Comparative analysis of tissue reactions to anesthetic solutions: histological analysis in subcutaneous tissue of rats.

Postanesthetic pain is a relatively common complication after local anesthesia. This complication may be caused by the anesthetic technique or by the anesthetic solution used. Tissue reactions induced by the anesthetic solutions may be one of the factors resulting in pain after anesthesia. The objective of this study was to comparatively analyze tissue reactions induced by different anesthetic solutions in the subcutaneous tissue of rats. The following solutions were utilized: 2% lidocaine without vasoconstrictor; a 0.5% bupivacaine solution with 1:200,000 adrenaline; a 4% articaine solution and 2% mepivacaine, both with 1:100,000 adrenaline; and a 0.9% sodium chloride solution as a control. Sterilized absorbent paper cones packed inside polyethylene tubes were soaked in the solutions and implanted in the subcutaneous region. The sacrifice periods were 1, 2, 5, and 10 days after surgery. The specimens were prepared and stained with hematoxylin and eosin for histological analysis. The results showed that there is a difference in tissue irritability produced by the local anesthetic solutions. The results also showed that there is no relation between the concentration of the drug and the inflammatory intensity, that the mepivacaine and articaine solutions promoted less inflammatory reaction than the bupivacaine, and that the lidocaine solution produced the least intense inflammation.

Toxicity of hypercaloric diet and monosodium glutamate: oxidative stress and metabolic shifting in hepatic tissue.

The present study examines the effects of a hypercaloric diet on hepatic glucose metabolism of young rats, with and without monosodium glutamate (MSG) administration, and the association of these treatments with evaluating markers of oxidative stress. Male weaned Wistar rats (21 days old) from mothers fed with a hypercaloric diet or a normal diet, were divided into four groups (n=6): control (C) fed with control diet; (MSG) treated with MSG (4 mg/g) and control diet; (HD) fed with hypercaloric diet and (MSG-HD) treated with MSG and HD. Rats were sacrificed after the oral glucose tolerance test (OGTT), at 45 days of treatments. Serum was used for insulin determination. Glycogen, hexokinase(HK), glucose-6-phosphatase(G6PH), lipid hydroperoxide, superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px) were determined in liver. HD rats showed hypoglycemia, hyperinsulinemia, and high hepatic glycogen, HK and decreased G6PH. MSG and MSG-HD had hyperinsulinemia, hyperglycemia, decreased HK and increased G6PH in hepatic tissue. These animals had impaired OGTT. HD, MSG and MSG-HD groups had increased lipid hydroperoxide and decreased SOD in hepatic tissue. Hypercaloric diet and monosodium glutamate administration induced alterations in metabolic rate of glucose utilization and decreased antioxidant defenses. Therefore, the hepatic glucose metabolic shifting induced by HD intake and MSG administration were associated with oxidative stress in hepatic tissue.

Evaluation of toxicity after one-months treatment with Bauhinia forficata decoction in streptozotocin-induced diabetic rats

Background: Previous experiments have shown that a decoction of Bauhinia forficata leaves reduces the changes in carbohydrate and protein metabolism that occur in rats with streptozotocin-induced diabetes. In the present investigation, the serum activities of enzymes known to be reliable toxicity markers were monitored in normal and streptozotocin-diabetic rats to discover whether the use of B. forficata decoction has toxic effects on liver, muscle or pancreas tissue or on renal microcirculation. Methods: An experimental group of normal and streptozotocin-diabetic rats received an aqueous decoction of fresh B. forficata leaves (150 g/L) by mouth for 33 days while a control group of normal and diabetic rats received water for the same length of time. The serum activity of the toxicity markers lactate dehydrogenase, creatine kinase, amylase, angiotensin-converting enzyme and bilirubin were assayed before receiving B. forficata decoction and on day 19 and 33 of treatment. Results: The toxicity markers in normal and diabetic rats were not altered by the diabetes itself nor by treatment with decoction. Whether or not they received B. forficata decoction the normal rats showed a significant increase in serum amylase activity during the experimental period while there was a tendency for the diabetic rats, both treated and untreated with decoction, to have lower serum amylase activities than the normal rats. Conclusions: Administration of an aqueous decoction of B. forficata is a potential treatment for diabetes and does not produce toxic effects measurable with the enzyme markers used in our study. © 2004 Pepato et al; licensee BioMed Central Ltd.

