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Andrade CBV, Lopes LVA, Ortiga-Carvalho TM, Matthews SG, Bloise E. Infection and disruption of placental multidrug resistance (MDR) transporters: Implications for fetal drug exposure. Toxicol Appl Pharmacol 2023; 459:116344. [PMID: 36526072 DOI: 10.1016/j.taap.2022.116344] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 12/07/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022]
Abstract
P-glycoprotein (P-gp, encoded by the ABCB1 gene) and breast cancer resistance protein (BCRP/ABCG2) are efflux multidrug resistance (MDR) transporters localized at the syncytiotrophoblast barrier of the placenta and protect the conceptus from drug and toxin exposure throughout pregnancy. Infection is an important modulator of MDR expression and function. This review comprehensively examines the effect of infection on the MDR transporters, P-gp and BCRP in the placenta. Infection PAMPs such as bacterial lipopolysaccharide (LPS) and viral polyinosinic-polycytidylic acid (poly I:C) and single-stranded (ss)RNA, as well as infection with Zika virus (ZIKV), Plasmodium berghei ANKA (modeling malaria in pregnancy - MiP) and polymicrobial infection of intrauterine tissues (chorioamnionitis) all modulate placental P-gp and BCRP at the levels of mRNA, protein and or function; with specific responses varying according to gestational age, trophoblast type and species (human vs. mice). Furthermore, we describe the expression and localization profile of Toll-like receptor (TLR) proteins of the innate immune system at the maternal-fetal interface, aiming to better understand how infective agents modulate placental MDR. We also highlight important gaps in the field and propose future research directions. We conclude that alterations in placental MDR expression and function induced by infective agents may not only alter the intrauterine biodistribution of important MDR substrates such as drugs, toxins, hormones, cytokines, chemokines and waste metabolites, but also impact normal placentation and adversely affect pregnancy outcome and maternal/neonatal health.
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Monteiro VRS, Andrade CBV, Gomes HR, Reginatto MW, Império GE, Fontes KN, Spiess DA, Rangel-Junior WS, Nascimento VMO, Lima COS, Sousa RPC, Bloise FF, Matthews SG, Bloise E, Pimentel-Coelho PM, Ortiga-Carvalho TM. Mid-pregnancy poly(I:C) viral mimic disrupts placental ABC transporter expression and leads to long-term offspring motor and cognitive dysfunction. Sci Rep 2022; 12:10262. [PMID: 35715474 PMCID: PMC9205917 DOI: 10.1038/s41598-022-14248-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 06/03/2022] [Indexed: 11/09/2022] Open
Abstract
Limited information is available about the effect of mid-pregnancy viral infections on the placental expression of efflux transporters and offspring behavior. We hypothesized that maternal exposure to polyinosinic-polycytidylic acid [poly(I:C)], a synthetic double-stranded RNA viral mimic, would impair placental cell turnover, the expression of selected ABC transporters and adult offspring behavior. C57BL/6 mice were administered poly(I:C) (10 mg/Kg;ip) or vehicle at gestational day (GD) 13.5 (mid-pregnancy). Dams were euthanized for blood collection 4 h after injection, fetal and placental collection at GD18.5 or allowed to deliver spontaneously at term. At GD 13.5, poly(I:C) induced an acute pro-inflammatory response characterized by an increase in maternal plasma levels of IL-6, CXCL-1 and CCL-2/MCP-1. At GD 18.5, poly(I:C) decreased cell proliferation/death in the labyrinthine and increased cell death in the junctional zones, characterizing a disruption of placental cell turnover. Abca1 and Abcg1 immunolabelling was decreased in the labyrinthine zone, whereas Abca1, Abcg1 and breast cancer resistance transporter (Bcrp) expression increased in the junctional zone. Moreover, adult offspring showed motor and cognitive impairments in the Rotarod and T-water maze tests. These results indicate that viral infection during mid-pregnancy may disrupt relevant placental efflux transporters, as well as placental cell turnover and offspring behavior in adult life.
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Martinelli LM, Reginatto MW, Fontes KN, Andrade CBV, Monteiro VRS, Gomes HR, Almeida FRCL, Bloise FF, Matthews SG, Ortiga-Carvalho TM, Bloise E. Breast cancer resistance protein (Bcrp/Abcg2) is selectively modulated by lipopolysaccharide (LPS) in the mouse yolk sac. Reprod Toxicol 2020; 98:82-91. [PMID: 32916274 PMCID: PMC7772890 DOI: 10.1016/j.reprotox.2020.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/06/2020] [Accepted: 09/03/2020] [Indexed: 01/18/2023]
Abstract
Bacterial infection alters placental ABC transporters expression. These transporters provide fetal protection against circulating xenobiotics and environmental toxins present in maternal blood. We hypothesized that lipopolysaccharide (LPS-bacterial mimic) alters the yolk sac morphology and expression of key ABC transporters in a gestational-age dependent manner. Yolk sac samples from C57BL/6 mice were obtained at gestational ages (GD) 15.5 and GD18.5, 4 or 24 h after LPS exposure (150ug/kg; n = 8/group). Samples underwent morphometrical, qPCR and immunohistochemistry analysis. The volumetric proportions of the histological components of the yolk sac did not change in response to LPS. LPS increased Abcg2 expression at GD15.5, after 4 h of treatment (p < 0.05). No changes in Abca1, Abcb1a/b, Abcg1, Glut1, Snat1, Il-1β, Ccl2 and Mif were observed. Il-6 and Cxcl1 were undetectable in the yolk sac throughout pregnancy. Abca1, breast cancer resistance protein (Bcrp, encoded by Abcg2) and P-glycoprotein (P-gp/ Abcb1a/b) were localized in the endodermal (uterine-facing) epithelium and to a lesser extent in the mesothelium (amnion-facing), whereas Abca1 was also localized to the endothelium of the yolk sac blood vessels. LPS increased the labeling area and intensity of Bcrp in the yolk sac's mesothelial cells at GD15.5 (4 h), whereas at GD18.5, the area of Bcrp labeling in the mesothelium (4 and 24 h) was decreased (p < 0.05). Bacterial infection has the potential to change yolk sac barrier function by affecting Bcrp and Abcg2 expression in a gestational-age dependent-manner. These changes may alter fetal exposure to xenobiotics and toxic substances present in the maternal circulation and in the uterine cavity.
