G-CSF administration attenuates brain injury in rats following carbon monoxide poisoning via different mechanisms

The effect of preconditioning agents on cardiotoxicity and neurotoxicity of carbon monoxide poisoning in animal studies: a systematic review

BACKGROUND

Carbon monoxide (CO) poisoning is a common intoxication and many people die yearly due to CO poisoning and preconditioning agents attenuate brain and cardiac injury caused by intoxication. It is critical to fully understand the efficacy of new methods to directly target the toxic effect of CO, such as conditioning agents, which are currently under development. This study aims to systematically investigate current evidence from animal experiments and the effects of administration preconditions in acute and late phases after CO poisoning on cardiotoxicity and neurotoxicity.

METHODS

Four databases (PubMed, Embase, Scopus, and Web of Science) were systematically searched without language restrictions, and hand searching was conducted until November 2021. We included studies that compare preconditioning agents with the control group after CO poisoning in animals. The SYRCLE RoB tool was used for risk of bias assessments.

RESULTS

Thirty-seven studies were included in the study. Erythropoietin, granulocyte colony-stimulating factor (GCSF), hydrogen-rich saline, and N-butylphthalide (NBP) were found to have positive effects on reducing neurotoxicity and cardiotoxicity. As other preconditions have fewer studies, no valuable results can be deduced. Most of the studies were unclear for sources of bias.

DISCUSSION

Administration of the examined preconditioning agents including NBP, hydrogen-rich saline, and GCSF in acute and late phases could attenuate neurotoxicity and cardiotoxicity of CO poisoned animals. For a better understanding of mechanisms and activities, and finding new and effective preconditioning agents, further preclinical and clinical studies should be performed to analyze the effects of preconditioning agents.

Umbelliprenin relieves paclitaxel-induced neuropathy

OBJECTIVES

Umbelliprenin (UMB) is a prenylated coumarin that acts as an in vitro antioxidant and inhibits lipoxygenase managing the inflammation pathways, while in vivo it exerts anti-inflammatory activities.

METHODS

In this study, neuropathic pain was induced by four intraperitoneal doses of 2 mg/kg per day of paclitaxel (PTX) on days 1, 3, 5 and 7. Here, 49 male mice were randomly divided in the following groups: sham (not treated animals), negative control (PTX-treated receiving normal saline), single-dose UMB 6.25, 12.5 and 25 mg/kg groups (PTX-treated receiving UMB 6.25, 12.5 and 25 mg/kg, respectively), prevention (PTX-treated receiving PTX along with UMB 12.5 mg/kg on days 1, 3, 5 and 7) and positive control group (PTX-treated receiving imipramine 10 mg/kg as acute treatment). Hot-plate test was done to assess response to heat. Finally, interleukin (IL)-6 levels in the sciatic nerve and lipid peroxidation in sera were assessed.

KEY FINDINGS

Umbelliprenin was found equally effective for acute treatment with imipramine, when comparing the prevention group and the positive control group. Single, 25 mg/kg UMB effectively attenuated hyperalgesia, lipid peroxidation and IL-6 levels.

CONCLUSIONS

Umbelliprenin alleviated neuropathic pain, and decreased serum IL-6 levels and oxidative stress. UMB deserves further investigations, especially in clinical settings.

Neuroprotective effects of low-dose G-CSF plus meloxicam in a rat model of anterior ischemic optic neuropathy

Non-arteritic anterior ischemic optic neuropathy (NAION) causes a sudden loss of vision and lacks effective treatment. Granulocyte colony-stimulating factor (G-CSF) provides neuroprotection against the experimental optic nerve injuries but also induce leukocytosis upon typical administration. We found synergetic neuroprotective effects of meloxicam and low dose G-CSF without leukocytosis in a rat model of anterior ischemic optic neuropathy (rAION). The WBC counts in the low-dose G-CSF-plus meloxicam-treated group were similar to the sham-operated group. Combination treatment of low-dose G-CSF plus meloxicam preserved RGCs survival and visual function, reduced RGC apoptosis and the macrophages infiltration, and promote more M2 phenotype of macrophage/microglial transition than the low-dose GCSF treatment or the meloxicam treatment. Moreover, the combination treatment induced higher serine/threonine kinase 1 (Akt1) expression. The combination treatment of low-dose G-CSF plus meloxicam lessened the leukocytotic side effect and provided neuroprotective effects via Akt1 activation in the rAION model. This approach provides crucial preclinical information for the development of alternative therapy in AION.