A preliminary report on the effect of laser therapy on the healing of cutaneous surgical wounds as a consequence of an inversely proportional relationship between wavelength and intensity: Histological study in rats

Objective: The objective of the present investigation was to assess the histological effects of different wavelengths and intensities on the healing process of cutaneous wounds. Background Data: Tissue repair is a dynamic interactive process which involves mediators, cells and extra-cellular matrix. Several reports on the use of laser therapy have shown that the healing process is positively affected when the correct parameters are used. Methods: Eighteen standardized wounds were surgically created on the dorsum of male and female Wistar rats, which were subsequently divided into two experimental groups according to wavelength used λ.670 or λ685 nm) for lasertherapy (LLLT). Each group was divided into three subgroups of three animals according to the intensity of the applied irradiation (2,15, or 25 mW). Twelve animals were used as entreated controls and were not irradiated. The irradiation was carried out during seven consecutive days. The animals were sacrificed eight days after surgery. The specimens were removed, kept in 4% formaldehyde for 24 h, routinely prepared to wax, stained with H&E, and analyzed under light microscopy. Results: For both groups, light microscopy showed a substitution repair process; however, when LLLT was used, a positive biomodulatory effect was detectable, chiefly associated with shorter wavelength and low intensity. Conclusions: The results of the present study indicate that LLLT improved cutaneous wound repair and that the effect is a result of an inversely proportional relationship between wavelength and intensity, with treatment more effective when combining higher intensity with short wavelength or lower intensity with higher wavelength.

Proteinase-activated receptor-2 (PAR2) agonist causes periodontitis in rats

Proteinase-activated receptor-2 (PAR2) is a G-protein-coupled receptor that mediates cellular responses to extracellular proteinases. Since PAR2 is expressed by oral epithelial cells, osteoblasts, and gingival fibroblasts, where its activation releases interleukin-8, we hypothesized that PAR2 activation may participate in periodontal disease in vivo. We investigated the role of PAR2 activation in periodontal disease in rats. Radiographic and enzymatic (myeloperoxidase) analysis revealed that topical application of PAR2 agonist causes periodontitis but also exacerbates existing periodontitis, leading to significant alveolar bone loss and gingival granulocyte infiltration. Inhibition of matrix metalloproteinase (MMP) and cyclo-oxygenase (COX) decreased PAR2 agonist-induced periodontitis. More specifically, the overexpression of COX-1, COX-2, MMP-2, and MMP-9 in gingival tissues suggests that they are involved in PAR 2-induced periodontitis. In conclusion, PAR2 agonist causes periodontitis in rats through a mechanism involving prostaglandin release and MMP activation. Inhibition of PAR2 may represent a novel approach to modulate host response in periodontitis.

Effects of long-term cyclosporin therapy on gingiva of rats--analysis by stereological and biochemical estimation.

Cyclosporin A (CsA) is used as an immunosuppressive agent and its prominent side effect is the induction of gingival overgrowth, which remains a significant problem. The risk factors appraised include the duration of treatment. However, there are no stereological and biochemical studies exploring the effects of long-term CsA therapy on gingival tissue. The purpose of the present study was to investigate the level of TGF-beta1 in saliva and describe the densities of fibroblasts and collagen fibers in the gingival tissue of rats treated with CsA for long periods. Rats were treated for 60, 120, 180 and 240 days with a daily subcutaneous injection of 10 mg/kg of body weight of CsA. At the end of the experimental periods, saliva was collected for the determination of TGF-beta1 levels. After histological processing, the oral epithelium and the connective tissue area were measured as well as the volume densities of fibroblasts (Vf) and collagen fibers (Vcf). After 60 and 120 days of CsA treatment, there was a significant increase in Vf and Vcf as well as a significant increase in TGF-beta1 levels. After 180 and 240 days, reduction in the gingival overgrowth associated with significant decreases in the level of TGF-beta1, and also decreased Vf and Vcf, were observed. The data presented here suggest that after long-term therapy, a decrease in TGF-beta1 levels occurs, which might contribute to an increase in the proteolytic activity of fibroblasts in the gingiva, favoring the normality of extracellular matrix synthesis.

Water-soluble extract of Coleus barbatus modulates weight gain, energy utilization and lipid metabolism in secondary biliary cirrhosis: an experimental study in young rats.

