Pregnancy-specific glycoprotein 1 (PSG1) activates TGF-ß and prevents dextran sodium sulfate (DSS)-induced colitis in mice.

Transforming growth factor-ßs (TGF-ßs) are secreted from cells as latent complexes and the activity of TGF-ßs is controlled predominantly through activation of these complexes. Tolerance to the fetal allograft is essential for pregnancy success; TGF-ß1 and TGF-ß2 play important roles in regulating these processes. Pregnancy-specific ß-glycoproteins (PSGs) are present in the maternal circulation at a high concentration throughout pregnancy and have been proposed to have anti-inflammatory functions. We found that recombinant and native PSG1 activate TGF-ß1 and TGF-ß2 in vitro. Consistent with these findings, administration of PSG1 protected mice from dextran sodium sulfate (DSS)-induced colitis, reduced the secretion of pro-inflammatory cytokines, and increased the number of T regulatory cells. The PSG1-mediated protection was greatly inhibited by the coadministration of neutralizing anti-TGF-ß antibody. Our results indicate that proteins secreted by the placenta directly contribute to the generation of active TGF-ß and identify PSG1 as one of the few known biological activators of TGF-ß2.

Characterization of receptors for murine pregnancy specific glycoproteins 17 and 23.

In primates and rodents, trophoblast cells synthesize and secrete into the maternal circulation a family of proteins known as pregnancy specific glycoproteins (PSG). The current study was undertaken to characterize the receptor for two members of the murine PSG family, PSG17 and PSG23. Binding of recombinant PSG17 and PSG23 to CHO-K1 and L929 cells and their derived mutants was performed to determine whether these proteins bound to cell surface proteoglycans. We also examined binding of these proteins to cells transfected with syndecans and glypican-1 by flow cytometry. The interaction with glycosaminoglycans was confirmed in solid phase assays. Our results show that PSG17 binds to CD9 and to cell surface proteoglycans while PSG23 binds only to the latter. We found that the amino acids involved in CD9 binding reside in the region of highest divergence between the N1-domains of murine PSGs. For both proteins, the N-terminal domain (designated as N1) is sufficient for binding to cells and the ability to bind cell surface proteoglycans is affected by the cell line employed to generate the recombinant proteins. We conclude that while substantially different at the amino acid level, some murine PSGs share with human PSG1 the ability to bind to cell surface proteoglycans and that at least one PSG binds to more than one type of molecule on the cell surface.

Expression of glutamate transporters GLT-1 and GLAST in different regions of rat brain during the course of experimental autoimmune encephalomyelitis.

Demyelination and oligodendroglial cell death accompanied by axonal injury are dominating features of multiple sclerosis (MS) a chronic demyelinating disease of the CNS. Accumulation of extracellular glutamate, observed during MS, is implicated in excitotoxic injury of nerve and oligodendroglial cells as a result of over-activation of glutamate receptors. The appropriate concentration of extracellular glutamate is maintained by glutamate transporters, the most predominant of which is glial transporter GLT-1 (excitatory amino acid transporter (EAAT) 2). The aim of this study is to determine the time-course of GLT-1 and glutamate-aspartate transporter (GLAST) expression in forebrain and cerebellum of rats subjected to experimental autoimmune encephalomyelitis (EAE). Our findings revealed that: (1) GLT-1 mRNA and to a lower extent GLAST mRNA are overexpressed in forebrain and cerebellum of EAE rats (2) expression of GLT-1 transporter mRNA shows a similar temporal pattern throughout the course of EAE in both structures examined, and is closely correlated with the appearance of neurological symptoms; and (3) the expression of GLT-1 and GLAST protein does not mirror mRNA changes during EAE and exhibits a differential spatial pattern. The protein levels of GLT-1 in cerebellum and GLAST in both structures are significantly reduced just before the acute phase and later during the recovery. The results imply that transcriptional up-regulation of the GLT-1 gene occurs early in both the forebrain and the cerebellum of the EAE rat model. This up-regulation is associated with the severity of symptoms but tends to precede the onset of maximal neurological deficits. The observations confirm the involvement of glutamate in the pathogenesis of EAE and provide an indication of the protective role of this glutamate transporter. However, changes in protein expression of both transporters suggest the existence of post-translational disturbances or the influence of regulating factors connecting with EAE conditions that may lead to the insufficient protection against glutamate excitotoxicity.

Environmental impacts on the developing CNS: CD15, NCAM-L1, and GFAP expression in rat neonates exposed to hypergravity.