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Fontes KN, Reginatto MW, Silva NL, Andrade CBV, Bloise FF, Monteiro VRS, Silva-Filho JL, Imperio GE, Pimentel-Coelho PM, Pinheiro AAS, Matthews SG, Bloise E, Ortiga-Carvalho TM. Dysregulation of placental ABC transporters in a murine model of malaria-induced preterm labor. Sci Rep 2019; 9:11488. [PMID: 31391498 PMCID: PMC6685947 DOI: 10.1038/s41598-019-47865-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/25/2019] [Indexed: 01/13/2023] Open
Abstract
Malaria in Pregnancy (MiP) is characterized by placental accumulation of Plasmodium-infected erythrocytes, intrauterine growth restriction (IUGR) and preterm delivery (PTD). Placental ATP-binding cassette (ABC) transporters mediate the efflux of nutrients, cytokines and xenobiotics. The expression and activity of these transporters are highly responsive to infection. We hypothesized that MiP would perturb the expression of placental ABC transporters, promoting PTD. Peripheral blood, spleens, livers and placentas of pregnant mice, infected with Plasmodium berghei ANKA on gestational day (GD) 13.5, were collected and analyzed on GD18.5. The primary consequences of human MiP, including IUGR, PTD (20%) and placental inflammation, were recapitulated in our mouse model. Electron microscopy revealed attenuated presence of labyrinthine microvilli and dilated spongiotrophoblasts -granular endoplasmic reticulum cisternae. Additionally, a decrease in placental Abca1 (ABCA1), Abcb1b (P-glycoprotein), Abcb9 and Abcg2 (BCRP) expression was observed in MiP mice. In conclusion, MiP associated with PTD impairs placental ABC transporters' expression, potentially modulating placental nutrient, environmental toxin and xenobiotic biodistribution within the fetal compartment, and may, at some degree, be involved with pregnancy outcome in MiP.
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Iqbal M, Baello S, Javam M, Audette MC, Gibb W, Matthews SG. Regulation of Multidrug Resistance P-Glycoprotein in the Developing Blood-Brain Barrier: Interplay between Glucocorticoids and Cytokines. J Neuroendocrinol 2016; 28:12360. [PMID: 26718627 DOI: 10.1111/jne.12360] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 12/07/2015] [Accepted: 12/28/2015] [Indexed: 01/04/2023]
Abstract
P-glycoprotein (P-gp) encoded by Abcb1 provides protection to the developing brain from xenobiotics. P-gp in brain endothelial cells (BECs) derived from the developing brain microvasculature is up-regulated by glucocorticoids and inhibited by pro-inflammatory cytokines in vitro. However, little is known about how prenatal maternal glucocorticoid treatment can affect Abcb1/P-gp function and subsequent cytokine regulation in foetal BECs. We hypothesised that glucocorticoid exposure increases Abcb1/P-gp in the foetal brain microvasculature and enhances the sensitivity of Abcb1/P-gp in BECs to the inhibitory effects of cytokines. BECs isolated from dexamethasone- or vehicle-exposed foetal guinea pigs were cultured and treated with interleukin-1β, interleukin-6 or tumour necrosis factor-α, and Abcb1/P-gp expression and function were assessed. Prenatal dexamethasone exposure significantly increased Abcb1/P-gp expression/activity and cytokine receptor levels in BECs of the foetal brain microvasculature. Foetal dexamethasone exposure in vivo also increased the subsequent responsiveness of BECs to pro-inflammatory cytokines in vitro. In conclusion, maternal treatment with synthetic glucocorticoids appears to prematurely mature P-gp mediated drug resistance at the foetal BBB in vivo and profoundly impact the subsequent responsiveness of P-gp to pro-inflammatory cytokines in the foetal BEC. The significance of these findings to foetal brain protection against xenobiotics and other P-gp substrates in vivo requires further elaboration. However, the results of the present study may have implications for human pregnancy and foetal brain protection, particularly in cases of preterm birth combined with infection.
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Bloise E, Ortiga-Carvalho TM, Reis FM, Lye SJ, Gibb W, Matthews SG. ATP-binding cassette transporters in reproduction: a new frontier. Hum Reprod Update 2015; 22:164-81. [PMID: 26545808 DOI: 10.1093/humupd/dmv049] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/19/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The transmembrane ATP-binding cassette (ABC) transporters actively efflux an array of clinically relevant compounds across biological barriers, and modulate biodistribution of many physiological and pharmacological factors. To date, over 48 ABC transporters have been identified and shown to be directly and indirectly involved in peri-implantation events and fetal/placental development. They efflux cholesterol, steroid hormones, vitamins, cytokines, chemokines, prostaglandins, diverse xenobiotics and environmental toxins, playing a critical role in regulating drug disposition, immunological responses and lipid trafficking, as well as preventing fetal accumulation of drugs and environmental toxins. METHODS This review examines ABC transporters as important mediators of placental barrier functions and key reproductive processes. Expression, localization and function of all identified ABC transporters were systematically reviewed using PubMed and Google Scholar websites to identify relevant studies examining ABC transporters in reproductive tissues in physiological and pathophysiological states. Only reports written in English were incorporated with no restriction on year of publication. While a major focus has been placed on the human, extensive evidence from animal studies is utilized to describe current understanding of the regulation and function of ABC transporters relevant to human reproduction. RESULTS ABC transporters are modulators of steroidogenesis, fertilization, implantation, nutrient transport and immunological responses, and function as 'gatekeepers' at various barrier sites (i.e. blood-testes barrier and placenta) against potentially harmful xenobiotic factors, including drugs and environmental toxins. These roles appear to be species dependent and change as a function of gestation and development. The best-described ABC transporters in reproductive tissues (primarily in the placenta) are the multidrug transporters p-glycoprotein and breast cancer-related protein, the multidrug resistance proteins 1 through 5 and the cholesterol transporters ABCA1 and ABCG1. CONCLUSIONS The ABC transporters have various roles across multiple reproductive tissues. Knowledge of efflux direction, tissue distribution, substrate specificity and regulation of the ABC transporters in the placenta and other reproductive tissues is rapidly expanding. This will allow better understanding of the disposition of specific substrates within reproductive tissues, and facilitate development of novel treatments for reproductive disorders as well as improved approaches to protecting the developing fetus.
