Prevention of Endometrial Apoptosis: Randomized Prospective Comparison of Human Chorionic GonadotropinVersusProgesterone Treatment in the Luteal Phase

Abstract

To study control of apoptosis in human endometrium, we examined late luteal-phase endometrial biopsies obtained in the late luteal phase for evidence of apoptosis and compared the effects of exogenous human chorionic gonadotropin (hCG) and progesterone on this process. Using a controlled, prospective, and randomized study design, 12 healthy, fertile, reproductive-age women (ages 20-34 yr) with regular menstrual cycles (range, 26-32 d) were recruited. Each underwent an endometrial biopsy 12 d after a urinary LH surge in a control and treatment cycle. After biopsy in a natural cycle, subjects were randomized to receive luteal doses of either 200 mg intravaginal progesterone (d 18-27) or a single im injection of 10,000 IU of hCG (d 19) followed by repeat endometrial biopsy and collection of serum on d 26. Apoptosis was assessed by DNA laddering, localizing apoptotic bodies using immunofluorescent labeling of DNA fragments (the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling method), and immunohistochemical assessment of apoptosis markers bcl-2, bcl-x, and bax. Serum progesterone levels were compared between treatment groups. Evidence of apoptosis in control cycles was significantly reduced in endometrium after both luteal-phase treatments. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling results demonstrated significantly less apoptosis in the hCG treatment group compared with controls. Immunostaining for bcl-2 was higher in hCG- and progesterone-treated cycles, whereas bax expression was decreased and bcl-x immunostaining was not different between treatments. Serum progesterone levels were highest in the hCG-treated group, although statistical significance was not reached (P = 0.08). These results demonstrate that signs of apoptosis, already apparent by d 26 of the menstrual cycle can be reduced with either hCG or progesterone treatment. The clinical utility of these findings includes a rational use of luteal-phase support for treatment of women with infertility and/or recurrent pregnancy loss.

Low-dose human chorionic gonadotropin may improve in vitro fertilization cycle outcomes in patients with low luteinizing hormone levels after gonadotropin-releasing hormone antagonist administration

“…Apoptosis of endometrial stromal cells can also be reduced by the administration of hCG (45,46). Additionally, hCG messenger RNA (mRNA) is transcribed as early as the two-cell stage of the embryo (47), and the hCG protein is already being secreted by the embryo before implantation (48,49).…”

The role of chorionic gonadotropin and Notch1 in implantation

“…Furthermore, in vivo treatment of women with (h)CG or progesterone significantly increased Bcl-2 in the late luteal phase. Bcl-X levels were higher in the (h)CG treated group compared to the progesterone treated group, while Bax was inhibited by progesterone primarily [59]. Notch1 has also been shown to up regulate the anti-apoptotic protein, Bcl-X L [52], suggesting that it may participate in this effect of (h)CG.…”

“…Apoptosis was first described in the human endometrium in 1975 [56] and subsequently shown to be rare in the proliferative endometrium, whereas levels of apoptosis increase in secretory tissue and peaks during the menstrual phase [57,58]. Treatment with (h)CG or progesterone in the midsecretory phase inhibits apoptosis in late secretory phase, implying a role for embryonic signals in inhibiting apoptosis [59].…”

“…Studies in human endometrial fibroblasts with an apoptosis-inducing agent which disrupts the actin microfilaments, cytochalasin D indicate that (h) CG can significantly inhibit cytochalasin D-induced apoptosis of stromal cells, and this effect is enhanced in the presence of estrogen and progesterone [70]. Studies in human endometrial tissue suggest that ovarian steroids regulate three apoptotic related proteins (Bcl-2, Bcl-X and Bax) [59,71,72]. Thus, (h)CG and progesterone significantly reduce apoptosis in the endometrium.…”

The Role of Low-Dose hCG in the Late Follicular Phase of Controlled Ovarian Hyper Stimulation (COH) Protocols

“…The effect of hCG on endometrium regulation and implantation has been suggested in previous studies (Filicori et al, 2005;Cameo et al, 2006;d'Hauterive et al, 2007). LH administration can increase the LH/hCG receptors during the pre-implantation window and also prevents apoptosis of the endometrial stromal cells (Lovely et al, 2005;Jasinska et al, 2006). Serafini et al (2006) showed that using a low-dose hCG protocol along with a GnRH antagonist treatment in normal ovarian responders avoids premature ovulation, and OHSS.…”