Temporal relationships among uterine pituitary adenylate cyclase-activating polypeptide, decidual prolactin-related protein and progesterone receptor mRNAs expressions during decidualization and gestation in rats

Female reproductive functions of the neuropeptide PACAP

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide originally isolated as a hypothalamic peptide. It has a widespread distribution in the body and has a diverse spectrum of actions. Among other processes, PACAP has been shown to be involved in reproduction. In this review we summarize findings related to the entire spectrum of female reproduction. PACAP is a regulatory factor in gonadal hormone production, influences follicular development and plays a role in fertilization and embryonic/placental development. Furthermore, PACAP is involved in hormonal changes during and after birth and affects maternal behavior. Although most data come from cell cultures and animal experiments, increasing number of evidence suggests that similar effects of PACAP can be found in humans. Among other instances, PACAP levels show changes in the serum during pregnancy and birth. PACAP is also present in the human follicular and amniotic fluids and in the milk. Levels of PACAP in follicular fluid correlate with the number of retrieved oocytes in hyperstimulated women. Human milk contains very high levels of PACAP compared to plasma levels, with colostrum showing the highest concentration, remaining steady thereafter for the first 7 months of lactation. All these data imply that PACAP has important functions in reproduction both under physiological and pathological conditions.

Possible effects of pituitary adenylate cyclase activating polypeptide (PACAP) on early embryo implantation marker HB-EGF in mouse

Pituitary adenylate cyclase activating polypeptide (PACAP) was originally isolated as a hypothalamic neuropeptide stimulating adenylate cyclase activity. Besides its neuroprotective effects, numerous data proved its role in reproductive processes. However, there are limited data on its role in preimplantation embryo development and implantation. Our aim was to analyse the mRNA expression of Adcyap1 (coding region of PACAP) and Hbegf [coding region of HB-EGF (Heparin-binding EGF-like growth factor)] in embryos and pregnant uterus to investigate the possible correlation between them. Eight-week-old BDF1 mice were superovulated and subsequently mated overnight or left in their cage after hCG treatment. Day4 embryos were flushed from mated females. After morphological analysis, Adcyap1 and Hbegf gene expression of embryos and uterine tissues was assessed with qPCR. Our results showed significantly higher Adcyap1 and Hbegf mRNA levels in females producing embryos compared to non-mated ones. Robust elevation of Adcyap1 and slight elevation of Hbegf were detected in females with blastocyst embryos compared with non-blastocysts. We found low rate of Hbegf mRNA expression in uncompacted embryos, whereas morulae and blastocysts expressed high amounts of Hbegf. However, we did not find detectable Adcyap1 mRNA in embryos. Strong correlation was found between uterine tissue and embryonic Hbegf levels, slight correlation between uterine Adcyap1 and Hbegf levels. Uterine tissue Adcyap1 and embryonic Hbegf showed no correlation. In summary, our present data show, for the first time, the correlation between PACAP and HB-EGF mRNA expression suggesting that PACAP might play a role during the peri-implantation period of early mouse embryo development.

