Tools for Controlling Activity of Neural Circuits Can Boost Gastrointestinal Research

We thank Prof U. G. Knaus and T. C. Collin for critical reading of the manuscript. GA is supported by the European Crohn's and Colitis Organization (ECCO) (J/15/2) and by the National Childrens' Research Centre (K/12/1). GD is supported by the University of Aberdeen Wellcome Trust Institutional Support Fund (105625/Z/14Z).Peer reviewedPublisher PD

Cellular ROS imaging with hydro-Cy3 dye is strongly influenced by mitochondrial membrane potential

Background: Hydrocyanines are widely used as fluorogenic probes to monitor reactive oxygen species (ROS) generation in cells. Their brightness, stability to autoxidation and photobleaching, large signal change upon oxidation, pH independence and red/near infrared emission are particularly attractive for imaging ROS in live tissue. Methods: Using confocal fluorescence microscopy we have examined an interference of mitochondrial membrane potential (ΔΨm) with fluorescence intensity and localisation of a commercial hydro-Cy3 probe in respiring and non-respiring colon carcinoma HCT116 cells. Results: We found that the oxidised (fluorescent) form of hydro-Cy3 is highly homologous to the common ΔΨm-sensitive probe JC-1, which accumulates and aggregates only in ‘energised’ negatively charged mitochondrial matrix. Therefore, hydro-Cy3 oxidised by hydroxyl and superoxide radicals tends to accumulate in mitochondrial matrix, but dissipates and loses brightness as soon as ΔΨm is compromised. Experiments with mitochondrial inhibitor oligomycin and uncoupler FCCP, as well as a common ROS producer paraquat demonstrated that signals of the oxidised hydro-Cy3 probe rapidly and strongly decrease upon mitochondrial depolarisation, regardless of the rate of cellular ROS production. Conclusions: While analysing ROS-derived fluorescence of commercial hydrocyanine probes, an accurate control of ΔΨm is required. General significance: If not accounted for, non-specific effect of mitochondrial polarisation state on the behaviour of oxidised hydrocyanines can cause artefacts and data misinterpretation in ROS studies

Diet induced obesity is independent of metabolic endotoxemia and TLR4 signalling, but markedly increases hypothalamic expression of the acute phase protein, SerpinA3N

The authors gratefully acknowledge Doctoral Training Partnership funding from the BBSRC (M.J.D.), MRC (GA) and funding from the Scottish Government (P.J.M., A.W.R., A.W.W. and P.B.). The authors would like to acknowledge the support of the Maxwell compute cluster funded by the University of Aberdeen. We also thank the Centre for Genome-Enabled Biology and Medicine, University of Aberdeen for performing next-generation sequencing and RNAseq, Dr Sophie Shaw, for bioinformatic analysis of the RNAseq data, and Lynn Thomson for assistance with the TLR4−/− and CD14−/− mouse study, and Dr Richard Anderson and Dana Wilson for assistance with the long term high fat diet study. Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-018-33928-4.Peer reviewedPublisher PD

Increased endocannabinoid levels reduce the development of precancerous lesions in the mouse colon

Colorectal cancer is an increasingly important cause of death in Western countries. Endocannabinoids inhibit colorectal carcinoma cell proliferation in vitro. In this paper, we investigated the involvement of endocannabinoids on the formation of aberrant crypt foci (ACF, earliest preneoplastic lesions) in the colon mouse in vivo. ACF were induced by azoxymethane (AOM); fatty acid amide hydrolase (FAAH) and cannabinoid receptor messenger ribonucleic acid (mRNA) levels were analyzed by the quantitative reverse transcription polymerase chain reaction (RT-PCR); endocannabinoid levels were measured by liquid chromatography–mass spectrometry; caspase-3 and caspase-9 expressions were measured by Western blot analysis. Colonic ACF formation after AOM administration was associated with increased levels of 2-arachidonoylglycerol (with no changes in FAAH and cannabinoid receptor mRNA levels) and reduction in cleaved caspase-3 and caspase-9 expression. The FAAH inhibitor N-arachidonoylserotonin increased colon endocannabinoid levels, reduced ACF formation, and partially normalized cleaved caspase-3 (but not caspase-9) expression. Notably, N-arachidonoylserotonin completely prevented the formation of ACF with four or more crypts, which have been show to be best correlated with final tumor incidence. The effect of N-arachidonoylserotonin on ACF formation was mimicked by the cannabinoid receptor agonist HU-210. No differences in ACF formation were observed between CB1 receptor-deficient and wild-type mice. It is concluded that pharmacological enhancement of endocannabinoid levels (through inhibition of endocannabinoid hydrolysis) reduces the development of precancerous lesions in the mouse colon. The protective effect appears to involve caspase-3 (but not caspase-9) activation

Anorectic and aversive effects of GLP-1 receptor agonism are mediated by brainstem cholecystokinin neurons, and modulated by GIP receptor activation

This work was funded by an MRC Career Development Award (MR/ P009824/1 and MR/P009824/2) to GD’A, as well as an MRC grant to SML/GD’A (MR/T032669/1), a BBSRC grant to SML (BB/M001067/1), and an additional direct contribution from Eli Lilly. D.J.H. was sup- ported by MRC (MR/N00275X/1 and MR/S025618/1), Diabetes UK (17/ 0005681), and the European Research Council (ERC) under the Eu- ropean Union’s Horizon 2020 research and innovation programme (Starting Grant 715884 to D.J.H.). AC was supported for part of this project by a travel grant from the Italian Society of Pharmacology and a fellowship from the Veronesi Foundation (Italy).Peer reviewedPublisher PD

Potent Antioxidant and Genoprotective Effects of Boeravinone G, a Rotenoid Isolated from Boerhaavia diffusa

Background and Aims: Free radicals are implicated in the aetiology of some gastrointestinal disorders such as gastric ulcer, colorectal cancer and inflammatory bowel disease. In the present study we investigated the antioxidant and genoprotective activity of some rotenoids (i.e. boeravinones) isolated from the roots of Boerhaavia diffusa, a plant used in the Ayurvedic medicine for the treatment of diseases affecting the gastrointestinal tract. Methods/Principal Findings: Antioxidant activity has been evaluated using both chemical (Electron Spin Resonance spectroscopy, ESR) and Caco-2 cells-based (TBARS and ROS) assays. DNA damage was evaluated by Comet assay, while pERK 1/2 and phospho-NF-kB p65 levels were estimated by western blot. Boeravinones G, D and H significantly reduced the signal intensity of ESR induced by hydroxyl radicals, suggesting a scavenging activity. Among rotenoids tested, boeravinone G exerted the most potent effect. Boeravinone G inhibited both TBARS and ROS formation induced by Fenton's reagent, increased SOD activity and reduced H 2O 2-induced DNA damage. Finally, boeravinone G reduced the levels of pERK 1 and phospho-NF-kB p65 (but not of pERK 2) increased by Fenton's reagent. Conclusions: It is concluded that boeravinone G exhibits an extraordinary potent antioxidant activity (significant effect in the nanomolar range). The MAP kinase and NF-kB pathways seem to be involved in the antioxidant effect of boeravinone G. Boeravinone G might be considered as lead compound for the development of drugs potentially useful against those pathologies whose aetiology is related to ROS-mediated injuries