Functional Recovery after Scutellarin Treatment in Transient Cerebral Ischemic Rats: A Pilot Study with (18) F-Fluorodeoxyglucose MicroPET

Angelica gigas root ameliorates ischaemic stroke-induced brain injury in mice by activating the PI3K/AKT/mTOR and MAPK pathways

CONTEXT

Traditionally, the root of Angelica gigas Nakai (Umbelliferae), has long been used to treat ischaemic diseases and is considered safe in humans.

OBJECTIVE

To investigate the neuroprotective effects of a methanol extract of A. gigas root (AGmex) on the middle cerebral artery occlusion (MCAO)-induced brain injury in mice, and the underlying mechanisms.

MATERIALS AND METHODS

Two hours of transient MCAO (tMCAO) was induced in C57BL/6 mice (MCAO control group and AGmex groups), AGmex was administered to the AGmex group at 300-3,000 mg/kg bw at 1, 1, and 24 h before tMCAO or at 1000 mg/kg bw at 1 h before and after tMCAO. Infarction volumes, tissue staining, and western blotting were used to investigate the mechanism underlying the neuroprotective effects of AGmex.

RESULTS

The median effective dose (ED₅₀) could not be measured because the AGmex treatment did not reduce the infarction volume caused by 2 h of tMCAO to within 50%; however, pre-treatment with AGmex twice at 1,000 mg/kg bw before tMCAO significantly reduced the infarction volumes. The proteins related to cell growth, differentiation, and death were upregulated by this treatment, and the major recovery mechanisms appeared to involve the attenuation of the mitochondrial function of Bcl-2/Bax and activation of the PI3K/AKT/mTOR and MAPK signalling pathways in ischaemic neurons.

CONCLUSIONS

This study provides evidence supporting the use of A. gigas root against ischaemic stroke and suggests a novel developmental starting point for the treatment of ischaemic stroke.

Panaxatriol saponins promotes angiogenesis and enhances cerebral perfusion after ischemic stroke in rats

Background

Panaxatriol saponins (PTS), an extract from the traditional Chinese herb Panax notoginseng, which has been used to treat ischemic stroke for many years in China. However, the mechanism underlying the effects of PTS remains unclear. This study aimed to determine whether PTS can protect against ischemic brain injury by promoting angiogenesis and to explore the possible mechanism by which it promotes angiogenesis.

Methods

Middle cerebral artery occlusion (MCAO) was induced in rats, and neurological deficit scores and brain infarct volumes were assessed. Micro-Positron emission tomography (PET) was adopted to assess cerebral perfusion, and real-time PCR and western blotting were used to evaluate vascular growth factor and Sonic hedgehog (Shh) pathway component levels. Immunofluorescence staining was used to determine capillary densities in ischemic penumbrae.

Results

We showed that PTS improved neurological function and reduced infarct volumes in MCAO rats. Micro-PET indicated that PTS can significantly increase ¹⁸F-fluorodeoxyglucose (¹⁸F-PDG) uptake by ischemic brain tissue and enhance cerebral perfusion after MCAO surgery. Moreover, PTS was able to increase capillary densities and enhance angiogenesis in ischemic boundary zones and up-regulate vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1) expression by activating the Shh signaling pathway.

Conclusion

These findings indicate that PTS exerts protective effects against cerebral ischemic injury by enhancing angiogenesis and improving microperfusion.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1579-5) contains supplementary material, which is available to authorized users.

Scutellarin as a Potential Therapeutic Agent for Microglia-Mediated Neuroinflammation in Cerebral Ischemia

The cerebral ischemia is one of the most common diseases in the central nervous system that causes progressive disability or even death. In this connection, the inflammatory response mediated by the activated microglia is believed to play a central role in this pathogenesis. In the event of brain injury, activated microglia can clear the cellular debris and invading pathogens, release neurotrophic factors, etc., but in chronic activation microglia may cause neuronal death through the release of excessive inflammatory mediators. Therefore, suppression of microglial over-reaction and microglia-mediated neuroinflammation is deemed to be a therapeutic strategy of choice for cerebral ischemic damage. In the search for potential herbal extracts that are endowed with the property in suppressing the microglial activation and amelioration of neuroinflammation, attention has recently been drawn to scutellarin, a Chinese herbal extract. Here, we review the roles of activated microglia and the effects of scutellarin on activated microglia in pathological conditions especially in ischemic stroke. We have further extended the investigation with special reference to the effects of scutellarin on Notch signaling, one of the several signaling pathways known to be involved in microglial activation. Furthermore, in light of our recent experimental evidence that activated microglia can regulate astrogliosis, an interglial "cross-talk" that was amplified by scutellarin, it is suggested that in designing of a more effective therapeutic strategy for clinical management of cerebral ischemia both glial types should be considered collectively.