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Javam M, Audette MC, Iqbal M, Bloise E, Gibb W, Matthews SG. Effect of oxygen on multidrug resistance in term human placenta. Placenta 2014; 35:324-30. [PMID: 24685282 DOI: 10.1016/j.placenta.2014.02.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/10/2014] [Accepted: 02/23/2014] [Indexed: 11/19/2022]
Abstract
INTRODUCTION The placenta contains efflux transporters, including P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), that limit the passage of xenobiotics, certain hormones and nutrients from the maternal to the fetal circulation. The expression of these transporters changes with gestational age, yet the mechanisms involved remain unknown. However, the changes in P-gp and BCRP transporter expression coincide with those of oxygen tension in the placenta, and oxygen tension has been shown to modulate P-gp and BCRP expression in other tissues. The objective of this study was to investigate the effects of oxygen tension on P-gp and BCRP expression in the term human placenta. METHODS Following equilibration in culture (96 h), term placental explants (n = 7) were cultured in 3% or 20% oxygen for 24 and 48 h. Culture medium was collected every 24 h to measure lactate dehydrogenase (LDH; explant viability) and human chorionic gonadotropin (hCG; syncytiotrophoblast function). P-gp (encoded by ABCB1) and BCRP (encoded by ABCG2) protein and mRNA, as well as VEGFA mRNA were measured using western blot and qRT-PCR. P-gp localization was determined using immunofluorescence. RESULTS Oxygen tension had a significant effect on P-gp expression, with ABCB1/P-gp mRNA and protein levels increased in the hypoxic condition (3% O2) after 48 h (p < 0.05). VEGFA mRNA was elevated by hypoxia at both 24 and 48 h (p < 0.05). In contrast, placental ABCG2/BCRP mRNA and protein expression were stable with changes in oxygen tension. We identified profound differences in the glycosylation of P-gp between cultured and non-cultured placental tissue, with cultured explants expressing deglycosylated P-gp. CONCLUSIONS These findings demonstrate that, at term, the expression of placental P-gp, is regulated by oxygen tension. This suggests that changes in oxygenation of the placenta in the third trimester may alter levels of placental P-gp, and in doing so alter fetal exposure to P-gp substrates, including xenobiotics and certain hormones.
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Lye P, Bloise E, Dunk C, Javam M, Gibb W, Lye SJ, Matthews SG. Effect of oxygen on multidrug resistance in the first trimester human placenta. Placenta 2013; 34:817-23. [PMID: 23790363 DOI: 10.1016/j.placenta.2013.05.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 05/16/2013] [Accepted: 05/27/2013] [Indexed: 12/25/2022]
Abstract
INTRODUCTION The multidrug resistance proteins, P-glycoprotein (P-gp, encoded by the ABCB1 gene) and breast cancer resistance protein (BCRP, encoded by ABCG2) are highly expressed in the first trimester placenta. These transporters protect the fetus from exposure to maternally derived toxins and xenobiotics. Since oxygen is a regulator of multidrug resistance in various tissues, we hypothesized that changes in oxygen tension alter placental ABCB1/P-gp and ABCG2/BCRP expression in the first trimester. METHODS Placental specimens were collected from first (n = 7), second (n = 5) and term pregnancies (n = 5). First trimester placental villous explants were incubated (24 or 48 h) in different oxygen tension (3-20%). ABCB1, ABCG2 and VEGFA mRNA expression levels were assessed by RT-PCR and protein was localized by IHC. RESULTS ABCB1 is expressed most highly in the first trimester placenta (p < 0.05), whereas ABCG2 expression does not change significantly over pregnancy. P-gp and BCRP staining is present in the syncytiotrophoblast and in cytotrophoblasts. ABCG2 mRNA is increased in hyperoxic (20%) conditions after 48 h (p < 0.05). In contrast, hypoxia (3%) did not change ABCB1 mRNA expression but significantly increased VEGFA mRNA (p < 0.05). Hypoxia resulted in increased BCRP staining in cytotrophoblasts and in the microvillous membrane of the syncytium. Whereas, hypoxia resulted in increased P-gp staining in proliferating cytotrophoblasts. CONCLUSION We conclude that placental multidrug resistance expression, specifically ABCG2, is regulated by oxygen tension in the first trimester. It is possible that changes in placental oxygen supply are capable of altering fetal drug exposure especially during early pregnancy.
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Mileva-Seitz V, Fleming AS, Meaney MJ, Mastroianni A, Sinnwell JP, Steiner M, Atkinson L, Levitan RD, Matthews SG, Kennedy JL, Sokolowski MB. Dopamine receptors D1 and D2 are related to observed maternal behavior. GENES BRAIN AND BEHAVIOR 2012; 11:684-94. [PMID: 22574669 DOI: 10.1111/j.1601-183x.2012.00804.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The dopamine pathway and especially the dopamine receptors 1 and 2 (DRD1 and DRD2) are implicated in the regulation of mothering in rats. Evidence for this in humans is lacking. Here, we show that genetic variation in both DRD1 and DRD2 genes in a sample of 187 Caucasian mothers predicts variation in distinct maternal behaviors during a 30-min mother-infant interaction at 6 months postpartum. Two DRD1 single-nucleotide polymorphisms (SNPs rs265981 and rs686) significantly associated with maternal orienting away from the infant (P = 0.002 and P = 0.003, respectively), as did DRD1 haplotypes (P = 0.03). Two DRD2 SNPs (rs1799732 and rs6277) significantly associated with maternal infant-directed vocalizing (P = 0.001 and P = 0.04, respectively), as did DRD2 haplotypes (P = 0.01). We present evidence for heterosis in DRD1 where heterozygote mothers orient away from their infants significantly less than either homozygote group. Our findings provide important evidence that genetic variation in receptors critical for mothering in non-human species also affect human maternal behaviors. The findings also highlight the importance of exploring multiple dimensions of the complex human mothering phenotype.
