bluuebunny/crossref_metadata_2025 huggingface dataset:
Overview of eicosanoid metabolism and relationship to platelet-activating factor
Authors: Dusting GJ , Stewart AG
Published: October 2005

The pathways of arachidonic acid metabolism are becoming increasingly complex. Although it is unlikely that every pharmacological action of these eicosanoids reflects a physiological function, some of these compounds undoubtedly act as mediators of pathophysiological processes. Analogues of PGs have been exploited to a limited extent, and the emphasis for future therapeutic approaches will be on development of specific inhibitors and antagonists of eicosanoids that will alter the profile of products formed. These will be in the areas of inflammation (including asthma), cytoprotection of gastric mucosa, ischaemic protection and reperfusion injury, prevention of vascular disease, and human and animal reproduction. Because of the broad range of biological functions in which eicosanoids are involved, it is difficult to predict upon which of these areas new drugs will have the greatest impact.
Embryo-derived platelet activating factor: interactions with the arachidonic acid cascade and the establishment and maintenance of pregnancy
Authors: O'Neill C , Wells X , Battye K
Published: October 2005

Two classes of potent lipid mediators are produced by the mouse and human pre-embryo: platelet activating factor (PAF) and prostaglandins (PGs). This paper reviews the evidence for their production by the pre-embryo and for their role in embryo development and the successful establishment of pregnancy. The biosynthesis of PAF and arachidonic acid may be linked, the synthesis of PAF resulting in the generation of arachidonic acid with its subsequent conversion to prostaglandins. Pharmacological inhibitor studies show that a major site of action of PAF is the embryo itself, acting as an embryonic autocrine growth factor, whereas PGs appear to act primarily on maternal tissues although they do modulate some aspects of early embryo metabolism. It is the maternal tissues that are the primary source of PG production in early pregnancy. Maternal PGs have a variety of functions including involvement in the proinflammatory response of early pregnancy and the control of corpus luteum function. In the ewe, pregnancy is associated with an attenuation of oxytocin-induced production of the luteolysin, prostaglandin F2 alpha (PGF2 alpha). PAF can mimic the effect of pregnancy, preventing the release of PGF2 alpha in response to exogenous oxytocin and, when administered into the uterine lumen, extending the life span of the corpus luteum. Thus, embryo-derived PAF appears to have an essential role in the establishment of pregnancy by acting as an autocrine growth factor for the embryo and by exerting a variety of effects on maternal physiology, including modulating maternal prostaglandin secretion and action.
Regulation of endometrial prostaglandins during the menstrual cycle and in early pregnancy
Authors: Salamonsen LA , Findlay JK
Published: October 2005

Prostaglandins are important regulators of endometrial function. In turn, their secretion is controlled by endocrine and paracrine mediators. Cyclical effects of ovarian oestrogen and progesterone throughout the menstrual or oestrous cycle result in overall higher levels of prostaglandin release during the secretory or luteal phase of the cycle than during the proliferative phase. Potential paracrine regulators of endometrial origin include cytokines, growth factors and histamine, some of which may arise from infiltrating cells. Embryo-derived factors can regulate endometrial prostaglandin release in early pregnancy. Both platelet-activating factor and ovine trophoblast protein-1 (an embryonic interferon) modify prostaglandin release from primary cultures of endometrial cells of human and ovine origin respectively. Manipulation of such mediators may provide new means for fertility control.
Experiences with gemeprost in first-trimester termination of pregnancy
Authors: Whelan N
Published: October 2005

Forty women undergoing first-trimester termination of pregnancy were treated with 1 mg gemeprost, 3 h preoperatively. In more than 60%, dilatation or effacement of the cervix occurred with minimal side effects. Gemeprost is therefore recommended for use before routine suction termination of pregnancy in the first trimester.
Control of pregnancy, parturition and luteolysis in marsupials
Authors: Hinds LA
Published: October 2005

In most eutherian species the function of the corpus luteum (CL) is influenced by extrinsic factors and it is subordinate to the pituitary, placenta, or uterus. In contrast, in marsupials the CL is relatively autonomous. Although the pituitary is essential for the formation of the CL, thereafter the secretory activity of the CL is independent of luteotrophic support, and the uterus is not luteolytic. Furthermore, the life span of the CL is unaffected by pregnancy, except in the Macropodidae (kangaroos and wallabies), in which the secretory activity of the CL is shortened under the influence of the fetus. At parturition the macropodid fetus, possibly via a release of glucocorticoids, causes the release of prostaglandins, presumed to be of uterine origin. The effect of the prostaglandin is to induce the release of prolactin from the maternal pituitary. Prolactin, and not prostaglandin, induces luteolysis and advances the events of post-partum oestrus. In the non-pregnant cycle, the mechanism of luteolysis is different; it does not involve prolactin, and the luteolytic signal is of non-uterine, possibly intrinsic, origin.
Prostaglandins as therapy for labour induction or therapeutic abortion
Authors: Calder AA
Published: October 2005