Altered regional homogeneity in delayed encephalopathy after carbon monoxide poisoning: A resting-state fMRI study

OBJECTIVE

To investigate alternations in spontaneous brain activities reflected by regional homogeneity (ReHo) in patients with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) using resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

Twenty-one patients with DEACMP and 21 age, sex and education matched healthy controls (HCs) received rs-fMRI scanning and clinical assessment. We used the ReHo method to analyze the interregional synchronized activity of all participants. Two sample t-tests were performed to compare the ReHo maps between the two groups. Pearson correlation analysis was then used to assess the correlations between clinical measures and abnormal ReHo in DEACMP patients.

RESULTS

Compared with HCs, DEACMP patients showed significantly decreased ReHo in bilateral cerebellum posterior lobe, pons, bilateral basal ganglia, while increased in the posterior cingulate, calcarine, bilateral occipital lobe(GRF correction, voxel P value <0.001, cluster P value <0.05). Negative correlation was found between Mini-mental State Examination (MMSE) scores and the ReHo values of posterior cingulate gyrus (r = -0.672, p < 0.05) in the DEACMP group, while positively related to the time from CO poisoning to MRI scan (r = 0.428, p < 0.05).

CONCLUSION

Patients with DEACMP exhibited altered ReHo in the multiple functional brain regions, which provide evidence for local brain dysfunctions and may help to understand the neuropathologic mechanism for the disease.

Activation of the Nrf2/HO-1 signaling pathway contributes to the protective effects of baicalein against oxidative stress-induced DNA damage and apoptosis in HEI193 Schwann cells

Baicalein, a flavonoid extracted from the roots of Scutellaria baicalensis Georgi., has various pharmacological effects due to its high antioxidant activity. However, no study has yet been conducted on the protective efficacy of baicalein against oxidative stress in Schwann cells. In this study, we evaluated the protective effect of baicalein on DNA damage and apoptosis induced by hydrogen peroxide (H₂O₂) in HEI193 Schwann cells. For this purpose, HEI193 cells exposed to H₂O₂ in the presence or absence of baicalein were applied to cell viability assay, immunoblotting, Nrf2-specific small interfering RNA (siRNA) transfection, comet assay, and flow cytometry analyses. Our results showed that baicalein effectively inhibited H₂O₂-induced cytotoxicity and DNA damage associated with the inhibition of reactive oxygen species (ROS) accumulation. Baicalein also weakened H₂O₂-induced mitochondrial dysfunction, increased the Bax/Bcl-2 ratio, activated caspase-9 and -3, and degraded poly(ADP-ribose) polymerase. In addition, baicalein increased not only the expression but also the phosphorylation of nuclear factor-erythroid 2 related factor 2 (Nrf2) and promoted the expression of heme oxygenase-1 (HO-1), a critical target enzyme of Nrf2, although the expression of kelch-like ECH-associated protein-1 was decreased. However, the inhibition of Nrf2 expression by transfection with Nrf2-siRNA transfection abolished the expression of HO-1 and antioxidant potential of baicalein. These results demonstrate that baicalein attenuated H₂O₂-induced apoptosis through the conservation of mitochondrial function while eliminating ROS in HEI193 Schwann cells, and the antioxidant efficacy of baicalein implies at least a Nrf2/HO-1 signaling pathway-dependent mechanism. Therefore, it is suggested that baicalein may have a beneficial effect on the prevention and treatment of peripheral neuropathy induced by oxidative stress.

Magnesium sulfate ameliorates carbon monoxide‑induced cerebral injury in male rats

Carbon monoxide (CO) has been shown to induce several cardiovascular abnormalities, as well as necrosis, apoptosis and oxidative stress in the brain. Magnesium sulfate (MS) has been shown to have beneficial activities against hypoxia in the brain. In the present study, the possible protective effects of MS against CO‑induced cerebral ischemia were investigated. For this purpose, 25 male Wistar rats were exposed to 3,000 ppm CO for 1 h. The animals were divided into 5 groups (n=5 in each group) as follows: The negative control group (not exposed to CO), the positive control group (CO exposed and treated with normal saline), and 3 groups of CO‑exposed rats treated with MS (75, 150 and 300 mg/kg/day) administered intraperitoneally for 5 consecutive days. On the 5th day, the animals were sacrificed and the brains were harvested for the evaluation of necrosis, apoptosis and oxidative stress. Histopathological evaluation revealed that MS reduced the number and intensity of necrotic insults. The Bax/Bcl2 ratio and malondialdehyde (MDA) levels were significantly decreased in a dose‑dependent manner in the MS‑treated rats compared to the positive control group, while a significant dose‑dependent increase in Akt expression, a pro‑survival protein, was observed. In addition, MS administration reduced pro‑apoptotic indice levels, ameliorated histological insults, favorably modulated oxidative status and increased Akt expression levels, indicating a possible neuroprotective effect in the case of CO poisoning. On the whole, the findings of this study indicate that MS may prove to be useful in protecting against CO‑induced cerebral injury.

