magistrsko delo
Ena Sanjković (Author), Marko Kreft (Reviewer), Nina Vardjan (Mentor)

Abstract

Nevroni so električno vzdražne celice, medtem ko so astrociti, podskupina glija celic, električno nevzdražne celice. Astrociti zaznavajo aktivnosti v možganih z receptorji, ki so na plazemski membrani. Z G-proteini sklopljeni receptorji (GPCR) so metabotropni receptorji, ki so izraženi tako na astrocitih kot na nevronih. Podskupina GPCR, značilna za vretenčarje, so adrenergični receptorji, tipa α (α1, α2) in ß (ß1-3), ki se odzivajo v možganih na stresni nevromodulator noradrenalin. V vinski mušici Drosophili melanogaster, in drugih nevretenčarjih, vlogo (nor)adrenergičnega sistema opravlja oktopaminergični/tiraminergični sistem. Signalni molekuli oktopaminergičnega/tiraminergičnega sistema sta monoamina oktopamin in tiramin, ki delujeta preko aktivacije oktopaminskih in/ali oktopamin/tiraminskih receptorjev, kar sproži aktivacijo Ca2+– in cAMP–signalnih poti. Ker vpliv oktopamina na znotrajcelično raven Ca2+ v možganskih celicah vinske mušice še ni popolnoma raziskan, smo želeli ugotoviti, ali se nevroni v možganih vinske mušice odzovejo na draženje z oktopaminom s porastom v znotrajcelični koncentraciji Ca2+, ki je koncentracijsko odvisen, in ali je Ca2+-vzdražnost nevronov v možganih vinske mušice po draženju z oktopaminom drugačna kot v nevrogliji, kot so astrociti. Z uporabo genetsko kodirajočega fluorescenčnega senzorja za Ca2+, jGCaMP7b, in konfokalno mikroskopijo v realnem času smo ugotovili, da se nevroni odzovejo na draženje z oktopaminom s porastom v znotrajcelični koncentraciji Ca2+, ki je koncentracijsko odvisen. Po izračunu polovične efektivne koncentracije (EC50) oktopamina za nevrone, ki je znašala 10 μM, smo dražili astrocite z 10 μM in rezultate primerjali z nevroni. Astrociti so se odzvali na 10 μM oktopamin s porastom znotrajcelične koncentracije Ca2+, vendar je bil porast 9-krat nižji kot v nevronih. Po drugi strani pa je bila EC50 za oktopamin v nevronih 10-krat višja kot v astrocitih, kar nakazuje, da je Ca2+-vzdražnost na oktopaminergični dražljaj v nevronih nižja kot v astrocitih.

Keywords

Drosophila melanogaster;nevroni;astrociti;oktopamin;Ca2+;EC50;konfokalna mikroskopija;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [E. Sanjković]
UDC: 575(043.2)
COBISS: 164359171 Link will open in a new window
Views: 7
Downloads: 1
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Other data

Secondary language: English
Secondary title: Excitability of cells in the brain of the fruit fly Drosophila melanogaster upon octopaminergic activation
Secondary abstract: Neurons are electrically excitable cells, while astrocytes, a subset of neuroglia cells, are electrically non-excitable cells. Astrocytes detect activities in the brain with receptors on the plasma membrane. G-protein coupled receptors (GPCRs) are metabotropic receptors that are expressed on both astrocytes and neurons. A subgroup of GPCRs specific to vertebrates are adrenergic receptors, type α (α1, α2) and ß (ß1-3), which respond in the brain to the stress neuromodulator noradrenaline. In the fruit fly Drosophila melanogaster and other invertebrates, the role of the (nor)adrenergic system is performed by the octopaminergic/tyraminergic system. The signaling molecules of the octopaminergic/tyraminergic system are the monoamines octopamine and tyramine, which act through the activation of octopamine and/or octopamine/tyramine receptors, which triggers the activation of Ca2+ and cAMP signaling pathways. As the effect of octopamine on the intracellular Ca2+ levels in the fruit fly brain cells is not yet fully understood, we wanted to determine whether neurons respond to octopamine stimulation with a concentration-dependent increase in intracellular Ca2+ concentration and whether the Ca2+-excitability of neurons in the fruit fly brain upon octopamine stimulation is different from that of neuroglia, such as astrocytes. Using a genetically encoded fluorescent Ca2+ sensor, jGCaMP7b, and real-time confocal microscopy, we found that neurons respond to octopamine stimulation with a concentration-dependent increase in intracellular Ca2+ concentration. After calculating the half-effective concentration (EC50) of octopamine for neurons, which was 10 μM, we stimulated astrocytes with 10 μM octopamin and compared the Ca2+-response with neurons. Astrocytes responded to 10 μM octopamine with an 9-fold lower increase in intracellular Ca2+ concentration than that in neurons. In contrast, the EC50 for octopamine was 10-fold higher in neurons than astrocytes, suggesting that Ca2+-excitability to the octopaminergic stimulus is lower in neurons than astrocytes.
Secondary keywords: Drosophila melanogaster;neurons;astrocytes;Ca2+;octopamine;EC50;confocal microscopy;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za biologijo, Magistrsko delo magistrskega študijskega programa 2. stopnje Molekulske in funkcionalne biologije
Pages: 1 spletni vir (1 datoteka PDF (XIV, 53 str.)
ID: 19929377