The effect of pre-pubertal exposure to di-(n-butyl) phthalate (dbp) on cell proliferation in adult male Japanese quail (Coturnix corutnix japonica) brains
Date
2018
Authors
Dlamini, Gcwalisile Frances
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Abstract
Neurogenesis is a process that comprises neuronal progenitor cell proliferation, migration differentiation, and integration of young neurons into existing neuronal circuits. Neurogenesis has been observed in avian species, including quail. Neuronal cell proliferation, which is part of adult neurogenesis, was investigated using cellular markers DCX and PCNA, in the hippocampus, mesopallium, nidopallium, medial striatum, medial pre-optic nucleus and ventricles of 14 week old male Japanese quail brains. This was after a 30 day pre-pubertal exposure to the environmental contaminant and endocrine disruptor di(n-butyl) phthalate (DBP), a well-known neuronal development disruptor and neuronal toxicant. Thirty birds were randomly grouped into groups of four (n=4 each) and were intragastrically fed DBP dissolved in corn-oil. The control was fed corn oil only, while three groups were fed 10 mg/bodyweight, 50 mg/bodyweight, 400 mg/bodyweight, effectively dividing them into a low medium and high dose groups. The birds were euthanised using carbon dioxide, brains were harvested and post fixed in a 1:1 mix of ethylene glycol and glycerol (antifreeze) in 0.244M PB (phosphate buffer) and stored at -20 0C. Repeated five series coronal sections of 50 µm were cut in a rostro-caudal direction using a freezing microtome. The 5th series sections were stained with cresyl violet for analysis of brain cytoarchitecture, while 3rd and 4th series sections were stained with DCX and PCNA. Intense staining was observed along the ventricles for both PCNA and DCX, and some PCNA-ir cells were present in the POM. DCX-ir cells were observed in the pallial brain areas of both treated and control groups. Statistically significant differences (p= 0.0001) in counts of DCX-ir between the control and treated groups in the five brain regions were observed, but there were no statistically significant differences (p=0.886) between the brain regions themselves across all dosage groups. DBP treatment affected DCX-ir cell counts in all brain areas under study, irrespective of brain area or dosage. There were significant differences (p=0.0067) of PCNA-ir cell counts between the treated groups and the control for the POM (p=0.0067) and PCNA-ir cell counts between the control and ventricles (p=0.0001). DBP affected cell proliferation in the ventricles and the POM.
Description
A Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand in fulfilment of the requirements for the degree of Master of Science in Medicine, 2018
Keywords
Pre-Pubertal Exposure