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Mileva-Seitz V, Kennedy J, Atkinson L, Steiner M, Levitan R, Matthews SG, Meaney MJ, Sokolowski MB, Fleming AS. Serotonin transporter allelic variation in mothers predicts maternal sensitivity, behavior and attitudes toward 6-month-old infants. GENES BRAIN AND BEHAVIOR 2011; 10:325-33. [PMID: 21232011 DOI: 10.1111/j.1601-183x.2010.00671.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Maternal behavior in the new mother is a multidimensional set of responses to infant cues that are influenced by the mother's early life experiences. In this study, we wanted to test if mothers' early life experiences and mothers' genotype have interactive effects on maternal behaviors and attitudes, something which has not been previously explored. In a sample of 204 mothers, we assessed maternal genotype at the serotonin transporter-linked polymorphic region (5-HTTLPR) and an adjacent upstream polymorphism (rs25531), together giving rise to three alleles: short (S), L(G) and L(A). Controlling for maternal age and parity, we showed that this genotype can predict differences in maternal sensitivity at 6 months postpartum: mothers with an S (or the functionally similar L(G)) allele were more sensitive than mothers who lacked the allele during a 30-min recorded mother-infant interaction (F (4,140) = 3.43; P = 0.01). Furthermore, we found highly significant gene-environment interactions in association with maternal behavior, such that mothers with no S or L(G) alleles oriented away more frequently from their babies if they also reported more negative early care quality (F (5,138) = 3.28; P = 0.008). Finally, we found significant gene-environment associations with maternal attitudes; mothers with the S allele and with greater early care quality scored higher on ratings of their perceived attachment to their baby (F (5,125) = 3.27; P = 0.008). The regression results show significant interactions between the reported quality of care mothers received from their own parents and genotype on both their frequency of orienting away from the infant during the interaction (F(5, 138) = 3.28; P = 0.008, Fig. 1a) and their perceived attachment feelings to the infant (F(5, 125) = 3.27; P = 0.008, Fig. 1b); however the direction of the effects for these two outcome measures were different from one another. With increasing care quality, mothers with the L(A)L(A) genotype (no S or L(G) allele) oriented away less frequently, while S or L(G) allele carriers showed no significant change. In contrast, with increasing early care quality. L(A)L(A) (no S or L(G) allele) mothers scored lower on perceived attachment to their infants, whereas S or L(G) allele carrying mothers scored higher. [corrected].
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Yeboah D, Kalabis GM, Sun M, Ou RC, Matthews SG, Gibb W. Expression and localisation of breast cancer resistance protein (BCRP) in human fetal membranes and decidua and the influence of labour at term. Reprod Fertil Dev 2008; 20:328-34. [PMID: 18255023 DOI: 10.1071/rd07133] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Accepted: 12/06/2007] [Indexed: 01/01/2023] Open
Abstract
Breast cancer resistance protein (BCRP) is a multidrug resistant ABC transport protein (ABCG-2). It extrudes a wide range of substrates, including many chemotherapy drugs, steroids and folate. It is present in many cancers, as well as normal tissues, in particular barrier tissues such as the blood-brain barrier, the intestine, blood vessels and the human placenta. Human fetal membranes (amnion and chorion laeve) provide the barrier between the maternal uterine environment and the fetus. In the present study, we defined the expression and localisation of BCRP mRNA and protein in human fetal membranes (amnion and chorion) and attached decidua obtained before and following labour at term. BCRP protein and mRNA was expressed in all tissues examined and the levels of expression were not altered by labour. BCRP was localised to the amnion epithelial cells, chorion trophoblast cells and decidua stromal cells, as well as the endothelial cells of maternal blood vessels in the decidua, but was absent from mesenchymal cells. In the amnion epithelium, BCRP protein was localised to the apical surface, cytoplasm and membrane between cells. In the chorion trophoblast and decidua stromal cells, BCRP protein was localised to the plasma membrane. However, in the chorion trophoblast, BCRP protein was also highly expressed in the nucleus. The level of BCRP protein in the membranes was comparable to that in the placenta. These high levels raise the possibility that this transporter plays an important role in the physiological function of the tissues.
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Kalabis GM, Petropoulos S, Gibb W, Matthews SG. Breast Cancer Resistance Protein (Bcrp1/Abcg2) in Mouse Placenta and Yolk Sac: Ontogeny and its Regulation by Progesterone. Placenta 2007; 28:1073-81. [PMID: 17524480 DOI: 10.1016/j.placenta.2007.03.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 03/22/2007] [Accepted: 03/23/2007] [Indexed: 11/20/2022]
Abstract
Breast Cancer Resistance Protein (BCRP), a recently-discovered transporter belonging to ABC superfamily, is highly expressed within the labyrinth of the placenta, the primary site of exchange between the maternal and fetal circulation. It has been proposed to function as an efflux pump protecting the fetus from a wide range of xenobiotics. It has also been recently shown that the yolk sac, in addition to the placenta, may be involved in transport of certain substances to and from the fetus. We hypothesised that there are changes in placental Bcrp1 (the mouse orthologue of human BCRP) expression during pregnancy and that these correlate with changes in progesterone production that occur in late gestation. We also hypothesised that Bcrp1 is expressed in the yolk sac, and that levels change with advancing gestation. Either whole concepti, or placenta and yolk sac, were collected from pregnant mice and analysed at embryonic (E) day 9.5, 12.5, 15.5 and 18.5 (term approximately E19.5). Peak expression of Bcrp1 mRNA was detected using in situ hybridisation within the placenta at E9.5 and the yolk sac at E12.5. There was a significant decrease thereafter in both tissues (p<0.001). In contrast, expression of Bcrp1 protein as assessed by immunohistochemistry and Western immunoblots did not change significantly during gestation either in the placenta nor the yolk sac, and no sex difference in Bcrp1 protein expression in either tissue was observed at E12.5. Daily progesterone treatment starting at E14.5 and continuing until E18.5 significantly increased maternal progesterone levels, but did not elicit any changes in the Bcrp1 mRNA or Bcrp1 protein expression either in the placenta or the yolk sac. Significant expression of Bcrp1 protein in fetal tissue was evident at the end of gestation, while expression in the fetal brain endothelium was evident as early as E12.5. We suggest that the placenta and the yolk sac, both of which express Bcrp1, may limit fetal exposure to the potentially adverse effects of xenobiotics including therapeutic drugs which the mother may be exposed to during pregnancy. The significant decrease in Bcrp1 mRNA expression in both the yolk sac and the placenta from mid to late gestation may be counter-balanced by an increase in Bcrp1 expression in fetal organs involved in absorption, excretion and protection.
