Propofol Pretreatment Research Articles

Propofol Pretreatment Reduces Ceramide Production and Attenuates Intestinal Mucosal Apoptosis Induced by Intestinal Ischemia/Reperfusion in Rats

Apoptosis has been shown to be a major mode of intestinal epithelial cell death caused by intestinal ischemia/reperfusion (II/R), a condition that is associated with increased oxidative stress. Ceramide has been proposed as a messenger of apoptosis. We investigated if pretreatment with propofol, an anesthetic with antioxidant properties, could reduce ceramide production, and consequently, mucosal epithelial apoptosis induced by II/R in rats. Rat II/R injury was produced by clamping the superior mesenteric artery for 1 h followed by 3 h of reperfusion. Thirty rats were randomly allocated into control, injury (II/R) and propofol (pretreatment) groups (n = 10 per group). In the propofol group, propofol 50 mg/kg, a dose that has been shown to cause the loss of reflex responses to a painful stimulus while remaining sensitive to skin incision in rats, was administered intraperitoneally 30 min before inducing intestinal ischemia, while animals in control and untreated injury groups received an equal volume of intralipid. Intestinal mucosal epithelial apoptosis was detected via electron microscopy and TUNEL analysis. Lipid oxidation product malondialdehyde and the activities of superoxide dismutase were assessed by colorimetric analyses. Ceramide generation and sphingomyelinase mRNA expression in intestinal mucosa were determined by high performance thin layer chromatography and reverse transcriptase polymerase chain reaction, respectively. II/R caused intestinal mucosal epithelial apoptosis and over-production of ceramide accompanied by up-regulation of sphingomyelinase mRNA expression and increases in lipid oxidation (all P < 0.01 versus control). Propofol pretreatment significantly attenuated these changes (all P < 0.01, propofol versus injury). The findings indicate that propofol pretreatment attenuates II/R-induced intestinal epithelial apoptosis, which might be attributable to its antioxidant property modulating the ceramide pathway.

Propofol Pretreatment Attenuates Aquaporin-4 Over-Expression and Alleviates Cerebral Edema After Transient Focal Brain Ischemia Reperfusion in Rats

Cerebral edema is a major threat for stroke victims. Most studies have focused on the neuroprotective activities of propofol, addressing infarct volume rather than cerebral edema. Aquaporin-4 (AQP4) plays an important role in maintaining brain water homeostasis under various neurological insults. We explored the effect of propofol pretreatment on cerebral edema in a rat model of brain ischemia reperfusion and assessed the involvement of AQP4. To induce brain ischemia reperfusion, we introduced a silicone-coated monofilament nylon suture into the origin of the middle cerebral artery, withdrawing it after 90 min. Treatment groups (n = 32), received propofol (0.1 mL x kg(-1) x min(-1)) infusion for 30 min before occlusion; the vehicle group (n = 32) and the sham-operated group (n = 28), which received the intralipid vehicle at the same time and rate. To assess cerebral infarct volume, we used 2, 3, 5-triphenyl-tetrazolium chloride staining; wet-dry weight ratio was the basis for cerebral edema estimation, and we used immunohistochemistry and Western blot to detect AQP4 expression. The wet-dry weight ratio decreased from 86.89% +/- 0.71% in the vehicle group (n = 6) to 72.42% +/- 0.74% in the propofol group (n = 6), corresponding to an average decrease of 16%. In parallel and based on immunohistochemical semi-quantification, the propofol group exhibited remarkable attenuation of AQP4 over-expression in the ischemic border zone compared with the vehicle group: 1.28 +/- 0.03 vs 1.40 +/- 0.05, n = 7, respectively; P < 0.05. Values derived from Western blot quantification were similarly decreased in the propofol group compared to the vehicle group: 20.85% +/- 4.18% vs 31.67% +/- 3.23%, n = 4, respectively; P < 0.05. However, infarct volume and neurologic deficit in postischemic rats in the propofol group were not statistically different from values in the vehicle group. We conclude that prestroke treatment with propofol reduces postischemic cerebral edema in rats, possibly through inhibiting AQP4 over-expression in the boundary zone of ischemia.

