Neuroprotective effect of hypothermia at defined intraischemic time courses in cortical cultures

Abstract

Many experimental and clinical studies have shown that hypothermia confers cerebroprotective benefits against ischemic insults. Because of the many conflicting reports on hypothermic neuroprotection, we undertook this cellular study to identify the optimal temperature or a range of temperatures for maximal neuroprotection at different times (6-24 hr) during ischemic insults. Cultured Wistar rat cortical neurons were exposed to oxygen deprivation at defined times and temperatures (37 degrees C normothermia, 32 degrees C mild hypothermia, 27 degrees C moderate hypothermia, 22 degrees C deep hypothermia, and 17 degrees C profound hypothermia). The survival rate of neurons was evaluated by assessing viable neurons on photomicrographs. The normothermic group demonstrated a significantly lower survival rate of cultured neurons (6 hr, 80.3% +/- 2.7%; 12 hr, 56.1% +/- 2.1%; 18 hr, 34.2% +/- 1%; 24 hr, 18.1% +/- 2.2%) compared to hypothermic groups (P < 0.001). The survival rate for the profound hypothermic group was significantly reduced (P < 0.01) compared to other hypothermic groups (at 17 degrees C: 12 hr, 85.9% +/- 2.5%, 18 hr, 74.7% +/- 3.7%, 24 hr, 58.7% +/- 2.7%). Almost equal survival rates were observed among mild, moderate, and deep hypothermic groups following <18 hr exposure to hypoxia, but the deep hypothermic group showed a significantly higher survival rate (84.1% +/- 1.6%; P < 0.001) when subjected to hypoxia for 24 hr. In conclusion, hypothermia offers marked neuroprotection against hypoxia, but attenuation of neuronal cell death was less with profound hypothermia compared to mild, moderate, and deep hypothermia. Deep hypothermia affords maximal protection of neurons compared to mild and moderate hypothermia during long-lasting hypoxia (>18 hr).

Characterization of the transportation of berberine in Coptidis rhizoma extract through rat primary cultured cortical neurons

“…Primary cultures of rat cerebral neurons were prepared from cerebral cortex of 1-day-old newborn rats as described previously (Shibuta et al, 2003;Varathan et al, 2001). Neurons were plated at a density of 5 × 10 5 cells/mL on poly-L-lysineprecoated 24-well plates.…”

The uptake behaviors of kaempferol and quercetin through rat primary cultured cortical neurons

“…Primary cultures of rat cerebral neurons were prepared from cerebral cortex of one-day-old new-born rats as described previously (Shibuta et al, 2003;Varathan et al, 2001). Neurons were plated at a density of 5 × 10 5 cells/mL on poly-L-lysine-precoated 24-well plates.…”

Cultured Neuronal Networks Express Complex Patterns of Activity and Morphological Memory

“…As an example of using network motifs as a tool for monitoring network reaction to stimuli, we conducted several experiments in which hypothermia was applied on the culture. Hypothermia of the brain is commonly used to reduce metabolism for the protection of the brain immediately after trauma, during surgical procedures and in recovery of patients (Sessler, 2001;Varathan et al 2001;McIntyre et al 2003). We studied the effect of hypothermia on network dynamics, by observing the apparent changes in the network activity during and following application of cold (Rubinsky et al 2007;Rubinsky et al, in press).…”