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Owen D, Matthews SG. Prenatal glucocorticoid exposure alters hypothalamic-pituitary-adrenal function in juvenile guinea pigs. J Neuroendocrinol 2007; 19:172-80. [PMID: 17280590 DOI: 10.1111/j.1365-2826.2006.01517.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The neurodevelopmental consequences of prenatal glucocorticoid exposure are not well-understood, particularly in species that give birth to neuroanatomically mature offspring. In the present study, we hypothesised that repeated prenatal glucocorticoid administration would alter hypothalamo-pituitary-adrenal (HPA) function in juvenile guinea pig offspring. Pregnant guinea pigs were injected with betamethasone (1 mg/kg) or vehicle on gestational days 40, 41, 50, 51, 60 and 61 (six doses). Prenatal glucocorticoid exposure abolished the pituitary-adrenal response to maternal separation in juvenile males, but had no effect in female offspring. Indeed, female offspring (vehicle and betamethasone) did not mount a significant HPA response to separation at 10 days of age. Although there were no effects of prenatal glucocorticoid exposure on hippocampal or hypothalamic corticosteroid receptor expression or corticotrophin-releasing factor (CRF) mRNA, there were significant effects in the pituitary and adrenal; again males were more affected than females. Prenatal glucocorticoid exposure increased pituitary pro-opiomelanocortin and CRF receptor mRNA, and markedly decreased adrenocortical CYP17 mRNA. In conclusion, repeated prenatal glucocorticoid exposure has profound influences on HPA function and regulation in the juvenile guinea pig, and this involves altered regulation at the level of the pituitary and adrenal cortex. Furthermore, juvenile males appear to be more vulnerable to the effects of prenatal glucocorticoid exposure than females.
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Yeboah D, Sun M, Kingdom J, Baczyk D, Lye SJ, Matthews SG, Gibb W. Expression of breast cancer resistance protein (BCRP/ABCG2) in human placenta throughout gestation and at term before and after labor. Can J Physiol Pharmacol 2006; 84:1251-8. [PMID: 17487233 DOI: 10.1139/y06-078] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Breast cancer resistance protein, BCRP, is a multidrug resistance protein that is highly expressed in the human placenta. In cancer tissues, this protein actively extrudes a wide variety of chemically and structurally unrelated chemotherapeutic drugs and other compounds. Studies in mice have shown that in the absence of BCRP activity in the placenta, there is a 2-fold increase in the uptake in BCRP substrates into fetus. This suggests that in the placenta, BCRP extrudes compounds that would otherwise cross the syncytiotrophoblast cells into fetal circulation. The purpose of this study was to examine the expression and localization of BCRP in the human placenta throughout gestation. Tissues from 6–13, 16–19, 24–29, 32–35, and 38–41 weeks of gestation were used. Real time RT-PCR analysis demonstrated that the mRNA levels of BCRP in the placenta do not change significantly as gestation progressed. However, Western blot analysis revealed that the protein levels increased towards the end of gestation. We demonstrated that BCRP is localized to the syncytiotrophoblast of the placenta and in some fetal blood vessels within the placenta. Tissues from the early stages of pregnancy (6–13 weeks) showed fewer BCRP positive blood vessels than term tissues (38–41 weeks).
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Iqbal U, Brien JF, Kapoor A, Matthews SG, Reynolds JN. Chronic prenatal ethanol exposure increases glucocorticoid-induced glutamate release in the hippocampus of the near-term foetal guinea pig. J Neuroendocrinol 2006; 18:826-34. [PMID: 17026532 DOI: 10.1111/j.1365-2826.2006.01479.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Exposure to high cortisol concentration can injure the developing brain, possibly via an excitotoxic mechanism involving glutamate (Glu). The present study tested the hypothesis that chronic prenatal ethanol exposure (CPEE) activates the foetal hypothalamic-pituitary-adrenal axis to produce high cortisol exposure in the foetal compartment and alters sensitivity to glucocorticoid-induced Glu release in the foetal hippocampus. Pregnant guinea pigs received daily oral administration of ethanol (4 g/kg maternal body weight/day) or isocaloric-sucrose/pair-feeding from gestational day (GD) 2 until GD 63 (term, approximately GD 68) at which time they were euthanised, 1 h after their final treatment. Adrenocorticotrophic hormone (ACTH) and cortisol concentrations were determined in foetal plasma. Basal and electrically stimulated Glu and gamma-aminobutyric acid (GABA) efflux in the presence or absence of dexamethasone (DEX), a selective glucocorticoid-receptor agonist, were determined ex vivo in foetal hippocampal slices. Glucocorticoid receptor (GR), mineralocorticoid receptor (MR) and N-methyl-D-aspartate (NMDA) receptor NR1 subunit mRNA expression were determined in situ in the hippocampus and dentate gyrus. In the near-term foetus, CPEE increased foetal plasma ACTH and cortisol concentrations. Electrically stimulated glutamate, but not GABA, release was increased in CPEE foetal hippocampal slices. Low DEX concentration (0.3 microM) decreased stimulated glutamate, but not GABA, release in both CPEE and control foetal hippocampal slices. High DEX concentration (3.0 microM) increased basal release of Glu, but not GABA, in CPEE foetal hippocampal slices. GR, but not MR, mRNA expression was elevated in the hippocampus and dentate gyrus, whereas NR1 mRNA expression was increased in the CA1 and CA3 fields of the foetal hippocampus. These data demonstrate that CPEE increases high glucocorticoid concentration-induced Glu release in the foetal hippocampus, presumably as a consequence of increased GR expression. These effects of CPEE, coupled with increased glutamate release and increased NMDA receptor expression, may predispose the near-term foetal hippocampus to GR and Glu-NMDA receptor-mediated neurodevelopmental toxicity.
