Impact of hyperthermia before and during ischemia reperfusion on neuronal damage and gliosis in the gerbil hippocampus induced by transient cerebral ischemia
Critical Care volume 19, Article number: P463 (2015)
Hyperthermia can exacerbate the brain damage produced by ischemia. In the present study, we investigated effects of hyperthermia before and during ischemia-reperfusion on neuronal damage and glial changes in the gerbil hippocampus following transient cerebral ischemia using cresyl violet staining, NeuN immunohistochemistry and Fluoro-Jade B histofluorescence staining.
The animals were randomly assigned to four groups: sham-operated animals with normothermia (normothermia + sham group); ischemia-operated animals with normothermia (normothermia + ischemia group); sham-operated animals with hyperthermia (hyperthermia + sham group); and ischemia-operated animals with hyperthermia (hyperthermia + ischemia group). Hyperthermia (39.5 ± 0.2°C) was induced by exposing the gerbils to a heating pad connected to a rectal thermistor for 30 minutes before and during ischemia-reperfusion.
In the normothermia + ischemia group, a significant delayed neuronal death was observed in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) 5 days after ischemia-reperfusion. In the hyperthermia + ischemia group, neuronal death in the SP of the CA1 occurred at 1 day post ischemia, and neuronal death was observed in the SP of the CA2/3 region at 2 days post ischemia. In addition, we examined activation of astrocytes and microglia using immunohistochemistry for anti-glial fibrillary acidic protein (GFAP) and anti-ionized calcium-binding adapter molecule 1 (Iba-1). GFAP-positive astrocytes and Iba-1-positive microglia in the ischemic hippocampus were activated much earlier and much more accelerated in the hyperthermia + ischemia group than those in the normothermia + ischemia group.
Based on our findings, we suggest that experimentally hyperthermic precondition before cerebral ischemic insult produces more extensive neuronal damage and glial activation in the ischemic hippocampus.
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Park, C., Cho, J., Ohk, T. et al. Impact of hyperthermia before and during ischemia reperfusion on neuronal damage and gliosis in the gerbil hippocampus induced by transient cerebral ischemia. Crit Care 19 (Suppl 1), P463 (2015). https://doi.org/10.1186/cc14543