A comparison of two populations of decidual cells by immunocytochemistry and prostaglandin production

The decidua has been implicated in the control of human labour, particularly through changes in prostaglandin production, but this tissue contains a number of different cell types. A density gradient system was used to obtain two populations of cells from term human decidua, and these populations were characterised. The more dense cells (population B) was a mixed population, predominantly macrophages (80%), but small numbers of T- and B-lymphocytes were also present, as identified by immunocytochemistry. Most of these cell types also contained detectable levels of cyclooxygenase enzyme. The less-dense cell population (population A) did not contain significant numbers of the above cell types and released prolactin, suggesting that they were decidual stromal cells. This preparation of decidual stromal cells may be of use in defining the functions of these cells in labour.     

Gestational age-dependent effects of lipopolysaccharide on prostaglandin production by murine decidual caps

We sought to determine whether the gestational age of the pregnant mouse had any relationship with its lipopolysaccharide (LPS) responsiveness. Murine decidual caps from days 13, 15 and 17 of gestation (term is day 20) were dissected out, placed in inserts and equilibrated in media overnight. The following day, media were removed, replaced with fresh media (+/-LPS at 10 microg/mL). After LPS stimulation (24 h), prostaglandin (PG)E2 production by decidual caps from days 13 and 15 increased by 80-fold and 5-fold, respectively. PGF2alpha, 6-keto-PGF1a and TxB2 production also increased. Day 17 decidual caps were unaffected by LPS, pregnant mice inoculated i.p. with LPS (50 microg) at day 13 of gestation induced 100% delivery within 24 h. However, mice treated at days 15 and 17 had an equal occurrence of premature delivery or fetal resorption. This change in LPS responsiveness may indicate changes in the fetal-maternal immune system in late pregnancy.     

The measurement of human endometrial prostaglandin production. A comparison of two in vitro methods

Two in vitro methods for measuring human endometrial prostaglandin production were compared. Endometrial samples from eight patients were incubated over eight hours by a perifusion and a superfusion technique. The collected fractions were assayed by radioimmunoassay for PGE2 and PGF2 alpha. There was no significant difference between the perifusion and superfusion methods for the pattern and amount of PGE2 and PGF2 alpha production with time. Significantly higher production levels of PGE2 and PGF2 alpha were found in secretory phase endometria than in proliferative phase endometria. Histological examination of the tissue specimens by light and electron microscopy showed that both methods caused gross tissue damage after eight hours experimentation. The superfusion method produced more morphological damage than the perifusion method. However, no tissue damage could be detected after one hour of incubation with either method. Over an eight hour period neither the perifusion nor the superfusion technique appears to be a good indicator of in vivo endometrial prostaglandin production. Either technique used for only one to two hours may better reflect the in vivo situation.     

A comparison of buttress drumming by male chimpanzees from two populations

Wild chimpanzees (Pan troglodytes) produce low-frequency sounds by hitting the buttresses and/or trunks of trees. This buttress drumming occurs in discrete bouts that may be integrated into the phrase sequence of the chimpanzees long-distance vocalization, the pant hoot. The aim of this study was to investigate whether regional variation exists in the drumming behavior of male chimpanzees from Kibale National Park (Kanyawara community), Uganda, and Taï National Park, Ivory Coast. Recordings were made during a 6-month field season at Taï in 1990, and a 12-month field season at Kanyawara in 1996–1997. Acoustic analysis revealed the following: (1) Kanyawara males drummed significantly less frequently in conjunction with a pant hoot or hoot than did Taï males; (2) drumming bouts by Kanyawara males included significantly fewer beats, and were significantly shorter in duration, than those of Taï males; these differences disappeared when only those bouts produced in conjunction with a call were compared; (3) when Kanyawara chimpanzees did call and drum together, they tended to integrate drumming into the vocalization at a later point than did Taï males; and (4) individual differences in the temporal patterning of drumming bouts were not apparent for Kanyawara males, whereas a previous analysis revealed individual differences among Taï males.     

Interleukin-1 beta stimulates decidual stromal cell cyclo-oxygenase enzyme and prostaglandin production.