(a) Prostaglandins (especially PGE2) are highly effective for ripening the cervix and inducing labour. If the cervix is already ripe, a small dose of PGE2 may be all that is required to initiate a labour which resembles spontaneous labour as closely as possible. (b) Amniotomy is the central event. Although it is possible for an infant to be born in the caul, i.e. in intact membranes, it is the general rule for the membranes to rupture or to be ruptured during labour. Such rupture leads to heightened activity of endogenous prostaglandins. The timing of amniotomy is crucial. Performed too early, before the cervix is ripe, it may lead to complications. Delayed too late, we may lose the advantage of its uterine sensitizing. (c) Oxytocin is a potent myometrial stimulant if the uterus is primed to respond to it by prostaglandins, either endogenous or exogenous. It must be given intravenously and many mothers find this disagreeable. In most instances of labour induction, a proper combination of prostaglandin therapy and amniotomy may allow the use of oxytocin to be avoided, but it remains the therapy of final resort to carry labour through to delivery if required.
Analysis of the responses of the fetal vessels of human perfused placental lobules to acute infusions of arachidonic acid
Authors: Gude NM , Rice GE , King RG , Boura AL , Brennecke SP
Published: October 2005

The vasodilatory response to arachidonic acid by the fetal vessels of human perfused placental lobules, in which tone had been increased by infusion of the thromboxane A2 mimetic U46619, was significantly reduced in the presence of the prostacyclin (PGI2) synthetase inhibitor tranylcypromine compared with saline infusion controls. HPLC analysis of the fetal effluent from human perfused placental lobules, in which radiolabelled arachidonic acid had been infused, identified two peaks of activity. The first peak displayed an elution profile similar to that of a 6-keto-PGF1 alpha standard; the presence of 6-keto-PGF1 alpha in this peak was confirmed by RIA. The second peak had an elution profile similar to that of an arachidonic acid standard. These results suggest that the vasodilatory response to the fetal vessels of human perfused placental lobules to acute infusions of arachidonic acid is mediated, at least in part, by the synthesis of PGI2. These data are consistent with the hypothesis that PGI2 may be involved in the maintenance of low vascular resistance of the fetal placenta in utero.
Effects of phenobarbital, dietary protein intake, and ewe liveweight on ovulation rate and concentrations of plasma FSH and hepatic microsomal enzymes
Authors: Smith JF , Payne E , Peterson AJ , McGowan LT , Cope B , McLaughlin R
Published: October 2005

Coopworth ewes were differentially fed from December 1985 to April 1986 to produce two liveweight classes: fat (55-60 kg) and thin (40-45 kg). The ewes were then fed on either high-protein (22%) or low-protein (12%) diets, with or without phenobarbital treatment for 10 days commencing on Day 7 of the oestrous cycle. Phenobarbital treatment caused an increase in ovulation rate that was most pronounced in thin ewes and those on the low-protein diet. Ewe liveweight produced an increase in ovulation rate, but increased dietary protein in the particular formulations used had no effect. Hepatic enzyme concentrations were increased by phenobarbital treatment and, to a lesser extent, by dietary protein intake and ewe liveweight. However, these metabolic changes and the increase in ovulation rate were not accompanied by interpretable changes in the plasma FSH concentrations.
In vitro assessment of the viability of sheep zygotes after pronuclear microinjection
Authors: Walker SK , Heard TM , Verma PJ , Rogers GE , Bawden CS , Sivaprasad AV , McLaughlin KJ , Seamark RF
Published: October 2005

Microinjected sheep zygotes were cultured in synthetic oviduct fluid medium (SOFM) for either 1 or 3 days and their subsequent developmental capacity was compared with that of microinjected zygotes cultured in vivo. Two experiments were carried out, using zygotes microinjected with one of three gene constructs containing the CysE and CysM genes from Salmonella typhimurium. In Experiment 1, microinjected zygotes were allocated to one of three treatments: (1) immediate transfer to recipient ewes (in vivo culture) followed by recollection 1 or 3 days later and subsequent transfer of viable embryos to other recipient ewes, (2) culture in SOFM (in vitro culture) for either 1 or 3 days before transfer to recipient ewes, and (3) immediate transfer to recipient ewes without subsequent interference. Recipient ewes were slaughtered on Day 14 of pregnancy and the number of elongated conceptuses determined. Although fewer zygotes failed to divide during in vitro culture than during in vivo culture, there were, overall, no significant differences between treatments in the percentage of zygotes that developed into elongated conceptuses (32.6-50.0%). In Experiment 2, microinjected zygotes were transferred immediately to recipient ewes or cultured in vitro for either 1 or 3 days before transfer. The number of fetuses per ewe on Day 50 of pregnancy and the number of lambs delivered per ewe were recorded. Neither the percentage of recipient ewes that became pregnant (overall 114/166, 68.7%) nor the percentage of zygotes that developed into lambs (overall 186/803, 23.2%) was significantly influenced by the culture treatment or by the gene construct microinjected.(ABSTRACT TRUNCATED AT 250 WORDS)
Glycine uptake in pre-implantation mouse embryos: kinetics and the effects of external
Authors: Hobbs JG , Kaye PL
Published: October 2005

