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Title:Spremembe znotrajcelične koncentracije kalcijevih ionov v akutnih tkivnih rezinah trebušne slinavke glodavskih modelov
Authors:ID Pohorec, Viljem (Author)
ID Stožer, Andraž (Mentor) More about this mentor... New window
ID Dolenšek, Jurij (Comentor)
Files:.pdf DOK_Pohorec_Viljem_2022.pdf (3,33 MB)
MD5: 4F78D87D462F3562388ABFA45C759C8D
 
Language:Slovenian
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:MF - Faculty of Medicine
Abstract:Sladkorna bolezen tipa 2 globalno predstavlja vse večji javnozdravstveni problem, številne raziskave pa se posledično osredotočajo na mehanizme normalnega in motenega delovanja Langerhansovih otočkov trebušne slinavke. Laboratorijske miši zaradi strukturnih in funkcionalnih podobnosti Langerhansovih otočkov s človeškimi predstavljajo pomemben model v raziskavah fizioloških procesov trebušne slinavke. Z razvojem genetskih, prehranskih, farmakoloških in kirurških mišjih modelov bolezni pa nudijo tudi vpogled v patofiziološke mehanizme od začetnih sprememb v tarčnih tkivih pri sladkorni bolezni tipa 2 do razvoja adaptacije Langerhansovih otočkov, dekompenzacije in dolgoročnih posledic sladkorne bolezni tipa 2. V zadnjem času postaja vse bolj jasno, da je pri razvoju mišjega modela sladkorne bolezni tipa 2 zelo pomembno genetsko ozadje, oziroma linija in podlinija miši, ki je osnova za model, saj lahko razlika v genetskem ozadju vodi do razlik v fenotipu, ki jih posledično napačno pripišemo učinkom proučevane intervencije raziskave. V doktorskem delu smo zato proučili z glukozo stimulirane spremembe znotrajcelične koncentracije kalcijevih ionov v celicah beta treh pogosto uporabljenih linij in podlinij miši, in sicer pri outbridirani podliniji NMRI in dveh inbridiranih podlinijah C57BL/6J in C57BL/6N. V ta namen smo uporabili metodo akutnih tkivnih rezin trebušne slinavke in fluorescenčno konfokalno mikroskopijo, ki omogoča zajemanje sprememb v kalcijevih signalih, ki nastanejo kot posledica stimulacije z glukozo, v številnih celicah beta sočasno. Tako smo neposredno primerjali vpliv koncentracijske odvisnosti glukoze na kalcijevo signalizacijo v omenjenih treh linijah miši, razlike med posameznimi linijami in variabilnost odzivov, in sicer v fazi aktivacije, kjer smo proučevali zamike od izpostavitve stimulacijski koncentraciji glukoze do odzivov, v fazi platoja, kjer smo proučevali trajanja in frekvence oscilacij kalcijevih ionov ter aktivni čas, in v fazi deaktivacije, kjer smo proučevali zamike od prenehanja izpostavitve stimulacijske koncentracije glukoze do prenehanja kalcijevih odzivov. Ugotovili smo razlike v vseh treh proučevanih fazah odziva kalcijevih ionov na stimulacijo z glukozo, pri čemer velja posebej izpostaviti desnostranski premik krivulje odnosa med odmerkom in odzivom v fazi aktivacije v primeru inbridiranih podlinij in levostranski premik te krivulje v fazi deaktivacije v primeru linije C57BL/6J. V fazi platoja smo opazili kvantitativne in kvalitativne razlike v dinamiki koncentracije kalcijevih ionov, ki so nastale med linijami in tudi znotraj posamezne linije ob stimulaciji z različnimi koncentracijami glukoze. Pomembno pa je poudariti, da se je aktivni čas, to je produkt med frekvenco in trajanjem kalcijevih oscilacij, izkazal za zelo robustno mero, ki narašča z naraščajočo koncentracijo glukoze pri vseh linijah z enako dinamiko. Opažene razlike med inbridiranimi in outbridiranimi linijami kot tudi znotraj obeh genetsko podobnih si inbridiranih podlinij govorijo v prid pomembnosti izbire in ustreznega poročanja genetskega ozadja miši v načrtovanju in pri objavljanju izsledkov raziskav nasploh, za mišje modele sladkorne bolezni tipa 2 pa pričujoče delo predstavlja pomemben referenčni okvir, ki ga doslej v tej obliki v literaturi ni bilo.
Keywords:celice beta, mišji model, slikanje kalcija, glukozna odvisnost, tkivna rezina
Place of publishing:Maribor
Year of publishing:2022
PID:20.500.12556/DKUM-81758 New window
COBISS.SI-ID:130056707 New window
Publication date in DKUM:27.10.2022
Views:826
Downloads:119
Metadata:XML DC-XML DC-RDF
Categories:MF
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Licences

License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:26.05.2022

Secondary language

Language:English
Title:Intracellular calcium dynamics of beta cells in acute pancreas tissue slices of mouse models
Abstract:Type 2 diabetes is a growing public health problem worldwide, and research has focused on the mechanisms of pancreatic islets of Langerhans function and dysfunction. Laboratory mice provide an important model of islets of Langerhans for the study of pancreatic physiology because of their structural and functional similarities to human islets. With the development of genetic, nutritional, pharmacological, and surgical mouse models of the disease, they also provide insights into the pathophysiological mechanisms of initial changes in type 2 diabetes, adaptation and decompensation within the islets of Langerhans, and complications of type 2 diabetes. Recently, it has become increasingly clear that genetic background, or the strain and substrain of mice, is of great importance in the development of a mouse model of type 2 diabetes, as differences in genetic background can lead to differences in phenotype that may then be incorrectly attributed to the effects of the research intervention under investigation. In this dissertation, we therefore examined glucose-stimulated calcium dynamics in beta cells of three commonly used mouse strains and substrains, namely the outbred NMRI substrain and two inbred substrains, C57BL/6J and C57BL/6N. To this end, we used the acute pancreas tissue slice method and confocal fluorescence microscopy, which allows the imaging of calcium changes resulting from glucose stimulation in a number of beta-cells simultaneously. This allowed us to examine the effects of glucose concentration-dependence on calcium signaling in the three strains of mice, the differences among the strains, and the variability of responses during the activation phase, in which we examined the delays from exposure to stimulatory glucose concentration to the responses, the plateau phase, in which the duration and frequency of calcium oscillations and active time were examined, and the deactivation phase, in which delays from cessation of stimulation to cessation of calcium responses were examined. We found differences in all three phases of the calcium ion response to glucose stimulation, most notably, a rightward shift of the dose-response curve in the activation phase in inbred substrains and a leftward shift of this curve in the deactivation phase in C57BL/6J mice. During the plateau phase, we observed quantitative and qualitative differences in calcium dynamics that occurred between groups and also within a group upon stimulation with different glucose concentrations. Importantly, active time, the product of frequency and duration of oscillations, proved to be a robust measure, increasing similarly with increasing glucose concentration in all three strains of mice. The observed differences both between inbred and outbred strains and within the two genetically similar inbred substrains indicate the importance of appropriate selection of genetic background in study design and reporting of mice used in studies in general. Furthermore, in the case of type 2 diabetes mouse models, this work provides an important reference for future studies.
Keywords:beta cell, mouse models, calcium imaging, glucose-dependence, tissue slice


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