Examining MMP-9 following early-life seizures in larval zebrafish

Date of Award

7-2023

Degree Type

Thesis

Degree Name

Master of Science in Biomedical Sciences

First Advisor

Jocelyn Lippman-Bell, PhD

Second Advisor

Marina D'Angelo, PhD

Third Advisor

Heather Montie, PhD

Abstract

Early-life seizures (ELS) can lead to the development of chronic conditions that impact an individual’s quality of life. An enzyme that may be involved in these changes is matrix metalloproteinase 9 (MMP-9). Here we examined gene expression, enzyme production and activity, and effects of MMP-9 inhibition following ELS in zebrafish. At five days post-fertilization (dpf), zebrafish were separated into three groups: ELS, Handled Controls (HC), and Unhandled Controls (UC). Seizures were induced in the ELS group by pentylenetetrazol (PTZ) for 40 minutes/day for 3 days. When challenged with PTZ again two weeks later, ELS fish showed significantly increased seizure susceptibility compared to the HC group. To assess molecular changes after ELS that might underlie the increase in seizure susceptibility, qPCR and ELISA were used to examine MMP-9 gene and protein, respectively. Mmp9 gene expression was significantly increased one-hour post-ELS, while expression of its inhibitor, timp2a, remained unchanged. There was no significant increase in protein 1 or 24 hours after ELS. We next tested the effects of blocking MMP-9 activity on seizures. Pretreatment with MMP-9 inhibitor JNJ0966 prevented seizures induction in 7 dpf zebrafish. Further, our preliminary data suggests that JNJ0966 treatment immediately following ELS at 7dpf attenuated the post-ELS increase in seizure susceptibility. Taken together, these data demonstrate that ELS increases seizure susceptibility in larval zebrafish, with similar molecular changes observed in other models. While prior studies have shown that larval zebrafish can have seizures, we are the first to show effects indicative of the onset of epileptogenic changes. Further, these data indicate that MMP9 is involved in the post-ELS changes, and that blocking MMP9 activity may represent a therapeutic pathway to prevent them.

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