PURPOSE: To test if a water extract of Coleus barbatus (WEB) has any effect on weight gain, food energy utilization and lipid metabolism in young rats with obstructive cholestasis. METHODS: Forty 21 day old (P21) Wistar rats, in groups of 10, were submitted to one of the following treatments: a sham operation with daily water or WEB administration, double ligature and resection of the bile duct with daily water or WEB administration. At P49 they were submitted for euthanasia when the following were determined: ingested feed (IF), energy utilization (EU) and weight gain (WG) from P29 to P49, together with total serum cholesterol (TC) and triacylglycerol (TG) concentrations, liver wet weight (LWW) and fat content (LFC). Two Way ANOVA and the S.N.K. test for paired comparisons were employed to study the effects of cholestasis and those of WEB and their interactions (p < or = 0.05). RESULTS: Cholestasis, independently of WEB, and WEB, independently of cholestasis both reduced IF, EU, and WG but there was no significant interaction between the two factors. Cholestasis, independently of WEB, increased LWW, LFC, the TC and TG The WEB, independently of cholestasis, reduced these values, and there was a significant interaction between the two factors; such that these effects were more accentuated in animals with cholestasis. CONCLUSION: The WEB reduced IF, WG, and EU, both in the presence and absence of cholestasis in the same proportion. It also partially inhibited the increase in LWW, LFC, TC and TG caused by cholestasis.

Early healing pattern of autogenous bone grafts with and without e-PTFE membranes: A histomorphometric study in rats

Objective. The aim of this study was to perform quantitative and qualitative analyses of the initial repair pattern of an autogenous bone block graft when covered or not with e-PTFE membranes. Study design. Sixty male Wistar rats received a bone graft plus an e-PTFE membrane (MB) or just the graft (B). A block graft was harvested from the animal's calvarium and was laid and stabilized on the external cortical area near the angle of the mandible. Descriptive histology and histomorphometric analyses were carried out and the data were analyzed statistically by ANOVA and the Tukey test, with the level of significance set at 5%. Results. The results for group B showed that there was bone loss during the healing period (B0 = 1.38, B45 = 1.05, F = 7.91 > F C = 3.02), that is, the initial volume of the graft decreased in time. Bone tissue loss was about 24%. In contrast, the MB group showed bone tissue gain along the observation period (MB0 = 1.54, MB45 = 2.40, F = 7.91 > FC = 3.02), meaning that the total volume of newly formed bone was greater than the original graft area. Bone tissue gain was approximately 55%. MB showed significantly greater bone gain when compared to B (B45 = 1.05, MB45 = 2.40, F = 39.86 > FC = 1.90). These significant differences between B and MB could already be observed after 21 days. Conclusions. The bone block graft underwent resorption at an early healing stage, while additional new bone formation was observed when the bone graft was covered with an e-PTFE membrane. © 2005 Mosby, Inc. All rights reserved.

Histological investigation of a 10% metronidazole and 2% lidocaine dressing on wound healing in rats.

AIM: Alveolitis is considered a disturbance of the alveolar healing process that is characterized by blood clot disintegration, alveolar wall infection and extreme pain. Several substances have been investigated to improve healing and guarantee postoperative comfort to patients. The aim of this study was to evaluate, microscopically, in rats, the healing process in non-infected tooth sockets, after application of a 10% metronidazole and 2% lidocaine dressing, using lanolin as vehicle and mint as flavoring. METHODS: Forty-five rats (Rattus norvegicus albinus, Wistar) had their right incisor extracted and were randomly assigned to 3 groups (n=15): Group I (control): the sockets were filled with blood clot; Group II: application of adrenaline solution at 1:1 000 with an absorbent paper point during 1 min plus filling of the socket with a 10% metronidazole and 2% lidocaine dressing, with lanolin as vehicle, and mint as flavoring; Group III: filling of the socket with the 10% metronidazole and 2% lidocaine dressing, with lanolin as vehicle and mint as flavoring. After 6, 15 and 28 days postoperatively, 5 animals per group were euthanized with an injectable anesthetic overdose. Histological and statistical analyses were performed. RESULTS: The results showed that the 10% metronidazole and 2% lidocaine dressing with lanolin as vehicle and mint as flavoring yielded similar response as that of the normal repair group and may be used to prevent the onset of alveolitis in those cases in which any predisposing factor is present. CONCLUSIONS: The use of this dressing has shown a good postoperative patient's comfort and does not cause a significant delay in the alveolar healing process.

Influence of simvastatin on bone regeneration of tibial defects and blood cholesterol level in rats

The purpose of this study was to evaluate the effects of simvastatin, by oral or subcutaneous administration, on tibial defects regeneration and blood cholesterol level in rats. A surgical defect was made on the right tibia of 40 male animals assigned to 4 groups (n=10), based on two routes of administration and on the use or not of simvastatin: subcutaneous injection of simvastatin (7 mg/kg) (group AT) or only the vehicle of drug suspension (group AC), above the defect area, for 5 days; and 20 mg/kg of simvastatin macerated on water (group BT) or only water (group BC), orally, daily, during the whole observation period. The animals were sacrificed after 15 or 30 days, when blood samples were analyzed to check plasma cholesterol levels. Tibiae were removed and, after decalcification and routine laboratorial processing, histological and histomorphometrical analyses were carried out. ANOVA was used for statistical analysis at 5% signficance level. The histological and histomorphometrical analyses showed significant differences only between the experimental periods (p<0.05). Animals sacrificed after 30 days showed better bone repair (p<0.05). There was no statistically significant difference (p>0.05) for blood cholesterol levels between the groups. In conclusion, simvastatin administration either orally or subcutaneously did not improve bone repair of experimental tibial defects and did not alter blood cholesterol levels in rats.

