Hippocampal cellular loss after brief hypotension

Abstract

Abstract Brief episodes of hypotension have been shown to cause acute brain damage inanimal models. We used a rat hemorrhagic shock model to assess functionaloutcome and to measure the relative neuronal damage at 1, 4 and 14 dayspost-injury (3 min of hypotension). All rats underwent a neurological assessmentincluding motor abilities, sensory system evaluation and retrograde memory atpost-hypotensive insult. Brains were harvested and stained for Fluorojade C andNissl. Stereology was used to analyze Fluorojade C and Nissl stained brainsections to quantitatively detect neuronal damage after the hypotensive insult.Statistical analysis was performed using Graphpad Prism 5 with the Bonferronitest at a 95% confidence interval after ANOVA. A Mixed Effect Model was usedfor the passive avoidance evaluation. Stereologically counted fluorojadepositive cells in the hippocampus revealed significant differences in neuronalcell injury between control rats and rats that received 3 min of hypotension oneday after insult. Quantification of Nissl positive neuronal cells showed asignificant decrease in the number hippocampal cells at day 14. No changes infrontal cortical cells were evident at any time, no significative changes inneurological assessments as well. Our observations show that brief periods ofhemorrhage-induced hypotension actually result in neuronal cell damage inSprague–Dawley rats even if the extent of neuronal damage that wasincurred was not significant enough to cause changes in motor or sensorybehavior.