Magnetic Resonance Imaging (MRI)-evidence of Blood-brain Barrier (BBB) Impairment in a Rat Model of Organophosphate-induced Status Epilepticus
Abstract number :
3.003
Submission category :
1. Basic Mechanisms / 1A. Epileptogenesis of acquired epilepsies
Year :
2022
Submission ID :
2204192
Source :
www.aesnet.org
Presentation date :
12/5/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:23 AM
Authors :
Pedro Negri Bernardino, DVM – University of California, Davis; Brad Hobson, PhD – Assistant Researcher Scientist, CMGI, UC Davis; Sydney Barker Baker, MS – UC Davis; Peter Andrew, Grad student – UC Davis; Jeremy Macmahon, Grad student – UC Davis; Donald Bruun, PhD – UC Davis; Abhijit Chaudhari, Professor – UC Davis; Pamela Lein, Professor – UC Davis
Rationale: Acute intoxication with organophosphate cholinesterase inhibitors (OPs) can cause a cholinergic toxidrome that includes seizures that rapidly progress to status epilepticus, respiratory failure and death. Individuals who survive often experience chronic cognitive impairment and spontaneous recurring seizures. The current standard of care increases survival, but does not prevent OP-induced epileptogenesis. BBB impairment has been implicated in epilepsy of diverse etiology, but there is little data regarding the effects of acute OP intoxication on BBB integrity.
Methods: Here, we used contrast-enhanced MRI and correlative immunohistochemistry (IHC) to evaluate BBB impairment in a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP). Adult male Sprague-Dawley rats (200-300g) were dosed with 3.75 mg/kg SC, of DFP or vehicle (phosphate-buffered saline), followed immediately by atropine sulfate (2 mg/kg, IM) and 2-pralidoxime (25 mg/kg, IM). At 40 and 50 min post-DFP, animals were treated with midazolam (0.65 mg/kg, IM). Seizure behavior was scored during the initial 4 hours using a modified Racine scale. DFP (n = 6-8 per time point) and vehicle control (n = 4 per time point) animals were evaluated by T1-weighted MRI before and after IV injection of gadolinium (Gd)-contrast at 6 h, or longitudinally at 24, 72, and 168 h post-exposure. IHC was used to detect albumin in the brain parenchyma at the same time points.
Results: After contrast infusion, DFP-intoxicated rats displayed hyperintense lesions indicative of BBB impairment within the hippocampus, thalamus, piriform cortex, amygdala, caudate putamen, and somatosensory cortex. Regional analysis of the percent change from pre-contrast image intensity revealed significant increase in BBB permeability in DFP animals that varied by brain area and time of exposure. Albumin immunoreactivity was observed in the brain parenchyma, presenting a diffuse pattern of immunostaining in the piriform cortex, amygdala, thalamus and hippocampus. The spatiotemporal pattern of albumin immunoreactivity closely resembled that of BBB impairment detected by Gd-enhanced MRI. The levels of albumin leakage were positively correlated with the seizure behavior score.
Conclusions: Our data provide compelling evidence of BBB impairment after acute OP intoxication. These findings support further studies to explore the BBB as a novel therapeutic target for mitigating OP-induced epileptogenesis, and inform the therapeutic window for the use of BBB dysfunction-target therapeutics.
Funding: Supported by the NIH CounterACT program (grant # U53 NS079202)
Basic Mechanisms