Investigation of the possible functions of PACAP in human trophoblast cells

Pituitary adenylate cyclase activating polypeptide (PACAP) is an endogenous neuropeptide having a widespread distribution both in the nervous system and peripheral organs including the female reproductive system. Both the peptide and its receptors have been shown in the placenta but its role in placental growth, especially its human aspects, remains unknown. The aim of the present study was to investigate the effects of PACAP on invasion, proliferation, cell survival, and angiogenesis of trophoblast cells. Furthermore, cytokine production was investigated in human decidual and peripheral blood mononuclear cells. For in vitro studies, human invasive proliferative extravillous cytotrophoblast (HIPEC) cells and HTR-8/SVneo human trophoblast cells were used. Both cell types were used for testing the effects of PACAP on invasion and cell survival in order to investigate whether the effects of PACAP in trophoblasts depend on the examined cell type. Invasion was studied by standardized invasion assay. PACAP increased proliferation in HIPEC cells, but not in HTR-8 cells. Cell viability was examined using MTT test, WST-1 assay, and annexin V/propidium iodide flow cytometry assay. Survival of HTR-8/SVneo cells was studied under oxidative stress conditions induced by hydrogen peroxide. PACAP as pretreatment, but not as co-treatment, significantly increased the number of surviving HTR-8 cells. Viability of HIPEC cells was investigated using methotrexate (MTX) toxicity, but PACAP1-38 could not counteract its toxic effect. Angiogenic molecules were determined both in the supernatant and the cell lysate by angiogenesis array. In the supernatant, we found that PACAP decreased the secretion of various angiogenic markers, such as angiopoietin, angiogenin, activin, endoglin, ADAMTS-1, and VEGF. For the cytokine assay, human decidual and peripheral blood lymphocytes were separated and treated with PACAP1-38. Th1 and Th2 cytokines were analyzed with CBA assay and the results showed that there were no significant differences in control and PACAP-treated cells. In summary, PACAP seems to play various roles in human trophoblast cells, depending on the cell type and microenvironmental influences.

Alterations of pituitary adenylate cyclase-activating polypeptide-like immunoreactivity in the human plasma during pregnancy and after birth

BACKGROUND

Since its discovery, several distinct effects of pituitary adenylate cyclase activating polypeptide (PACAP) have been established - predominantly in animal studies - in the nervous system, various peripheral organs as well as in the endocrine regulation. It is unknown whether PACAP has any effect on human pregnancy regarding either utero-maternal or perinatal aspects of the gestation.

AIM

We investigated alterations of PACAP38-like immunoreactivity (PACAP38-LI) in the human plasma throughout normal pregnancy, during and after delivery, and its level in the umbilical vessels, as well as in the peripheral blood of term healthy newborns.

MATERIALS AND METHODS

A 2 ml blood sample was used for each test, PACAP38-LI was determined by radioimmunoassay.

RESULTS

In the 2nd and 3rd trimester significant elevation was observed in the PACAP38-LI compared to the earlier gestation and non-pregnant conditions. During delivery its level significantly decreased and returned to the original values 3 days after birth. In the neonates PACAP38-LI level of the peripheral blood was similar to that of healthy adults, but umbilical arteries and veins contained significantly lower concentrations of PACAP38-LI. Besides, the levels were lower in the umbilical vein compared to the artery.

CONCLUSIONS

PACAP38-LI levels show sensitive change during normal pregnancy and delivery. Our findings suggest that the fetal organs actively synthesize PACAP. Further investigations are required to elucidate the physiological importance of the alterations observed.

Changes in the expression of pituitary adenylate cyclase-activating polypeptide in the human placenta during pregnancy and its effects on the survival of JAR choriocarcinoma cells

Pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide with survival-promoting actions, has been observed in endocrine organs and is thought to play a role in reproductive functions, including pregnancy. PACAP occurs in two forms, 27 and 38 amino acid residues, with PACAP38 being the predominant form in human tissues. In the present study, we determined the concentrations of PACAP38 and PACAP27 in first-trimester and full-term human placentas using radioimmunoassay. We found high levels of PACAP38 and lower levels of PACAP27 in different parts of the full-term human placenta. PACAP38 content increased in the placenta during pregnancy, both on the maternal side and on the fetal side. The effects of PACAP on the survival of JAR human choriocarcinoma cells were investigated using flow cytometry and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) cell viability assay in cells exposed to the widely used chemotherapeutic agent methotrexate (MTX). It was found that PACAP neither influenced the survival of JAR cytotrophoblast cells nor affected cellular response to the death-inducing effect of the chemotherapeutic agent MTX. The present observations further support the significance of PACAP in the human placenta. The observation that PACAP did not influence the effects of MTX may have future clinical importance, showing that PACAP does not decrease the effects of certain chemotherapeutic agents.

