Date of Award

12-2023

Document Type

Honors Thesis

Degree Name

Bachelor of Science

Department

Biological Science

Advisor/Committee Chair

Damian Shin

Committee Member

Pauline Carrico

Abstract

Parkinson’s disease (PD) is a neurodegenerative disorder in which there is a depletion of dopaminergic neurons in the substantia nigra pars compacta (SNc). Symptoms include those that are motor, such as tremors and rigidity, along with symptoms that are nonmotor, such as depression. Depression in Parkinson’s disease is seen in up to 50% of PD patients, and is often treated with traditional antidepressants, with varying levels of efficacy. In this research project, focused ultrasound was used as a non-pharmacological and non-invasive treatment to improve depressive-like behavior in a hemi-Parkinsonian rat model. To induce a hemi-Parkinsonian phenotype in rats, stereotaxic surgeries were performed. The neurotoxin 6-hydroxydopamine was infused in the right medial forebrain bundle, which contains neurons extending from the SNc to the striatum. This resulted in a PD phenotype on the left side, contralateral to the lesion. The limb-use asymmetry test was then used to confirm this phenotype. Focused ultrasound treatments were given to target the celiac plexus, the downstream arm to the vagus nerve. The forced swim test was then used to see if depressive, despair-like behavior improved following focused ultrasound treatment. Brains were then collected via trans-cardiac perfusions for post-mortem tissue analysis with tyrosine hydroxylase staining. Focused ultrasound treatment was not found to alter the contralateral akinesia-like immobility seen in PD rats. Weight decreased for all groups, regardless of focused ultrasound treatment. Based on current data, the efficacy of focused ultrasound as an antidepressant treatment for despair-like behavior in hemi-Parkinsonian rats remains to be seen. Further research with alternative experimental methods is suggested to truly see if focused ultrasound can improve despair-like behavior in hemi-Parkinsonian rats.

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