Oral administration of geranylgeranylacetone plus local somatothermal stimulation: A simple, effective, safe and operable preconditioning combination for conferring tolerance against ischemia-reperfusion injury in rat livers

Effects from the induction of heat shock proteins in a murine model due to progression of aortic atherosclerosis

Heat shock proteins (HSPs) are molecular chaperones that repair denatured proteins. The relationship between HSPs and various diseases has been extensively studied. However, the relationship between HSPs and atherosclerosis remains unclear. In this study, we induced the expression of HSPs and analyzed the effects on the development/progression of atherosclerosis in vivo. Remarkably, when HSPs were induced in apolipoprotein E deficient (ApoE^-/-) mice prior to the formation of atheromas, the progression of atherosclerosis was inhibited; the short-term induction of HSPs significantly decreased the mRNA expression of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) in the aorta. In contrast, the induction of HSPs after the formation of atheromas promoted the progression of atherosclerosis. In fact, the short-term induction of HSPs, after the formation of atheromas, significantly increased the mRNA expression of tumor necrosis factor-alpha, and interleukin 6 in the aorta. Of note, the induction of HSPs also promoted the formation of macrophage-derived foam cells. Overall, these results indicate that HSPs exerts different effects in the context of aortic atherosclerosis, depending on its degree of progression. Therefore, the induction and inhibition of HSPs should be considered for the prevention and treatment of atherosclerosis, respectively.

Geranylgeranyl acetone prevents glutamate-induced cell death in HT-22 cells by increasing mitochondrial membrane potential

Geranylgeranyl acetone (GGA) protects against various types of cell damages by upregulating heat shock proteins. We investigated whether GGA protects neuronal cells from cell death induced by oxidative stress. Glutamate exposure was lethal to HT-22 cells which comprise a neuronal line derived from mouse hippocampus. This configuration is often used as a model for hippocampus neurodegeneration in vitro. In the present study, GGA protected HT-22 cells from glutamate-induced oxidative stress. GGA pretreatment did not induce heat shock proteins (Hsps). Moreover, reactive oxygen species increased to the same extent in both GGA-pretreated and untreated cells exposed to glutamate. In contrast, glutamate exposure and GGA pretreatment increased mitochondrial membrane potential. However, increases in intracellular Ca²⁺ concentration were inhibited by GGA pretreatment. In addition, the increase of phosphorylated ERKs by the glutamate exposure was inhibited by GGA pretreatment. These findings suggest that GGA protects HT-22 cells from glutamate-provoked cell death without Hsp induction and that the mitochondrial calcium buffering capacity plays an important role in this protective effect.

Geranylgeranylacetone attenuates myocardium ischemic/reperfusion injury through HSP70 and Akt/GSK-3β/eNOS pathway

Early reperfusion of myocardial infarction area is the most effective and important therapy to acute myocardial infarction, but could induce reperfusion injury. Geranylgeranylacetone (GGA), an acyclic polyisoprenoid used as an oral anti-ulcer medication, has been reported to have protective effects on reperfusion injury. In the present study, we explored the protective effect of GGA against MIRI and the underlying mechanism. We pretreated rats with four daily GGA, and then observed its effects on heart function parameters following in situ ischemia/reperfusion. GGA exhibited dramatic improvement in cardiac functions, as manifested by increased LVSP and ± (dP/dt) max and decreased LVDP. Oxidative injury and inflammatory response were also relieved by GGA. Western blot showed that the HSP70 protein expression and the Akt/GSK-3β/eNOS pathway were activated. The inhibition of HSP70 and the Akt/GSK-3β/eNOS pathway significantly reversed the protective effects of GGA on MIRI, indicating the involvements of HSP70 and the Akt/GSK-3β/eNOS pathway.

Additional Effects of Back-Shu Electroacupuncture and Moxibustion in Cardioprotection of Rat Ischemia-Reperfusion Injury

Many preclinical studies show that electroacupuncture (EA) on PC6 and ST36 can reduce infarct size after ischemia-reperfusion (IR) injury. Yet studies to enhance the treatment effect size are limited. The purpose of this study was to explore whether EA has additional myocardial protective effects on an ischemia-reperfusion (IR) injury rat model when back-shu EA and moxibustion are added. SD rats were divided into several groups and treated with either EA only, EA + back-shu EA (B), or EA + B + moxibustion (M) for 5 consecutive days. Transthoracic echocardiography and molecular and immunohistochemical evaluations were performed. It was found that although myocardial infarct areas were significantly lower and cardiac function was also significantly preserved in the three treatment groups compared to the placebo group, there were no additional differences between the three treatment groups. In addition, HSP20 and HSP27 were expressed significantly more in the treatment groups. The results suggest that adding several treatments does not necessarily increase protection. Our study corroborates previous findings that more treatment, such as prolonging EA duration or increasing EA intensity, does not always lead to better results. Other methods of increasing treatment effect size should be explored.