Alpha-lipoic acid treatment is neurorestorative and promotes functional recovery after stroke in rats

The antioxidant properties of alpha-lipoic acid (aLA) correlate with its ability to promote neuroproliferation. However, there have been no comprehensive studies examining the neurorestorative effects of aLA administration after the onset of ischemia. The middle cerebral artery (MCA) of adult rats was occluded for 2 hours and then reperfused. aLA (20 mg/kg) was administered in 71 animals (aLA group) through the left external jugular vein immediately after reperfusion. An equivalent volume of vehicle was administered to 71 animals (control group). Functional outcome, levels of endogenous neural precursors with neurogenesis, glial cell activation, and brain metabolism were evaluated. Immediate aLA administration after reperfusion resulted in significantly reduced mortality, infarct size, and neurological deficit score (NDS) in the test group compared to the control group. Long-term functional outcomes, measured by the rotarod test, were markedly improved by aLA treatment. There was a significant increase in the number of cells expressing nestin and GFAP in the boundary zone and infarct core regions after aLA treatment. Furthermore, significantly more BrdU/GFAP, BrdU/DCX, and BrdU/NeuN double-labeled cells were observed along the boundary zone of the aLA group on days 7, 14, and 28 days, respectively. And brain metabolism using ¹⁸F-FDG microPET imaging was markedly improved in aLA group. The effects of aLA was blocked by insulin receptor inhibitor, HNMPA (AM)3. These results indicate that immediate treatment with aLA after ischemic injury may have significant neurorestorative effects mediated at least partially via insulin receptor activation. Thus, aLA may be useful for the treatment of acute ischemic stroke.

In vitro inhibitory effects of scutellarin on six human/rat cytochrome P450 enzymes and P-glycoprotein

Inhibition of cytochrome P450 (CYP) and P-glycoprotein (P-gp) are regarded as the most frequent and clinically important pharmacokinetic causes among the various possible factors for drug-drug interactions. Scutellarin is a flavonoid which is widely used for the treatment of cardiovascular diseases. In this study, the in vitro inhibitory effects of scutellarin on six major human CYPs (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and six rat CYPs (CYP1A2, CYP2C7, CYP2C11, CYP2C79, CYP2D4, and CYP3A2) activities were examined by using liquid chromatography-tandem mass spectrometry. Meanwhile, the inhibitory effects of scutellarin on P-gp activity were examined on a human metastatic malignant melanoma cell line WM-266-4 by calcein-AM fluorometry screening assay. Results demonstrated that scutellarin showed negligible inhibitory effects on the six major CYP isoenzymes in human/rat liver microsomes with almost all of the IC50 values exceeding 100 μM, whereas it showed values of 63.8 μM for CYP2C19 in human liver microsomes, and 63.1 and 85.6 μM for CYP2C7 and CYP2C79 in rat liver microsomes, respectively. Scutellarin also showed weak inhibitory effect on P-gp. In conclusion, this study demonstrates that scutellarin is unlikely to cause any clinically significant herb-drug interactions in humans when co-administered with substrates of the six CYPs (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and P-gp.

PET Demonstrates Functional Recovery after Treatment by Danhong Injection in a Rat Model of Cerebral Ischemic-Reperfusion Injury

This study aimed to investigate neuroprotection of Danhong injection (DHI) in a rat model of cerebral ischemia using ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET). Method. Rats were divided into 5 groups: sham group, ischemia-reperfusion untreated (IRU) group, DHI-1 group (DHI 1 mL/kg/d), DHI-2 group (DHI 2 mL/kg/d), and DHI-4 group (DHI 4 mL/kg/d). AII the treated groups were intraperitoneally injected with DHI daily for 14 days. The therapeutic effects in terms of cerebral infarct volume, neurological function, and cerebral glucose metabolism were evaluated. Expression of TNF-α and IL-1β was detected with enzyme-linked immunosorbent assay (ELISA). Levels of mature neuronal marker (NeuN), glial marker (GFAP), vascular density factor (vWF), and glucose transporter 1 (GLUT1) were assessed by immunohistochemistry. Results. Compared with the IRU group, rats treated with DHI showed dose dependent reductions in cerebral infarct volume and levels of proinflammatory cytokines, improvement of neurological function, and recovery of cerebral glucose metabolism. Meanwhile, the significantly increased numbers of neurons, gliocytes, and vessels and the recovery of glucose utilization were found in the peri-infarct region after DHI treatment using immunohistochemical analysis. Conclusion. This study demonstrated the metabolic recovery after DHI treatment by micro-PET imaging with ¹⁸F-FDG and the neuroprotective effects of DHI in a rat model of cerebral ischemic-reperfusion injury.