Propofol pretreatment attenuates LPS-induced granulocyte–macrophage colony-stimulating factor production in cultured hepatocytes by suppressing MAPK/ERK activity and NF-κB translocation

Propofol (PPF), a widely used intravenous anesthetic for induction and maintenance of anesthesia during surgeries, was found to possess suppressive effect on host immunity. This study aimed at investigating whether PPF plays a modulatory role in the lipopolysaccharide (LPS)-induced inflammatory cytokine expression in a cell line of rat hepatocytes. Morphological observation and viability assay showed that PPF exhibits no cytotoxicity at concentrations up to 300 μM after 48 h incubation. Pretreatment with 100 μM PPF for 24 h prior to LPS stimulation was performed to investigate the modulatory effect on LPS-induced inflammatory gene production. The results of semi-quantitative RT-PCR demonstrated that PPF pretreatment significantly suppressed the LPS-induced toll-like receptor (TLR)-4, CD14, tumor necrosis factor (TNF)-α, and granulocyte–macrophage colony-stimulating factor (GM-CSF) gene expression. Western blotting analysis showed that PPF pretreatment potentiated the LPS-induced TLR-4 downregulation. Flow cytometrical analysis revealed that PPF pretreatment showed no modulatory effect on the LPS-upregulated CD14 expression on hepatocytes. In addition, PPF pretreatment attenuated the phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) and IκBα, as well as the nuclear translocation of NF-κB primed by LPS. Moreover, addition of PD98059, a MAPK kinase inhibitor, significantly suppressed the LPS-induced NF-κB nuclear translocation and GM-CSF production, suggesting that the PPF-attenuated GM-CSF production in hepatocytes may be attributed to its suppressive effect on MAPK/ERK signaling pathway. In conclusion, PPF as an anesthetic may clinically benefit those patients who are vulnerable to sepsis by alleviating sepsis-related inflammatory response in livers.

The Inhibitory Effect of Propofol on Splenocytes Proliferations to Lipopolysaccharide in BALB/c Mice: Based on the Measurement of BrdU Incorporationin vitro

Anesthetics have been suspected of impairing various aspects of the immune function either directly by affecting the function of immunocompetent cells or indirectly by modulating the stress response. Splenocytes play important roles in the cellular host defense against infection. In order to assess the immune modulatory effects of propofol, this study examined the cytotoxic and proliferative effects of propofol on splenocytes. Methods: Splenocytes, as responders, were isolated from BALB/c mice (n = 10). The cells were pretreated with different propofol concentrations (0μM, 30μM, 100μM, 300μM) for 24 hours. The cytotoxic effect was assayed by the NADH dehydrogenase activity and the proliferation was evaluated by the level of 5-bromo-2’-deoxyunridine (BrdU) incorporation during DNA synthesis in the presence or absence of propofol, in addition to lipopolysaccharide (LPS, 1 μg/ml) for mitogenic stimulation. A cell proliferation enzyme-linked immuno-sorbent assay (ELISA) system was used, and the stimulation index was calculated in the presence or absence of propofol. Results: The percentage of the NADH dehydrogenase activity was changed by the propofol pretreatment (P ＜ 0.001). LPS stimulation significantly decreased the NADH dehydrogenase activity at 100μM and 300μM compared with the propofol-added or pretreated cells (P ＜ 0.05). The stimulation index to LPS was lower at concentrations of 100μM and 300μM than at 30μM, and proliferative response of splenocytes were completely abrogated by adding toxic concentrations (100μM) of propofol (P ＜ 0.05). Conclusions: Neither cytotoxicity, as defined by the NADH dehydrogenase activity, nor a proliferative effect, as measured by the level of (BrdU) incorporation in the splenocytes, were affected by the clinical concentration of propofol.