The cytokine interleukin-1 (IL-1 beta) increased prostaglandin production by decidual stromal cells in culture in a time and dose dependent manner. Optimum conditions for stimulation were found to be for 24 hours at a concentration of 100 pg IL-1 beta/ml. An apparent increase in cyclo-oxygenase enzyme synthesis accompanied the increase in prostaglandin production, and both changes were inhibited by the protein synthesis inhibitor cycloheximide. This implicates protein synthesis in the stimulatory effects of IL-1 beta, which may be mediated through the increase in cyclo-oxygenase enzyme. A pre-incubation period of 72 hours was found to be necessary to observe the stimulatory effect of IL-1 beta on prostaglandin production, but this did not seem to be due to any change in the sensitivity of the cells to IL-1 beta; the increase in the number of cyclo-oxygenase positive cells was the same if IL-1 beta was added on day 1, day 2 or day 3 of culture, even though prostaglandin production was not stimulated on day 1 or day 2. Cycloheximide increased prostaglandin production on the first two days of culture and had no effect on the third day of culture. This was interpreted as indicating that a factor inhibiting cyclo-oxygenase activity was synthesised during the initial period of culture, which prevented any increase in prostaglandin production following the increase in enzyme synthesis.     

Stimulation of myometrial and decidual prostaglandin production by amniotic fluid from term,but not midtrimester pregnancies

The effect of amniotic fluid obtained from second trimester (16–20 wks) and term pregnancies (38–41 wks) on the production of PGE and F by human amnion, decidua and myometrium at term was determined using tissue slices incubated in vitro. Midpregnancy amniotic fluid neither inhibited nor stimulated the prostanoid production by any of the tissues. In contrast, term amniotic fluid obtained before as well as after the onset of labor markedly increased the production of both PGE and PGF in decidua and myometrium from levels in Krebs solution. The prostanoid production (PGE + PGF) in amnoin was not significantly increased but the proportion of PGF was raised during incubations in term amniotic fluid. In decidua and myometrium the increase in PGE and PGF production in term amniotic fluid was approximately 200 and 400 percent respectively, from control values in Krebs solution. We propose that the stimulatory activity in term amniotic fluid in responsible for the accelerated synthesis of prostaglandins after of membranes, which is reflected in raised PGF metabolite levels in maternal circulation. It may also be the reason for the rise in amniotic fluid prostaglandin levels around the 35th week of gestation, and perhaps for the onset of labor.     

Prostaglandin production by amnion and decidual cells in response to bacterial products

Media from bacterial cultures have been tested for actions on prostaglandin biosynthesis by human amnion and decidual cells. The bacterial species, which are commonly associated with intrauterine infections, were Group B streptococcus, Escherichia coli, Fusobacterium nucleatum, Bacteroides fragilis, Gardnerella vaginalis, Neisseria gonorrhea, Mycoplasma hominis and Ureaplasma urealyticum. Overall, low doses of bacterial products were stimulatory of amnion prostaglandin production, whereas high doses were inhibitory. A similar pattern of results was obtained for effects on decidual prostaglandin production, although stimulatory actions at low doses were less pronounced. In all experiments interleukin 1 beta consistently induced a stimulation of prostaglandin production that greatly exceeded that caused by any bacterial product. It is possible that the inhibitory action of high doses of bacterial products on prostaglandin biosynthesis may contribute to the poor course of labor experienced by women with chorioamnionitis. Furthermore, these data lend credence to the view that the host response to infection (i.e. cytokine secretion) is the major mediator of subsequent preterm labor.     

Regulation of prostaglandin production by osteoblast-rich calvarial cells

The effect of various factors upon prostaglandin (PG) production by the osteoblast was examined using osteoblast-rich populations of cells prepared from newborn rat calvaria. Bradykinin and serum, and to a lesser extent, thrombin, were all shown to stimulate PGE2 and 6-keto-PGF1 alpha (the hydration product of PGI2) secretion by the osteoblastic cells. Several inhibitors of prostanoid synthesis, dexamethasone, indomethacin, dazoxiben and nafazatrom, were tested for their effects on the calvarial cells. All inhibited PGE2 and PGI2 (the major arachidonic acid metabolites of these cells) production with half-maximal inhibition by all four substances occurring at approximately 10(-7) M. For dazoxiben and nafazatrom, this was in contrast to published results from experiments in vivo which have indicated that the compounds stimulated PGI2 production. Finally, since the osteoblast is responsive to bone-resorbing hormones, these were tested. Only epidermal growth factor (EGF) was shown to modify PG production. At early times EGF stimulated PGE2 release, however, the predominant effect of the growth factor was an inhibition of both PGE2 and PGI2 production by the osteoblastic cells. The present results suggest that the bone-resorbing hormones do not act to cause an increase in PG by the osteoblast and that any increase in PG production by these cells may be in response to vascular agents.     

