Exploring the early developmental and epilepsy phenotype in a novel rat model of Alexander’s disease
Abstract number :
3.396
Submission category :
1. Basic Mechanisms / 1E. Models
Year :
2021
Submission ID :
1886496
Source :
www.aesnet.org
Presentation date :
12/6/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:56 AM
Authors :
Florencia Chena-Becerra, BS,PhD - Albert Einstein College of Medicine; Qianyun Li, BS - Saul R. Korey Department of Neurology - Albert Einstein College of Medicine; Wei Liu, BS - Saul R. Korey Department of Neurology - Albert Einstein College of Medicine; Tracy Hagemann, PhD - Waisman Center - University of Wisconsin-Madison; Albee Messing, VMD,PhD - Department of Comparative Biosciences, School of Veterinary Medicine - Unisersity of Wisconsin-Madison; Solomon L Moshé, MD - Saul R. Korey Department of Neurology - Albert Einstein College of Medicine; Aristea S Galanopoulou, MD, PhD - Saul R. Korey Department of Neurology - Albert Einstein College of Medicine
Rationale: Alexander disease (AxD) is a rare form of autosomal dominant leukodystrophy attributed to mutations in the glial fibrillary acidic protein (GFAP) gene (~95% of patients), causing GFAP overexpression and characteristic cytoplasmic aggregates called Rosenthal fibers. The infantile form of AxD encompasses motor and cognitive deficits, macrocephaly, and early onset seizures, including reports of infantile spasms. We have recently developed a rat model of AxD using CRISPR/Cas9 targeted mutagenesis at the Gfap gene (R237H) which is equivalent to the human R239H mutation. In this study, we have investigated whether the rat AxD model manifests epileptic spasms and developmental deficits in motor milestones.
Methods: Offspring of male heterozygous AxD (R237H) and wild type (WT) female Sprague Dawley rats were used. Postnatal day 0 (PN0) corresponded to the first day the litter was found in the cage. Both sexes were studied. Daily body weights and motor milestones were assessed: surface righting time (SRT), open field activity (OFA), negative geotaxis (NG) starting on PN3. Two-hour daily video-monitoring starting on PN4 were evaluated for the presence of spasms. Data collection and analyses were done by individuals blinded to genotype. A different cohort of animals was studied using video electroencephalography (vEEG) starting on PN6. Brains were collected for histology or protein and mRNA analyses on PN5, PN7, PN14 or PN20. Statistics included linear mixed model analyses considering repeated measures and exact test.
Results: A total of 36 AxD (male: 24, female 12) and 33 WT (male:17, female 16) pups were studied for milestones. Weight gain rates between PN15-20 were significantly affected by sex [F(1,17)=11.48, p=0.004] and genotype [F(1,17)=0.002]. AxD rats demonstrated lower body weight gain rates between PN15 and PN20: AxD females 1.44±0.44 (n=5) vs WT females 2.22±0.36 (n=3) gram/day (p=0.036); AxD males 2.18±0.67 (n=8) vs WT males 3.26±0.57 (n=5) gram/day respectively (p=0.015) (Wilcoxon Exact test). There was no significant difference in SRT, OFA or NG. There were no significant differences in spasms counts on PN4: AxD 0.8±1.4 spasms/hr (n=26), WT 0.6 ± 1 spasms/hr (n=22). The vEEG, histological and protein/mRNA analyses are in progress.
Conclusions: Motor milestone development during the first two postnatal weeks appears normal in this rat AxD model, with no evidence of spasms at PN4. The earliest evidence of thriving difficulties appears during the 3rd week of life with slower weight gain rates in both sexes. Ongoing studies aim to fully evaluate the early vEEG findings, histology and protein and mRNA expression during the first 3 postnatal weeks to determine whether vEEG evidence of early epileptic phenotype or specific molecular and histological abnormalities may underlie the early thriving difficulties.
Funding: Please list any funding that was received in support of this abstract.: AES seed grant, NINDS NS RO1 NS091170, U54 NS100064, HD076892, NS110719, NS43409 and HD090256.
Basic Mechanisms