Understanding the effect of protocol variations in the zebrafish light/dark transition test

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dc.contributor.advisorSmith, Carineen_ZA
dc.contributor.authorGelderblom, Michelleen_ZA
dc.contributor.otherStellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Dept. of Medicine. Division of Clinical Pharmacology.en_ZA
dc.date.accessioned2023-02-09T10:28:57Zen_ZA
dc.date.accessioned2023-05-18T07:00:27Zen_ZA
dc.date.available2023-02-09T10:28:57Zen_ZA
dc.date.available2023-05-18T07:00:27Zen_ZA
dc.date.issued2023-03en_ZA
dc.descriptionThesis (MSc)--Stellenbosch University, 2023.en_ZA
dc.description.abstractENGLISH ABSTRACT: Anxiety disorders have devastating individual and societal costs, and are a major contributor to years lost to disability worldwide. They appear to be increasing in prevalence, both in South Africa and the world at large. Although there are medications to treat anxiety, there is a need for more treatment options. Anxiety is often not treated effectively due to treatment resistance or non-compliance to medication due to side effects. One of the best options for identifying novel anxiolytics is to use animal models. Zebrafish are useful for screening of potential anxiolytic treatments because they are the most well-studied vertebrate model that shares the size, cost and fecundity benefits of invertebrate models. The light/dark transition test (LDTT) is the most widely used zebrafish larvae behavioural test. It has many applications in pharmacology, particularly in toxicology and screening for potential pharmaceuticals, including treatments for anxiety disorders. It is likely to be one of the first tests used when screening for neuroactivity in zebrafish larvae. During the test, zebrafish larvae are exposed to a period of light followed by an abrupt transition to darkness which produces a hyperlocomotion response that responds to anxiolytics and anxiogenics. The design of the LDTT varies between studies, but it is unclear how common protocol variations affect the comparison of results and contextualisation of data generated using slightly varied protocols. Through both prospective experiments and retrospective data analysis, the effect of age (from 2 dpf to 5 dpf), lighting conditions during rearing (standard or continuous darkness), capture order, repeated light/dark cycles, repeated light/dark transition tests, duration of the light period (1 minute or 10 minutes), light intensity during the light period, and breeding stocks on the response to the light/dark transition test was measured. All experiments consisted of an acclimation period, and at least one cycle consisting of a light period and a dark period. Experiments were recorded using the DanioVision system and activity was measured automatically using the EthoVision XT software. Variations in age, time of day, light period and breeding stock had a significant impact on the response to the light/dark transition test and should therefore be carefully controlled. Light conditions during rearing did not have a statistically significant effect, but more research is needed to confirm that variations in light-rearing do not affect response to the light/dark transition test. Finally, capture order, repeated cycles, repeated light/dark transition tests and light/dark transition intensity did not have a significant effect, suggesting that they can vary according to logistical requirements without affecting results. This opens up the use of repeated measurements that facilitate identifying neuroactivity when the amount of time it will take for the onset of action is unknown. This informs both experimental design, and which studies are comparable. It will also facilitate the use of the light/dark transition test to screen for potential anxiolytics. en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Kostes verwant aan angsversteurings is astronomies vir die individu, maar ook die ekononomiese kostes verwant aan ongeskikteheid, soos mediese kostes en produktiwiteitsverlies in die werkplek. Ons sien steeds ‘n styging in die tendens, nie net in Suid Afrika nie, maar wereld wyd. Medikasie vir die behandeing van angstoestande bestaan, maar behandeling vir angsversteurings is nie altyd bekostigbaar nie en huidige behandelings het dikwels newe effekte. Daar is dus steeds ruimte vir verbetering. Een van die beste opsies om nuwe medikasie te ontwikkel is om na diere modelle te kyk. Die zebravis is veral geskik vir hierdie doeleinde omdat hulle die mees bestudeerde gewerwelde model is en die grootte, koste en vrugbaarheidsvoordele van ongewerwelde modelle ewenaar. Die lig/donker oorgangstoets (LDOT) is een van die mees wydgebruikte toetse om die gedrag van die sebravis larwe te bestudeer. Dit het baie toepassings in farmakologie, veral in toksikologie en die skandering vir potensiële farmakologiese bates vir angsversteurings. Dit is waarskynlik die eerste toets wat gedoen sal word om die neuroaktiwiteit van die sebravis te bepaal. Gedurende die toets word die sebravis larwe aan lig blootgestel vir ‘n periode en dan skielik oorgeskakel na donker, wat ‘n hiperaktiwiteitsreaksie veroorsaak wat deur op angswekkers en kalmeermiddels reageer. Die protokol van die LDOT wissel tussen studies, maar dit is onduidelik hoe algemeen die protokol variasies is en hoe dit die uitslae, of vergelyking van data verkry deur verskillende protokolle, beïnvloed. Prospektiewe eksperimente en retrospektiewe data analise is gebruik om die effek van ouderdom, ligtoestande tydens groei (standaard of deurlopende donker), volgorde van vangs, herhaalde lig/donker siklusse, herhaalde lig/donker veranderings, periode van die lig periode (een of tien minute), die intensiteit van beligting, en die broei kolonie op die LDOT te bepaal. Alle eksperimente het ‘n aanpasperiode en ten minste een siklus van lig en donker ingesluit. Eksperimentele data is vasgevang met die DanioVision sisteem en EthoVIsion XT sagteware. Variasies in ouderdom, tyd van die dag, periode van beligting en teelvoorraad het ‘n merkbare impak gemaak op die resultate van die LDOT en behoort aan streng kontrole onderhewig te wees. Toestande tydens die lig groeiperiode het nie ‘n statisties betekenisvolle effek getoon nie, maar verdere navorsing is nodig om te bevestig dat variasies in die lig tydens groeifases nie ‘n effek op die LDOT reaksie het nie. Ten slotte, die volgorde van vangs van die larva, herhaaldelike siklusse, herhaalde toetsing en die intensiteit van die lig/donker veranderinge het nie ‘n merkwaardig impak gehad op die kwaliteit van die resultate van die LDOT nie. Daarom kan daar verskille werwant aan die logistieke uitleg wees sonder om resultate te beïnvloed. Dit beteken dat verskillende toets formate en herhaaldelike toetsing gebruik kan word om die neuroaktiwiteit te bepaal wanneer ons nie weet wat die spesifieke reaksietyd van medikasie is nie. Dit beïnvloed die eksperimentele formaat en ook watter studies vergelykbaar is. Dit beïnvloed weer die potensiaal vir die gebruik van die LDOT in die soektog na effektiewe opsies vir die behanding van angstoestande.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentix, 76 pages : illustrationsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/127020en_ZA
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshAnxiety disorders -- Animal modelsen_ZA
dc.subject.lcshTranquilizing drugsen_ZA
dc.subject.lcshZebrafish larvaeen_ZA
dc.subject.lcshBehavioral modelen_ZA
dc.titleUnderstanding the effect of protocol variations in the zebrafish light/dark transition testen_ZA
dc.typeThesisen_ZA
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