Effects of hypothalamic paraventricular nuclei on apoptosis and proliferation of gastric mucosal cells induced by ischemia/reperfusion in rats

Effects of Electrical Stimulation of the Cell: Wound Healing, Cell Proliferation, Apoptosis, and Signal Transduction

Electrical stimulation of the cell can have a number of different effects depending on the type of cell being stimulated. In general, electrical stimulation can cause the cell to become more active, increase its metabolism, and change its gene expression. For example, if the electrical stimulation is of low intensity and short duration, it may simply cause the cell to depolarize. However, if the electrical stimulation is of high intensity or long duration, it may cause the cell to become hyperpolarized. The electrical stimulation of cells is a process by which an electrical current is applied to cells in order to change their function or behavior. This process can be used to treat various medical conditions and has been shown to be effective in a number of studies. In this perspective, the effects of electrical stimulation on the cell are summarized.

Liquid Metal Enabled Electrobiology: A New Frontier to Tackle Disease Challenges

In this article, a new conceptual biomedical engineering strategy to tackle modern disease challenges, called liquid metal (LM) enabled electrobiology, is proposed. This generalized and simple method is based on the physiological fact that specially administrated electricity induces a series of subsequent desired biological effects, either shortly, transitionally, or permanently. Due to high compliance within biological tissues, LM would help mold a pervasive method for treating physiological or psychological diseases. As highly conductive and non-toxic multifunctional flexible materials, such LMs can generate any requested electric treating fields (ETFields), which can adapt to various sites inside the human body. The basic mechanisms of electrobiology in delivering electricity to the target tissues and then inducing expected outputs for disease treatment are interpreted. The methods for realizing soft and conformable electronics based on LM are illustrated. Furthermore, a group of typical disease challenges are observed to illustrate the basic strategies for performing LM electrobiology therapy, which include but are not limited to: tissue electronics, brain disorder, immunotherapy, neural functional recovery, muscle stimulation, skin rejuvenation, cosmetology and dieting, artificial organs, cardiac pacing, cancer therapy, etc. Some practical issues regarding electrobiology for future disease therapy are discussed. Perspectives in this direction for incubating a simple biomedical tool for health care are pointed out.

Effects of electrical stimulation on cell proliferation and apoptosis

The application of exogenous electrical stimulation (ES) to cells in order to manipulate cell apoptosis and proliferation has been widely investigated as a possible method of treatment in a number of diseases. Alteration of the transmembrane potential of cells via ES can affect various intracellular signaling pathways which are involved in the regulation of cellular function. Controversially, several types of ES have proved to be effective in both inhibiting or inducing apoptosis, as well as increasing proliferation. However, the mechanisms through which ES achieves this remain fairly unclear. The aim of this review was to comprehensively summarize current findings from in vitro and in vivo studies on the effects of different types of ES on cell apoptosis and proliferation, highlighting the possible mechanisms through which ES induced these effects and define the optimum parameters at which ES can be used. Through this we hope to provide a greater insight into how future studies can most effectively use ES at the clinical trial stage.

Glutamate microinjection into the hypothalamic paraventricular nucleus attenuates ulcerative colitis in rats

AIM

To investigate the effects of glutamate microinjection into hypothalamic paraventricular nucleus (PVN) on ulcerative colitis (UC) in rats and to explore the relevant mechanisms.

METHODS

2,4,6-Trinitrobenzenesulfonic acid (100 mg/kg in 50% ethanol) was instilled into the colon of adult male SD rats to induce UC. A colonic damage score (CDS) was used to indicate the severity of the colonic mucosal damage. The pathological changes in the colonic mucosa were evaluated using immunohistochemistry, Western blotting, biochemical analyses or ELISA. Ten minutes before UC induction, drugs were microinjected into the relevant nuclei in rat brain to produce chemical stimulation or chemical lesion.

