Alberto Palomino

The human corpus luteum: life cycle and function in natural cycles.

OBJECTIVE To summarize recent advances in the understanding of the endocrine signaling pathways between the hypothalamus, pituitary, and human corpus luteum (CL); to examine the major paracrine and autocrine mechanisms and the key genes and proteins involved in CL development, function, and regression in natural cycles; to review the endocrine and molecular response of the midluteal phase CL to in vivo administration of human chorionic gonadotropin (hCG); and to describe the ultrasonographic and Doppler evaluation of the ovary and endometrium throughout the luteal phase. DESIGN Published data in the literature, including the basic and clinical research studies of the authors. SETTING University-affiliated hospital and research centers. PATIENT(S) None. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Clinical and molecular analysis of human CL function. RESULT(S) The endocrine function of the subpopulations of luteal cells is critical for the maintenance of CL function, including neovacularization and steroid hormones production. We consider the key genes and proteins that favor development of luteal structure and function throughout the menstrual cycle and in our model of hCG treatment resembling early pregnancy. CONCLUSION(S) These data indicate that the functional lifespan of the CL depends on paracrine and autocrine mechanisms. Therefore, the significance of the key genes and proteins that we analyze in lutein cells during CL development, function, demise, and rescue by hCG is likely to bring new therapeutic applications for the management of fertility defects and the control of fertility.

Expression of steroid receptors and proteins related to apoptosis in endometria of women with polycystic ovary syndrome

OBJECTIVE To evaluate the expression of steroid hormone receptors, proteins related to apoptosis, and cell proliferation in endometria from women with polycystic ovary syndrome (PCOS). DESIGN Case-control study. SETTING Hospital research unit. PATIENT(S) Eight women with PCOS and 12 fertile healthy women of similar age to those with PCOS. INTERVENTION(S) Endometrial samples were obtained from women with PCOS (PCOSE) and normal (NE) women during the proliferative phase of the menstrual cycle. MAIN OUTCOME MEASURE(S) Expression studies (immunohistochemistry and reverse transcription-polymerase chain reaction) and DNA fragmentation [TdT-mediated dUTP nick end labeling (TUNEL)]. RESULT(S) In stroma, protein expression of estrogen receptor alpha, Bcl-2, and Bax was higher in PCOSE than in NE; epithelial cells had a greater expression of androgen receptor in the nucleus and a lower expression in the cytoplasm of PCOSE. Cell proliferation was higher in the epithelia of NE, while the expression of caspase-3 and DNA fragmentation was similar in both groups. The bax mRNA expression was higher in PCOSE, and bcl-2 mRNA expression was similar between groups. A higher bcl-2/bax relative ratio in PCOSE was observed. CONCLUSION(S) An alternating expression of proteins related to cell survival in endometria from PCOSE may potentially be associated with the disruption of their endometrial cell cycle.

Molecular regulation of progesterone secretion by the human corpus luteum throughout the menstrual cycle

The present study examines the expression of the steroidogenic acute regulatory protein (StAR) within the human corpus luteum (CL) in conjunction with other molecules that regulate the apoptotic process of the CL. Our results indicate that the primary 1.6 kb StAR transcript occurs in greater abundance in early and mid-luteal phase compared with late luteal phase CL. Mature StAR protein (30 kDa) was present in lower amounts within late CL compared with early and mid-luteal phase. The pre-protein (37 kDa), which has been considered the active isoform to favor cholesterol translocation and subsequently steroid hormone synthesis, was also detected in lower amount in late CL. Several molecules, including pro-inflammatory cytokines, reactive oxygen species, steroids and inducible nitric oxide synthase (iNOS), have been linked as pro-apoptotic regulatory agents. Moreover, many of these molecules diminish progesterone synthesis in human cultured luteal cells. Interestingly, these molecules preferentially decrease progesterone biosynthesis in mid and late luteal cells in culture. These data suggest that the inhibitory effect of these molecules, as well as the amount of apoptotic cells in the CL are age dependent. The number of luteal apoptotic cells, as well as luteal cells stained positive for iNOS, increased from early to late CL. To examine the effects of hCG on StAR expression and apoptosis, we used two models-(1) in vivo hCG administration during the late luteal phase; and (2) in vitro incubation of explants of late CL with hCG. hCG increased both the level of StAR expression and the level of anti-apoptotic protein Bcl-2 within the late CL. We conclude that mRNA and protein expression of StAR and bcl-2 are important target elements for hCG during the CL rescue.

Antisteroidogenic action of nitric oxide on human corpus luteum in vitro : Mechanism of action ()

To analyze the mechanism by which nitric oxide (NO) exerts its antisteroidogenic action, human luteal cells were cultured during 24 and 48 h with l-arginine (l-Arg, 1 mmol/L); 1,2(2-trifluoromethylphenyl)imidazole (TRIM) (50 μmol/L and 1 mmol/L) and cyclic guanosine monophosphate (cGMP) analog (8-Br-cGMP, 1 mmol/L). Estradiol, nitrite, and P450 AROM activity were determined in culture media. Total cGMP concentration was evaluated in the cells and culture media by radioimmunoassay, and NADPH diaphorase was used as a histochemical marker for NO synthase (NOS) activity. During the corpus luteum (CL) life-span, NO affected estradiol secretion in an age-dependent manner, with an inhibition in mid-CL (37%; p<0.05) in agreement with our previous results, and no significant modification in early and late CL. Basal nitrite concentration in 24 and 48 h of midluteal cell cultures (42 and 93 pmol/106 cells, respectively) was increased by l-Arg (53% and 88%) and inhibited by the two TRIM concentrations; also, an intense diaphorase reactivity was observed in endothelial cells and luteal parenchyma. Total cGMP was not detected in cell cultures and 8-Br-cGMP did not modify estradiol secretion, whereas aromatase activity was strongly inhibited by l-Arg (70%, p<.05). These results suggest that both NOS isoforms are active in midluteal cells, and the mechanism of action for NO on in vitro estradiol secretion may be an inhibition of P450 AROM activity.

Antenatal diagnosis of a third trimester interstitial pregnancy: a case report.

Interstitial pregnancy cases that advance to term, or near term, are occasionally reported. We present an unusual case of a third trimester interstitial pregnancy with antenatal diagnosis and expectant management. She presented at 20 weeks of pregnancy with an early preterm premature rupture of membranes, and expectant management was initiated. The ultrasound suggested an interstitial location and a posterior magnetic resonance image, obtained at 26 weeks, confirmed the diagnosis. Because of the risk of uterine rupture, an elective cesarean section was performed at 28 weeks. During the laparotomy, the uterine fundus appeared intact with an asymmetric bulge that provided evidence of placenta increta. The baby was delivered, and an obstetric hysterectomy was performed. The newborn was admitted to the neonatal intensive care unit with a severe respiratory distress syndrome. No response to mechanical ventilation was observed, and neonatal death was reported. A uterine pathological examination confirmed the diagnosis.

Neuroendocrinology and ovarian aging

The ovarian aging, a dynamic process that precedes the clinical manifestations of menopause, can be assessed using ovarian reserve biomarkers. It is well-known that reproduction during the later years of reproductive life has known limitations that challenge the success of assisted reproduction. Therefore, a review of the neuroendocrine modifications during this critical period of reproductive life may help to elucidate the ovarian aging process and its impact on reproduction. In this review, we aim to further the discussion of neuroendocrine changes taking place during the ovarian aging process that may impact reproductive function.