The kinetic parameters (with standard errors) describing glycine uptake by mouse 2-cell embryos and blastocysts were determined by non-linear regression. Uptake at both stages was best described by a combination of a non-saturable component and a single saturable uptake system. During development, the rate constants for both components increased, as would be expected from the known increases in surface area, from 9.4 +/- 3.7 pL per 10 min per embryo and 128 +/- 12 fmol per 10 min per embryo in 2-cell embryos to 38.9 +/- 2.1 pL per 10 min per embryo and 258 +/- 15 fmol per 10 min per embryo in blastocysts. In contrast to earlier reports, there was no change in Km, which was 88 +/- 13 microM in 2-cell embryos and 115 +/- 10 microM in blastocysts. Reducing the external [Na+] from 230 mM increased Km for both stages. This effect on Km appeared to be related to [Na+]-2 or [Na+]-3. Vmax was increased in embryos of both stages by increasing [Na+] from 60 to 100 mM. However, whilst further increases to 400 mM were without major effect on uptake by 2-cell embryos, they inhibited uptake by blastocysts. This may result from osmotic effects on trophectodermal transport in the blastocysts. These results suggest that during development to blastocysts, the gly-system that operates in 2-cell embryos may be modified to a less restricted system with a similar Km and a complex dependence on [Na+].
Oocyte production and ovarian steroid concentrations of immature rats in response to some commercial gonadotrophin preparations
Authors: Henderson KM , Weaver A , Wards RL , Ball K , Lun S , Mullin C , McNatty KP
Published: October 2005

Four commercial gonadotrophin preparations, namely Folligon, F.S.H.-P., Folltropin and Ovagen, were examined for their effects on oocyte production and ovarian steroid concentrations in immature rats. The ratios of the FSH to LH concentrations of the preparations, determined by radioreceptor assays, were Folligon 5, F.S.H.-P. 18, Folltropin 49 and Ovagen 1090. Forty-eight hours after administering each gonadotrophin preparation to immature rats, ovulation was induced by injection of chorionic gonadotrophin. Twenty-four hours later, oocytes were recovered from the oviducts and counted. Oocytes were produced after injection of chorionic gonadotrophin following a single injection of Folligon (10-50 i.u.). However, no oocytes were produced in response to the other gonadotrophin preparations unless they were administered by continuous infusion (30-1000 micrograms day-1). When given by injection (Folligon) or infusion (others), the gonadotrophin preparations all promoted a dose-dependent increase in mean oocyte production, except at the highest doses when mean oocyte numbers either remained unchanged or declined significantly in the cases of Folligon and F.S.H.-P. The highest mean numbers of oocytes produced in response to Folltropin (48 +/- 9 oocytes, mean +/- s.e.m.) and Ovagen (47 +/- 7) were greater than those attained with Folligon (21 +/- 6) or F.S.H.-P. (31 +/- 5). Mean ovarian weights also increased in a dose-dependent fashion in response to each of the gonadotrophin preparations. Measurements of ovarian steroid concentrations 48 h after the onset of gonadotrophin treatment (i.e. immediately prior to ovulation induction with chorionic gonadotrophin) showed that the gonadotrophin preparations markedly influenced the ratios of ovarian oestradiol-17 beta and androgen (androstenedione plus testosterone) concentrations. At low doses the gonadotrophin preparations increased the ratio of oestradiol-17 beta to androgens, but at the highest doses, with the exception of Ovagen, the ratio was reduced relative to peak values. Co-infusion of ovine LH (NIADDK-oLH-25; 10-20 micrograms day-1) with Ovagen (250 micrograms day-1) or ovine FSH (10 micrograms day-1, NIADDK-oFSH-17), both low in LH content, increased the mean number of oocytes produced and also the ovarian oestradiol-17 beta:androgen concentration ratio. However, with 40 micrograms LH day-1, the oestradiol-17 beta:androgen ratio fell due to a continued increase in mean ovarian androgen concentrations and a decrease in mean ovarian oestradiol-17 beta concentration. The mean number of oocytes produced also fell significantly.(ABSTRACT TRUNCATED AT 400 WORDS)
Cloning, cDNA analysis and prolactin-dependent expression of a marsupial alpha-lactalbumin
Authors: Collet C , Joseph R , Nicholas K
Published: October 2005

The gene for alpha-lactalbumin has been cloned from a tammar wallaby (Macropus eugenii) mammary gland cDNA library. Tammar alpha-lactalbumin has approximately 50 and 30% homology to the alpha-lactalbumins of eutherians at the levels of nucleotide and protein sequence respectively. Comparison of the inferred tammar polypeptide sequence with the sequence of the eutherian proteins reveals extensive divergence at almost all of the non-essential amino acid residues. However, the hydropathy plots of the tammar protein are almost identical to those of eutherian alpha-lactalbumins, suggesting that protein conformation is conserved. The tammar gene encodes a transcript of approximately 975 bases. Northern blot analysis of hormone-stimulated mammary gland explants shows that maximal induction of alpha-lactalbumin mRNA is dependent on prolactin and that expression is not modulated by other hormones that play a role in the initiation of lactation in eutherians.
Effects of progesterone antagonists RU486 and ZK98734 on embryo transport, development and implantation in laboratory mice
Authors: Vinijsanun A , Martin L
Published: October 2005

Two progesterone antagonists blocked the actions of progesterone on uterine mitosis and epithelial morphology, but had no oestrogenic, anti-oestrogenic, cytotoxic or gestagenic activities in the mouse uterus. They interrupted early pregnancy and were luteolytic. These actions were reversed by treatment with exogenous progestins, but not dexamethasone. Doses of antagonists which blocked pregnancy and were luteolytic induced premature entry of embryos into the uterus on Day 3 and loss from the tract by Day 4. With the more potent RU486, most embryos remaining in the tract on Day 4 were in the oviduct. This 'tube-locking' and accelerated loss were probably due to 'unopposed' actions of ovarian oestrogen. They were reversed by progestin treatment; this suggests that progesterone is essential for normal embryo transport. Doses of antagonists which prevented normal embryo transport and implantation had little effect on preimplantation embryo development. Small increases in numbers of abnormal embryos on Day 4 were not significant or dose dependent. Abnormalities were not correlated with location of embryos, nor prevented by progestin treatment which reversed antagonist effects on embryo transport and implantation. Hence, progesterone is apparently not essential for successful completion of preimplantation development of mouse embryos in vivo.
Visualization of insulin receptors on mouse pre-embryos
Authors: Harvey MB , Kaye PL
Published: October 2005