Propofol attenuates reperfusion injury after testicular torsion and detorsion

Propofol, which is widely used as an intravenous anesthetic, has been shown to have an antioxidant activity on several tissues. This study was designed to investigate the prevention of reperfusion injury with propofol after testicular torsion. Five groups of rats (seven in each group) were used. Animals in the control group (group I) did not received any treatment, while animals in the sham group (group II) underwent scrotal incision and testicular fixation only. After 2 h of 720 degrees left testicular torsion in groups III, IV and V, subsequent detorsion was done for 2 h in groups IV and V. Propofol (50 mg/kg) was injected transperitoneally 30 min prior to detorsion in group V. Both testicles in all rats were retrieved and tissue malondialdeyhde (MDA) level, which is a measure of the amount of free oxygen radicals, and enzymatic activity of xanthine oxidase (XO), which converts hypoxanthine to xanthine and uric acid were studied. In addition, tissue catalase (CAT) and glutathione peroxidase (GSH-Px) activities, which are endogenous scavenger enzymes, protecting tissues against free radicals, were studied. Additionally, histological evaluations were performed after hematoxylin and eosin staining. Testicular MDA levels, and XO and CAT activities were higher in the torsion group compared to sham control group (P<0.05). Detorsion caused a further increase in MDA levels, contrasting with a decrease in the levels of XO activity, while CAT activity was not changed. Pretreatment with propofol prevented a further increase in MDA levels and significantly decreased CAT activity following detorsion. GSH-Px activities were not effected either by torsion/detorsion or propofol pretreatment. Histologically, torsion caused some separation between germinal cells in the seminiferous tubules, which became much more prominent in the detorsion group and attenuated with propofol pretreatment. There was no significant change in any of the above-mentioned enzymatic activities nor were there histopathological changes in the contralateral testicle in any groups. It is concluded that biochemically and histologically reperfusion injury occurs in the ipsilateral testis following detorsion up to 2 h. Preference of propofol for anaesthesia during the detorsion procedure may attenuate such reperfusion injury.

Effects of propofol on mitochondrial function and intracellular calcium shift in bovine aortic endothelial model.

Hypotension was commonly encountered in clinical practice during induction of anesthesia with propofol. The purpose of this study is to investigate the effect of propofol on mitochondrial membrane potential and morphology so as to infer its relation with intracellular calcium mobilization in bovine aortic endothelium. In this study, we used the cultured bovine aortic endothelial cells (Gm 7372a) to elucidate the impact of propofol upon the membrane potential and morphology of mitochondria in correlation with its effect on intracellular calcium shift. The intracellular calcium mobilization within the cells preincubated with or without propofol was evaluated using a fluorescent spectrophotometer (confocal microscope) after being treated with Fluo-3. The mobilization of intracellular calcium was demonstrated by the appearance of "hot spots" released from intracellular stores after the addition of an ionophore, ionomycin, to the incubation system. The membrane potential of mitochondria was measured by DiOC6 and the morphology of the mitochondria was evaluated by the treatment of TM Ros and compared with that by the treatment of the uncoupler, FCCP, as control. The release of calcium "hot spots" from the intracellular stores (e.g. mitochondria) after the addition of ionomycin was visualized to decrease dramatically within the endothelial cells after preincubation with propofol. The membrane potential of mitochondria was significantly inhibited by pretreatment of propofol at 0.01 mM, 37 degrees C for 30 min. Morphologically, the integrity of mitochondria was distorted and fragmented in the presence of propofol as compared with that of control. Our data showed that propofol in clinical concentration, 0.01 mM, could inhibit intracellular calcium shift from the intracellular stores and decrease the membrane potential and distort the morphology of mitochondria in bovine aortic endothelial cells. These inhibitions of the function and disfiguration of the morphology of mitochondria signify that the clinical hypotension induced by propofol might be of a potential mechanism.

Study of propofol in bovine aortic endothelium: I. Inhibitory effect on bradykinin-induced intracellular calcium immobilization.

