Plasma from uninephrectomized rats stimulates phospholipid methylation and arachidonic acid release in renal-cortical slices.
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ABSTRACT:
SUBMITTER: Banfic H
PROVIDER: S-EPMC1138678 | biostudies-other | 1989 Jun
REPOSITORIES: biostudies-other
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Project description:BackgroundArachidonic acid (AA), a major long-chain n-6 polyunsaturated fatty acid in animal foods, has been linked to inflammation, coagulation, and testosterone, which might relate to atherosclerotic cardiovascular diseases (ASCVD). We assessed the associations of genetically predicted plasma phospholipid AA with ASCVD and other CVD overall and by sex using Mendelian randomization (MR).MethodsWe conducted two-sample MR, applying eight genetic variants, independent of a highly pleiotropic variant (rs174547), strongly (p < 5 × 10-8) predicting AA, primarily to summary statistics of genetic associations with ASCVD, including ischaemic heart disease (IHD), ischaemic stroke, and peripheral artery disease (PAD) from CARDIoGRAMplusC4D 1000 Genomes (60,801 IHD cases, 123,504 controls), MEGASTROKE (34,217 ischaemic stroke cases, 406,111 controls), and Pan-UK Biobank (n=~420,531), and secondarily to genetic associations with other CVD from Pan-UK Biobank, Atrial Fibrillation Consortium, HERMES consortium, and FinnGen. We also assessed sex differences.FindingsGenetically predicted AA was associated with ASCVD (odds ratio (OR) per % of total fatty acids increase 1.03, 95% confidence interval (CI) 1.01 to 1.05) and its subtypes IHD (OR 1.03, 95% CI 1.004 to 1.05), ischaemic stroke (OR 1.03, 95% CI 1.004 to 1.06) and possibly PAD (OR 1.08, 95% CI 1.00 to 1.17), possibly more strongly in men than women. AA was also associated with venous thromboembolism (OR 1.12, 95% CI 1.05 to 1.19). A similar pattern was observed when using rs174547 to genetically predict AA.InterpretationOur study suggests positive associations of AA with ASCVD and venous thromboembolism, with possibly stronger associations in men than women.FundingNo funding.
| S-EPMC7804604 | biostudies-literature
Project description:Using TEA3A1 rat endocrine thymic epithelial cells, we demonstrated that kallikrein (EC 3.4.21.35) not only stimulated the release of arachidonic acid (AA) and its metabolites from TEA3A1 cells but also enhanced the intracellular synthesis of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) by approx. 2-fold. The stimulatory effect of kallikrein was dose- and time-dependent and could be blocked by aprotinin, a kallikrein inhibitor. It was found that the phospholipase A inhibitors ONO RS082 [2-(p-amylcinnamoyl)amino-4-chlorobenzoic acid], and mepacrine (6-chloro-9-[(4-dimethylamino)-1-methyl)]amino-2-methoxyacridine; quinacrine) also inhibited the kallikrein-stimulated release of AA and its metabolites. It is suggested that the kallikrein-induced stimulatory effect might be mediated through a phospholipase A2 pathway. The effect of bradykinin was studied and no significant stimulation was observed, even at a high dose (10 micrograms/ml). This suggested that the formation of kinin does not have a role in the kallikrein-induced stimulation of AA release from TEA3A1 cells. Furthermore, the effect of kallikrein was also totally abolished by adding pepstatin A, a known inhibitor of renin, pepsin and cathepsin D which does not inhibit kallikrein itself. This indicates that kallikrein did not act on the phospholipase-like enzyme directly. There is at least one more enzyme, a pepstatin A-inhibitable proteinase, that acts as a mediator for kallikrein-induced regulation of AA release.
| S-EPMC1138368 | biostudies-other
Project description:Timing is a fundamental part of sensory and motor processing. However, little is known about the neural mechanisms underlying timing in the range of tens to hundreds of milliseconds. Although many theoretical hypotheses have been put forth on the possible underpinnings of temporal processing, there is little cellular experimental data, particularly in vitro, as to the neural mechanisms that could potentially function as timers. We use organotypic cortical slices to show that reliably timed action potentials (or excitatory postsynaptic potentials) can be observed up to 300 ms after a single stimulus. There was no relationship between the latency of the late responses and distance from the stimulating electrode. Paired recordings and pharmacological manipulations suggest that the timed late responses are the result of the propagation of activity throughout functionally defined networks. These results show that cortical networks may be intrinsically able to process temporal information.
