Abstract

Prostaglandin (PG) production by human fetal membranes (amnion and chorion laeve) may be important in the onset and progression of labour, cervical ripening and membrane rupture. Prostaglandin H synthase (PGHS) is a key enzyme in PG formation and has two isoforms, a constitutive form (PGHS-1) and an inducible form (PGHS-2). The present study examined the cellular distribution of the PGHS-2 enzyme and PGHS-2 mRNA in term human fetal membranes and decidua prior to and following labour, using immunohistochemistry and in situ hybridization with an ³⁵S-labelled oligonucleotide probe. The PGHS-2 protein was found to be localized in amnion epithelial cells and chorion laeve trophoblast, but was absent or at low levels in the decidual stroma in most tissues, although cells surrounding some of the blood vessels in the decidua did express PGHS-2. In situ hybridization demonstrated that PGHS-2 mRNA had a similar distribution and was localized to amnion epithelial cells, cells in the amnion-chorion mesenchyme, chorion laeve trophoblast and, occasionally, to cells surrounding blood vessels in the decidua. Of particular note was the high mRNA expression in some cells and low expression in other cells, particularly in the chorion, and the low level of PGHS-2 mRNA in decidua. There was no observable difference in the cellular localization of PGHS-2 protein or PGHS-2 mRNA in tissues obtained prior to and following labour. The studies indicate that, at term, the inducible form of PGHS, PGHS-2, is expressed at a high level in fetal tissues in a number of different cell types rather than in the maternal decidua.

Journal of Endocrinology (1996) 150, 497–503

Abstract

The human fetal membranes and decidua may be important in the onset and/or progression of human labor by providing prostaglandins for this process. Glucocorticoids have been implicated in the regulation of prostaglandin production by these tissues but to date there is no direct evidence for glucocorticoid receptors (GRs) being present in human intrauterine tissues. The purpose of the present study was to determine, using immunohistochemistry, whether the human fetal membranes and decidua contained GRs; to determine the localization of receptors to the cytoplasm or nuclei, and to examine the content and distribution of the GRs in tissues obtained during pregnancy following preterm labor (<37 weeks) and at term prior to and following term labor. Term tissues were obtained prior to labor by elective Cesarian section (n=9) or following vaginal delivery (n=9). Tissues from 14 patients who delivered preterm but with no clinical evidence of infection were also examined. Cryostat sections were thaw-mounted onto microscope slides. The immunoreactive GRs were visualized with an Elite Vectastain ABC Kit using a polyclonal antibody prepared against a synthetic peptide corresponding to amino acids 346–367 of the human GR. At term, nuclear GRs were found in amnion epithelial cells, mesenchyme and the chorion laeve. GRs were present, but were less defined, in the decidua. A similar distribution was found in the preterm tissues. However, nuclear staining in the amnion epithelial cells, mesenchymal cells, chorion and decidua was more pronounced in tissues obtained following preterm labor. This study provides direct evidence for the presence of GRs in human fetal membranes and decidua, and suggests the possible importance of multiple cell types in the action of glucocorticoids in these tissues.

Journal of Endocrinology (1996) 149, 243–248

The homoeostatic regulation of metabolism is highly complex and involves multiple inputs from both the nervous and endocrine systems. The gut is the largest endocrine organ in our body and synthesises and secretes over 20 different hormones from enteroendocrine cells that are dispersed throughout the gut epithelium. These hormones include GLP-1, PYY, GIP, serotonin, and CCK, each of which play pivotal roles in maintaining energy balance and glucose homeostasis. Some are now the basis of several clinically used glucose-lowering and weight loss therapies. The environment in which these enteroendocrine cells exist is also complex, as they are exposed to numerous physiological inputs including ingested nutrients, circulating factors and metabolites produced from neighbouring gut microbiome. In this review, we examine the diverse means by which gut-derived hormones carry out their metabolic functions through their interactions with different metabolically important organs including the liver, pancreas, adipose tissue and brain. Furthermore, we discuss how nutrients and microbial metabolites affect gut hormone secretion and the mechanisms underlying these interactions.

Increased prostaglandin production by tissues in the sheep uterus and placenta are thought to be important for the onset of parturition. In the sheep placenta, this is most likely due to increased expression of prostaglandin synthase type-2 (PGHS-2) rather than prostaglandin synthase type-1 (PGHS-1). However, there is no information concerning expression of PGHS isoenzymes in maternal uterine tissues during pregnancy. Therefore, the purpose of the present study was to examine the expression of PGHS-1 and PGHS-2 in the sheep myometrium and endometrium during late gestation using in situ hybridization and immunohistochemistry. Using (35)S-labelled oligonucleotide probes, which give specific hybridization signals in other tissues, we localized PGHS-2 mRNA to endometrial epithelium, and apparently to other cells in both endometrium and myometrium. This artefactual signal was still present with 100-fold excess unlabelled oligonucleotide probe and with sense probes, but was resolved with the use of (33)P-oligonucleotides. Using (33)P-labelled oligonucleotide probes we could not detect either PGHS-1 or PGHS-2 mRNA in myometrium, and found expression only of PGHS-2 mRNA in endometrium. PGHS-2 mRNA localized to the endometrial epithelium and was undetectable in glandular epithelium. The level of PGHS-2 expression rose significantly between days 80 and 85 of pregnancy and term, and this corresponded to the appearance of immunoreactive PGHS-2 protein, measured by immunohistochemistry, in the endometrial epithelium. Therefore we conclude that (33)P-labelled probes are preferred for detection of mRNAs encoding PGHS-2 in ovine uterine tissues. Expression of PGHS-2 mRNA is greater than that of PGHS-1, increases during gestation, and predominates in the endometrial epithelium, consistent with the site of PGHS-2 protein localization.

