Effects of regional body temperature variation during asphyxial cardiac arrest on mortality and brain damage in a rat model

Electroacupuncture reduces microglial pyroptosis via P2X7R/NLRP3 axis in the rat model of asphyxial cardiac arrest and cardiopulmonary resuscitation

Asphyxial cardiac arrest and cardiopulmonary resuscitation (ACA/CPR) can severely damage the brain, but electroacupuncture may help reduce this damage through its anti-inflammatory effects. This study explored whether EA could mitigate microglial pyroptosis via the P2X7R/NLRP3 pathway in a rat ACA/CPR model, given that P2X7R activates the NLRP3 inflammasome, leading to pyroptosis and the release of inflammatory factors. Rats underwent an 8-minute ACA/CPR model, with EA stimulation at Baihui (GV 20), Shuigou (DU 26), and bilateral Neiguan (PC 6) every 12 h for three days. P2X7R was modulated using the inhibitor AZ10606120 and the agonist BzATP. Protein expression changes were analyzed using western blotting, ELISA, flow cytometry, and immunofluorescence. ACA/CPR outcomes assessed included survival rate, neurological deficits, brain injury serum markers, and hippocampal ATP levels. The data indicated that microglia activation and co-localization with P2X7R/GSDMD occurred in the hippocampus of the ACA/CPR model, while EA reduced pyroptosis and P2X7R expression 24 h after the restoration of spontaneous circulation (ROSC). In the primary microglial oxygen and glucose deprivation-reoxygenation (OGD/R) model, P2X7R expression increased and then gradually decreased as reoxygenation time progressed. P2X7R and GSDMD levels were high 6 h post-reoxygenation, but AZ10606120 reduced their expression. BzATP counteracted EA's suppression of P2X7R, NLRP3, caspase-1, cleaved caspase-1, GSDMD-FL, and GSDMD-N. Comparable assessments were conducted within the ACA/CPR + AZ10606120 and ACA/CPR cohorts. Consequently, it was deduced that EA exerts a neuroprotective effect following ACA/CPR by modulating P2X7R expression and suppressing microglial pyroptosis.

Pre-hospital mild therapeutic hypothermia for patients with severe traumatic brain injury

BACKGROUND

We aimed to assess the effects of pre-hospital mild therapeutic hypothermia (MTH) on patients with severe traumatic brain injury (sTBI).

METHODS

Eighty-six patients with sTBI were prospectively enrolled into the pre-hospital MTH group and the late MTH group (initiated in hospital). Patients in the pre-hospital MTH group were maintained at a tympanic temperature of 33°C-35°C before admission and continued to be treated with a therapeutic hypothermia device for 4 days. Patients in the late MTH group were treated with the same MTH parameters. Intracranial pressure (ICP), complications and Glasgow Outcome Scale (GOS) scores were monitored.

RESULTS

ICP was significantly lower for patients in the pre-hospital MTH group 24, 48, and 72 h after treatment (17.38 ± 4.88 mmHg, 18.40 ± 4.50 mmHg, and 16.40 ± 4.13 mmHg, respectively) than that in the late MTH group (20.63 ± 3.00 mmHg, 21.80 ± 6.00 mmHg, and 18.81 ± 4.50 mmHg) (P < .05). The favorable prognosis (GOS scores 4-5) rate in the pre-hospital MTH group was higher tha n the late MTH group (65.1% vs. 37.2%, respectively; P < .05) without complications .

CONCLUSION

Pre-hospital MTH for patients with STBI can reduce ICP and improve neurological outcomes.

Effects of hypothermia on inflammatory cytokine expression in rat liver following asphyxial cardiac arrest

Hypothermic treatment is known to protect against cardiac arrest (CA) and improve survival rate. However, few studies have evaluated the CA-induced liver damage and the effects of hypothermia on this damage. Therefore, the aim of the present study was to determine possible protective effects of hypothermia on the liver after asphyxial CA. Rats were subjected to a 5-min asphyxial CA followed by return of spontaneous circulation (ROSC). The body temperature was controlled at 37±0.5˚C (normothermia group) or 33±0.5˚C (hypothermia group) for 4 h after ROSC. Livers were examined at 6, 12 h, 1 and 2 days after ROSC. Histopathological examination was performed by H&E staining. Alterations in the expression levels of pro-inflammatory (TNF-α and interleukin IL-2) and anti-inflammatory cytokines (IL-4 and IL-13) were investigated by immunohistochemistry. Sinusoidal dilatation and vacuolization were observed after asphyxial CA by histopathological examination. However, these CA-induced structural alterations were prevented by hypothermia. In immunohistochemical examination, the expression levels of pro-inflammatory cytokines were reduced in the hypothermia group compared with those in the normothermia group while the expression levels of anti-inflammatory cytokines were increased in the hypothermia group compared with those in the normothermia group. In conclusion, hypothermic treatment for 4 h following asphyxial CA in rats inhibited the increase of pro-inflammatory cytokines and stimulated the expression of anti-inflammatory cytokines compared with the normothermic group. The results of the present study suggested that hypothermic treatment after asphyxial CA reduced liver damage via the regulation of inflammation.

Repetitive anodal transcranial direct current stimulation improves neurological recovery by preserving the neuroplasticity in an asphyxial rat model of cardiac arrest

BACKGROUND

Non-shockable rhythms present an increasing proportion of out-of-hospital cardiac arrest (CA) patients, but are associated with poor prognosis and received limited therapeutic effect of targeted temperature management (TTM). Previous study showed repetitive anodal transcranial direct current stimulation (tDCS) improved neurological outcomes in animals with ventricular fibrillation. Here, we examine the effectiveness of tDCS on neurological recovery and the potential mechanisms in a rat model of asphyxial CA.

METHOD

Cardiopulmonary resuscitation was initiated after 5 min of untreated asphyxial CA. Animals were randomized to three experimental groups immediately after successful resuscitation (n = 12/group, 6 males): no-treatment control (NTC) group, TTM group, and tDCS group. Post resuscitation hemodynamics, quantitative electroencephalogram (EEG), neurological deficit score, and 96-h survival were evaluated. Brain tissues of additional animals undergoing same experimental procedure was harvested for enzyme-linked immunoassay-based quantification assays of neuroplasticity-related biomarkers and compared with the sham-operated rats (n = 6/group).

RESULTS

We observed that after resuscitation tDCS-treated animals exhibited significantly higher mean arterial pressure and left ventricular ejection fraction than NTC group and showed greatly improved EEG characteristics including weighted-permutation entropy and gamma band power, and neurologic deficit scores and 96-h survival rates compared to NTC and TTM groups. Furthermore, neuroplastic biomarkers including microtubule-associated protein 2, growth-associated protein 43, postsynaptic density protein 95 and synaptophysin, were significantly higher in tDCS group when compared with NTC and TTM groups.

CONCLUSION

In this rat model of asphyxial CA, repetitive anodal tDCS commenced after resuscitation improved neurological recovery, and it may exert a neuroprotective effect by preserving the neuroplasticity.