8 women in the HCG group and all of the women in the vitamin E group had CL-RI < 0.51.
Conclusion:
Patients undergoing GnRHa long protocol had high luteal blood flow impedance with very low serum LH levels. HCG administration improved luteal blood flow impedance. This suggests that luteal blood flow is regulated by LH.
Related Concept Videos
01:22Hormonal Regulation of the Menstrual Cycle
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH release.
01:27Ovarian Cycle