Hemodynamic response of ovarian artery after hCG injection

Stimulation of LH, FSH, and luteal blood flow by GnRH during the luteal phase in mares

A study was performed on the effect of a single dose per mare of 0 (n = 9), 100 (n = 8), or 300 (n = 9) of GnRH on Day 10 (Day 0 = ovulation) on concentrations of LH, FSH, and progesterone (P4) and blood flow to the CL ovary. Hormone concentration and blood flow measurements were performed at hours 0 (hour of treatment), 0.25, 0.5, 1, 2, 3, 4, and 6. Blood flow was assessed by spectral Doppler ultrasonography for resistance to blood flow in an ovarian artery before entry into the CL ovary. The percentage of the CL with color Doppler signals of blood flow was estimated from videotapes of real-time color Doppler imaging by an operator who was unaware of mare identity, hour, or treatment dose. Concentrations of LH and FSH increased (P < 0.05) at hour 0.25 and decreased (P < 0.05) over hours 1 to 6; P4 concentration was not altered by treatment. Blood flow resistance decreased between hours 0 and 1, but the decrease was greater (P < 0.05) for the 100-μg dose than for the 300-μg dose. The percentage of CL with blood flow signals increased (P < 0.05) between hours 0 and 1 with no significant difference between the 100- and 300-μg doses. The results supported the hypothesis that GnRH increases LH concentration, vascular perfusion of the CL ovary, and CL blood flow during the luteal phase; however, P4 concentration was not affected.

The water permeability channels aquaporins 1-4 are differentially expressed in granulosa and theca cells of the preovulatory follicle during precise stages of human ovulation

CONTEXT

Changes in vascular permeability and expansion of the fluid-filled antrum are major events in the LH-induced ovulatory process.

OBJECTIVES

Our objective was to investigate the presence and expression levels of aquaporins (AQPs) in the granulosa and theca cell compartments of the follicle during defined phases of human ovulation.

DESIGN AND SETTING

We conducted a prospective experimental study at the Department of Obstetrics and Gynaecology at a university hospital.

PARTICIPANTS

Twenty-eight women underwent laparoscopic sterilization and at the same time follicle retrieval at four periovulatory phases.

MAIN OUTCOME MEASURES

mRNA levels of AQP1-4 were measured in separated granulosa and theca cells from preovulatory phase, early ovulatory (EO) phase, late ovulatory phase, and postovulatory phase. Immunohistochemistry was done for AQP1-4 in intact human follicles.

RESULTS

All four AQPs were expressed in both the theca and granulosa cells during ovulation. In granulosa cells, AQP1 levels increased in the late ovulatory and postovulatory phases. Expression of AQP2-3 followed a similar pattern with a marked increase in the EO phase, whereas AQP4 levels decreased from preovulatory to the EO phase. The presence of AQP1-4 in the human follicle was verified by immunohistochemistry.

CONCLUSIONS

The results show for the first time the presence of AQP1-4 in human follicles during ovulation. The marked early rise in expression of AQP2 and AQP3 suggests a role during the process leading to follicular rupture, and the late rise of AQP1 suggests a role in corpus luteum formation.

Effects of human chorionic gonadotropin on luteal blood flow and progesterone secretion in cows and in vitro-microdialyzed corpora lutea

To check human chorionic gonadotropin (hCG) effects on luteal blood flow (LBF) and progesterone (P(4)) synthesis, six cows received either 3000 IU hCG or saline (NaCl) on Day 7 (Day 1=ovulation) during two estrous cycles. Plasma P(4) and LBF were measured before (0h) and up to 48h after treatment. Luteal blood flow increased by 51% (P<0.05) at 1h after hCG administration and returned to baseline levels thereafter. Plasma P(4) levels were increased from pretreatment levels by 30% at 1h (P=0.05) and 81% at 48h (P=0.02) after hCG treatment. In contrast, NaCl did not cause changes in LBF and P(4) (P>0.05). Additionally, central and peripheral parts of 14 abattoir-derived corpora lutea of the mid-luteal phase (Day 8 to 12) were perfused with Ringer solution in an in vitro microdialysis system, supplemented with 50 or 150 IU/mL hCG for 1h. Application of 50 IU/mL hCG showed no influence on P(4) response (P>0.05) in both central and peripheral parts, whereas 150 IU/mL hCG resulted in an increase of P(4) synthesis (P=0.002) in the central parts only. In vivo, hCG provoked an immediate and long-term rise in P(4) but only a temporary elevation of LBF. Luteal blood flow itself does not seem to be the exclusive cause for an increase in P(4), because the in vitro data clearly showed direct effects of hCG on P(4) secretion. Interestingly, different P(4) secretion patterns could be found between central and peripheral parts of the corpus luteum in both control and hCG perfused corpora lutea.