RESULTS

Microinjection of glutamate (3, 6 and 12 μg) into the PVN dose-dependently decreased the CDS in UC rats. This protective effect was eliminated after kainic acid (0.3 μg) was microinjected into PVN or into the nucleus tractus solitarius (NTS) that caused chemical lesion of these nuclei. This protective effect was also prevented when the AVP-V1 receptor antagonist DPVDAV (200 ng) was microinjected into the NTS. The discharge frequency of the vagus was markedly decreased following microinjection of glutamate into the PVN. Microinjection of glutamate into the PVN in UC rats significantly increased the cell proliferation and anti-oxidant levels, and decreased the apoptosis and Bax and caspase 3 expression levels and reduced the pro-inflammatory factors in the colonic mucosa.

CONCLUSION

The activation of hypothalamic PVN exerts protective effects against UC, which is mediated by the NTS and vagus. The effects may be achieved via anti-oxidative, anti-apoptotic, and anti-inflammatory factors.

Differential expression of Bcl-2 and Bax during gastric ischemia-reperfusion of rats

AIM: To investigate expression of Bcl-2 and Bax in gastric ischemia-reperfusion (GI-R) and involvement of extracellular signal-regulated kinase (ERK) 1/2 activation.

METHODS: The GI-R model was established by ligature of the celiac artery for 30 min and reperfusion in Sprague-Dawley rats. Rats were assigned to groups in accordance with their evaluation period: control, 0, 0.5, 1, 3, 6, 24, 48, and 72 h. Expression and distribution of Bcl-2 and Bax proteins were analyzed by immunohistochemistry and western blotting in gastric tissue samples after sacrifice.

RESULTS: Compared with controls, the percentage of positive cells and protein levels of Bcl-2 decreased in the early phases of reperfusion, reached its minimum at 1 h (P < 0.05); it then increased, reaching its peak at 24 h of reperfusion (P < 0.05). The pattern of Bax expression was opposite to that of Bcl-2. Bax expression increased after reperfusion, with its peak at 1 h of reperfusion (P < 0.05), and then it decreased gradually to a minimum at 24 h after reperfusion (P < 0.05). On the other hand, inhibition of activation of ERK1/2 induced by PD98059, a specific upstream MEK inhibitor, had significant effects on Bcl-2 and Bax in GI-R. Compared with GI-R treatment only at 3 h of reperfusion, PD98059 reduced the number of Bcl-2 positive cells (0.58% of R3h group, P < 0.05) and Bcl-2 protein level (74% of R3h group, P < 0.05) but increased the number of Bax-positive cells (1.33-fold vs R3h group, P < 0.05) and Bax protein level (1.35-fold of R3h group, P < 0.05).

CONCLUSION: These results indicated that the Bcl-2 and Bax played a pivotal role in the gastric mucosal I-R injury and repair by activation of ERK1/2.

Cellular and molecular mechanisms of 17beta-estradiol postconditioning protection against gastric mucosal injury induced by ischemia/reperfusion in rats

AIMS

To investigate the protective effects of 17beta-estradiol postconditioning against ischemia/reperfusion (I-R)-induced gastric mucosal injury in rats.

MAIN METHODS

The animal model of gastric ischemia/reperfusion was established by clamping of the celiac artery for 30 min and reperfusion for 30 min, 1h, 3h, 6h, 12h or 24h. 17beta-estradiol at doses of 5, 50 or 100 microg/kg (rat) was administered via peripheral veins 2 min before reperfusion. In a subgroup of rats, the estrogen receptor antagonist fulvestrant (Ful, 2mg/kg) was intravenously injected prior to 17beta-estradiol administration. Histological and immunohistochemical methods were employed to assess the gastric mucosal injury index and gastric mucosal cell apoptosis and proliferation. The malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, xanthine oxidase (XOD) activity and hydroxyl free radical (-OH) inhibitory ability were determined by colorimetric assays. Subsequently, the expression of Bcl-2 and Bax in rat gastric mucosa was examined by western blotting.

KEY FINDINGS

17beta-estradiol dose-dependently inhibited gastric I-R (GI-R) injury, and 17beta-estradiol (50 microg/kg) markedly attenuated GI-R injury 1h after reperfusion. 17beta-estradiol inhibited gastric mucosal cell apoptosis and promoted gastric mucosal cell proliferation in addition to increasing SOD activity and -OH inhibitory ability and decreasing the MDA content and XOD activity. The Bax protein level increased 1h after GI-R and was markedly reduced by intravenous administration of 17beta-estradiol. In contrast, the level of Bcl-2 protein decreased 1h after GI-R and was restored to normal levels by intravenous administration of 17beta-estradiol. These effects of 17beta-estradiol were inhibited by pretreatment with fulvestrant.