| S-EPMC153652 | biostudies-literature
Project description:Alarin is a recently discovered member of the galanin peptide family encoded by a splice variant of galanin-like peptide (GALP) mRNA. Galanin and GALP regulate energy homeostasis and reproduction. We therefore investigated the effects of alarin on food intake and gonadotrophin release.Alarin was administered into the third cerebral ventricle (i.c.v.) of rats, and food intake or circulating hormone levels were measured. The effect of alarin on the hypothalamo-pituitary-gonadal axis was investigated in vitro using hypothalamic and anterior pituitary explants, and immortalized cell lines. Receptor binding assays were used to determine whether alarin binds to galanin receptors.The i.c.v. administration of alarin (30?nmol) to ad libitum fed male rats significantly increased acute food intake to 500%, and plasma luteinizing hormone (LH) levels to 170% of responses to saline. In vitro, 100?nM alarin stimulated neuropeptide Y (NPY) and gonadotrophin-releasing hormone (GnRH) release from hypothalamic explants from male rats, and 1000?nM alarin increased GnRH release from GT1-7 cells. In vivo, pretreatment with the GnRH receptor antagonist cetrorelix prevented the increase in plasma LH levels observed following i.c.v. alarin administration. Receptor binding studies confirmed alarin did not bind to any known galanin receptor, or compete with radiolabelled galanin for hypothalamic binding sites.These results suggest alarin is a novel orexigenic peptide, and that it increases circulating LH levels via hypothalamic GnRH. Further work is required to identify the receptor(s) mediating the biological effects of alarin.
| S-EPMC2990158 | biostudies-other
Project description:Background & aimsArachidonic acid (AA) is metabolized by cyclooxygenases and lipoxygenases to pro-inflammatory eicosanoids, which according to experimental research modulate tumor cell proliferation, differentiation, and apoptosis. We employed the Mendelian randomization design to test the hypothesis that higher plasma phospholipid AA concentrations are associated with increased risk of 10 site-specific cancers.MethodsTwo genetic variants associated with plasma phospholipid concentrations of AA (rs174547 in FADS1 [P = 3.0 × 10-971] and rs16966952 in PDXDC1 [P = 2.4 × 10-10]) in the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium were used as genetic instruments. The associations of those variants with cancer were taken from the UK Biobank (n = 367,643), FinnGen consortium (n = 135,638), International Lung Cancer Consortium (n = 27,209), Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome consortium (n = 140,254), Breast Cancer Association Consortium (n = 228,951), Ovarian Cancer Association Consortium (n = 66,450), and BioBank Japan (n = 212,453).ResultsHigher genetically predicted plasma phospholipid AA concentrations were associated with increased risk of colorectal and lung cancer. Results were consistent across data sources and variants. The combined odds ratios per standard deviation increase of AA concentrations were 1.08 (95% CI 1.05-1.11; P = 6.3 × 10-8) for colorectal cancer and 1.07 (95%CI 1.05-1.10; P = 3.5 × 10-7) for lung cancer. Genetically predicted AA concentrations had a suggestive positive association with esophageal cancer (odds ratio 1.09; 95% CI 1.02-1.17; P = 0.016) but were not associated with cancers of the stomach, pancreas, bladder, prostate, breast, uterus, or ovary.ConclusionThese results indicate that AA may be implicated in the development of colorectal and lung cancer and possibly esophageal cancer. Treatments with plasma AA-lowering properties should be evaluated for clinical benefit.
| S-EPMC7612929 | biostudies-literature
Project description:BackgroundBiolistic gene gun transfection has been used to transfect organotypic cultures (OTCs) or dissociated cultures in vitro. Here, we modified this technique to allow successful transfection of acute brain slices, followed by measurement of neuronal activity within a few hours.New methodWe established biolistic transfection of murine acute cortical slices to measure calcium signals. Acute slices are mounted on plasma/thrombin coagulate and transfected with a calcium sensor. Imaging can be performed within 4 h post transfection without affecting cell viability.ResultsFour hours after GCaMP6s transfection, acute slices display remarkable fluorescent protein expression level allowing to study spontaneous activity and receptor pharmacology. While optimal gas pressure (150 psi) and gold particle size used (1 μm) confirm previously published protocols, the amount of 5 μg DNA was found to be optimal for particle coating.Comparison with existing methodsThe major advantage of this technique is the rapid disposition of acute slices for calcium imaging. No transgenic GECI expressing animals or OTC for long periods are required. In acute slices, network interaction and connectivity are preserved. The method allows to obtain physiological readouts within 4 h, before functional tissue modifications might come into effect. Limitations of this technique are random transfection, low expression efficiency when using specific promotors, and preclusion or genetic manipulations that require a prolonged time before physiological changes become measurable, such as expression of recombinant proteins that require transport to distant subcellular localizations.ConclusionThe method is optimal for short-time investigation of calcium signals in acute slices.
