Astragaloside IV alleviates early brain injury following experimental subarachnoid hemorrhage in rats

Abstract

Astragaloside IV, one of the main effective components isolated from Astragalus membranaceus, has multiple neuroprotective properties, while the effects of astragaloside IV on the attenuation of subarachnoid hemorrhage (SAH)-induced early brain injury (EBI) and its possible mechanisms are unknown. In the present study, we aimed to determine whether astragaloside IV could inhibit oxidative stress, reduce neuronal apoptosis, and improve neurological deficits after experimental SAH in rats. Rats (n=68) were randomly divided into the following groups: Sham group, SAH group, SAH+vehicle group, and SAH+astragaloside IV group. Astragaloside IV or an equal volume of vehicle was administered at 1 h and 6 h after SAH, all the rats were subsequently sacrificed at 24 h after SAH. Mortality, neurological scores, and brain edema were assessed, biochemical tests and histological studies were also performed at that point. SAH induced an increase in the malondialdehyde (MDA) level, neuronal apoptosis, cleaved caspase 3, brain edema and decreased activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Astragaloside IV treatment reversed these changes and improved neurobehavioral outcomes of SAH rats. Our findings suggested that astragaloside IV may alleviate EBI after SAH through antioxidative and anti-apoptotic effects.

Keywords: apoptosis; astragaloside IV; early brain injury; oxidative stress; subarachnoid hemorrhage..

Figure 1

Chemical structure of astragaloside IV.

Figure 2

Experimental design and animal group classification.

Figure 3

(A) Representative photos of rat brains after surgery. The same part of basal cortical brain tissue was taken for tests (circled areas). (B) Mortality was not significantly different among SAH groups (P> 0.05). (C) Summary of SAH grade in different groups (n=17). (D) Neurological score decreased markedly in SAH group (n=17, P< 0.05) and increased after administration of astragaloside IV (n=17, P< 0.05). (E) Brain water content increased significantly after SAH and decreased with astragaloside IV treatment (n=5, P< 0.05). *P< 0.05 compared with sham group; **P< 0.05 compared with SAH+vehicle group.

Figure 4

MDA (A) elevated markedly in SAH and SAH+vehicle groups compared to sham group, and was reversed by astragaloside IV treatment (n=6, P< 0.05). GSH-Px (B) and SOD (C) activities reduced obviously after SAH and increased after astragaloside IV treatment (n=6, P< 0.05). (D) Immunofluorence of cleaved caspase 3. (E,F). Western blot analysis of cleaved caspase 3 in the basal cortex of left hemisphere (n=6, P< 0.05). *P< 0.05 compared with sham group; **P< 0.05 compared with SAH+vehicle group.

Figure 5

(A) Double staining of TUNEL (green) and NeuN (red); nuclei were counterstained with DAPI (blue). TUNEL-positive cells mainly colocalized with neurons. Massive numbers of apoptotic cells were observed in SAH and SAH+vehivle groups; Astragaloside IV inhibited apoptosis significantly compared to SAH groups (n=6). Nissl staining (B) and quantitative analysis (C) showed that neurons were normal with sharp demarcations in the sham group. Damaged neurons were present with deformations and condensation of cytoplasm and nuclei in SAH and SAH+vehicle groups, and this was attenuated by treatment with astragaloside IV (n=6).