Does troncular vagotomy modify the proliferative gastric lesions induced in rats by duodenogastric reflux?

Purpose: to investigate if combining VT to DGR through the pylorus can modulate the biological behavior of PL induced by DGR and to verify if TV alone can induce morphologic lesions in the gastric mucosa. Methods: 62 male Wistar rats were assigned to four groups: 1 - Control (CT) gastrotomy; 2 - Troncular Vagotomy (TV) plus gastrotomy; 3 - Duodenogastric reflux through the pylorus (R) and 4 - Troncular vagotomy plus DGR (RTV). The animals were killed at the 54 week of the experiment. DGR was obtained by anastomosing a proximal jejunal loop to the anterior gastric wall. TV was performed through isolation and division of the vagal trunks. Gastrotomy consisted of 1 cm incision at the anterior gastric wall. PL were analyzed gross and histologically in the antral mucosa, at the gastrojejunal stoma and at the squamous portion of the gastric mucosa. Results: Groups R and RTV developed exophytic lesions in the antral mucosa (R=90.9%; RTV=100%) and at the gastrojejunal stoma (R=54.54%; RTV=63.63%). Histologically they consisted of proliferative benign lesions, without cellular atypias, diagnosed as adenomatous hyperplasia. Both groups exposed to DGR presented squamous hyperplasia at the squamous portion of the gastric mucosa (R= 54.5%; RTV= 45.4%). TV, alone, did not induce gross or histological alterations in the gastric mucosa. TV did note change the morphologic pattern of the proliferative lesions induced by DGR. Conclusions: DGR induces the development of PL in the pyloric mucosa and at the gastrojejunal stoma. TV does not change the morphologic pattern of the proliferative lesions induced by DGR. TV alone is not able to induce morphologic lesions in the gastric mucosa.

Nerolidol, an antiulcer constituent from the essential oil of Baccharis dracunculifolia DC (Asteraceae)

In this study, the antiulcerogenic effect of essential oil from Baccharis dracunculifolia was evaluated using the model of acute gastric lesions induced by ethanol. The ulcerative lesion index (ULI) was significantly reduced by oral administration of the essential oil of B. dracunculifolia at doses of 50, 250 and 500 mg/kg which reduced the lesions by 42.79, 45.70 and 61.61%, respectively. The analysis of the chemical composition of the essential oil from B. dracunculifolia by GC showed that this was composed mainly of mono- and sesquiterpenes and the majority compound was nerolidol. Therefore, antiulcerogenic activity of nerolidol (50, 250 and 500 mg/kg) was investigated using ethanol-, indomethacin- and stress-induced ulcer models in rat. In the stress-induced ulcer model, a significant reduction of the ULI in animals treated with nerolidol (50, 250 and 500 mg/kg) and cimetidine (100 mg/kg) was observed, compared to the control group (p < 0.05). The percentage of inhibition of ulcer was 41.22, 51.31, 56.57 and 53.50% in groups treated with 50, 250, 500 mg/kg of nerolidol and 100 mg/kg of cimetidine (positive control), respectively. Regarding ethanol- and indomethacin-induced ulcer models, it was observed that the treatment with nerolidol (250 and 500 mg/kg) significantly reduced the ULI in comparison with the control group (p < 0.05). The dose of 50 mg/kg reduced the parameters analyzed but this was not statistically significant. In the ethanol-induced model percentage of inhibition of ulcer was 34.20, 52.63, 87.63 and 50.87% in groups treated with 50, 250, 500 mg/kg of nerolidol and 30 mg/kg of omeprazol (positive control), respectively. In indomethacin-ulcer the percentage of inhibition of ulcer was 34.69, 40.80, 51.02 and 46.93% in groups treated with 50, 250, 500 mg/kg of nerolidol and 100 mg/kg of cimetidine (positive control), respectively. The results of this study show that nerolidol displays antiulcer activity, as it significantly inhibited the formation of ulcers induced in different animal models. However, further pharmacological and toxicological investigations, to delineate the mechanism(s) of action and the toxic effects, are required to allow the use of nerolidol for the treatment of gastric ulcer. © 2007 Verlag der Zeitschrift für Naturforschung.