Link protein (LP), an extracellular matrix protein in cartilage, stabilizes aggregates of hyaluronic acid (HA) and proteoglycans, including aggrecan and inter-alpha-trypsin inhibitor (ITI). We have shown previously that cartilage LP is present in the maturing rat and mouse ovary. In the present study, we have employed immunohistochemistry to examine the anatomical distribution of cartilage LP in the human ovary. The expression of cartilage LP was selectively detected in the cells within the granulosa compartment of the preovulatory dominant follicle. The HA-positive granulosa-lutein cells were found to be a cartilage LP-positive subpopulation. We subsequently studied the in vitro expression of cartilage LP in cultured human granulosa-lutein cells obtained at oocyte retrieval for in vitro fertilization. Analysis of cultured cells by enzyme-linked immunoaffinity assay, Western blotting and immunofluorescence microscopy revealed that gonadotropin stimulates cartilage LP production. Time-course studies indicated that the cartilage LP production was induced as early as with gonadotropin stimulation for 2 h, and the effect was sustained up to 8 h. Western blot analysis further revealed the presence of the macroaggregates composed of HA, ITI and cartilage LP in the gonadotropin-stimulated granulosa-lutein cell extracts. Collectively, the present results raise the possibility that cartilage LP forms extracellular structures that may have a regulatory function in the developing follicle in the human ovary.

During spermatogenesis, spermiation takes place at the adluminal edge of the seminiferous epithelium at stage VIII of the epithelial cycle during which fully developed spermatids (i.e. spermatozoa) detach from the epithelium in adult rat testes. This event coincides with the migration of preleptotene/leptotene spermatocytes across the blood–testis barrier from the basal to the apical (or adluminal) compartment. At stage XIV of the epithelial cycle, Pachytene spermatocytes (diploid, 2n) differentiate into diplotene spermatocytes (tetraploid, 4n) in the apical compartment of the epithelium, which begin meiosis I to be followed by meiosis II to form spermatids (haploid, 1n) at stage XIV of the epithelial cycle. These spermatids, in turn, undergo extensive morphological changes and traverse the seminiferous epithelium until they differentiate into elongated spermatids. Thus, there are extensive changes at the Sertoli–Sertoli and Sertoli–germ cell interface via protein ‘coupling’ and ‘uncoupling’ between cell adhesion protein complexes, as well as changes in interactions between integral membrane proteins and their peripheral adaptors, regulatory protein kinases and phosphatases, and the cytoskeletal proteins. These precisely coordinated protein–protein interactions affect cell adhesion and cell movement. In this review, we focus on the 14-3-3 protein family, whose members have different binding partners in the seminiferous epithelium. Recent studies have illustrated that 14-3-3 affects protein–protein interactions in the seminiferous epithelium, and regulates cell adhesion possibly via its effects on intracellular protein trafficking and cell-polarity proteins. This review provides a summary on the latest findings regarding the role of 14-3-3 family of proteins and their potential implications on spermatogenesis. We also highlight research areas that deserve attentions by investigators.

Thyroid dysfunction is classified into hyperthyroidism and congenital hypothyroidism (CH). Both hyperthyroidism and CH can cause heart lesions; however, the mechanisms involved remain unclear. The left ventricle was collected from eu-, hyper-, and hypothyroid rat. RNA was extracted and reverse-transcripted to cDNA. Real-time fluorescence quantitation-PCR was used to quantify the differential expression of thyroid hormone receptor (TR) subtype mRNA among eu-, hyper-, and hypothyroid rat myocardium. Here, we show that compared with the normal myocardium, TRα1 mRNA expression was upregulated by 51% (P<0.01), TRα2 mRNA expression was downregulated by 58% (P<0.01), and TRβ1 mRNA expression remained unchanged in hyperthyroid rat myocardium (P>0.05). TRα1, TRα2, and TRβ1 were expressed in normal and hypothyroid rat myocardium throughout the developmental process. In hypothyroid rats, myocardial TRα1 mRNA expression was generally downregulated and the expression peak appeared late. Myocardial TRα2 mRNA expression was generally upregulated and the expression peak appeared late. Myocardial TRβ1 mRNA expression was generally downregulated and changed similarly with the control group. In addition, the hypogenetic myocardium can be seen in the hypothyroid rat by pathology study. Taken together, the abnormal expression of TR subtype mRNA may have a close relationship with the pathogenesis of CH and hyperthyroidism heart disease.

Sexual differences have been observed in the onset and prognosis of human cardiovascular diseases, but the underlying mechanisms are not clear. Here, we found that zebrafish heart regeneration is faster in females, can be accelerated by estrogen and is suppressed by the estrogen-antagonist tamoxifen. Injuries to the zebrafish heart, but not other tissues, increased plasma estrogen levels and the expression of estrogen receptors, especially esr2a. The resulting endocrine disruption induces the expression of the female-specific protein vitellogenin in male zebrafish. Transcriptomic analyses suggested heart injuries triggered pronounced immune and inflammatory responses in females. These responses, previously shown to elicit heart regeneration, could be enhanced by estrogen treatment in males and reduced by tamoxifen in females. Furthermore, a prior exposure to estrogen preconditioned the zebrafish heart for an accelerated regeneration. Altogether, this study reveals that heart regeneration is modulated by an estrogen-inducible inflammatory response to cardiac injury. These findings elucidate a previously unknown layer of control in zebrafish heart regeneration and provide a new model system for the study of sexual differences in human cardiac repair.