Objective Ginsenoside Rg1 could increase the tolerance of neural hypoxia and ischemia under stress, and play an anti-apoptotic effect in hypoxia ischemia brain damage (HIBD). To investigate the effects of ginsenoside Rg1 on neural apoptosis and recovery of neurological function in neonatal rats with HIBD, and to explore the possible mechanism. Methods Fifty-four 10-day-old SD rats (weighing 16-22 g) were randomly allocated into sham-operation group (Sham group, n=6), HIBD model group (HIBD group, n=24), and ginsenoside Rg1 treatment group (Rg1 group, n=24). SDrats in HIBD group and Rg1 group were made the models of HIBD by l igation of the right common carotid artery (CCA) and subsequently hypoxic ventilation (8%O2 plus 92%N2) for 2.5 hours; and in Sham group, the right CCA was only exposed without l igation of CCA and hypoxic ventilation. Intraperitoneal injection of 0.1 mL normal sal ine (NS) containing 40 mg/kg Rg1 was given immediately after operation in Rg1 group, intraperitoneal injection of 0.1 mL pure NS was given in both HIBD group and Sham group and was repeated every 24 hours. The general state of SD rats was monitored after operation, and Longa scores were recorded to evaluate the neurological function at 4, 8, 24, and 72 hours after HIBD. Western blot and immunohistochemistry staining were used to detect protein expressions of both hypoxia inducible factor 1α (HIF-1α) and cleaved caspase 3 (CC3). TUNEL staining was used to evaluate neural apoptosis in situ. Results All rats survived to the end of the experiment. Neurological dysfunction was observed in both HIBD group and Rg1 group, showing significant difference in Longa score when compared with that in Sham group (P lt; 0.05). There was significant difference in Longa score between Rg1 group and HIBD group at 72 hours after HIBD (P lt; 0.05). Western blot showed that the protein expressions of both HIF-1α and CC3 were observed at every time point in every group. The expressions of HIF-1α protein in HIBD group and Rg1 group were significantly higher than those in Sham group at 4, 8, 24, and 72 hours (P lt; 0.05), and the expressions in Rg1 group were significantly higher than those in HIBD group (P lt; 0.05). The expressions of CC3 protein in HIBD group were significantly higher than those in Sham group at 4, 8, 24, and 72 hours (P lt; 0.05), and significant difference was found between Rg1 group and Sham group only at 4 hours (P lt; 0.05). Immunohistochemistry staining demonstrated that HIF-1α and CC3 protein mainly distributed in nucleusand cytoplasma, the results of HIF-1α and CC3 protein expression were similar to the results by Western blot. TUNEL staining showed that the positive cells were characterized by yellow or brown particle confined within nucleus. The number of apoptotic cells at every time point in HIBD group was significantly higher when compared with that in Sham group (P lt; 0.05), and the number of apoptotic cells in Rg1 group was significantly lower when compared with that in HIBD group at 8, 24, and 72 hours (P lt; 0.05). Conclusion Rg1 could inhibit Caspase 3 activation by strengthening and stabil izing HIF-1α signal pathway, and plays a role of anti-apoptosis in neonatal rats with HIBD.
ObjectiveTo investigate the anti-apoptotic effect of ginsenoside Rg1 in neonatal rats with hypoxia ischemia brain damage (HIBD), and to explore the possible signaling pathway involved in anti-apoptosis. MethodsForty-eight 10-day-old Sprague Dawley (SD) rats (weighing 17-21 g, male or female) were randomly allocated into 4 groups (12 rats in each group): sham-operation group (sham group), HIBD group (HI group), HIBD+ginsenoside Rg1 group (HI+Rg1 group), and HIBD+ginsenoside Rg1+U0126 group (HI+Rg1+U0126 group). SD rats in HI group, HI+Rg1 group, and HI+Rg1+U0126 group underwent ligation of the right common carotid artery (CCA) and hypoxic ventilation (8%O2+92%N2) for 2.5 hours to prepare the HIBD model, and rats in sham group underwent only separation of the right CCA. SD rats in HI+Rg1+U0126 group received intraventricular injection of 5 μL phosphate buffer saline (PBS) containing U0126 (25 μg/kg) at 1 hour before HIBD, and rats in the other three groups received intraventricular injection of PBS at the same time. The rats in HI+Rg1 group and HI+Rg1+U0126 group received intraperitoneal injection of 0.1 mL normal saline (NS) containing Rg1 (40 mg/kg) at immediate after HIBD, while rats in HI group and sham group received intraperitoneal injection of 0.1 mL NS at immediate after HIBD. At 4 and 24 hours after HIBD, the right hemisphere and hippocampus were collected to detect the protein expression and distribution of extracellular signal-related protein kinase 1/2 (Erk1/2), phospho-Erk1/2 (p-Erk1/2), hypoxia inducible factor 1α (HIF-1α), and cleaved Caspase-3 (CC3) by Western blot and immunohistochemistry staining. TUNEL staining was used to evaluate neural apoptosis in situ. ResultsWestern blot results showed that there were expressions of Erk1/2, p-ERK1/2, HIF-1α, and CC3 proteins at 4 and 24 hours after HIBD in each group. The expressions of HIF-1α and CC3 protein at 4 and 24 hours, and expression of p-Erk1/2 protein at 4 hours were significantly increased in HI group when compared with sham group (P < 0.05). When compared with HI group, the expressions of p-Erk1/2 and HIF-1α protein in HI+Rg1 group were significantly increased (P < 0.05), while the expression of CC3 protein was significantly decreased at 4 and 24 hours (P < 0.05). When compared with HI+Rg1 group, the expressions of p-Erk1/2 and HIF-1α proteins in HI+Rg1+U0126 group were significantly decreased (P < 0.05), while expression of CC3 protein was significantly increased at 4 and 24 hours (P < 0.05). There was no significant difference in Erk1/2 protein expression between groups at different time points (P > 0.05). Immunohistochemistry staining displayed that HIF-1α and CC3 proteins mainly distributed in the nucleus and cytoplasma, while Erk1/2 and p-Erk1/2 proteins mainly distributed in the cytoplasma. The expression levels of protein by immunohistochemistry results were similar to the results by Western blot. TUNEL staining showed that the apoptotic neurons were characterized by yellow or brown particle in the nucleus. The apoptotic index (AI) of neurons at 4 and 24 hours was significantly increased in HI group when compared with sham group (P < 0.05), and the AI of neurons was significantly decreased in HI+Rg1 group when compared with HI group and HI+Rg1+U0126 group at 24 hours (P < 0.05). ConclusionRg1 could enhance HIBD induced HIF-1α expression and inhibit activation of Caspase-3 by Erk1/2 signaling pathway, and play an anti-apoptotic role in neonatal rats with HIBD.