Effect of an alcoholic diet on dental caries and on Streptococcus of the mutans group: Study in rats

The objective of this study was to evaluate the effects of an alcohol diet on Streptococcus of the mutans group and on dental caries in the oral cavity of rats. Forty animals were divided into 3 groups according to the following liquid diets: 20% ethanol solution (Alcohol Group, AG), 27% sucrose solution (Isocaloric Group, IG), and water (Control Group, CG). After 56 days, samples were collected and plated on Mitis Salivarius Bacitracin agar to assess the number of colony forming units (CFU/mL) of Streptococcus of the mutans group. The animals were sacrificed and the jaws were removed in order to assess the occurrence of dental caries on the smooth and occlusal surfaces using stereomicroscopy. The data were submitted to ANOVA and Tukey test. The average numbers of CFU/mL (10 3) were: 8.17 (AG), 9.78 (IG), and 5.63 (CG). There was no significant difference among the groups for the occurrence of occlusal caries. Regarding smooth surface caries, in the upper jaw, the caries number in the IG (1.58) was similar to that in the AG (2.06) and in the CG (1.14), and the number of caries in the AG was higher than in the CG; in the lower jaw there was significant difference among the 3 groups: AG (1.14), IG (2.00) and CG (0.43). The diets with the alcohol and sucrose solutions presented a tendency of increasing the colonization by Streptococcus of the mutans group and of increasing the occurrence of smooth surface dental caries in rat molars when compared to the control diet.

The influence of ovariectomy, simvastatin and sodium alendronate on alveolar bone in rats

Bisphosphonates are currently used in the treatment of many diseases involving increased bone resorption such as osteoporosis. Statins have been widely used for the treatment of hypercholesterolemia and recent studies have shown that these drugs are also capable of stimulating bone formation. The purpose of this study was to evaluate thel influence of an estrogen deficient state and the effects of simvastatin and sodium alendronate therapies on alveolar bone in female rats. Fifty-four rats were either ovariectomized (OVX) or sham operated. A month later, the animals began to receive a daily dose of simvastatin (SIN - 25 mg/kg), sodium alendronate (ALN - 2 mg/kg) or water (control) orally. Thirty-five days after the beginning of the treatment, the rats were sacrificed and their left hemimandibles were removed and radiographed using digital X-ray equipment. The alveolar radiographic density under the first molar was determined with gray-level scaling and the values were submitted to analysis of variance (α = 5%). Ovariectomized rats gained more weight (mean ± standard deviation: 20.06 ± 6.68%) than did the sham operated animals (12.13 ± 5.63%). Alveolar radiographic density values, expressed as gray levels, were lowest in the OVX-water group (183.49 ± 6.47), and differed significantly from those observed for the groups receiving alendronate (sham-ALN: 193.85 ± 3.81; OVX-ALN: 196.06 ± 5.11) and from those of the sham-water group (193.66 ± 4.36). Other comparisons between groups did not show significant differences. It was concluded that the ovariectomy reduced alveolar bone density and that alendronate was efficient for the treatment of this condition.

Vascular hyporeactivity to angiotensin II induced by Escherichia coli endotoxin is reversed by Nω-Nitro-L-Arginine, an inhibitor of nitric oxide synthase

Septic shock or sepsis is reported to be one of the major causes of death when followed by systemic infectious trauma in humans and other mammals. Its development leads to a large drop in blood pressure and a reduction in vascular responsiveness to physiological vasoconstrictors which, if not contained, can lead to death. It is proposed that this vascular response is due to the action of bacterial cell wall products released into the bloodstream by the vascular endothelium and is considered a normal response of the body's defenses against infection. A reduction in vascular reactivity to epinephrine and norepinephrine is observed under these conditions. In the present study in rats, the aim was to assess whether those effects of hypotension and hyporeactivity are also related to another endogenous vasoconstrictor, angiotensin II (AII). We evaluated the variation in the power of this vasoconstrictor over the mean arterial pressure in anesthetized rats, before and after the establishment of hypotension by Escherichia coli endotoxin (Etx). Our results show that in this model of septic shock, there is a reduction in vascular reactivity to AII and this reduction can be reversed by the inhibitor of nitric oxide synthase, Nω-Nitro-L- Arginine (NωNLA). Our results also suggest that other endogenous factors (not yet fully known) are involved in the protection of rats against septic shock, in addition to the L-arginine NO pathway.