We have previously reported that the developing rat cerebellum is affected by hypergravity exposure. The effect is observed during a period of both granule and glial cell proliferation and neuronal migration in the cerebellum and coincides with changes in thyroid hormone levels. The present study begins to address the molecular mechanisms involved in the cerebellar response to hypergravity. Specifically, the study focuses on the expression of cerebellar proteins that are known to be directly involved in cell-cell interactions [protein expressing 3-fucosyl-N-acetyl-lactosamine antigen (CD15), neuronal cell adhesion molecule (NCAM-L1)] and those that affect cell-cell interactions indirectly [glial fibrillary acidic protein (GFAP)] in rat neonates exposed to centrifuge-produced hypergravity. Cerebellar mass and protein expression in rat neonates exposed to hypergravity (1.5 G) from gestational day (G) 11 to postnatal day (P) 30 were compared at one of six time points between P6 and P30 against rat neonates developing under normal gravity. Proteins were analyzed by quantitative western blots of cerebellar homogenates prepared from male or female neonates. Cerebellar size was most clearly reduced in male neonates on P6 and in female neonates on P9, with a significant gender difference; differences in cerebellar mass remained significant even when change in total body mass was factored in. Densitometric analysis of western blots revealed both quantitative and temporal changes in the expression of selected cerebellar proteins that coincided with changes in cerebellar mass and were gender-specific. In fact, our data indicated certain significant differences even between male and female control animals. A maximal decrease in expression of CD15 was observed in HG females on P9, coinciding with maximal change in their cerebellar mass. A shift in the time-course of NCAM-L1 expression resulted in a significant increase in NCAM-L1 in HG males on P18, an isolated time at which cerebellar mass does not significantly differ between HG and SC neonates. A maximal decrease in expression of GFAP was observed in HG males on P6, coinciding with maximal change in their cerebellar mass. Altered expression of cerebellar proteins is likely to affect a number of developmental processes and contribute to the structural and functional alterations seen in the CNS developing under altered gravity. Our data suggest that both cerebellar development and its response to gravitational manipulations differ in males and females.

Effects of hypergravity exposure on the developing central nervous system: possible involvement of thyroid hormone.

The present study examined the effects of hypergravity exposure on the developing brain and specifically explored the possibility that these effects are mediated by altered thyroid status. Thirty-four timed-pregnant Sprague-Dawley rats were exposed to continuous centrifugation at 1.5 G (HG) from gestational Day 11 until one of three key developmental points: postnatal Day (P) 6, P15, or P21 (10 pups/dam: 5 males/5 females). During the 32-day centrifugation, stationary controls (SC, n = 25 dams) were housed in the same room as HG animals. Neonatal body, forebrain, and cerebellum mass and neonatal and maternal thyroid status were assessed at each time point. The body mass of centrifuged neonates was comparatively lower at each time point. The mass of the forebrain and the mass of the cerebellum were maximally reduced in hypergravity-exposed neonates at P6 by 15.9% and 25.6%, respectively. Analysis of neonatal plasma suggested a transient hypothyroid status, as indicated by increased thyroid stimulating hormone (TSH) level (38.6%) at P6, while maternal plasma TSH levels were maximally elevated at P15 (38.9%). Neither neonatal nor maternal plasma TH levels were altered, suggesting a moderate hypothyroid condition. Thus, continuous exposure of the developing rats to hypergravity during the embryonic and neonatal periods has a highly significant effect on the developing forebrain and cerebellum and neonatal thyroid status (P < 0.05, Bonferroni corrected). These data are consistent with the hypothesized role of the thyroid hormone in mediating the effect of hypergravity in the developing central nervous system and begin to define the role of TH in the overall response of the developing organism to altered gravity.

Can rhesus monkeys spontaneously subtract?

Animals, including pigeons, parrots, raccoons, ferrets, rats, New and Old World monkeys, and apes are capable of numerical computations. Much of the evidence for such capacities is based on the use of techniques that require training. Recently, however, several studies conducted under both laboratory and field conditions have employed methods that tap spontaneous numerical representations in animals, including human infants. In this paper, we present the results of 11 experiments exploring the capacity of semi-free-ranging adult rhesus monkeys to spontaneously compute (i.e. single trial, no training) the outcome of subtraction events. In the basic design, we present one quantity of objects on one stage, a second quantity on a second stage, occlude both stages, and then remove one or no objects from each stage. Having watched these events, a subject is then allowed to approach one stage and eat the food objects behind the occluder. Results show that rhesus monkeys correctly compute the outcome of subtraction events involving three or less objects on each stage, even when the identity of the objects is different. Specifically, when presented with two food quantities, rhesus monkeys select the larger quantity following subtractions of one piece of food from two or three; this preference is maintained when subjects must distinguish food from non-food subtractions, and when food is subtracted from either one or both initial quantities. Furthermore, rhesus monkeys are capable of representing zero as well as equality when two identical quantities are contrasted. Results are discussed in light of recent attempts to determine how number is represented in the brains of animals lacking language.

