Different Responses to Identical Trauma Between BALB/C and C57BL/6 Mice.

BACKGROUND Different responses to identical trauma may be related to the genetic background of individuals, but the molecular mechanism is unclear. In this study we investigated the heterogeneity of trauma in mice and the potential biological explanations for the differences. MATERIAL AND METHODS Compared with other organs, the pathological response of the lung after injury is the earliest and most serious. We used C57BL/6 and BALB/C mice to explore the genetic background of different responses to trauma in the lung. We measured mortality rate, pulmonary microvascular permeability, and Cxcl15 gene expression in BALB/C and C57BL/6 mice before and after blast-wave injury. Microvascular permeability was measured using a fluorescent tracer, and Cxcl15 gene expression level and expression distribution were measured using fluorogenic probe quantitative polymerase chain reaction and northern blot. RESULTS C57BL/6 mice showed lower mortality rates and pulmonary microvascular permeability than BALB/C mice after blast-wave injury; there was no significant difference in the permeability before blast-wave injury. The Cxcl15 gene was expressed specifically in the lung tissue of mice. The level of Cxcl15 expression in BALB/C mice was higher than in C57BL/6 mice before and after injury, and the variation trend of Cxcl15 expression level after injury was significantly different between BALB/C and C57BL/6 mice. CONCLUSIONS Our results indicated that BALB/C and C57BL/6 mice had significant heterogeneity in posttraumatic response in terms of mortality and degree of lung damage. The differences in genetic factors such as Cxcl15 may have played a role in this heterogeneity.

Changes in phenolic compounds of Phyllanthus emblica juice during different storage temperature and pH conditions.

The aim of this experiment was to investigate the effect of storage temperature and pH on phenolic compounds of Phyllanthus emblica juice. Juice was stored at different temperatures and pH for 15 days and sampled on 2-day intervals. The browning index (BI, ABS420 nm), pH, centrifugal precipitation rate (CPR), and phenolic compounds were evaluated. The results showed 4°C and pH 2.5 could effectively inhibit browning and slow down pH drop of P. emblica juice. The result of orthogonal partial least square-discriminant analysis showed P. emblica juice stored at 4°C and pH 2.5 still had a similar phenolic composition, but at 20°C, 37°C, and pH 3.5, the score plots were concentrated only in the first 3 days. Additionally, gallic acid (GA) and ellagic acid (EA) were screened out to be the differential compounds for browning of P. emblica juice. The contents of GA, epigallocatechin (EGC), corilagin (CL), gallocatechin gallate (GCG), chebulagic acid (CA), 1,2,3,4,6-O-galloyl-d-glucose (PGG), and EA were more stable at 4°C and pH 2.5. Overall, during storage at 4°C and pH 2.5, it could inhibit the increase of GA and EA and decrease of CL, GCG, CA, and PGG, whereas EGC did not show significant difference between storage conditions. The CPR was higher at 4°C, while pH 2.5 could reduce the CPR. In conclusion, in order to maintain stability of phenolic compounds and extended storage period, the P. emblica juice could be stored at low temperature and adjust the pH to increase the stability of juice system.

Local glutamate level dictates adenosine A2A receptor regulation of neuroinflammation and traumatic brain injury.

During brain injury, extracellular adenosine and glutamate levels increase rapidly and dramatically. We hypothesized that local glutamate levels in the brain dictates the adenosine-adenosine A(2A) receptor (A(2A)R) effects on neuroinflammation and brain damage outcome. Here, we showed that, in the presence of low concentrations of glutamate, the A(2A)R agonist 3-[4-[2-[[6-amino-9-[(2R,3R,4S,5S)-5-(ethylcarbamoyl)-3,4-dihydroxy-oxolan-2-yl]purin-2-yl]amino]ethyl]phenyl]propanoic acid (CGS21680) inhibited lipopolysaccharide (LPS)-induced nitric oxide synthase (NOS) activity of cultured microglial cells, an effect that was dependent on the protein kinase A (PKA) pathway. However, in high concentrations of glutamate, CGS21680 increased LPS-induced NOS activity in a protein kinase C (PKC)-dependent manner. Thus, increasing the local level of glutamate redirects A(2A)R signaling from the PKA to the PKC pathway, resulting in a switch in A(2A)R effects from antiinflammatory to proinflammatory. In a cortical impact model of traumatic brain injury (TBI) in mice, brain water contents, behavioral deficits, and expression of tumor necrosis factor-alpha, interleukin-1 mRNAs, and inducible NOS were attenuated by administering CGS21680 at post-TBI time when brain glutamate levels were low, or by administering the A(2A)R antagonist ZM241385 [4-(2-{[5-amino-2-(2-furyl)[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-yl]amino}ethyl)phenol] at post-TBI time when brain glutamate levels were elevated. Furthermore, pre-TBI treatment with the glutamate release inhibitor (S)-4C3HPG [(S)-4-carboxy-3-hydroxyphenylglycine] converted the debilitating effect of CGS21680 administered at post-TBI time with high glutamate level to a neuroprotective effect. This further indicates that the switch in the effect of A(2A)R activation in intact animals from antiinflammatory to proinflammatory is dependent on glutamate concentration. These findings identify a novel role for glutamate in modulation of neuroinflammation and brain injury via the adenosine-A(2A)R system.