Stimulation of epithelial repair is a likely mechanism for the action of mifepristone in reducing duration of bleeding in users of progestogen-only contraceptives

Many women using progestogen (P)-only contraceptives experience uterine bleeding problems. In clinical trials, a single low dose of mifepristone, given to Implanon users at the beginning of a bleeding episode reduced the number of bleeding days by ∼50% compared with controls. In this study, a single dose of mifepristone was administered to etonogestrel (ENG)-exposed pseudo-pregnant mice, 5 days after artificial decidualization was induced when the endometrium showed signs of bleeding. Control mice received vehicle alone. Mice were culled 12-, 18-, 24- and 48-h post-treatment. In the continued presence of ENG, a single dose of mifepristone stimulated tissue breakdown followed by very rapid repair: most treated tissues were fully restored to the pre-decidualized state by 48 h post-treatment. During repair, proliferating cells (Ki67 immunostained) were localized to a band of cells around the basal area in breaking down tissues and to the repairing luminal epithelium and glands. Progesterone receptor-positive cells were largely localized to the basal area of the breaking down tissue in treated mice compared with decidual cells in controls. Oestrogen receptor-positive cells were observed in the repairing luminal epithelium and glands compared with the decidua and the basal region in control tissues. It is concluded that mifepristone treatment stimulates rapid restoration of luminal epithelial integrity: such action may be a key event in reducing the number of bleeding days observed in women using Implanon who were treated with a single dose of mifepristone.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is important for embryo implantation in mice

Mice lacking pituitary adenylate cyclase-activating polypeptide (PACAP) show high mortality during the postnatal period, as well as impaired reproduction in females. This study characterizes the reproductive phenotype in female mice lacking PACAP due to targeted disruption (knockout) of the single copy pacap gene (Adcyap1) to determine the site(s) of action of PACAP in the cascade of reproductive events. PACAP null females showed normal puberty onset, estrous cycles, and seminal plugs when paired with a male of proven fertility. However, significantly fewer PACAP null females (21%) than wild-type females (100%) gave birth following mating. Although a defect was not detected in ovulation, ovarian histology or fertilization of released eggs in PACAP null females, only 13% had implanted embryos 6.5 days after mating. Associated with the decrease in implantation, prolactin and progesterone levels were significantly lower in females lacking PACAP than in wild types on day 6.5 after mating. Our evidence suggests that impaired implantation is the defect responsible for decreased fertility in PACAP null female mice.

Alteration of pregnancy related hormones and fetal survival in F-344 rats exposed by inhalation to benzo(a)pyrene

The objective of this study was to evaluate the effect of subacute exposure to inhaled benzo(a)pyrene (BaP) on fetal survival and luteal maintenance using timed-pregnant Fisher 344 rats. Prior to assignment of pregnant rats to treatment and control groups, numbers of implantation sites were determined on gestation day (GD) 8 via midventral laparotomy. Subsequently, animals were assigned randomly to three treatment groups and two control groups. Treatment consisted of subacute exposure of rats via inhalation to BaP 25, 75, and 100 micro g/m(3), 4h daily for 10 days (GD-11-20). Control animals were either sham exposed to carbon black (CB) to control for inert BaP carrier or remained unexposed (UNC). Blood samples were collected on days 15 and 17 of gestation via sinus orbital veini-puncture for plasma. Number of pups per litter was determined postpartum and fetal survival rate was expressed as a percentage of the corresponding implantation sites. Radioimmunoassays were used to determine plasma progesterone, estrogen, and prolactin (indirect measurement of decidual luteotropin) concentrations. Fetal survival among BaP-treated rats declined in a dose-dependent manner (25 micro g/m(3), 78.3% per litter; 75 micro g/m(3), 38.0% per litter; 100 micro g/m(3), 33.8% per litter; P<0.05) compared with CB (96.7% per litter) and UNC (98.9% per litter). Plasma progesterone, estrogen, and prolactin concentrations also declined as a result of subacute exposure of rats to BaP compared to controls. These data suggest that inhaled BaP compromised fetal survival and consequently luteotropic activity in the exposed animals.