| S-EPMC7125026 | biostudies-literature
Project description:Background and purposeThe functional characterization of secreted peptides can provide the basis for the development of novel therapeutic agents. Augurin is a recently identified secreted peptide of unknown function expressed in multiple endocrine tissues, and in regions of the brain including the hypothalamus. We therefore investigated the effect of hypothalamic injection of augurin on the hypothalamo-pituitary-adrenal (HPA) axis in male Wistar rats.Experimental approachAugurin was given as a single injection into the third cerebral ventricle (i.c.v.) or into the paraventricular nucleus (iPVN) of the hypothalamus. Circulating hormone levels were then measured by radioimmunoassay. The effect of augurin on the release of hypothalamic neuropeptides was investigated ex vivo using hypothalamic explants. The acute effects of iPVN augurin on behaviour were also assessed.Key resultsi.c.v. injection of augurin significantly increased plasma ACTH and corticosterone, compared with vehicle-injected controls, but had no effect on other hypothalamo-pituitary axes hormones. Microinjection of lower doses of augurin into the PVN caused a similar increase in plasma ACTH and corticosterone, without significant alteration in behavioural patterns. Incubation of hypothalamic explants with increasing doses of augurin significantly elevated corticotrophin-releasing factor (CRF) and arginine vasopressin release. In vivo, peripheral injection of a CRF(1/2) receptor antagonist prevented the rise in ACTH and corticosterone caused by i.c.v. augurin injection.Conclusions and implicationsThese data suggest that augurin stimulates the release of ACTH via the release of hypothalamic CRF. Pharmacological manipulation of the augurin system may therefore be a novel target for regulation of the HPA axis.
| S-EPMC2925489 | biostudies-literature
Project description:Arachidonic acid (AA) stimulates cell adhesion through a p38 mitogen activated protein kinase-mediated RhoA signaling pathway. Here we report that a proteomic screen following AA-treatment identified nucleolin, a multifunctional nucleolar protein, in a complex with the GTPase, RhoA, that also included the Rho kinase, ROCK. AA-stimulated cell adhesion was inhibited by expression of nucleolin-targeted shRNA and formation of the multiprotein complex was blocked by expression of dominant-negative RhoA. AA-treatment also induced ROCK-dependent serine phosphorylation of nucleolin and translocation of nucleolin from the nucleus to the cytoplasm, where it appeared to co-localize with RhoA. These data suggest the existence of a new signaling pathway through which the location and post-translational state of nucleolin are modulated.
| S-EPMC3089762 | biostudies-literature
Project description:In rabbit proximal tubular cells, ANG II type 2-receptor (AT2)-induced arachidonic acid release is PLA2 coupled and dependent of G protein βγ (Gβγ) subunits. Moreover, ANG II activates ERK1/2 and transactivates EGFR via a c-Src-dependent mechanism. Arachidonic acid has been shown to mimic this effect, at least in part, by an undetermined mechanism. In this study, we determined the effects of ANG II on fibronectin expression in cultured rabbit proximal tubule cells and elucidated the signaling pathways associated with such expression. We found that ANG II and transfection of Gβγ subunits directly increased fibronectin protein expression, and this increase was inhibited by overexpression of β-adrenergic receptor kinase (βARK)-ct or DN-Src. Moreover, ANG II-induced fibronectin protein expression was significantly abrogated by the AT2 receptor antagonist PD123319. In addition, inhibition of cystolic PLA2 diminished ANG II-induced fibronectin expression. Endogenous arachidonic acid mimicked ANG II-induced fibronectin expression. We also found that overexpression of Gβγ subunits induced c-Src, ERK1/2, and EGFR tyrosine phosphorylation, which can be inhibited by overexpression of βARK-ct or DN-Src. Gβγ also induced c-Src SH2 domain association with the EGFR. Supporting these findings, in rabbit proximal tubular epithelium, immunoblot analysis indicated that βγ expression was significant. Interestingly, arachidonic acid- and eicosatetraenoic acid-induced responses were preserved in the presence of βARK-ct. This is the first report demonstrating the regulation of EGFR, ERK1/2, c-Src, and fibronectin by Gβγ subunits in renal epithelial cells. Moreover, this work demonstrates a role for Gβγ heterotrimeric proteins in ANG II, but not arachidonic acid, signaling in renal epithelial cells.
| S-EPMC4121571 | biostudies-literature
Project description:Transient adenosine signaling has been recently discovered in vivo, where the concentration is on average 180 nM and the duration only 3-4 s. In order to rapidly screen different brain regions and mechanisms of formation and regulation, here we develop a rat brain slice model to study adenosine transients. The frequency, concentration, and duration of transient adenosine events were compared in the prefrontal cortex (PFC), hippocampus (CA1), and thalamus. Adenosine transients in the PFC were similar to those in vivo, with a concentration of 160 ± 10 nM, and occurred frequently, averaging one every 50 ± 5 s. In the thalamus, transients were infrequent, occurring every 280 ± 40 s, and lower concentration (110 ± 10 nM), but lasted twice as long as in the PFC. In the hippocampus, adenosine transients were less frequent than those in the PFC, occurring every 79 ± 7 s, but the average concentration (240 ± 20 nM) was significantly higher. Adenosine transients are largely maintained after applying 200 nM tetrodotoxin, implying they are not activity dependent. The response to adenosine A1 antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) differed by region; DPCPX had no significant effects in the PFC, but increased the average transient concentration in the thalamus and both the transient frequency and concentration in the hippocampus. Thus, the amount of adenosine available to activate receptors, and the ability to upregulate adenosine signaling with DPCPX, varies by brain region. This is an important consideration for designing treatments that modulate adenosine in order to cause neuroprotective effects.
| S-EPMC6050173 | biostudies-literature