Propofol has been found to affect the intracellular calcium concentration with clinical manifestations of hypotension and bradycardia. The purpose of this study is to examine the effect of propofol on intracellular calcium immobilization in bovine aortic endothelium under the stimulation of bradykinin. In order to validate the effect of propofol on the alteration of intracellular calcium concentration, we used the cultured bovine endothelial cells (Gm 7372a) to measure the calcium immobilization within the cells preincubated with or without propofol of clinical concentration. Using Fluo-3 staining and a fluorescence spectrophotometer (confocal microscope), intracellular calcium immobilization was demonstrated by the appearance of "hot spots" within the cytoplasm and perinuclear regions after addition of bradykinin to the cells. The changes of fluorescence density measured within these areas versus the effect of time were analyzed and compared with the cells in control group. After addition of bradykinin, intracellular calcium hot spots increased dramatically within seconds and reached a maximal level within 20 seconds. The concentrations of calcium gradually decreased to a constant level after about 3 min following the addition of bradykinin to the cells. With pretreatment of propofol at 0.01 mM and 37 degrees C for 30 min, the immobilization of intracellular calcium from the intracellular stores were significantly inhibited that was demonstrated by the decreased appearance of hot spots when compared with control. Our data demonstrated that under the stimulation of bradykinin, propofol at 0.01 mM, could inhibit intracellular calcium release from the intracellular stores in bovine aortic endothelial cells. This phenomenon might explain the possible mechanism for the clinical manifestations of hypotension and/or bradycardia associated with propofol.

Effectiveness of propofol pretreatment on the extent of deranged cerebral mitochondrial oxidative enzyme system after incomplete forebrain ischemia/reperfusion in rats.

It has been suggested that propofol has the protective effect on cerebral ischemia-reperfusion injury. The aim of this study is to evaluate the effect of propofol pretreatment on incomplete forebrain ischemia-reperfusion injury in rats. Thirty Sprague-Dawley rats were anesthetized with isoflurane in oxygen and randomly allocated into propofol group (n=13) and saline group (n=17). In propofol group, propofol was pretreated in a step-down scheme before inducing forebrain ischemia by occlusion of both common carotid arteries and arterial hypotension. After ischemia (20 min) and reperfusion (30 min), rats were decapitated. Brain was sliced to obtain coronal slices of 4-12 mm from frontal pole, which were reacted with 2% 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) for 10 min to differentiate the damaged tissues from normal tissues. Median (interquartile range) values of the average percent infarct area were 0.0 (8.6)% and 20.1 (41.2)% in propofol and saline groups, respectively. There was significant difference between the groups. In conclusion, propofol may have a protective effect on incomplete forebrain ischemia-reperfusion injury.

The Effect of Propofol Pretreatment on the Focal Ischemic Injury of Brain in the Rat

The Effect of Propofol Pretreatment on the Focal Ischemic Injury of Brain in the Rat