Geranylgeranylacetone ameliorates lung ischemia/reperfusion injury by HSP70 and thioredoxin redox system: NF-kB pathway involved

Geranylgeranylacetone (GGA) has been clinically used as an anti-ulcer drug. In the present study, we explored the protective effects of GGA on lung ischemia/reperfusion injury (IRI) and the underlying mechanism. The results demonstrated that GGA ameliorated the lung biochemical and histological alterations induced by IRI, which was reversed by HSP70 inhibition. To further explore the mechanism of GGA action, we focused on NF-kB and thioredoxin (Trx) redox system. It was shown that GGA induced the HSP70 and Trx-1 expression, NF-kB nuclear translocation and activated thioredoxin reductase (TrxR). The Trx-1 expression and TrxR activity was suppressed by HSP70 and NF-kB inhibition, while the nuclear NF-kB p65 expression was suppressed by HSP70 inhibitor. These results indicated that GGA may protect rat lung against IRI by HSP70 and Trx redox system, in which NF-kB pathway may be involved.

Geranylgeranylacetone protects against cerebral ischemia and reperfusion injury: HSP90 and eNOS phosphorylation involved

Cerebral ischemia and reperfusion (I/R) can trigger a cytotoxic cascade with overflow of reactive oxygen species, paradoxically causing neurological dysfunction, redox imbalance, inflammation and apoptosis. The present study aims to investigate the effect of geranylgeranylacetone(GGA) on cerebral I/R injury and the underlying mechanism. The results demonstrated that cerebral I/R increased the neurological function abnormality, brain edema, inflammation and oxidative injury in rats as well as the cognitive impairment, which was significantly reversed by GGA in a dose-dependent manner. GGA also suppressed the cell injury and apoptosis caused by cerebral I/R. Moreover, the protective effect of GGA was found to involve heat shock protein 90 (HSP90) and phosphorylated endothelial nitric oxide synthase (eNOS) expression and activity. Both the HSP90 and eNOS inhibitor abolished the effect of GGA. The data showed that GGA could protect rats against cerebral I/R injury, which may be related to the induction of HSP90 and activation of eNOS.

How does moxibustion possibly work?

“Acupmoxa” is a hybrid word of “acupuncture” and “moxibustion” that more closely resembles the Chinese ideograph for this treatment. People in Western countries are more familiar with acupuncture, while moxibustion is less popular, partially due to the paucity of scientific studies. Although the evidence-based efficacy of moxibustion needs to be further clarified, the mechanisms by which moxibustion may work include temperature-related and nontemperature-related ones. Local somatothermal stimulation (LSTS), one type of moxibustion, is achieved by application of a heat source to and above the acupoint. Such mild heat stimulation of the acupoint induces little skin damage, in contrast to the burning effect of moxibustion, but does provoke mild oxidative stress in the viscera. Thus, preconditioned LSTS at the peripheral acupoints LR 14 and PC 6 of animals is able to induce visceral HSP70 expression and to protect the liver and the heart against ischemia-reperfusion injury. Nontemperature-related mechanisms include smoke, herbs, and biophysical (far infrared) stimulation. We conclude that LSTS, a remote preconditioning method, has potential clinical usefulness. However, evidence-based efficacy and safety studies involving large-scaled clinical trials are needed in order that this approach will pass muster with Western scientists.

Effect of stretching force on the cells of epithelial rests of malassez in vitro

Background and Objective. The aim of this study was to investigate the behavior of cells from epithelial rest of Malassez (ERM) against stretching force. Material and Methods. ERM-cultured cells were stretched for 1 hour, at the cycle of 18% elongation for 1 second followed by 1-second relaxation. The cells without addition of stretching force were used as controls. The cells were observed by immunohistochmical staining using actin 0, 12, 24, 36, 48, and 72 hours. Furthermore, expressions of HSP70-, VEGF-, and OPN-mRNAs of cells were also evaluated using quantitative RT-PCR. Results. Actin filaments were randomly orientated in the cytoplasm in the control group, whereas in the stretching group, actin filaments were orientated comparatively parallel to the stretching direction. Expression of HSP70-mRNA in the stretching group was significantly higher than that of control group at 12, 24, 36 hours (P < .05). Expression of VEGF-mRNA in the stretching group was significantly higher than that of control group at 24, 36, 48, and 72 hours (P < .05). Expression of OPN-mRNA in the stretching group was significantly higher than that of control group at 12 and 24 hours (P < .05). Conclusion. ERM cells response against the stretching force by expressing HSP70, VEGF, and OPN.