Because insulin stimulates pre-embryonic protein metabolism and growth, the presence of insulin receptors on early mouse embryos was investigated immunohistochemically, using a specific anti-insulin receptor IgG. Staining was not present on fertilized eggs or on 2-cell, 4-cell or uncompacted 8-cell embryos, but insulin receptors were visible on compacting 8-cell embryos and on morulae and blastocysts. This ontogeny correlates with functional studies showing that insulin affects protein synthesis during these post-compaction stages. Insulin receptors were also present on isolated inner cell masses, which have also been shown to be responsive to insulin. Because the ontogeny of the appearance of insulin receptors and the presence of these receptors on both cell populations in the blastocyst coincide with the stimulatory effects of insulin observed in previously reported functional studies on pre-embryos, we believe that these insulin receptors mediate insulin's regulatory actions during early mouse embryogenesis.
Composition of uterine flushings from Large White and prolific Chinese Meishan gilts
Authors: Bazer FW , Thatcher WW , Matinat-Botte F , Terqui M , Lacroix MC , Bernard S , Revault M , Dubois DH
Published: October 2005

This study examined differences in selected components of uterine secretions from Large White and prolific Chinese Meishan gilts during the oestrous cycle or early pregnancy. Total recoverable protein, uteroferrin (measured as acid phosphatase activity), acyl aminopeptidase, calcium, sodium, potassium, immunoglobulins A and G, glucose, fructose, oestradiol-17 beta, and prostaglandins F2 alpha (PGF2 alpha) and E2 (PGE2) in uterine flushings were measured. During the oestrous cycle, breed effects were detected only for total protein (P = 0.07), which tended to be higher for Large White gilts. However, for pregnant gilts, total recoverable glucose (P less than 0.05), fructose (P less than 0.05) sodium (P less than 0.05), immunoglobulin A (P less than 0.01), PGF (P less than 0.01), PGE (P less than 0.01), and acyl aminopeptidase (P less than 0.05) were greater in uterine flushings from Meishan gilts. Only uteroferrin was higher (P = 0.06) in uterine flushings from Large White gilts. Concentrations of prolactin were higher (P less than 0.05) in plasma from cyclic or pregnant Meishan gilts, but concentrations of total oestrogens and progesterone were not affected by pregnancy status or breed. These results suggest that Meishan conceptuses, individually or collectively, are more stimulatory to endometrial secretion and/or transport of the components of histotroph into the uterine lumen, or that the endometrium of Meishan gilts is more sensitive to conceptus signals responsible for the accumulation of histotroph in the uterine lumen.
Insulin increases cell numbers and morphological development in mouse pre-implantation embryos in vitro
Authors: Gardner HG , Kaye PL
Published: October 2005

Insulin, alone or in combination with bovine serum albumin (BSA), was investigated for its effects on cell proliferation and on the proportions of mouse pre-implantation embryos reaching compaction and forming blastocysts during culture in a common basal medium in vitro. Insulin promoted cleavage by 16-20% when added to medium for culture of 2-cell embryos to morulae, blastocysts and expanded blastocysts over 24, 48 and 72 h. These effects on cell division were supported by increases of 65-100% and 31-100% in the rates of compaction and blastocyst formation respectively. The results indicate that the receptor responsible for these actions is probably expressed prior to compaction and possibly at the 4-cell stage. Identical responses to 1.7 and 170 nM insulin suggest that the insulin receptor is capable of mediating both of these developmental effects, although similar mediation by an insulin-like growth factor-1 (IGF-1) receptor is not excluded. BSA, normally a component of culture media, promoted cleavage between 24 and 48 h of culture as well as compaction and blastocyst formation at 15 microM (1 g L-1), probably through nutritional support. Compaction appeared to be promoted by some non-specific action of BSA. Blastocysts that had developed in the presence of both 170 nM insulin and 15 microM BSA contained similar numbers of cells to blastocysts that had developed in vivo.
Formulation of a complex serum-free medium (CSM) for use in the co-culture of mouse embryos with cells of the female reproductive tract
Authors: Sakkas D , Trounson AO
Published: October 2005

Co-culture of pre-implantation embryos with cells of the reproductive tract requires a medium that is beneficial to both embryos and cells. However, many studies in this area utilize media originally formulated for specific cell lines. In the present study, a complex serum-free medium (CSM) was formulated on the basis of the ionic compositions of existing embryo culture media and mouse oviductal fluid as well as the concentrations of growth factors that appear to benefit mouse embryo development. The study began by investigating the effect of altering the concentrations of K+ ions (0-40 mM) and sulfate ions (0-10 mM) in embryo culture media on the development of 2-cell mouse embryos. Mouse embryos showed improved cell numbers at the blastocyst stage when cultured in 10 mM K+ compared with Whittingham's T6 medium. Embryos were also cultured in T6 supplemented with bovine serum albumin (BSA) containing various concentrations of insulin, insulin-like growth factors I and II, fibroblast growth factor, and epidermal growth factor. Insulin concentrations of 100 ng mL-1 significantly (P less than 0.05) improved the cell numbers of 2-cell embryos cultured to the morulae and blastocyst stages compared with those cultured in T6 + BSA alone. CSM was formulated on the basis of the results of these experiments and was found to support both improved development of 2-cell mouse embryos and the culture of mouse fibroblast and mouse oviduct cells.
A simple glycerol-based freezing protocol for the semen of a marsupial Trichosurus vulpecula, the common brushtail possum
Authors: Rodger JC , Cousins SJ , Mate KE
Published: October 2005