SIGNIFICANCE

17beta-estradiol postconditioning should be investigated further as a possible strategy against gastric mucosal injury.

The role of nuclear factor-kappaB in the effect of angiotensin II in the paraventricular nucleus in protecting the gastric mucosa from ischemia-reperfusion injury in rats

BACKGROUND

The purpose of this study was to elucidate the role of nuclear factor kappaB (NF-kappaB) in the development of gastric ischemia-reperfusion (GI-R) injury and in mediating the effects of angiotensin II (Ang II) in the paraventricular nucleus (PVN) on GI-R injury.

METHODS

GI-R injury was induced in rats by clamping the celiac artery for 30 min and then reperfusing for 1 h. A cannula was inserted into the unilateral PVN for microinjection of Ang II. The expressions and levels of NF-kappaB (p65), IkappaB-alpha, and phosphorylated IkappaB-alpha in rat gastric mucosa were examined by Western blotting and immunohistochemistry. A laser Doppler flowmeter was used to assess gastric blood flow (GBF). Malondialdehyde (MDA) was determined using the thiobarbituric acid (TBA) method, and superoxide dismutase (SOD) activity was determined by the xanthine/xanthine oxidase method.

RESULTS

Microinjection of Ang II (3, 30, and 300 ng) into the PVN dose-dependently inhibited GI-R injury. The levels and expressions of NF-kappaB (p65) and phosphospecific IkappaB-alpha protein increased 1 h after GI-R and were markedly reduced by microinjection of Ang II into the PVN. In contrast, the level and expression of IkappaB-alpha protein decreased 1 h after ischemia-reperfusion and recovered to the normal level by microinjection of Ang II into the PVN. The effects of Ang II were prevented by pretreatment with the Ang II AT1 receptor antagonist losartan (5 microg) microinjected into the lateral cerebral ventricle. Inhibition of NF-kappaB activity by pyrrolidine dithiocarbamate (PDTC, 200 mg/kg) produced similar effects in rats subjected to ischemia-reperfusion with or without microinjection of Ang II into the PVN. Administration of PDTC attenuated gastric mucosal injury and suppressed the activation of NF-kappaB (p65). Ang II microinjection into the PVN increased GBF and decreased the MDA content but did not alter SOD activity in the gastric mucosa following ischemia-reperfusion.

CONCLUSIONS

NF-kappaB plays a role in PVN Ang II-mediated protection against GI-R injury. These central effects of Ang II are mediated by AT1 receptors.

Suppression of inflammatory cytokine production and oxidative stress by CO-releasing molecules-liberated CO in the small intestine of thermally-injured mice

AIM

To determine whether carbon monoxide (CO)-releasing molecules-liberated CO suppress inflammatory cytokine production and oxidative stress in the small intestine of burnt mice.

METHODS

Twenty-eight mice were assigned to 4 groups. The mice in the sham group (n=7) underwent sham thermal injury, whereas the mice in the burn group (n=7) received 15% total body surface area full-thickness thermal injury, the mice in the burn+CO-releasing molecules (CORM)-2 group (n=7) underwent the same injury with immediate administration of CORM-2 (8 mg/kg, i.v.), and the mice in the burn+inactivated CORM (iCORM)-2 group (n=7) underwent the same injury with immediate administration of iCORM-2. The levels of inflammatory cytokines in the tissue homogenates were measured by ELISA. The levels of malondialdehyde (MDA), nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) in the small intestine were also assessed. In the in vitro experiment, Caco-2 cells were stimulated by experimental mouse sera (50%, v/v) for 4 h. Subsequently, the levels of interleukin (IL)-8 and NO in the supernatants were assessed. Reactive oxygen species (ROS) generation in Caco-2 cells was also measured.