Preinduction of HSP70 promotes hypoxic tolerance and facilitates acclimatization to acute hypobaric hypoxia in mouse brain

It has been shown that induction of HSP70 by administration of geranylgeranylacetone (GGA) leads to protection against ischemia/reperfusion injury. The present study was performed to determine the effect of GGA on the survival of mice and on brain damage under acute hypobaric hypoxia. The data showed that the mice injected with GGA survived significantly longer than control animals (survival time of 9.55 +/- 3.12 min, n = 16 vs. controls at 4.28 +/- 4.29 min, n = 15, P < 0.005). Accordingly, the cellular necrosis or degeneration of the hippocampus and the cortex induced by sublethal hypoxia for 6 h could be attenuated by preinjection with GGA, especially in the CA2 and CA3 regions of the hippocampus. In addition, the activity of nitric oxide synthase (NOS) of the hippocampus and the cortex was increased after exposure to sublethal hypoxia for 6 h but could be inhibited by the preinjection of GGA. Furthermore, the expression of HSP70 was significantly increased at 1 h after GGA injection. These results suggest that administration of GGA improved survival rate and prevented acute hypoxic damage to the brain and that the underlying mechanism involved induction of HSP70 and inhibition of NOS activity.

Modified mild heat shock modality attenuates hepatic ischemia/reperfusion injury

BACKGROUND

Hepatic ischemia/reperfusion (I/R) injury is a pathologic process caused by hepatic surgery and transplantation, and still remains a severe clinical problem. It was shown that preconditioning by hyperthermia might protect tissues against I/R injury. But hyperthermia could be laborious and time-consuming. Alternatively, the application of mild electrical stimulation (MES) has been reported to have positive effects in clinical settings on several medical ailments. Thus, we modified the preconditioning approach by combining short-term mild heat shock (HS) and MES, and evaluated the effect of HS+MES pretreatment on hepatic injury induced by I/R.

MATERIALS AND METHODS

C57BL/6J mice were sham treated or treated three times with HS (42 degrees C) and/or MES (12V) for 20min, carried out every other d within 1 wk. After the last treatment, mice were subjected to hepatic ischemia for 30 or 60min and reperfusion for 6h. Liver injury was assessed by evaluating the levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The expressions of pro-inflammatory cytokines and heat shock protein (Hsp) 72 in liver tissues were also assessed by real-time PCR and Western blotting analyses, respectively.

RESULTS

HS+MES pretreatment suppressed the hepatic I/R-induced release of serum AST and ALT and the mRNA levels of some pro-inflammatory cytokines. In addition, HS+MES up-regulated the expression of Hsp72 in mice liver.

CONCLUSIONS

HS+MES preconditioning ameliorated hepatic I/R injury possibly through Hsp72 induction, and suppressed pro-inflammatory cytokine expression in mice liver.

Effects of colon hydrotherapy on liver injury induced by hyperthermia in dogs

AIM: To investigate the effect of colon hydrothe-rapy on the liver injury induced by hyperthermia in dogs.

METHODS: After the dog models of heat stroke were set up, the dogs were randomly divided into two groups, receiving colon hydrotherapy and conventional therapy, respectively. Cooling time as well as serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), malondialdehyde (MDA) and superoxide dismutase (SOD) levels before heat stroke, 6, 24 and 48 h after heat stroke were determined. The dogs were sacrificed 48 h after heat stroke. The contents of liver MDA and SOD were also measured and pathological changes were observed by light and electron microscopy.

RESULTS: In compared with those in conventional therapy group, the cooling time of dogs in colon hydrotherapy group was decreased (t = 5.39, P < 0.01), accompanied with reduced ALT, AST, MDA and elevated SOD at the 24^th (t = 3.46, P < 0.01; t = 3.74, P < 0.01; t = 2.43, P < 0.05; t = 2.44, P < 0.05) and 48^th (t = 3.33, P < 0.01; t = 2.97, P < 0.05; t = 3.32, P < 0.01; t = 4.34, P < 0.01) after heat stroke. The content of liver MDA was decreased (t = 4.08, P < 0.01) while that of SOD was increased (t = 6.52, P < 0.01) in colon hydrotherapy group. The values of LDH were similar between the two groups (P > 0.05). Light microscopy showed that hepatocellular cholestasis, fatty changes and focal necrosis were lessened, accompanied by lessened congestion of sinus hepaticus and decreased inflammatory cells in colon hydrotherapy group. In addition, ultrastructural observation showed that fusion of mitochondrial cristaes and degranulation of rough endoplasmic reticulum were decreased in colon hydrotherapy group.

CONCLUSION: Colon hydrotherapy is a more rapid cooling technique than conventional therapy, and it can promote the decrease of serum enzymes and relieve the hepatic injury induced by lipid peroxidation and pathological lesion.