Mild Hypothermia Alleviates Post-Resuscitation Cerebral Injury in Rats via Modulating the Balance of the Renin–Angiotensin System

Figures

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  Fig. 1. Neurological deficit scores in each group at 24 h post-resuscitation. Both N and H groups showed significantly reduced scores compared to the sham group. The H group exhibited notably higher NDS values than the N group. sham, sham-operated group; N, Normothermia group; H, Mild hypothermia group. *: P < 0.05. Data are presented as mean ± standard deviation. n = 8.

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  Fig. 2. Line chart of body temperature changes and mean arterial pressure changes in CA/CPR rats. A: Line graph depicting body temperature changes for each rat during the surgical procedure. B: Line graph illustrating mean arterial pressure (MAP) variations for each rat throughout the surgery. Each data point represents a recording event, with measurements documented at 10-min intervals during the first hour, followed by 30-min intervals for the subsequent five hours. n = 8.

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  Fig. 3. HE staining of cerebral primary motor cortex M1 area of rats in each group. HE staining of cerebral primary motor cortex M1 area 24 h post-ROSC. In the N group, neurons appeared disordered with evidence of necrosis, nuclear shrinkage and deformation, cellular swelling, and vacuolation. The H group displayed notably improved neuronal morphology compared to the N group, with only occasional necrotic cells observed. Scale bars: 100 μm (10×), 400 μm (40×); HE: Hematoxylin and Eosin staining; sham, sham-operated group; N, normothermia group; H, mild hypothermia group.

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  Fig. 4. AGT expression of brain tissue in each group. A: Representative western blot bands of AGT protein expression. B: Quantitative analysis of AGT western blot results. Both N and H groups exhibited significantly elevated AGT levels compared to the sham group, and the H group showed a more pronounced increase than the N group. *P < 0.05. All experimental data are expressed as mean ± standard deviation. Band intensity values were normalized to β-actin as internal reference. sham, sham-operated group; N, normothermia group; H, mild hypothermia group. n = 6.

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  Fig. 5. Renin expression of brain tissue in each group. A: Representative western blot bands of Renin. B: Quantitative analysis of Renin western blot results. Renin expression in the brain increased significantly after CA/CPR, with a more evident rise observed in the H group. *P < 0.05. All data are expressed as mean ± standard deviation. Band intensity values were normalized to GAPDH as the internal reference. sham, sham-operated group; N, normothermia group; H, mild hypothermia group. n = 6.

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  Fig. 6. Serum Angiotensin II concentrations in each group. Serum Angiotensin II concentrations at 24 h post-ROSC were elevated in both N and H groups compared to the sham group. However, no significant difference was found between the N and H groups. *P < 0.05. sham, sham-operated group; N, normothermia group; H, mild hypothermia treatment group. ns: no significant difference. All data are expressed as mean ± standard deviation. n = 6.

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  Fig. 7. ACE and AT1R expression of brain tissue in each group. A: Representative western blot bands of ACE and AT1R. B–C: Quantitative analysis of ACE and AT1R western blot results. Both N and H groups demonstrated significantly increased ACE expression versus sham, with the H group showing greater elevation. AT1R expression was markedly elevated in the N group but not significantly altered in the H group relative to sham. *P < 0.05. All data are expressed as mean ± standard deviation. Band intensity values were normalized to β-actin. ns, no significant difference; sham, sham-operated group; N, normothermia group; H, mild hypothermia group. n = 6.

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  Fig. 8. Serum Ang (1-7) levels in each group. Serum Ang-(1-7) levels were significantly increased in both N and H groups compared to sham, with a more substantial increase observed in the H group. *P < 0.05. All data are expressed as mean ± standard deviation. sham, sham-operated group; N, normothermia group; H, mild hypothermia treatment group. ns: no significant difference. n = 6.

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  Fig. 9. ACE2 and MasR expression of brain tissue in each group. A: Representative western blot bands of ACE2 and Mas receptor (MasR). B–C: Quantitative analysis of ACE2 and MasR western blot results. ACE2 expression did not differ significantly between N and sham groups, but was significantly higher in the H group. Similarly, MasR levels remained unchanged in the N group but showed a marked increase in the H group. *P < 0.05. All data are expressed as mean ± standard deviation. Band intensity values were normalized to β-actin and β-tubulin. sham, sham-operated group; N, normothermia group; H, mild hypothermia group; ns: no significant difference. n = 6.

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  Supplementary Fig. 1.