Discovery and SAR of para-alkylthiophenoxyacetic acids as potent and selective PPARdelta agonists.

Synthesis and SAR of para-alkylthiophenoxyacetic acids is described. Achiral compounds 30, 31 and 32 were identified as potent and selective PPARdelta agonists.

Synthesis and SAR study of novel pseudo-steroids as potent and selective progesterone receptor antagonists.

Synthesis of novel 7-pseudo-steroids 1c has been achieved from trenbolone 3 via an efficient 14 step sequence with overall yields of 10-15%. Various substitutions were incorporated at both the aromatic side chain as well as the D ring. The orientation of aromatic side chain at C10 plays a crucial role for progesterone receptor (PR) activity. Compound 2a (T47D=1nM) with -NMe(2) para to the aromatic group along with spirofurane groups in the D ring was the optimal substitution. All compounds were also evaluated for glucocorticoid receptor (GR) antagonist activities in vivo in a rat and found efficacious in uterine complement C3 assay via the oral route of administrations.

Sustained vascular endothelial growth factor blockade by antivascular endothelial growth factor antibodies results in nonunion in the process of fracture healing in rabbits.

OBJECTIVE: To study the role of vascular endothelial growth factor (VEGF) in the process of fracture healing and the effect of VEGF and anti-VEGF polyclonal antibody on fracture healing. METHODS: One hundred and five New Zealand white rabbits were subjected to fracture of the middle part of the left radius, and were randomly divided into control, VEGF, and VEGF polyclonal antibody groups. The blood flow at the fracture site was measured by single photoemission computerized tomography after 8 hours, 24 hours, and 72 hours, and 1 weeks, 3 weeks, 5 weeks, and 8 weeks. X-ray films were taken after 1 weeks, 3 weeks, 5 weeks, and 8 weeks to observe the results of fracture healing. RESULTS: The blood flow at the fracture site in the VEGF group significantly increased compared with the control group during 8 hours to 1 week, but no obvious difference was seen on the X-ray films between the two groups. In the VEGF polyclonal antibody group, the blood flow at the fracture sites decreased significantly at all time points compared with the control group. The fracture healing process was disturbed, and nonunion signs were seen at the fracture site. CONCLUSIONS: The lack of VEGF may impede the fracture healing process, and results in nonunion at the fracture site.

Identification of interleukin-6 promoter polymorphisms in the Chinese Han population and their functional significance.

OBJECTIVE: Interleukin-6 (IL-6) is a pivotal cytokine in both innate and adaptive immunity. Several polymorphisms in the IL-6 promoter have been reported in Western populations. However, little is known about their occurrence in the Chinese population. The functionality of IL-6 promoter polymorphisms remains controversial. DESIGN: Genetic, functional, and association studies. SETTING: National key laboratory of trauma and departments of traumatic surgery in two teaching hospitals. SUBJECTS: A total of 348 healthy blood donors and 105 patients with major trauma. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Identification of polymorphisms in the IL-6 promoter was performed using sequencing and restriction fragment length polymorphism methods. Their functionality was assessed by observation of transcription activity, IL-6 production, and their clinical relevance in 105 patients with major trauma. Only one variant (C-572G) was identified in IL-6 promoter in Chinese Han population. This polymorphism was associated with IL-6 production by peripheral leukocytes in response to ex vivo lipopolysaccharide stimulation in an allele-dose-dependent effect. The C-->G variation at position -572 could reduce transcriptional activity of the IL-6 promoter as shown in both U-937 and K562 cell lines. Moreover, the -572 polymorphism was associated with lower risk of sepsis in major trauma patients. CONCLUSIONS: The -572 polymorphism, a unique variation in the IL-6 promoter in the Chinese Han population, may be used as a relevant risk estimate for sepsis in trauma patients.