Frozen storage of semen and embryos is now a well established part of the breeding of many eutherian mammals but it has not been applied to marsupials. This paper reports the first successful technique for the frozen preservation of marsupial spermatozoa. Semen was collected by electroejaculation under anaesthesia from a pool of five brushtail possums. The ejaculated semen was diluted 1:1 with Krebs Henseleit Ringer, centrifuged at 800 g for 5 min, resuspended in the test cryoprotectant media at 1, 2 and 5 x 10(6) spermatozoa mL-1 and 7, 10.5, 14 and 17.5% glycerol and then drawn up into 0.25 mL plastic straws. The spermatozoa were rapidly frozen in the vapour phase, 6 cm above liquid nitrogen, for 30 min before the straws were plunged into the liquid. Sperm motility was assessed blind for coded straws by phase-contrast microscopy on a warmed stage (35 degrees C), before freezing and after rapid thawing in a water bath at 37 degrees C (10 s). The highest recovery of both percentage motility (around 50-60%) and progressive motility (around 0.5-1 unit lower than prefreeze) occurred when spermatozoa were frozen and thawed in the presence of 17.5% glycerol. Recovery of motility was greater at the higher sperm concentrations (2 and 5 x 10(6) mL-1). There was no evidence of acrosomal damage or loss after freezing and thawing in high concentrations of glycerol. The only defect detected in spermatozoa subjected to the protocol was a variable tendency to bending of the neck region. This ranged from heads inclined at a slight angle to the tail through to complete flexure.(ABSTRACT TRUNCATED AT 250 WORDS)
Rapid freezing of the mouse blastocyst: effects of cryoprotectants and of time and temperature of exposure to cryoprotectant before direct plunging into liquid nitrogen
Authors: Li R , Trounson A
Published: October 2005

This study investigates the effects of time and temperature of exposure to a high concentration (4.5 M) of dimethyl sulfoxide (DMSO), glycerol, 1,2-propanediol (PROH), or a mixture of DMSO and glycerol (DG) in a solution containing 0.25 M sucrose, on the survival and development of rapidly frozen mouse blastocysts. Embryos had significantly (P less than 0.01) higher rates of survival and development when exposed to cryoprotectant at 0 degree C compared with room temperature. The time of exposure to cryoprotectant at either 0 degree C or room temperature before being plunged into liquid nitrogen significantly (P less than 0.01) affected the survival and development of frozen-thawed embryos. Survival and development of blastocysts in vitro and in vivo was significantly (P less than 0.05) higher when exposed at 0 degree C for 10 min to DG, DMSO and glycerol than to PROH. It is concluded that, unlike early-cleavage stage embryos, blastocysts need to be equilibrated at a low temperature (0 degree C) with high concentrations of cryoprotectant before rapid freezing. Exposure of blastocysts to 4.5 M cryoprotectant and 0.25 M sucrose at room temperature either was toxic or else markedly reduced their viability after freezing and thawing, depending on the duration of the initial exposure.
The biphasic modulation of inhibin mRNA levels and secretion by PMSG in rat granulosa cells in vitro
Authors: Michel U , Krozowski Z , McMaster J , Yu JH , Findlay JK
Published: October 2005

Granulosa cell cultures derived from diethylstilboestrol-treated immature rats were used to study the in vitro effect of pregnant mare serum gonadotrophin (PMSG) on steady state mRNA levels for the inhibin alpha and beta A subunits and the secretion of immunoreactive inhibin and progesterone. After 48 h treatment the dose-response curve of PMSG revealed a maximum stimulation (2.5-3.5 fold) of cytosolic alpha and beta A mRNAs over the range of 1 to 10 mU PMSG mL-1, with corresponding stimulation of inhibin secretion. A high dose of PMSG (160-500 mU mL-1) clearly suppressed inhibin alpha mRNA levels as well as inhibin secretion, whereas progesterone (P) was maximally stimulated (up to 600 fold). Although the level of cytosolic inhibin beta A subunit mRNA was also down-regulated by a high concentration of PMSG in the culture medium, the doses required to suppress its mRNA level to less than those of the control varied. These data demonstrate that low doses of follicle stimulating hormone/luteinizing hormone (FSH/LH)-like (PMSG) activity enhances and high doses decrease the steady-state mRNA levels of inhibin in rat granulosa cells in vitro; this biphasic regulation in vitro reflects the differential regulation of inhibin secretion observed during the rat oestrous cycle.
Do histocompatibility genes influence sex ratio (% males)?
Authors: Beamer WG , Whitten WK
Published: October 2005