INFLUENCES OF GABA RECEPTOR SUBTYPES ON NEUROPROTECTIVE ACTION OF PROPOFOL USING MONGOLIAN GERBIL BRAIN ISCHEMIC MODEL

S465 Introduction: It might be possible to explain that the neuroprotective mechanisms of intravenus anesthetics, relate to the potentiation of the gamma-amino butyric acid (GABA) neurons, since barbiturates and benzodiazepines (BZP) bind to the GABAa/BZP receptor complex and stimulate the Cl- influx to the neuronal cells. In the neurochemical studies, the physiological properties of GABA receptor subtypes in the central nervous system (CNS) have been identified. In particular, the different localization between GABAa and GABAb receptors in the neuronal system might be linked to their dissimilar physiological functions appeared in CNS. In this presentation, using the pathopharmacological techniques, we examined the neuroprotective effects of propofol on the brain ischemia of Mongolian gerbil and the functional role of GABA receptor subtypes on the neuroprotective mechanism of propofol. Materials and Methods: The male Mongolian gerbils (body weight; 50-80g) were anesthetized with 1.0% isoflurene and 70% N2O in O2. Each drug was injected intraperitoneal at 15 min before the treatment of ischemia. Under the anesthesia. the brain ischemia was induced by bilateral common carotid artery clamping (2VO) for 4 min. During brain ischemia and recovery from anesthesia, both temperatures of brain and body were kept at 37[degree sign]C by means of heating lamps. One week after ischemia, the ischemic animals were reanesthetized and perfusion-fixed with 4% formaldehyde, and these brains were dissected for the preparations of pathological estimations. The score of pathological estimation detected in the hippocampal CA1 area was divided for five grades depending on the severity. The following drugs were used in this experiment; propofol (25 and 50 mg/kg), muscimol (GABAa agonist; 0.5-4 mg/kg), bicuculline (GABAa antagonist; 5, 7.5 mg/kg), baclofen (GABAb agonist; 2, 4mg/kg) and phaclofen (GABAb antagonist; 1.5, 3mg/kg). Results: 1) One week after brain ischemia induced by a 4 min-2VO, more than 90 % of neuronal cells in CA1 region of hippocampus were injured, and the degenerated cells and vacuolarized cells were appeared in most cases. 2) The pretreatment of propofol significantly attenuated the brain injury induced by 2VO in a dose-dependent manner. The pretreatment of muscimol reduced the number of cell injury and improved the severe conditions in a dose-dependent manner, although this neuroprotection is less potent compared to that of propofol. However it was so hard to detect the significant neuronal protection after the pretreatment of baclofen. 3) The neuroprotecitive effects of propofol was attenuatedby the coadministration of bicuculline, but not phaclofen. Discussion: Our results indicate that propofol and GABAa receptor agonist suppress the severity of brain injury after 2VO, and then GABAa antagonists block these neuronal protections. These results, taken together with others [1,2,3] suggest that delayed neuronal death induced by ischemia may be partially modulated by the inhibition and/or attenuation of GABAa receptor activity and that the pharmacological mechanism of propofol may involve the potentiation of GABAa receptor.

Propofol modulates the effects of chemoconvulsants acting at GABAergic, glycinergic, and glutamate receptor subtypes.

Propofol has been used to treat status epilepticus, but its use in patients with seizure disorders remains controversial, because of concerns that it produces paroxysmal motor phenomenon. Chemoconvulsants act by known discrete mechanisms and neurotransmitters, and therefore, they are useful tools for screening anticonvulsant activity. The main objective of this study was to characterize the effect of propofol pretreatment on convulsions induced by picrotoxin, bicuculline, and strychnine, all which decrease inhibitory neurotransmission, and by N-methyl-D-aspartic acid, kainic acid, and quisqualic acid, which enhance excitatory neurotransmission. Groups of male Swiss Webster mice (n > or = 10/group) were given either vehicle (intralipid, 10 ml.kg-1, control groups) or propofol (50 mg.kg-1, test groups) injected intraperitoneally. Five min after injection, convulsions were induced with either bicuculline (1.36-5.44 nmoles), picrotoxin (0.21-1 nmol), N-methyl-D-aspartic acid (0.51-2 nmol), quisqualic acid (1-10 nmol), kainic acid (0.252-2 mole), or strychnine (1.35-10.78 nmol) injected intracerebroventricularly. The number of animals with convulsions after each dose was recorded. Analysis of statistical significance was based on the log-probit lines of the quantal dose-response for the respective control and test groups, calculated 50% effective doses (ED50), the potency ratios (ED50higher/ED50lower) and their 95% confidence limits. Propofol pretreatment decreased the potency ratio of both bicuculline (0.47, 95% confidence interval = 0.23-0.94) and picrotoxin (0.61, 0.47-0.79), signifying an anticonvulsant effect. Conversely, propofol pretreatment significantly enhanced the convulsive potency of kainic acid (potency ratio and 95% confidence interval = 1.66, 1.21-2.29), quisqualic acid (3.17, 1.98-5.09), and strychnine (1.76, 0.79-3.89). Current results suggest that propofol augments the paroxysmal motor phenomenon induced by kainic acid, quisqualic acid, and strychnine. This action may be, at least partly, responsible for the motor manifestations reported after propofol administration. These in vivo results on modulation of gamma-aminobutyric acid, glycine, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate receptor-mediated transmission may be of significance in understanding the mechanism of propofol action at the excitatory and inhibitory amino acid receptors.