Synthesis and structure-activity relationships of thiadiazole-derivatives as potent and orally active peroxisome proliferator-activated receptors alpha/delta dual agonists.

Replacement of the methyl-thiazole moiety of GW501516 (a PPARdelta selective agonist) with [1,2,4]thiadiazole gave compound 21 which unexpectedly displayed submicromolar potency as a partial agonist at PPARalpha in addition to the high potency at PPARdelta. A structure-activity relationships study of 21 resulted in the identification of 40 as a potent and selective PPARalpha/delta dual agonist. Compound 40 and its close analogs represent a new series of PPARalpha/delta dual agonists. The high potency, high selectivity, significant gene induction, excellent PK profiles, low P450 inhibition or induction, and good in vivo efficacy in four animal models support 40 being selected as a pre-clinical study candidate, and may render 40 as a valuable pharmacological tool in elucidating the complex roles of PPARalpha/delta dual agonists, and the potential usage for the treatment of metabolic syndrome.

Expressions of scavenger receptor, CD14 and protective mechanisms of carboxymethyl-beta-1, 3-glucan in posttraumatic endotoxemia in mice.

BACKGROUND: Previous studies in our laboratory have demonstrated the downregulation of surface expression of scavenger receptor (SR) and upregulation of CD14 in the presence of endotoxemia, which directly correlates to the excessive inflammatory response in lung injuries. This study aims to analyze the dynamics of the expressions of SR and CD14 in traumatic endotoxemia, and to investigate the receptor mechanism of immunomodulator, carboxymethyl-beta-1, 3-glucan (CMG), on the protection of traumatic infections. METHODS: By using a sublethal fracture plus endotoxemia model, experimental mice were assigned to sham group (Sham), trauma group (T), traumatic endotoxemia group (TE), and traumatic endotoxemia plus CMG group (TE + C). Alveolar macrophages were isolated from each group. Expressions of SR and CD14 were examined at the cell and tissue levels by immunohistochemistry assay. The effects of CMG on the phagocytosis of alveolar macrophages, tissue injury, and mortality were also determined. RESULTS: Expressions of SR and CD14 in lungs and livers decreased and increased, respectively. Alteration of SR and CD14 levels was more evident in lungs than in livers in posttraumatic endotoxemia. CMG up-regulated the SR expression in lipopolysaccharide-stimulated alveolar macrophages, alleviated the tissue injury, reduced mice mortality, and increased the opsonin-independent phagocytosis of Staphylococcus aureus, which was inhibited by SR mono-antibody. CONCLUSION: Significant correlation was found between inflammatory responses and the imbalance between SR and CD14 in posttraumatic endotoxemia. The more dramatic changes in lungs might be related to the sequential preferred injury in uncontrolled inflammation. CMG could be a promising bioactive reagent in immunomodulating sepsis.

[Different effects of adenosine A2A receptors in the models of traumatic brain injury and peripheral tissue injury].

Recently, activation of the adenosine A2A receptors has been shown to exert protection against peripheral tissue injuries but aggravation in the central nervous system (CNS) injuries. To explore the different effects of adenosine A2A receptors and try to perform some new treatment strategies for peripheral tissue and CNS traumas, we constructed the mouse models of skin trauma, skin combined radiation-impaired wound and traumatic brain injury (TBI), respectively. Wild type mice and A2A receptor gene knockout mice were both used in the experiments. In skin trauma and combined radiation-impaired wound models, the time of wound healing was observed, while in TBI model, neurological deficit scores, water content in injured brain and glutamate concentration in cerebral spinal fluid (CSF) were detected at 24 h after TBI. The results showed that in skin trauma and combined radiation-impaired wound models, CGS21680 (an agonist of the A2A receptors) promoted while A2A receptor gene knockout delayed the course of skin wound healing. On the contrary, in TBI model, A2A receptor gene knockout, not CGS21680, showed a protective role by inhibition of glutamate release. These data further indicate that promoting glutamate release may account for the different effects of A2A receptor activation in CNS injury and peripheral tissue injury models. These findings may provide some experimental evidence and a new strategy for clinical treatment of peripheral tissue damages by agonists of A2A receptors, while treatment of CNS injuries by antagonists of A2A receptors.

