Neuroprotection Of Hypothermia Combined With Salvia Miltiorrhiza Bunge On Hypoxic-Ischemic Brain Damage In The Immature Rats

Neonatal hypoxic-ischemia brain damage (HIBD) following perinatal asphyxia is one of the most common diseases, which leads to neonatal death and severly neurologic defect in survivors. Mild hypothermia (28℃-35℃) can inhibit cell metabolism, inactivate enzymes, reduce free radical production and delay neuronal apoptosis. Salvia miltiorrhiza bunge (SMB) can clear out free radicals prevent lipid peroxidation, improve ATPase activities and protect respiratory chain basis function, go through microcirculation , promote blood circulation and immune regulatory effects. In this study , we evaluted the effect of a combined hypothermia and salvia miltiorrhiza bunge by the parameters of maleic dialdehyde and superoxide dismutase and nitric oxide in the 7-day-old rats with HIBD.Objective: Sixty-seven-day-old newborn Sprague-Dawley rats were randomly divided into groups: 1. sham control; 2. HIBD; 3. HIBD and SMB; 4. HIBD and hypothermia; 5. HIBD, hypothermia and SMB (HCS). Each group consisted of 12 rat pups. We randomly chose 2 pups from each group for pathologic examination, and the rest for determination of MDA,SOD and NO. Methods: For preparation of HIBD model, on postnatal day 7, the pups were anesthetized by ether inhalation, then the left common carotid artery was ligated. After surgical procedure, the pups were allowed to recover for 2 hours, then exposed to a gas mixture of 8％ oxygen in 92％ nitrogen for 2 hours. The Sham control group subjected to neither ligation nor hypoxia. Hypothermia: animals were placed in a stable water bath and the temperature can be adjusted according to the hypothermia protocol. SMB treatment: After hypoxia, 10 ml/kg SMB was injected intraperitoneally, then 5 ml/kg per 2 hour, for up to 4 times altogether. Pathologic examination: pups were sacrificed 24 h after hypoxia. The brain was removed out and immersion-fixed in 10％paraformaldehyde, then dehydrated and paraffin embedded. Six coronal sections were stained with hematoxylin and eosin staining. Measurement of MDA,SOD,NO, and tissue proteins Statistical analysis: ANOVA was used for continuous parameters between groups. All the data expressed as ±s. The significant different level was P＜0.05. Results: 1. HE staining: compared with sham operation group, neuronal degeneration, edema and necrosis were found in HI group, the changes occurred less in HI and SMB, least in HCS. 2. Measurement of MDA, SOD, NO: MDA and NO decreased significantly in the hypothermia group and SMB (?), and SOD increased compared with HI (P＜0.01＝; MDA and NO decreased in HCS, SOD increased compared with hypothermia group or SMB (P＜0.05)；there were no significant difference between hypothermia and SMB groups. Conclusion: Both hypothermia and SMB have protective effects on neuron, and their combination in the HCS group has the best neuroprotective effects .