Document Type

Honors Thesis




Jennifer Newell-Caito

Committee Members

Edward bernard, Margaret Killinger

Graduation Year

May 2023

Publication Date

Spring 2023


Neurodegeneration is a condition present in Alzheimer’s disease (AD) and Parkinson’s disease (PD) in which the cells of the nervous system experience loss of function and death. Around the world, each year PD and AD affect 6.2 million and 29.8 million people, respectively, with the exact causes remaining unknown. Manganese (Mn) is a transition metal which is essential for human survival in trace concentrations. However, overexposure to Mn can induce neurodegeneration through the accumulation of reactive oxygen species and the eventual onset of oxidative stress. An extract produced from winterberry leaves (Ilex verticillata) exhibits antioxidant properties as it has been shown to protect against Mn-induced oxidative stress in the nematode worm, Caenorhabditis elegans. Due to this observed response in C. elegans, it was hypothesized that the winterberry leaf extract (WLE) could offer protection against neurodegeneration of dopaminergic neurons. To evaluate dopaminergic integrity and its effect on nematode behavior, a wild-type C. elegans strain was treated with several concentrations of WLE and manganese chloride (MnCl2). A motility assay with the wild-type N2 worm strain was anticipated to produce a dose-dependent increase in movement upon treatment with WLE. Mn-exposed worms pre-treated with WLE were expected to also have an increase in movement. In a 1-nonanol dopamine-dependent repulsion assay, worms pre-treated with WLE were predicted to repulse faster from 1-nonanol exposure compared to Mn-treated worms. The expected results of a progeny assay would show that pre-treatment of worms with WLE would increase the percentage of hatched progeny compared to the Mn control. Overall, our hypothesis is that pre-treatment with WLE may offer C. elegans protection against Mn-induced dopaminergic neurodegeneration and merits further exploration as a potential alternative medicine which could be used to treat people affected by neurodegenerative disorders.

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