Vascular endothelial growth factor and its receptor expression during the process of fracture healing.

OBJECTIVE: To study the expression regularity of vascular endothelial growth factor (VEGF) during the process of fracture healing, and the type of VEGF receptor expressed in the vascular endothelial cells of the fracture site. METHODS: The fracture model was made in the middle part of left radius in 35 rabbits. The specimens from the fracture site were harvested at 8, 24, 72 hours and 1, 3, 5, 8 weeks, and then fixed, decalcified, and sectioned frozenly to detect the expression of VEGF and its receptor at the fracture site by in situ hybridization and immunochemical assays. RESULTS: VEGF mRNA and VEGF expression was detected in many kinds of cells at the fracture site during 8 hours to 8 weeks after fracture. Flt1 receptor of VEGF was found in the vascular endothelial cells at the fracture site during 8 hours to 8 weeks after fracture, and strong expression of flk1 receptor was detected from 3 days to 3 weeks after fracture. CONCLUSIONS: The expression of VEGF and flt1 receptor appears during the whole course of fracture healing, especially from 1 to 3 weeks. Flk1 receptor is highly expressed in a definite period after fracture. VEGF is proved to be involved in the vascular reconstruction and fracture healing.

Synthesis and identification of [1,2,4]thiadiazole derivatives as a new series of potent and orally active dual agonists of peroxisome proliferator-activated receptors alpha and delta.

Cardiovascular disease is the most common cause of morbidity and mortality in developed nations. To effectively target dyslipidemia to reduce the risk of cardiovascular disease, it may be beneficial to activate the peroxisome proliferator-activated receptors (PPARs) PPARalpha and PPARdelta simultaneously through a single molecule. Replacement of the methylthiazole of 5 (the PPARdelta selective agonist) with [1,2,4]thiadiazole gave compound 13, which unexpectedly displayed submicromolar potency as a partial agonist at PPARalpha in addition to the high potency at PPARdelta. Optimization of 13 led to the identification of 24 as a potent and selective PPARalpha/delta dual agonist. Compound 24 and its close analogs represent a new series of PPARalpha/delta dual agonists. The high potency, significant gene induction, excellent PK profiles, and good in vivo efficacies in three animal models may render compound 24 as a valuable pharmacological tool in elucidating the complex roles of PPARalpha/delta dual agonists and as a potential treatment of the metabolic syndrome.

Functional significance of the TLR4/11367 polymorphism identified in Chinese Han population.

Toll-like receptor 4 (TLR4) is the central signaling receptor for lipopolysaccharide (LPS) in mammals. This study was designed to investigate the functional significance of the G11367C polymorphism, which is a novel variant we identified in the 3' untranslated region of TLR4 gene in Chinese Han population. Three hundred seventy healthy volunteers were selected. The TLR4/11367 polymorphism was genotyped using single-tube bidirectional allele-specific amplification method. The TLR4 protein expression on peripheral leukocytes and plasma tumor necrosis factor alpha levels were determined by means of flow cytometry and enzyme-linked immunosorbent assay. The post-transcriptional effect of the 11367 polymorphism was evaluated by means of reporter gene assay and real-time quantitative polymerase chain reaction. The G11367C polymorphism is a common allele in Chinese Han population, with minor allele frequency of 14.7%. In response to ex vivo LPS stimulation, the TLR4 expression on the surface of peripheral leukocytes and the plasma tumor necrosis factor alpha levels were significantly lower in carriers of 11367C variant allele than in carriers of 11367G allele. This association was allele dose dependent. We also found that the activity and the mRNA expression of luciferase was significantly smaller in human embryonic kidney 293 cells transfected with construct containing 11367C allele than in those transfected with construct containing 11367G allele. Together, these results suggest that the TLR4/11367 polymorphism may be a functional single nucleotide polymorphism, which could attenuate the LPS-induced transmembrane signaling through the alteration of post-transcriptional regulation of 3' untranslated region and target gene expression.

The expression patterns of vascular endothelial growth factor and thrombospondin 2 after corneal alkali burn.