Regulation of prostaglandin production by osteoblast-rich calvarial cells

The effect of various factors upon prostaglandin (PG) production by the osteoblast was examined using osteoblast-rich populations of cells prepared from newborn rat calvaria. Bradykinin and serum, and to a lesser extent, thrombin, were also shown to stimulate PGE₂ and 6-keto-PGF_1α (the hydration product of PGI₂) secretion by the osteoblastic cells. Several inhibitors of prostanoid synthesis, dexamethasone, indomethacin, dazoxiben and nafazatrom, were tested for their effects on the calvarial cells. All inhibited PGE₂ and PGI₂ (the major arachidonic acid metabolites of these cells) production with half-maximal inhibition by all four substances occuring at approximately 10⁻⁷ M. For dazoxiben and nafazatrom, this was in contrast to published results from experiments which have indicated that the compounds stimulated PGI₂ production. Finally, since the osteoblasts is responsive to bone-resorbing hormones, these were tested. Only epidermal growth factor (EGF) was shown to modify PG production. At early time EGF stimulated PGE₂ release, however, the predominant effect of the growth factor was an inhibition of both PGE₂ and PGI₂ production by the osteoblastic cells. The present results suggest that the bone-resorbing hormones do not act to cause an increase in PG by the esteoblast and that any increase in PG production by these cells may be in response to vascular agents     

Prostaglandin and thromboxane production by rat decidual microsomes

The preparation of a microsomal fraction from the decidual tissue of pregnant rat uteri is described. Incubation of such microsomes with a mixture of radiolabelled and cold arachidonic acid (51 micrometer) plus cofactors resulted in a 30% substrate conversion. Products were resolved into four peaks (A, B, C and D) by thin-layer chromatography. Combined gas-liquid chromatography-mass spectrometry and further thin-layer chromatography identified the products as PGF2 alpha (A); thromboxane B2 (B); a mixture of 6-OXO PGF1 alpha and PGE2 (C); PGD2 and PGE2 (D). PGE2 was the major product.     

Inflammatory activation of prostaglandin production by microglial cells antagonized by amyloid peptide

The murine cell line MMGT-16 is of microglial origin and capable of releasing immunoinflammatory cytokines. When stimulated by the proinflammatory stimulus lipopolysaccharide (LPS), MMGT-16 cells secrete large amounts of prostaglandin E(2) (PGE(2)). This PGE(2) production is nearly abolished if amyloid beta-peptide (Abeta (1-40)) is present in the incubation medium. In addition, Abeta (1-40) inhibits cyclooxygenase-2 (COX-2) induction by LPS. Since these effects are not reproduced by the reverse control Abeta (40-1), these results suggest a novel, intriguing modulatory role for amyloid beta peptide in the inflammatory response of microglial cells.     

Oxytocin stimulates the release of arachidonic acid and prostaglandin F2 alpha from human decidual cells

Oxytocin at a physiological concentration stimulated the immediate release of free arachidonic acid from dispersed human decidual cells in a perfusion system. This indicates that oxytocin activates phospholipase(s) thus enhancing prostaglandin synthesis. The effect of oxytocin on the release of [3H]-arachidonic acid from decidual cells of women in labor was significantly greater (1036 +/- 207, mean dpm +/- SEM, n = 23) than from those of women not-in-labor (505 +/- 121 dpm, n = 12) or with endometrial cells of non-pregnant women (711 +/- 210 dpm, n = 18), and correlates well with reported oxytocin receptor concentrations in these tissues. These new findings are consistent with a role for endogenous oxytocin in stimulating prostaglandin synthesis at the onset of parturition.     