Breeding records for 15 of the 42 C57BL/10SnJ Congenic Histocompatibility Mouse Strains from the Special Mouse Stocks Resource (SMSR) showed three with a significant excess of male offspring. Strain B10.R111(71NS), hereafter R, gave the highest proportion of males (55.68 +/- 0.59% of 7129 newborn) which is significantly more than the proportion of male offspring (49.81 +/- 0.94% of 2853 newborn) from the C57BL/10SnJ progenitor strain, hereafter B. All mice in the SMSR colonies were fed Old Guildford 96 and Old Guildford 96W liberally on alternate weeks. Breeding females of B and R strains were established in a research colony at the Jackson Laboratory under conditions similar to those in SMSR except that they were fed Wayne Sterilizable Rodent Blox. More than 5000 inbred, hybrid and backcross fetuses were examined but no evidence of an excess of males was found. Also, there were no strain differences in the neonatal data. However, the sex ratio of the 4396 neonates was just significantly higher (P less than 0.05) than that of the fetuses, indicating some perinatal loss of females. An even greater loss of females was most probably the cause of the high sex ratios in the preliminary and follow-up surveys of SMSR R mice, which we ascribe to an interaction between the H-2 haplotype of the R strain, or a gene linked thereto, and the Old Guildford diet that is unfavourable to female survival. The sex ratio of fetuses agreed so closely with the Mendelian expectation as to indicate that the primary sex ratio was 50% males and that the R strain is not a model for the human male bias. There were no hermaphrodites or twins and the sex ratio of the fetuses in litters without resorptions was normal. These findings emphasize the variability of presumptive secondary sex ratios.
Transillumination patterns of seminiferous tubules in two species of Australian rodents, Pseudomys australis and Notomys alexis
Authors: Pollanen P , Breed WG
Published: October 2005

The transillumination-assisted isolation of segments of seminiferous tubules in defined stages of the wave of the seminiferous epithelium was investigated in Pseudomys australis and Notomys alexis. In P. australis, three different transillumination patterns (pale, spotty and dark) of the seminiferous tubules could be isolated. They corresponded to histological stages 1-2, 3-5 and 6-8 of the wave of the seminiferous epithelium. The dark pattern made up about 40% of the wave, the pale pattern about 31%, and the spotty pattern about 24%. In N. alexis, no such isolation of segments with particular cell associations was possible. In a comparison of P. australis with the laboratory rat, the dark, pale and spotty transillumination patterns of seminiferous tubule segments corresponded to the same cell associations in both species, but the length of the spotty segments in the laboratory rat made it possible to subdivide the spotty region into pale spotty and dark spotty areas and thus to isolate four different transillumination patterns. Further separation into other subgroups to isolate additional types of segments could not be performed repeatedly in any of the studied species because of the gradual change of one subgroup of transillumination pattern into another and the short length of some of the subgroups.
[3H]thymidine uptake by the epididymis, seminal vesicles and prostate gland during postnatal development of the rat
Authors: Sujarit S , Jones RC
Published: October 2005

The uptake of [3H]thymidine by the epididymis, ventral prostate gland and seminal vesicles was determined in vivo for rats aged 15, 20, 25, 30, 35, 45 and 55 days. The pattern of uptake varied considerably between organs and generally was different from patterns of growth measured as mass or ratio of mass of DNA:tissue. The 'initial segment' of the epididymis and caput and corpus epididymidis showed a similar pattern of [3H]thymidine uptake, being greatest in 15-day-old animals and declining thereafter. On Day 15 the cauda epididymidis had a lower uptake than more proximal regions of the epididymis, but it subsequently showed two significant peaks of increased uptake on Days 25-30 and Day 45. The uptake by the seminal vesicles was high on Day 15, fell to low levels on Day 20, increased considerably from Days 20 to 35, then gradually decreased from Day 35 to 55. The uptake by the prostate gland was a little lower than by the seminal vesicles on Days 15 and 20, then reduced to about the same level as non-reproductive tissues.
Placental transport function
Authors: Schneider H
Published: October 2005

Placental transport provides a means of supplying nutrients to and removing metabolites from the fetus. Transport is based on substrate exchange and net flux from mother to fetus or vice versa and can be a result of a concentration difference or of unidirectional carrier-mediated transport. Blood flow regulates delivery to and removal from the area of placental exchange, and rapidly crossing compounds are dependent on blood flow for their rate of passage. There are substantial species differences in terms of flow rates normalized for fetal weight and also in terms of vascular arrangement. The barrier can be overcome via paracellular water-filled channels or via a transcellular route. Hydrophilic molecules that are not actively transported diffuse through paracellular channels, and the placentae of rodents and primates are much more permeable than the placenta of the sheep. Many different substrates such as glucose, amino acids, electrolytes and vitamins are transported by carrier systems. Transport proteins are located in the microvillous and basal membranes of the trophoblast. Asymmetry in the kinetics of binding results in differences in influx and efflux at the interface with maternal and fetal blood, allowing directional net flux across the placenta. Immunoglobulins are believed to cross by receptor-mediated endocytosis.
Placental toxicology: tobacco smoke, abused drugs, multiple chemical interactions, and placental function
Authors: Sastry BV
Published: October 2005