The aim of the investigation was to explore the expression patterns of VEGF and TSP2 after corneal alkali burn in vivo. After the model of corneal alkali burn was established in mice, the expression levels of VEGF and TSP2 were determined by immunohistochemistry (IHC), RT-PCR, image analysis and statistical evaluation. Compared with control group, the expression level of VEGF increased significantly at 6h after alkali burn and reached its maximum at 12h. Then, it increased again till the second peak appeared at 96h and 192h. The VEGF-positive reaction mainly gathered in the stroma of cornea. On the other hand, the expression of TSP2 enhanced at 3h and attained two peaks at 6h and 96h, respectively, with the process of wound healing. TSP2 was expressed mainly in the base of epithelial layer. The expression patterns of VEGF and TSP2 reflect the complicated interaction with many factors including promoted and inhibited vascularization in vivo. Moreover, it might provide a novel method for controlling vascular hyperplasia in future clinical work according to the data of VEGF and TSP2.

A bio-mathematical model of time prediction in corneal angiogenesis after alkali burn.

BACKGROUND: The determination of angiogenesis time is the key prerequisite to obtaining a balance between valid repair and excessive angiogenesis in wound healing. The aim of the investigation was to establish a bio-mathematical model predicting corneal angiogenesis time after alkali burn by back propagation neural network (BP neural network). METHODS: The corneas of mice in 24 groups were burned by 0.01 mol/l NaOH. Five mice in each group were sacrificed at 6h after alkali burn. The expression levels of vegf and tsp2, determined by real-time quantitive PCR, were used as input vectors in BP neural network. Meanwhile, the corneal angiogenesis of other mice, inspected every 3h in 24 groups till the angiogenesis time were determined, served as output vectors. The data of 18 groups were randomly chosen for network adaptation while that of other 6 groups for simulation forecasting with functions of minmax (), postreg, prepca, trapca, respectively. RESULTS: A bio-mathematical model of two-level BP neural network was established, for its purpose to predict the angiogenesis time through the expression values of vegf and tsp2. The performance index (0.00999996) was smaller than the target value (0.01) after adapting 36,557 times and the accuracy rate of this predict system was 83.33%. Furthermore, the ideal regression line and the optimization regression line were almost coincident (R=0.988 in network adaptation and R=0.793 in simulation forecasting). CONCLUSIONS: The investigation indicated that the bio-mathematical model had available performance of simulation and forecasting. It might provide a novel method to solve clinical problems.

Regulation of vascular endothelial growth factor on the expression of fracture healing-related factors.

OBJECTIVE: To study the effect of vascular endothelial growth factor (VEGF)and anti-VEGF on the expression of fracture healing-related factors and observe pathological changes at fractured sites. METHODS: Fracture models were established in 105 New Zealand white rabbits and they were randomly divided into control group, VEGF group and anti-VEGF group. The relevant factors expression at fractured sites was assayed and pathological changes were observed in decalcified samples at 8, 24, 72 hours and 1,3,5,8 weeks after fracture. RESULTS: After application of VEGF, the expression of BMP appeared earlier and expression time lasted longer. On the contrary, anti-VEGF completely inhibited the expression of BMP. The fractured sites were filled with fibrous callus, cartilaginous callus and bony callus at the 3rd week and woven bone was constructed at the 5th week. Fracture healing was accomplished at the 8th week in VEGF group. In anti-VEGF polyclonal antibody group, cellular necrosis increased at early period. Continuous focal necrosis was seen in the fractured sites from the 1st week to 5th week. Vascularization reduced obviously at the 3rd week. CONCLUSIONS: Fracture healing is a result of mutual regulation and coordination among many factors. VEGF may be an important factor in fracture healing.

[Relationship of myeloid differentiation-2 gene promoter polymorphisms with susceptivity of complications after severe trauma in Chinese Han population].