Cardioprotective effects of insulin on carbon monoxide-induced toxicity in male rats

Carbon monoxide (CO) poisoning is a significant cause of death especially in developing countries. The current study investigated cardioprotective effects of insulin in CO-poisoned rats. Male rats were exposed to 3000 ppm CO for 1 h. Insulin (100 and 120 U/kg intraperitoneally) was immediately administered after CO exposure and on the next 4 days, on a daily basis (a total of 5 doses). On day 5, animals were euthanized, and the hearts were harvested for Western blotting and histopathological studies. The electrocardiograms (ECG) were recorded postexposure to CO and after the completion of insulin treatment period. Histopathological evaluations showed reduction of myocardial necrosis in insulin-treated animals compared to controls. BAX/BCL2 ratio, as a proapoptotic index, was significantly reduced in treatment groups ( p < 0.01). The ECG findings showed no differences among groups; also, compared to control animals, myocardial Akt levels were not markedly affected by insulin. The current study showed that insulin significantly reduces myocardial necrotic and apoptotic indices in CO-poisoned rats.

Magnesium sulfate protects the heart against carbon monoxide-induced cardiotoxicity in rats

Carbon monoxide (CO), a toxic gas produced via incomplete fossil fuel combustion, has several poisonous effects in the heart including induction of necrosis, apoptosis, and electrocardiogram (ECG) changes. Magnesium sulfate (MS) is a drug with cardioprotective effects especially when used after ischemia/reperfusion. In the current study, we aimed to evaluate MS cardioprotective effects following CO poisoning. Animals were exposed to CO 3000 ppm for 1 h and immediately after the exposure period and on the next 4 days (a total of 5 consecutive doses given on a daily basis), MS (75, 150 and 300 mg/kg) was injected intraperitoneally (i.p.) and ECG was recorded focusing on ST-segment, T-wave, and Q-pathologic wave changes. On day 5, animals were sacrificed and their heart was excised for determination of BAX, BCL2 and Akt expression level using western blot analysis and necrosis investigations. The results showed that MS significantly decreased necrosis and BAX/BCL2 ratio (P < 0.001) while pro-survival protein Akt was significantly increased (P < 0.001). Moreover, CO-induced ST-segment depression, T-wave inversion, and atrioventricular block (AV-block) were decreased following treatment with MS. In conclusion, our results showed that MS could decrease cardiac deleterious effects of CO poisoning including necrosis and apoptosis while increased the expression of Akt, as a cell survival protein.

Neuro-Protective Effects of Resveratrol on Carbon Monoxide-Induced Toxicity in Male Rats

Acute carbon monoxide (CO) poisoning causes neurotoxicity through induction of necrosis, apoptosis, lipid peroxidation and oxidative stress. Resveratrol (RES) is a natural polyphenolic phytoalexin that exhibits neuroprotective effects in ischemia/reperfusion due to its anti-apoptotic, anti-necrotic and strong anti-oxidant properties as well as its ability to activate pro-survival pathways. In this study, rats were exposed to CO 3000 ppm for 1 h. Immediately after poisoning and on the next four consecutive days, RES (1, 5 and 10 mg/kg) was administered intraperitoneally. On the fifth day, animals' brains were excised, and necrosis, lipid peroxidation level and the level of Akt, BAX and BCL2 expression were evaluated. The results showed that RES 10 mg/kg significantly reduced lipid peroxidation, but RES 1 and 5 mg/kg had no significant effect on this parameter. Furthermore, RES 5 and 10 mg/kg significantly increased Akt expression level, while BAX/BCL2 ratio was reduced by RES 1, 5 and 10 mg/kg. Moreover, RES reduced necrotic foci in the brain, but the best results were seen following treatment with RES 10 mg/kg. In summary, RES showed neuroprotective effect in CO-poisoned rats as it decreased necrosis and BAX/BCL2 ratio and increased Akt expression levels. Copyright © 2017 John Wiley & Sons, Ltd.