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MESH Headings
- Adrenocorticotropic Hormone/blood
- Animals
- Central Nervous System Depressants/toxicity
- Electric Stimulation
- Ethanol/toxicity
- Female
- Fetus/drug effects
- Fetus/metabolism
- Glucocorticoids/metabolism
- Glutamic Acid/drug effects
- Glutamic Acid/metabolism
- Guinea Pigs
- Hippocampus/drug effects
- Hippocampus/metabolism
- Hydrocortisone/blood
- Hypothalamo-Hypophyseal System/drug effects
- Hypothalamo-Hypophyseal System/metabolism
- Maternal-Fetal Exchange
- Neurotoxins/toxicity
- Organ Culture Techniques
- Pituitary-Adrenal System/drug effects
- Pituitary-Adrenal System/metabolism
- Pregnancy
- RNA, Messenger/analysis
- Random Allocation
- Receptors, Glucocorticoid/drug effects
- Receptors, Glucocorticoid/genetics
- Receptors, Glucocorticoid/metabolism
- Receptors, Mineralocorticoid/drug effects
- Receptors, Mineralocorticoid/genetics
- Receptors, Mineralocorticoid/metabolism
- Receptors, N-Methyl-D-Aspartate/drug effects
- Receptors, N-Methyl-D-Aspartate/metabolism
- Statistics, Nonparametric
- Toxicity Tests, Chronic
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Erdeljan P, Andrews MH, MacDonald JF, Matthews SG. Glucocorticoids and serotonin alter glucocorticoid receptor mRNA levels in fetal guinea-pig hippocampal neurons, in vitro. Reprod Fertil Dev 2006; 17:743-9. [PMID: 16364229 DOI: 10.1071/rd05043] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Accepted: 09/20/2005] [Indexed: 11/23/2022] Open
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis is susceptible to programming during fetal life. Such programming occurs, at least partially, at the level of the hippocampus. The hippocampus plays a central role in regulation of the HPA axis and release of endogenous glucocorticoids, via mediation of glucocorticoid negative feedback. Fetal exposure to synthetic glucocorticoids can permanently alter glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) levels within the hippocampus, and serotonin is thought to be involved in this process. In the present study, we hypothesised that dexamethasone, cortisol and serotonin exposure would modify GR mRNA expression within fetal guinea-pig hippocampal cultures. Cultures were derived from 40-day-old guinea-pig fetuses, and were exposed to 0, 1, 10 and 100 nM dexamethasone, cortisol or serotonin for 4 days. Expression of GR and MR mRNA was examined by in situ hybridisation followed by high-resolution silver emulsion autoradiography. Four-day exposure to dexamethasone (P < 0.05; 100 nM) or cortisol (P = 0.08; 100 nM) downregulated the expression of GR mRNA within neurons. There was no change in the expression of MR mRNA levels following cortisol treatment. Exposure to serotonin (100 nM) significantly increased GR mRNA levels in hippocampal neurons. We conclude that synthetic and endogenous glucocorticoids, as well as serotonin, can influence GR expression during hippocampal development and in this way may act to permanently programme HPA function.
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Sun M, Kingdom J, Baczyk D, Lye SJ, Matthews SG, Gibb W. Expression of the multidrug resistance P-glycoprotein, (ABCB1 glycoprotein) in the human placenta decreases with advancing gestation. Placenta 2005; 27:602-9. [PMID: 16143395 DOI: 10.1016/j.placenta.2005.05.007] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Revised: 05/15/2005] [Accepted: 05/13/2005] [Indexed: 10/25/2022]
Abstract
The multidrug resistance p-glycoprotein (P-gp), encoded by the ABCB1 gene, is a plasma membrane protein that actively extrudes a wide variety of substances from cells. Preliminary studies in mice have shown that the ABCB1/P-gp can protect the fetus from a number of toxic substances. ABCB1/P-gp is expressed in the human placenta and is potentially capable of protecting the fetus from a large number of drugs and toxins, including herbicides and pesticides. The protein can also extrude various steroids including certain glucocorticoids and may therefore play an important role in regulating fetal access of glucocorticoids. The aim of the present study was to examine the expression profile and cellular localization of ABCB1/P-gp in human placenta throughout gestation. We hypothesized that there would be gestational age-related changes in the expression of the protein. ABCB1/P-gp mRNA was measured by Real-Time PCR using specific probes in tissues obtained from 6 weeks gestation to term. ABCB1/P-gp mRNA levels in placental tissue obtained at 6-10 weeks (n=5) and 24-35 weeks (n=5) were significantly higher than in tissues obtained at term (38-41 weeks gestation) by elective C-section (n=6) or following labor (n=6). The profile of ABCB1/P-gp protein levels, quantified using Western analysis, demonstrated a similar decrease with advancing gestation. At all gestational ages ABCB1/P-gp was localized by immunohistochemistry to the syncytiotrophoblast. In term tissues, it appeared to be localized to some areas of the villi and not others. Together, these data indicate that with advancing gestation there is a decrease in the level of ABCB1/P-gp in the human placenta indicating that the fetus may be more susceptible to toxic insults in the latter part of gestation. Further, the reduction in ABCB1/P-gp expression may contribute to the increased transfer of maternal cortisol to the fetus that is known to occur in late gestation.
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Iqbal U, Brien JF, Banjanin S, Andrews MH, Matthews SG, Reynolds JN. Chronic prenatal ethanol exposure alters glucocorticoid signalling in the hippocampus of the postnatal Guinea pig. J Neuroendocrinol 2005; 17:600-8. [PMID: 16101899 DOI: 10.1111/j.1365-2826.2005.01349.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present study tested the hypothesis that chronic prenatal ethanol exposure causes long-lasting changes in glucocorticoid signalling in postnatal offspring. Pregnant guinea pigs were treated with ethanol (4 g/kg maternal body weight/day), isocaloric-sucrose/pair-feeding or water throughout gestation, and maternal saliva cortisol concentration was determined 2 h after treatment at different stages of gestation. Electrically-stimulated release of glutamate and GABA, in the presence or absence of dexamethasone, as well as glucocorticoid and mineralocorticoid receptor mRNA expression, was determined in the hippocampus and prefrontal cortex of adult offspring of treated pregnant guinea pigs. Maternal saliva cortisol concentration increased throughout pregnancy, which was associated with increased foetal plasma and amniotic fluid cortisol concentration. Ethanol administration to pregnant guinea pigs increased maternal saliva cortisol concentration during early and mid-gestation. In late gestation, ethanol administration did not increase saliva cortisol concentration above that induced by pregnancy. Chronic prenatal ethanol exposure had no effect on stimulated glutamate or GABA release, but selectively prevented dexamethasone-mediated suppression of stimulated glutamate release, and decreased expression of mineralocorticoid, but not glucocorticoid, receptor mRNA in the hippocampus of adult offspring. These data indicate that maternal ethanol administration leads to excessively increased maternal cortisol concentration that can impact negatively the developing foetal brain, leading to persistent postnatal deficits in glucocorticoid regulation of glutamate signalling in the adult hippocampus.