RESULTS

The treatment of burnt mice with CORM-2 significantly attenuated the levels of IL-1beta, TNF-alpha, MDA, and NO in tissue homogenates. This was accompanied by a decrease of iNOS expression. In parallel, the levels of IL-8, NO, and intracellular ROS generation in the supernatants of Caco-2 stimulated by the CORM-2-treated burnt mouse sera was markedly decreased.

CONCLUSION

CORM-released CO attenuates the production of inflammatory cytokines, prevents burn-induced ROS generation, and suppresses the oxidative stress in the small intestine of burnt mice by interfering with the protein expression of iNOS.

Carbon liberated from CO-releasing molecules attenuates leukocyte infiltration in the small intestine of thermally injured mice

AIM

To determine whether Carbon (CO) liberated from CO-releasing molecules attenuates leukocyte infiltration in the small intestine of thermally injured mice.

METHODS

Thirty-six mice were assigned to four groups. Mice in the sham group (n = 9) were underwent to sham thermal injury; mice in the burn group (n = 9) received 15% total body surface area full-thickness thermal injury; mice in the burn + CORM-2 group (n = 9) were underwent to the same thermal injury with immediate administration of tricarbonyldichlororuthenium (II) dimer CORM-2 (8 mg/kg, i.v.); and mice in the burn+DMSO group (n = 9) were underwent to the same thermal injury with immediate administration of 160 muL bolus injection of 0.5% DMSO/saline. Histological alterations and granulocyte infiltration of the small intestine were assessed. Polymorphonuclear neutrophil (PMN) accumulation (myeloperoxidase assay) was assessed in mice mid-ileum. Activation of nuclear factor (NF)-kappa B, expression levels of intercellular adhesion molecule-1 (ICAM-1) and inducible heme oxygenase in mid-ileum were assessed.

RESULTS

Treatment of thermally injured mice with CORM-2 attenuated PMN accumulation and prevented activation of NF-kappa B in the small intestine. This was accompanied by a decrease in the expression of ICAM-1. In parallel, burn-induced granulocyte infiltration in mid-ileum was markedly decreased in the burn mice treated with CORM-2.

CONCLUSION

CORM-released CO attenuates leukocyte infiltration in the small intestine of thermally injured mice by interfering with NF-kappa B activation and protein expression of ICAM-1, and therefore suppressing the pro-adhesive phenotype of endothelial cells.

Carbon liberated from CO-releasing molecules attenuates leukocyte infiltration in the small intestine of thermally injured mice

AIM: To determine whether Carbon (CO) liberated from CO-releasing molecules attenuates leukocyte infiltration in the small intestine of thermally injured mice.

METHODS: Thirty-six mice were assigned to four groups. Mice in the sham group (n = 9) were underwent to sham thermal injury; mice in the burn group (n = 9) received 15% total body surface area full-thickness thermal injury; mice in the burn + CORM-2 group (n = 9) were underwent to the same thermal injury with immediate administration of tricarbonyldichlororuthenium (II) dimer CORM-2 (8 mg/kg, i.v.); and mice in the burn+DMSO group (n = 9) were underwent to the same thermal injury with immediate administration of 160 μL bolus injection of 0.5% DMSO/saline. Histological alterations and granulocyte infiltration of the small intestine were assessed. Polymorphonuclear neutrophil (PMN) accumulation (myeloperoxidase assay) was assessed in mice mid-ileum. Activation of nuclear factor (NF)-κΒ, expression levels of intercellular adhesion molecule-1 (ICAM-1) and inducible heme oxygenase in mid-ileum were assessed.

RESULTS: Treatment of thermally injured mice with CORM-2 attenuated PMN accumulation and prevented activation of NF-κΒ in the small intestine. This was accompanied by a decrease in the expression of ICAM-1. In parallel, burn-induced granulocyte infiltration in mid-ileum was markedly decreased in the burn mice treated with CORM-2.

CONCLUSION: CORM-released CO attenuates leukocyte infiltration in the small intestine of thermally injured mice by interfering with NF-κΒ activation and protein expression of ICAM-1, and therefore suppressing the pro-adhesive phenotype of endothelial cells.