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PubMed2002

Inhibition of septic shock in mice by an oligopeptide from the beta-chain of human chorionic gonadotrophin hormone.

Human chorionic gonadotrophin (hCG) is a heterodimeric placental glycoprotein hormone required in pregnancy. In human pregnancy urine and in commercial hCG preparations (c-hCG) it occurs in a variety of forms, including breakdown products. Several reports have suggested modulation of the immune system by intact hormone, but such effects of breakdown products have not been reported. In a related article (Hum Immunol 62:1315, 2001), it is reported that a 400-2000 Dalton (Da) fraction from c-hCG and from human pregnancy urine inhibits Th1-mediated diabetes in NOD mice. The active component(s) were called natural (immuno)modulatory pregnancy factor(s) (NMPF). This study reports that a single treatment with the same low molecular weight NMPF fraction up to 24-h after high dose lipopolysaccharide (LPS) injection inhibited septic shock in mice. This counteracting effect of NMPF paralleled the downregulation of the effects of LPS on the production of macrophage migration inhibitory factor (MIF) by spleen cells, on the plasma level of liver aminotransferase, and on the expression of several splenic lymphocyte and macrophage surface markers. Based on the primary structure of the beta-chain of hCG a synthetic hexapeptide Valine-Leucin-Proline-Alanine-Leucine-Proline (VLPALP) was designed, which demonstrated it to have the same protective effects as the 400-2000 Da NMPF fraction. These results indicate a new strategy for the treatment of septic shock and the potential of therapeutic use of this synthetic oligopeptide.

Adjuvants, Immunologic↗
PubMedDate not supplied

Human placental gonadotrophin-releasing hormone (GnRH) binding sites: I. Characterization, properties and ligand specificity.

Radioiodinated gonadotrophin-releasing hormone tracers were prepared from mammalian (m GnRH), salmon (s GnRH), lamprey (l GnRH) and the two forms of chicken GnRH (ch GnRH I and ch GnRH II), and also from the GnRH agonist (GnRHA) analogues, Buserelin ([D-Ser(tBu)6] 1-9 GnRH ethylamide) and Tryptorelin ([D-Trp6 GnRH] 1-9 ethylamide) and a GnRH antagonist (GnRHANT; [Ac 3,4-dehydro-Pro1, D-p-F-Phe2, D-Trp3,6] LHRH). Specific binding of hormone tracers was compared in homogenates and membrane fractions from human placenta and rat pituitary. GnRH agonist tracers bound readily to pituitary and placental binding sites. Binding of m GnRH to rat pituitary membranes was low compared to agonist binding, whereas other GnRH iso-forms were not bound. Binding of 125I-labelled m GnRH to human placental membranes was also low compared to that of Buserelin, and l GnRH and ch GnRH I tracers bound poorly. However, human placental membranes bound s GnRH and ch GnRH II to the same extent as GnRHA. Studies of the inactivation of GnRH tracers following incubation with rat pituitary and human placental membranes demonstrated that, although GnRH isoforms were degraded at different rates in these tissues, the differential ability of GnRH isoforms to bind to pituitary or placental binding sites was not related to differences in degradation of tracers, but rather to differences in ligand specificity. Specific binding of 125I-labelled GnRH agonists (GnRHA) and mammalian GnRH (m GnRH), s GnRH and ch GnRH II tracers to human placental membrane fractions increased linearly with increasing membrane protein at low concentrations. Binding was dependent on both the duration and temperature of incubation, and pH profiles of 125I-labelled GnRHA, s GnRh and ch GnRH II binding to placental membranes were similar. Once bound s GnRH formed a tighter complex with placental receptors than GnRHA, though 125I-labelled s GnRH was inactivated more rapidly than agonist tracer during incubation with placental membranes. Binding of GnRH tracers was specific for molecules with the GnRH structure. Deletions of amino acid residues at positions 1-3 and/or deamidation at Gly10 reduced binding potencies for both human placental and rat pituitary binding sites, indicating that both ends of the GnRH molecule were required for optimal binding. Modifications which conferred increased agonist activity led to markedly increased receptor binding potency in the rat pituitary, but only slightly increased potency for placental receptors. In contrast, GnRH antagonist analogues had increased potency towards pituitary receptors, but much reduced potency towards human placental binding sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1979

Prolactin receptors in human breast cancer cells in long-term tissue culture.

Prolactin receptors have been identified for the first time in a number of human breast cancer cell lines and a normal human breast cell line maintained in long-term tissue culture. Optimal conditions for determining the binding of 125I-labeled human prolactin to these cells were established. Five different tumor cell lines have different content of prolactin receptors ranging from 2,300 to 26,000 sites/cell. All tumor cell lines contained more prolactin receptors than does one normal breast cell line (1700 sites/cell). The prolactin receptors in these human mammary tumor cells not only bind human prolactin but also recognize other lactogenic hormones such as human growth hormone, human placental lactogen, and sheep prolactin, but not animal growth hormone, which are not lactogenic. The affinity (Ka) of binding of human prolactin to these cells is 4 x 10(9) M-1 (Kd = 2.5 x 10(-10)M). The hormone specificity and affinity for hormone of these human mammary tumor cells are very similar to that found for the rabbit mammary gland. These human mammary tumor cell lines in long-term culture should prove very useful to study the biology of prolactin receptors in living human cells and the role of prolactin in the tumorigenesis of the human breast.

Breast↗
PubMedDate not supplied

The role of ACTH in placental steroidogenesis.

We have studied the possible function of the placental adrenocorticotrophic hormone-(ACTH-) like substance (PALS) in placental steroidogenesis by measuring oestradiol (E2) and progesterone (P4) in term human placental explants incubated with commercially available porcine ACTH I-39. There was a dose-dependent increase in the E2 and P4 released into the medium at 24 h as compared to controls. At 48 h, no significant effect was noted. Propranolol (10(-5) M) did not block the effect of ACTH on P4 release. The data suggest that ACTH may have a regulatory role on placental steroidogenesis. The possible mechanisms of action of PALS on the placenta and the adrenal are discussed, and the role of PALS in the maintenance of pregnancy and in maternal response to stress is suggested.

Adrenocorticotropic Hormone↗
PubMed1997

Expression of human placental lactogen and variant growth hormone genes in placentas.

Previous studies comparing the expression levels of human placental lactogen (hPL) genes have shown varying results, due to, perhaps, the fact that in all of them only one placenta was being analyzed. Here, the expression of hPL and growth hormone variant (hGH-V) genes in fifteen term placentas was comparatively analyzed at the RNA level, using reverse transcription coupled to polymerase chain reaction (RT-PCR). The abundance of the combined RNA transcripts derived from these genes varied from one placenta to another. The authors found that hPL-4 transcripts were more abundant than those of hPL-3 in most samples (ratios from 1:1 to 6:1), transcripts from the putative hPL-1 pseudogene were more abundant at the unprocessed stage while those of the hGH-V gene were mostly processed. Again, the authors of this study observed wide variation from placenta to placenta in the abundance of both of these types of transcripts. The same was observed when a group of six placentas from abortuses and nine from pregnancies complicated by preclampsia, diabetes and hypertension was studied. The authors conclude that the disagreeing results reported in the literature which are not in agreement concerning the expression levels of hPL genes could be explained by normal variations of their expression levels among the different placentas analyzed.

Animals↗