There are increasing numbers of reports on the tobacco smoking and ingestion of abused drugs (e.g. morphine, cocaine) by pregnant women and the effects of the substances on the developing fetus and newborn infant. The passage of drugs and chemicals from the mother to the fetus is influenced by the placental transport and metabolism of the substances. Further, these drugs and chemicals affect the nutrient transport systems in the placenta. The three major drugs of abuse-nicotine, morphine and cocaine-depress both active amino-acid uptake by human placental villi and transplacental amino-acid transport by reason of the drugs' influence on placental cholinergic and opiate systems. Part of this depression (10-16%) is not reversible. Nicotine blocks the cholinergic receptor and thus blocks acetylcholine (ACh)-facilitated amino-acid transport. Morphine stimulates opiate kappa receptors and depresses ACh release. Cocaine blocks Ca2+ influx and thus blocks ACh release. ACh causes dilation of blood vessels and maintains placental blood flow by the activation of endothelial muscarinic receptors. By interfering with ACh release and placental blood flow, the three drugs of abuse may depress the diffusion of amino acids and other nutrients from the trophoblast into the placental circulation. Three regulatory systems are delineated for amino-acid uptake by the placenta: placental ACh, phospholipid N-methyltransferase, and the gammaglutamyl cycle. These systems operate in concert with one another and are dependent on cellular formation of adenosine 5'-triphosphate (ATP). Placental hypoxia induced by carbon monoxide and other tobacco gases depresses the energy-dependent processes and thus the ATP levels of placental cells. Maternal tobacco smoking and drug abuse cause placental insufficiencies for amino-acid transport, which may partially explain the fetal intrauterine growth retardation caused by these substances. Part of the amino-acid deficits may be compensated for by the induction of new amino-acid transport systems. Specific receptors or drug-binding proteins for the three drugs of abuse are present in the placenta. A DNA adduct selective for maternal smoking has been demonstrated in the placenta. DNA adducts selective for cocaine, morphine and other environmental chemicals have yet to be demonstrated ins the placenta.
The human placental bed in health and disease
Authors: Khong TY , Sawyer IH
Published: October 2005

The morphology of the human placental bed is reviewed. The pathological features seen in spontaneous abortion, pregnancy-induced hypertension, intrauterine growth retardation, placenta accreta and postpartum haemorrhage suggest that abnormal placentation may be a common feature. A defect in the normal materno-trophoblastic interaction is implicated in the pathogenesis of abnormal placentation.
Human decidual and placental relaxins
Authors: Bryant-Greenwood GD
Published: October 2005

The human placenta and decidua are intrauterine production sites for a range of polypeptide hormones. Relaxin is one of these hormones, its production having been demonstrated by immunocytochemistry and Northern analysis. There are two relaxin genes in the human genome, termed H1 and H2; only the latter is expressed in cyclic and pregnant corpus luteum. However, it has recently been shown that both genes are expressed in the decidua and placenta. It is not known whether both are translated. These hormone(s) may act in a paracrine fashion and be partly responsible for the control of enzymes and inhibitors involved in collagen remodelling in the fetal membranes in the last weeks of pregnancy. An autocrine role of decidual relaxin and a possible decidual-cell/macrophage/extracellular-matrix interaction is described; this may act as a unit in the elaboration of a range of hormones.
Perifused ovine placental tissue secretes beta-endorphin immunoreactivity
Authors: Davies JJ , Falconer J , Zhang HP , Chan EC , McLean M , Smith R
Published: October 2005

In vitro release of one of the pro-opiomelanocortin (POMC)-derived peptides, the endogenous opioid beta-endorphin (beta EP) has been examined in the sheep placenta by means of a perifusion system. Two zones of the cotyledon, the chorionic villus (highly vascularized fetal and maternal tissues in close apposition) and the maternal basal plate (or capsule), were examined in placenta at two stages of gestation--120 days (119.0 +/- 4.7, N = 4) and 140 days (143 +/- 1.8, N = 5) just before term. The chorionic villous tissue released more beta EP-like immunoreactivity (beta EP-IR) than did the basal plate tissue at both gestational ages. At 120 days' gestation the basal concentration of beta EP-IR released from the chorionic villus was 52 +/- 0.5 fmol mL-1 (n = 4), almost double the maternal basal plate tissue at 28.4 +/- 0.4 fmol mL-1 (n = 8). beta EP-IR secretory capacity increased significantly (P less than 0.05) with advancing gestational age. By Day 140, release had increased 3-4-fold to 181.8 +/- 0.8 fmol mL-1 (n = 16) in the chorionic villous tissue, and to a lesser extent in the basal plate tissue to 50.7 +/- 0.6 fmol mL-1 (n = 14). No stimulation of beta EP-IR secretion was observed in any tissue as a result of 30 min exposure to corticotrophin-releasing hormone (100 nmol L-1), a vital physiological secretagogue.(ABSTRACT TRUNCATED AT 250 WORDS)
Human placental acetylcholine
Authors: King RG , Gude NM , Krishna BR , Chen S , Brennecke SP , Boura AL , Rook TJ
Published: October 2005

The human placenta contains both acetylcholine (ACh) and choline acetyltransferase, and in vitro bilaterally perfused placental lobules release ACh. The function of this placental cholinergic system has not yet been clearly defined, although changes occur in it during parturition and it may be linked to placental prostaglandin generation at this time. It has also been suggested that ACh may regulate placental amino-acid transport and/or blood flow. It has been found that ACh release from fetal vessels of bilaterally perfused placental lobules is reduced during preeclampsia but is not necessarily correlated with any change in perfusion pressure or materno-fetal transfer of the nonmetabolizable amino acid alpha-aminoisobutyric acid. However, a correlation has been found between releases from human placental explants of ACh (when inhibited by (2-benzoylethyl)trimethylammonium or vesamicol) and of prostaglandins E2 and F2 alpha. Thus, although the evidence for a role of ACh in the control of placental amino-acid transfer or vascular tone is not conclusive, inhibition of the human placental cholinergic system has been shown to be associated with reduced output of prostaglandins from this tissue.
The role of light and sound technologies in the detection of vasa praevia
Authors: Young M , Yule N , Barham K
Published: October 2005

