Differential induction of adrenomedullin, interleukins and tumour necrosis factor-α by lipopolysaccharide in rat tissues in vivo

1. The aim of the present study was to determine the temporal changes in tissue adrenomedullin (AM) and cytokine contents and cytokine and preproAM mRNA levels in the kidney, liver, adrenal gland and spleen of lipopolysaccharide (LPS)-treated rats. 2. Rats were injected with LPS (10 mg/kg, i.p.). Radioimmunoassay and solution hybridization-RNase protection assays were used to follow the changes in AM and its mRNA levels, respectively; ELISA and reverse transcription-polymerase chain reaction were used to follow the changes in cytokines and their mRNA levels, respectively. 3. In the kidney, the preproAM mRNA levels were increased 1 and 3 h after LPS treatment, whereas AM levels were decreased at 3 h. Interleukin (IL)-6 and IL-1β levels were increased at 3 and 6 h, respectively. 4. The preproAM mRNA levels were elevated in the liver 3 h after LPS injection. Concentrations of tumour necrosis factor (TNF)-α and IL-1β were increased at l and 6 h, respectively. 5. There were no changes in the levels of either preproAM mRNA or AM in the adrenal gland and the spleen. In the spleen, TNF-α levels were elevated at 1 and 3 h after LPS injection and IL-1β was elevated at 1 and 6 h after LPS injection, whereas in the adrenal gland IL-1β was elevated at 6 h after injection. 6. The mRNA levels of the three cytokines were elevated at all three time intervals examined in the kidney, liver, adrenal gland and spleen, with the exception that TNF-α mRNA was not elevated in the adrenal gland at 6 h after LPS injection and IL-1β mRNA was not elevated in the spleen at 3 and 6 h. 7. The plasma concentrations of TNF-α were increased at 1 and 3 h after LPS injection, whereas plasma concentration of IL-1β and IL-6 were elevated at 3 and 6 h for both. 8. The present results suggest that the biosynthesis and secretion of AM may be differentially regulated in various tissues of rats injected with LPS and that AM may interact with cytokines during inflammation. © 2005 Blackwell Publishing Asia Pty Ltd.link_to_subscribed_fulltex

Dynamic transcriptomic profiles of zebrafish gills in response to zinc supplementation

<p>Abstract</p> <p>Background</p> <p>Dietary zinc supplementation may help to promote growth, boost the immune system, protect against diabetes, and aid recovery from diarrhoea. We exploited the zebrafish (<it>Danio rerio</it>) gill as a unique vertebrate ion transporting epithelium model to study the time-dependent regulatory networks of gene-expression leading to homeostatic control during zinc supplementation. This organ forms a conduit for zinc uptake whilst exhibiting conservation of zinc trafficking components.</p> <p>Results</p> <p>Fish were maintained with either zinc supplemented water (4.0 μM) and diet (2023 mg zinc kg^-1) or water and diet containing Zn²⁺at 0.25 μM and 233 mg zinc kg^-1, respectively. Gill tissues were harvested at five time points (8 hours to 14 days) and transcriptome changes analysed in quintuplicate using a 16 K microarray with results anchored to gill Zn²⁺influx and whole body nutrient composition (protein, carbohydrate, lipid, elements). The number of regulated genes increased up to day 7 but declined as the fish acclimated. In total 525 genes were regulated (having a fold-change more than 1.8 fold change and an adjusted P-value less than 0.1 which is controlling a 10% False discovery rate, FDR) by zinc supplementation, but little overlap was observed between genes regulated at successive time-points. Many genes displayed cyclic expression, typical for homeostatic control mechanisms. Annotation enrichment analysis revealed strong overrepresentation of "transcription factors", with specific association evident with "steroid hormone receptors". A suite of genes linked to "development" were also statistically overrepresented. More specifically, early regulation of genes was linked to a few key transcription factors (e.g. Mtf1, Jun, Stat1, Ppara, Gata3) and was followed by hedgehog and bone morphogenic protein signalling.</p> <p>Conclusions</p> <p>The results suggest that zinc supplementation reactivated developmental pathways in the gill and stimulated stem cell differentiation, a response likely reflecting gill remodelling in response to its altered environment. This provides insight to the role of zinc during cell differentiation and illustrates the critical nature of maintaining zinc status. The study also highlights the importance of temporal transcriptomics analysis in order resolve the discrete elements of biological processes, such as zinc acclimation.</p