A comparison of neuropeptide immunocytochemistry in fluid-fixed and freeze-dried brains

Summary Immunocytochemical staining of luteinizing hormone-releasing hormone (LHRH), somatostatin, and neurophysin was compared in rat brains fixed with 1) formalin, 2) Bouin's solution, 3) freeze-dried (FD), or 4) freeze-dried + paraformaldehyde vapor perfused (FDV). The distribution of LHRH fibers was similar in all preparations; however, beads of granular reaction product often appeared finer and more numerous in the median eminence of FD- and FDV brains. Positively stained LHRH perikarya were not observed in any of the preparations. In contrast, somatostatin-immunoreactive perikarya were present in the fluid-fixed and FD brains, although few were observed in FDV brains. Somatostatin-immunoreactive fibers were present in all preparations, but appeared most numerous in the median eminence of FD brains. Staining of neurophysin-containing perikarya and fibers was similar in all preparations. These observations suggest that the FD brain can provide a suitable tissue substrate for immunocytochemistry, demonstrating staining comparable to or surpassing that of more conventional preparations. However, staining of antigens in FD brain was not uniformly successful and may depend on stereochemical characteristics of each antigen as well as properties of the primary antisera used in the staining procedure.     

Transforming growth factor-beta inhibits prostaglandin production in amnion and A431 cells

We studied the effect of transforming growth factor-beta (TGF-beta) on prostaglandin E2 (PGE2) production and mitogenesis in human amnion cells and compared the response in amnion cells with that in A431 cells. Both amnion cells and A431 cells respond to epidermal growth factor (EGF) with increased production of PGE2 whereas EGF promotes mitogenesis in amnion cells but not in A431 cells. In amnion cells, TGF-beta was not mitogenic, and did not alter the mitogenic response of cells to EGF. Treatment of amnion cells with TGF-beta did, however, cause a decrease in PGE2 production relative to untreated cells, although EGF stimulated PGE2 production was not attenuated. In A431 cells, TGF-beta acted to decrease PGE2 production relative to untreated cells and to attenuate the stimulation of PGE2 production effected by EGF. The inhibitory action of TGF-beta on PG production in amnion and A431 cells is contrary to the stimulation of PG production in mouse calvaria reported by others and is suggestive that the effect of TGF-beta on prostaglandin production, like its effect on growth, varies between different cell types. Inhibition of PG production by treatment of amnion or A431 cells with mefenamic acid did not alter thymidine incorporation into DNA in response to EGF; similarly, the addition of PGE2 or PGF2 alpha to culture media of amnion or A431 cells had no effect on mitogenesis (in the absence or presence of EGF). Based on these findings, we conclude that PG production and EGF action on proliferation (stimulation in amnion cells; inhibition in A431 cells) are dissociated.     

A demographic comparison of two Nordic populations of Greylag Geese Anser anser

Greylag Geese Anser anser have been neck-banded on an annual basis in Scania, southern Sweden since 1984 and in Norway since 1986 as part of a Nordic Greylag project. This has yielded a large database of resightings, which we used here to estimate and compare survival rates between the two populations by means of mark–recapture models. Estimated adult survival was sex-dependent in the Scanian population, probably a result of differential neck band retention rates in this population. Mean juvenile survival was about 12% higher in the Scanian population (0.603 vs. 0.485). Adult survival in the Norwegian population was 0.728 (males 0.733; females 0.725), and in males and females from the Scanian population was 0.711 (0.752 after accounting for higher neck band loss in males) and 0.771, respectively. Over the course of the study, juvenile survival in the Scanian population increased substantially, and adult survival was constant, whereas both these parameters declined in the Norwegian population. This study demonstrates that the two Nordic populations are demographically distinct and gives further support to the notion that they should be treated as separate management units. The decline of 10% in adult survival in the Norwegian population, the cause of which still remains uncertain, is likely to have had a major impact on the growth of this population.     

A comparison of pectoral fin contact between two different wild dolphin populations

Contact behaviour involving the pectoral fin has been documented in a number of dolphin species, and various explanations about its function have been offered. Pectoral fin contact can take a variety of forms, and involves a number of body parts and movements, likely differing depending upon social or ecological context. For this study, we compare the pectoral fin contact behaviour of two species of wild dolphins: Indo-Pacific bottlenose dolphins (Tursiops aduncus) from around Mikura Island, Japan, and Atlantic spotted dolphins (Stenella frontalis) from The Bahamas. The two study populations exhibit surprising similarity in the ways in which pectoral fin contacts are used, despite differences in species and environmental conditions at the two sites. Differences in contact rates for calves between the two sites suggest that calf-focused aggression from adult dolphins is more prevalent at Mikura than in The Bahamas. Our results suggest that pectoral fin contact behaviour seems to be driven primarily by social pressures, and may be similar in function to allogrooming described in primates.