Velamentous vessels across the internal os are rare (1 in 5000) but the high perinatal mortality (50-70%) has not improved with traditional methods of detection. In late pregnancy, Low Intrauterine Transcervical Endoscopy (LITE) can aid detection. Using LITE, such vessels have been 'seen' in 3 of 5000 patients examined; one case was detected fortuitously in 2500 patients examined during 1965-70, and two were detected in a special subgroup from 2500 patients examined during 1971-89 in which LITE was performed prior to labour with the express aim of excluding vasa praevia. Detection occurred before labour and in the absence of antepartum haemorrhage. In all three cases, the cervix was not dilated beyond 1 cm and a single velamentous vessel was found. The absence of labour and haemorrhage probably contributed to a zero perinatal mortality. Recently, ultrasound has been used in the detection of vasa praevia. Combination of abdominal real-time ultrasonography with LITE has permitted comparison of the efficacy of these two techniques; two of the patients with vas praevium were ultrasound negative but LITE positive. The risk of vasa praevia should be considered (a) when ultrasonography has shown a bilobed or succenturiate placenta, a low-lying placenta where the cord has a battledore insertion, a migrating placenta, or a suspicion of velamentous vessel traversing the internal os, (b) when there is a multiple or IVF pregnancy, or (c) when there is intrapartum bleeding or an irregularity in fetal heart rate. Inexperienced practitioners using LITE risk the rupture of a vas praevium. However, efficiently performed for those patients at increased risk of fetal hypoxia, or to detect meconium pollution of the amniotic sac or prior to amniotomy, LITE may fortuitously reveal a vas praevium and thereby enable action that prevents iatrogenic or spontaneous rupture.
Effect of (2-benzoylethyl)trimethylammonium and vesamicol on acetylcholine and prostaglandin release from human placental explants
Authors: Chen YS , Brennecke SP , Rook TJ , King RG
Published: October 2005

Human placental explants were incubated in the presence of physostigmine (3.08 microM), and release of acetylcholine (ACh) and prostaglandin (PG) were measured in the fourth hour by bioassay and radioimmunoassay, respectively. The choline acetyltransferase inhibitor (2-benzoylethyl)trimethylammonium (100 microM, n = 6) significantly reduced ACh release by 36 +/- 6%, PGE2 release by 23 +/- 8% and PGF2 alpha release by 29 +/- 10%. The inhibitor of vesicular acetylcholine storage, vesamicol (100 microM, n = 7), significantly reduced ACh release by 22 +/- 4%, PGE2 release by 46 +/- 13% and PGF2 alpha release by 32 +/- 9%. In the absence of physostigmine, ACh release was reduced by 89 +/- 2%, whereas PG release did not change compared with that in the presence of physostigmine. The presence of atropine (14.4 microM) did not affect PG release. These results suggest that if there is a relationship between human placental production of ACh and PGs, it does not appear to depend on muscarinic receptor activation or the activity of placental cholinesterase.
Regulation of fetal vascular tone in the human placenta
Authors: Walters WA , Boura AL
Published: October 2005

Using an in vitro placental lobule perfusion technique, the human fetal placental vasculature has been found to respond vigorously with high sensitivity to various vasoconstrictor substances, including angiotensin II, endothelins 1 and 3, prostaglandins F2 alpha, E2 and D2 and the thromboxane A2 agonist U46619. Thromboxane A2 receptors mediating vasoconstriction have been characterized in fetal placental vessels and appear to be identical to those on human platelets and pulmonary blood vessels. Although the isolated fetal placental vessels are largely unresponsive to exogenous vasodilatory stimuli, when preconstricted they respond by vasodilatation to several vasodilator substances, including arachidonate, prostacyclin, prostaglandin E1, theophylline and nitroglycerine. The resistance offered to flow in vitro by the villous vasculature is therefore low, as it is in vivo. Both intrinsic and extrinsic mechanisms probably operate to cause relaxation of the vascular smooth muscle with the vasodilatory effects of locally released autacoids dominating the effects of those having vasoconstrictor actions.
Glucose utilization by sheep embryos derived in vivo and in vitro
Authors: Thompson JG , Simpson AC , Pugh PA , Wright RW , Tervit HR
Published: October 2005

Embryos were collected from superovulated donors at various intervals from onset of oestrus, ranging from Day 1.5 to Day 6. In addition, blastocysts obtained from the culture of 1-cell embryos collected in vivo or of oocytes matured and fertilized in vitro were used to assess the effects of in vitro manipulation and culture on glucose utilization. Glycolytic activity was determined by the conversion of [5-3H]glucose to 3H2O, and oxidation of glucose was determined by the conversion of [U-14C]glucose to 14CO2. Glucose utilization increases significantly from the 8-cell stage and during compaction and blastulation. Glucose oxidation was at a relatively low level (5-12% of total utilization) compared with glycolysis. No difference was observed between the glycolytic activity of blastocysts derived from in vivo or in vitro sources. However, glucose oxidation was lower (P less than 0.05) in blastocysts derived from the culture of 1-cell embryos or from oocytes matured and fertilized in vitro. Exogenous tricarboxylic acid cycle substrates (i.e. pyruvate and lactate supplied in the medium) affected the level of glucose oxidation.