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Owen D, Banjanin S, Gidrewicz D, McCabe L, Matthews SG. Central regulation of the hypothalamic-pituitary-adrenal axis during fetal development in the Guinea-pig. J Neuroendocrinol 2005; 17:220-6. [PMID: 15842233 DOI: 10.1111/j.1365-2826.2005.01294.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously shown that the foetal guinea-pig hypothalamic-pituitary-adrenal (HPA) axis is activated near the time of parturition and that this is associated with changes in limbic glucocorticoid receptors (GR) and mineralocorticoid receptors. In the present study, we hypothesized that the foetal hypothalamic paraventricular nucleus (PVN) and pituitary contribute significantly to foetal HPA drive but that these areas remain sensitive to negative feedback by circulating glucocorticoids in late gestation. However, we observed decreased corticotrophin-releasing hormone mRNA expression in the PVN and decreased pro-opiomelanocortin (POMC) mRNA levels in the anterior pituitary with advanced gestational age. The reduction in POMC mRNA expression was likely the result of negative feedback via circulating glucocorticoids because GR mRNA was unchanged during development in the foetal pituitary. Furthermore, we found that maternally administered glucocorticoids significantly decreased foetal pituitary POMC mRNA expression in a dose-dependent manner at gestational day (gd) 62 with male foetuses being more sensitive to these effects. These findings show that the foetal HPA axis remains highly sensitive to glucocorticoid feedback even as plasma adrenocorticotropic hormone and cortisol levels are elevated at the end of gestation.
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Matthews SG, Owen D, Kalabis G, Banjanin S, Setiawan EB, Dunn EA, Andrews MH. Fetal glucocorticoid exposure and hypothalamo-pituitary-adrenal (HPA) function after birth. Endocr Res 2004; 30:827-36. [PMID: 15666833 DOI: 10.1081/erc-200044091] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The fetus may be exposed to increased endogenous glucocorticoid or synthetic glucocorticoid in late gestation. Indeed, 7-10% of pregnant women in Europe and North America are treated with synthetic glucocorticoid to promote lung maturation in fetuses at risk of preterm delivery. Such therapy is effective in reducing respiratory complications. However, very little is known about the mechanisms by which synthetic glucocorticoid or prenatal stress influence neurodevelopment in the human, or whether specific time windows of increased sensitivity exist. Glucocorticoids are essential for many aspects of normal brain development. However, there is growing evidence that exposure of the fetal brain to excess glucocorticoid can have lifelong effects on neuroendocrine function and behavior. We have shown that both endogenous glucocorticoid and synthetic glucocorticoid exposure has a number of rapid effects in the fetal brain in late gestation, including modification of neurotransmitter systems and transcriptional machinery. Such fetal exposure permanently alters hypothalamo-pituitary-adrenal (HPA) function in prepubertal, postpubertal, and aging offspring, in a sex-dependent manner. These effects are linked to changes in central glucocorticoid feedback machinery after birth. Prenatal glucocorticoid manipulation also leads to modification of HPA-associated behaviors, brain and organ morphology, as well as altered regulation of other endocrine systems. Permanent changes in endocrine function will have a long-term impact on health, since elevated cumulative exposure to endogenous glucocorticoid is linked to the premature onset of pathologies associated with aging.
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Chan O, Inouye K, Riddell MC, Vranic M, Matthews SG. Diabetes and the hypothalamo-pituitary-adrenal (HPA) axis. MINERVA ENDOCRINOL 2003; 28:87-102. [PMID: 12717340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Patients and animals with poorly controlled or uncontrolled diabetes present with diurnal hypersecretion of glucocorticoids and altered regulation of the hypothalamo-pituitary-adrenocortical (HPA) axis. Although some of these changes are reversed with insulin replacement therapy, neuroendocrine function is not always restored to normal, even with rigorous glycemic control. In addition, stress responsiveness is also impaired in diabetes and this has important implications in the way patients with diabetes cope with many stress challenges, including the metabolic challenge of insulin-induced hypoglycemia. HPA dysregulation in diabetes appears to involve complex interactions between impaired glucocorticoid negative feedback sensitivity and factors such as hypoinsulinemia, hyperglycemia and/or hypoleptinemia, that may increase central drive of the axis. This review examines some of the evidence indicating hyperactivation of the HPA axis in patients with diabetes. Using the streptozotocin-diabetic rat as a model of type-1 diabetes, we will focus on elucidating some of the mechanisms underlying HPA dysregulation in diabetes. Hyperactivation of the HPA axis in diabetes is associated with increased expression of hypothalamic corticotrophin-releasing hormone (CRH) mRNA and hippocampal mineralocorticoid receptor (MR) mRNA. Although insulin replacement restores ACTH and corticosterone levels to normal, likely through glucocorticoid-mediated suppression of ACTH secretion, CRH and MR mRNA expression remain elevated. A better understanding of these mechanisms may be important in developing new treatment modalities for patients with diabetes mellitus.