OBJECTIVE: To investigate the polymorphisms of myeloid differentiation-2 (MD-2) gene promoters, and to explore whether such polymorphisms are associated with the susceptibility to multiple organ dysfunction syndrome (MODS) and sepsis in Chinese Han population. METHODS: Using polymerase chain reaction-restriction fragment length polymorphism method, the authors detected the single nucleotide polymorphisms of the promoter region of MD-2 gene at position - 1625C/G in 105 severe trauma patients (42 with sepsis). The organ function was scored. RESULTS: The frequency of CC genotype in MD-2 gene promoter region at position - 1625 was 0.5 (21/42) in septic patients and 0.7 (44/63) in non-septic patients. The frequency of CG genotype was 0.38 (16/42) in septic patients and 0.27 (17/63) in non-septic patients. The frequency of GG genotype was 0.12 (5/42) in septic patients and 0.03 (2/63) in non-septic patients. The MODS scores in trauma patients carrying G allele at position - 1625 were significantly higher than those carrying C allele (P<0.001 for dominant effect, and P>0.05 for recessive effect). Moreover, trauma patients carrying G allele appeared to have higher risk of sepsis comparing to those carrying C allele (OR 0.477, 95% CI 0.266-0.855, P<0.05). Sepsis morbidity was significantly different between subjects with C and G alleles (P<0.05 for dominant effect, P>0.05 for recessive effect). CONCLUSIONS: The polymorphisms of the promoter region of MD-2 gene at position - 1625 C/G is correlated with MODS and sepsis after severe trauma in Chinese Han population. The people with - 1625 G allele in the promoter region of MD-2 gene may be a risk factor of severe complications.

Effects of haplotypes in the interleukin 1beta promoter on lipopolysaccharide-induced interleukin 1beta expression.

Previous studies have indicated that there are 3 common haplotypes composed of the -1470, -511, and -31 loci in the interleukin 1beta (IL-1beta) promoter in the Chinese population. The purpose of this study was to investigate the relationship between these haplotypes and lipopolysaccharide (LPS)-stimulated IL-1beta expression by whole blood leukocytes in vitro and to evaluate the effects of these haplotypes on IL-1beta gene transcription. Genomic DNAs were obtained from 105 healthy subjects. The genotypes at the 3 sites of the IL-1beta promoter were determined by restriction fragment length polymorphism analysis. Haplotype frequency was evaluated by using the Arlequin software. Plasma IL-1beta level was measured by enzyme-linked immunosorbent assay. The transcriptional activity of the haplotypes was determined by in vitro reporter gene. The results indicated that after the exposure to LPS, whole blood leukocytes from subjects with the homozygous haplotype -1470G, -511C, and -31T (G-C-T) produced more IL-1beta in vitro than those from subjects with haplotype -1470C, -511T, and -31C (C-T-C) and that the transcriptional activity of the haplotype G-C-T was also higher than that of the haplotype C-T-C. It is suggested that the haplotypes of the IL-1beta promoter influence the expression and transcriptional activity of the IL-1beta gene and that the upregulation of IL-1beta gene expression after LPS exposure in subjects with haplotype G-C-T may be due to an increased transcriptional activity of the haplotype.

Novel phosphorus-containing 17beta-side chain mifepristone analogues as progesterone receptor antagonists.

A novel series of steroidal compounds were designed and synthesized with various phosphorus-containing groups on the 17beta-side chain as progesterone receptor antagonists. The structure-activity relationships of these compounds are discussed. Selected compounds were tested in an rat progesterone-sensitive assay. Some of these compounds are more potent than mifepristone, with a better selectivity profile in differentiating progesterone receptor from glucocorticoid receptor.

Comparative observation of protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure.

OBJECTIVE: To explore the protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure (BUP). METHODS: The hearing thresholds of the guinea pigs were assessed with auditory brainstem responses (ABR). The traumatic levels of tympanic membrane and ossicular chain were observed under stereo-microscope. The rate of outer hair cells (OHCs) loss was analyzed using a light microscope. The changes of guinea pigs protected with barrel and earplug were compared with those of the control group without any protection. RESULTS: An important ABR threshold shift of the guinea pigs without any protection was detected from 8h to 14d after being exposed to BUP with a peak ranging from -64.5 kPa to -69.3 kPa ( P<0.01). The rate of perforation of tympanic membrane reached 87.5% and that of total OHCs loss was 19.46% +/- 5.38% at 14d after exposure. The guinea pigs protected with barrel and earplug had lower ABR threshold and total OHCs loss rate compared with the animals without any protection (P<0.01). All of the tympanic membrane and ossicular chain of the protected animals maintained their integrities. Meanwhile, the guinea pigs protected with the barrel had lower ABR threshold and total OHCs loss rate than those with earplug (P<0.01). CONCLUSIONS: The earplug and barrel have protective effects against BUP-induced trauma on auditory organs of the guinea pigs and the protective effects of barrel are better than those of earplug.