Alteration of dopamine transport and dopamine D(2) receptor binding in the brain induced by early and late consequences of global ischaemia caused by cardiac arrest in the rat.

This study was designed to determine the effects of global cerebral ischaemia caused by temporary cardiac arrest and the early and late consequences of this ischaemia on dopamine transport and dopamine D(2) receptor binding in rat brain. The effects of 10 min of global ischaemia were measured immediately and after 1 h and 7 days post-resuscitation. A decrease of dopamine uptake in the rats by synaptosomes was noted immediately following global ischaemia and 1 h after resuscitation. However, at 7 days post-resuscitation, the dopamine uptake returned to control values. Reversibility of the changes in the synaptosomal dopamine uptake is undoubtedly a favourable sign. Global ischaemia and reperfusion after 1 h or 7 days did not show altered rates of dopamine release but did affect the dopamine D(2) receptor. An observed increase of receptor affinity may be an adaptive response to the reduction in binding capacity. The reduction of visible D(2) receptor binding sites in the early post-resuscitation phase, which was extended to the period of 7 days after resuscitation without recovery, is probably associated with neuronal necrotic damage.

Acute lead intoxication in vivo affects myelin membrane morphology and CNPase activity.

The aim of the present study was to assess the sensitivity of central nervous system myelin to acute Pb-toxicity in an animal model, that imitates lead toxicity in occupationally exposed workers, or in occasional incidents of poisoning. Our results indicated that in vivo acute lead intoxication affected both the morphology of myelin and enzymatic activity of the myelin marker, CNPase (2'3'-cyclic nucleotide 3'-phosphodiesterase). The multilayered structure of myelin sheaths was regionally disturbed, with loosely arranged membranes or ovoid-shaped swollen fragments. The activity of CNPase was diminished and Michaelis-Menten kinetics showed a decreased affinity and lower velocity of the enzyme. These data suggest that the disturbances in CNPase activity may contribute, in some extent, to the changes in myelin morphology observed in acute Pb-intoxication.

Inhibition of dopamine transport and binding of [3H] spiperone to dopamine D2 receptor by acute Pb-toxicity in vivo.

Alterations of dopamine transport and binding of [3H] spiperone to dopamine D2 receptor following acute lead intoxication in an in vivo experimental model in adult rats imitate the acute action of Pb2+ in occupationally exposed workers or in occasional incidents of poisoning. The results show that lead-intoxication causes an increased Pb level in blood, a decrease in dopamine uptake and release in synaptosomes and affects the dopamine D2 receptor. These data show that Pb-intoxication may cause severe disturbances in the transport and receptor binding of dopamine, which is involved in the regulation of a variety of functions including locomotor activity, emotion and neuroendocrine secretion.

Chronic lead intoxication affects the myelin membrane status in the central nervous system of adult rats.

The aim of the experiments presented here was to discern whether prolonged consumption of leaden water, which imitates an environmental exposure, affects the structure of myelin in the central nervous system of adult rats and whether the observed morphological destruction is reflected in biophysical and/or biochemical changes. The results indicated that during chronic lead (Pb) intoxication, the Pb level of the myelin fraction increases significantly. Electron microscopy studies show that myelin in control experiments is built up of ordered layers, whereas in a Pb-intoxicated sample, this order is destroyed in large areas of all preparations. Morphological disturbances in Pb-intoxicated in vivo myelin were reflected by changes in myelin membrane fluidity measured by spectrofluorometry and electron paramagnetic resonance (EPR). Prolonged Pb toxicity also caused significant changes in the morphological structure of oligodendrocytes, an increase of phosphatidylethanolamine, and decrease of protein SH group levels. Simultaneously, we found that the protein and total phospholipid content and levels of phosphatidylinositol, sphingomyelin, phosphatidyloserine, cholesterol, and the pattern of total myelin protein obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in Pb-intoxicated myelin did not change compared to control values. Also, Pb intoxication did not induce peroxidation by itself and did not accelerate peroxidation produced by iron (Fe) in brain myelin.