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22
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Matthews SG, Owen D, Banjanin S, Andrews MH. Glucocorticoids, hypothalamo-pituitary-adrenal (HPA) development, and life after birth. Endocr Res 2002; 28:709-18. [PMID: 12530687 DOI: 10.1081/erc-120016991] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Approximately 10% of women in North America are treated with synthetic glucocorticoid (sGC) between 24 and 32 weeks of pregnancy (term approximately 40 weeks), to promote lung maturation in fetuses at risk of preterm delivery. Such therapy is highly effective in reducing the frequency of respiratory complications, and as a result, repeated course treatment has become widespread. Nothing is known about the impact of repeated sGC treatment on neuroendocrine development in the human, or if specific time windows of increased sensitivity exist. Glucocorticoids are essential for many aspects of normal brain development. However, there is growing evidence from a number of species, that exposure of the fetal brain to excess glucocorticoid can have life-long effects on behaviour and neuroendocrine function. We have shown that exposure of fetuses to sGC in late gestation permanently alters HPA function in pre-pubertal, post-pubertal, and aging offspring, in a sex-dependent manner. These effects are linked to changes in central glucocorticoid feedback. Prenatal glucocorticoid exposure also leads to modification of HPA-associated behaviours and organ morphology, as well as altered regulation of other neuroendocrine systems. Permanent changes in HPA function will have a long-term impact on health, since elevated cumulative exposure to endogenous glucocorticoid has been linked to the premature onset of pathologies associated with aging.
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Inouye K, Chan O, Riddell MC, Akirav E, Matthews SG, Vranic M. Mechanisms of impaired hypothalamic-pituitary-adrenal (HPA) function in diabetes: reduced counterregulatory responsiveness to hypoglycaemia. DIABETES, NUTRITION & METABOLISM 2002; 15:348-55; discussion 355-6, 362. [PMID: 12625483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
In summary, our data suggest that in uncontrolled diabetes, increased HPA activity is caused by increased central drive at or above the level of the PVN. Insulin treatment only restores HPA activity at and below the pituitary level, presumably by GC-mediated suppression of ACTH secretion. We hypothesize that the defective HPA response to hypoglycaemia is at least in part due to a lack of a decrease in MR mRNA in response to hypoglycaemia, and diminished sensitivity of the pituitary and adrenal gland to stimulation. Interestingly, insulin treatment restores the HPA response, but not the defective epinephrine response. Therefore, defective epinephrine responses are not linked to defective HPA responses. Similarly, antecedent hypoglycaemia specifically impairs epinephrine responses, but not HPA responses to hypoglycaemia. These studies have revealed some of the mechanisms of impaired HPA function in diabetes and its impaired responsiveness to hypoglycaemia. Further investigations are essential for understanding poor counterregulation in insulin-treated diabetes and may lead to new strategies for preventing hypoglycaemia.
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Challis JR, Sloboda D, Matthews SG, Holloway A, Alfaidy N, Patel FA, Whittle W, Fraser M, Moss TJ, Newnham J. The fetal placental hypothalamic-pituitary-adrenal (HPA) axis, parturition and post natal health. Mol Cell Endocrinol 2001; 185:135-44. [PMID: 11738803 DOI: 10.1016/s0303-7207(01)00624-4] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A general characteristic of fetal endocrine maturation across different species is the enhanced activity of the fetal hypothalamic-pituitary-adrenal (HPA) axis during late gestation. Precocious activation of this axis may occur when the fetus is exposed to an adverse intra-uterine environment, such as hypoxemia. HPA development is associated with increased levels of ACTH(1-39) and adrenal corticosteroids (cortisol in sheep and human) in the fetal circulation, and increased expression of mRNA encoding corticotrophin releasing hormone (CRH) in the hypothalamus, proopiomelanocortin (POMC) in the pituitary, and key steroidogenic enzymes in the fetal adrenal. At term, increased levels of cortisol act on the placenta/trophoblast derived cells to increase expression of prostaglandin synthase Type II (PGHS-II). In human gestation, cortisol also decreases expression of 15-hydroxyprostaglandin dehydrogenase (PGDH) in chorionic trophoblast cells. Increased synthesis and decreased metabolism of prostaglandin (PG) results, during late gestation, in enhanced output of primary PG, which in turn increases the activity of 11 beta-hydroxysteroid dehydrogenase (11 beta HSD) in the human fetal membranes. Increased chorionic 11 beta HSD-1 results in increased local generation of cortisol from cortisone, with further paracrine/autocrine stimulation of PG output. Increased fetal cortisol contributes to the maturation of organ systems required for postnatal extra-uterine survival. However, excessive levels of feto-placental glucocorticoid, derived from maternal administration of synthetic corticosteroids or sustained endogenous fetal cortisol production, results in intrauterine growth restriction. Fetal sheep, exposed to maternal betamethasone in late gestation, develop insulin resistance and exaggerated adrenal responses to HPA stimulation by 6-12 months postnatal life. Thus, the level of fetal HPA activity is crucial not only for determining gestation length, but may also predict pathophysiologic adjustments in later life.
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Chan O, Chan S, Inouye K, Vranic M, Matthews SG. Molecular regulation of the hypothalamo-pituitary-adrenal axis in streptozotocin-induced diabetes: effects of insulin treatment. Endocrinology 2001; 142:4872-9. [PMID: 11606455 DOI: 10.1210/endo.142.11.8474] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Increased hypothalamo-pituitary-adrenocortical (HPA) activity in diabetes is likely important in the development of some pathologies associated with the disorder. We hypothesized that central regulation of HPA activity differs among normal, streptozotocin (STZ)-diabetic, and insulin-treated diabetic rats. Blood glucose, ACTH, and corticosterone were elevated, 8 d after inducing diabetes. Insulin treatment normalized these parameters. Plasma norepinephrine was similar in all groups, but epinephrine was lower in STZ-diabetic and higher in insulin-treated rats vs. normals. Increased ACTH with diabetes corresponded with increased hypothalamic CRH mRNA, but no change in pituitary POMC mRNA. With insulin-treatment, CRH mRNA remained elevated, and POMC mRNA was unaltered. Hippocampal MR mRNA expression was dramatically increased with diabetes and, moreover, was not normalized by insulin. No differences in GR mRNA were detected between normal and STZ-diabetic rats. However, insulin treatment increased GR mRNA levels in the paraventricular nucleus and pituitary. We postulate that, in STZ-diabetes: 1) increased HPA activity is caused by increased central drive at and/or above the level of the paraventricular nucleus and is associated with decreased epinephrine; and 2) normalized pituitary-adrenal activity with insulin may be caused by the compensatory increase in GR mRNA allowing glucocorticoid-mediated suppression of ACTH secretion despite the residual increase in central HPA activity. Thus, insulin apparently restored HPA activity at and below the pituitary but, surprisingly, not above it.
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