Andréa Horst

Assessment of Oxidative Parameters in Rat Spinal Cord After Chronic Constriction of the Sciatic Nerve

Although reactive oxygen species (ROS) are involved in neuropathic pain, the direct relationship between these species and chronic constriction of sciatic nerve (CCI) has not been studied in spinal cord. Thus, this study induced CCI in rats and these animals were sacrificed 3 and 10xa0days after the surgical procedure to determine the superoxide dismutase (SOD) and catalase activities, as well as ascorbic acid, hydrogen peroxide (H2O2) and lipid hydroperoxide levels in lumbosacral spinal cord. Von Frey Hair and hot plate tests were performed to assess the degree of mechanical and thermal hyperalgesia at days 0, 3 and 10. The results showed that CCI significantly induced mechanical and thermal hyperalgesia at days 3 and 10. Parallel there was increase in spinal cord lipid hydroperoxide at days 3 and 10 in rats submitted to CCI. In Sham rats a significant increase in this parameter occurred at day 10. H2O2 decreased at day 10 only in CCI group. SOD activity was decreased in Sham and CCI groups at day 3, while catalase activity was increased in CCI rats at days 3 and 10. Ascorbic acid levels were reduced only in CCI rats at day 3. Although the role of such changes is unclear, many were not specific to neuropathic pain and the differences could be related to different degrees of central sensitization in Sham and CCI rats.

Systemic administration of vitamins C and E attenuates nociception induced by chronic constriction injury of the sciatic nerve in rats

Antioxidants have been tested to treat neuropathic pain, and α-Tocopherol (vitamin E--vit. E) and ascorbic acid (vitamin C--vit. C) are potent antioxidants. We assessed the effect of intraperitoneal administration of vit. C (30 mg/kg/day) and vit. E (15 mg/kg/day), given alone or in combination, on the mechanical and thermal thresholds and the sciatic functional index (SFI) in rats with chronic constriction injury (CCI) of the sciatic nerve. We also determined the lipid hydroperoxides and total antioxidant capacity (TAC) in the injured sciatic nerve. Further, we assessed the effects of oral administration of vit. C+vit. E (vit. C+E) and of a combination of vit. C+E and gabapentin (100mg/kg/day, i.p.) on the mechanical and thermal thresholds of CCI rats. The vitamins, whether administered orally or i.p., attenuated the reductions in the mechanical and thermal thresholds induced by CCI. The antinociceptive effect was greater with a combination of vit. C+E than with each vitamin given alone. The SFI was also improved in vitamin-treated CCI rats. Co-administration of vit. C+E and gabapentin induced a greater antinociceptive effect than gabapentin alone. No significant change occurred in TAC and lipid hydroperoxide levels, but TAC increased (45%) while lipid hydroperoxides decreased (38%) in the sciatic nerve from vit. C+E-treated CCI rats. Thus, treatment with a combination of vit. C+E was more effective to treat CCI-induced neuropathic pain than vitamins alone, and the antinociceptive effect was greater with co-administration of vit. C+E and gabapentin than with gabapentin alone.

Effect of N-acetylcysteine on the spinal-cord glutathione system and nitric-oxide metabolites in rats with neuropathic pain.

Since N-acetylcysteine (NAC) is a donor of cysteine, we studied the relationship between NAC and concentration of oxidized and reduced glutathione (GSH/GSSG ratio), and glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities in the lumbosacral spinal cord of rats with chronic constriction injury (CCI) of the sciatic nerve that received NAC (150mg/kg/day, i.p.) or 0.9% saline solution for 3 or 10 days. Hydrogen peroxide (H2O2) and nitric-oxide (NO) metabolites were also measured. Von Frey hair and hot-plate tests showed hyperalgesia at day 1 in CCI rats. Hyperalgesia persisted at all other times in saline-treated CCI rats, but returned to pre-injury values in NAC-treated CCI rats after 3 postoperative days. GST activity and the GSH/GSSG ratio increased in saline-treated CCI rats, while the NAC treatment increased GST and GPx activities at day 10, with no significant change in the GSH/GSSG ratio. NAC treatment did not affect H2O2 levels, but it reduced NO metabolites in CCI rats 3 days after the surgery. Thus, the anti-hyperalgesic effect of NAC appears not to involve its action as a cysteine precursor for GSH synthesis, but involves a decrease in NO.

Redox profile in liver of Leporinus macrocephalus exposed to different dissolved oxygen levels

Aquatic organisms are continuously exposed to environmental variations, which can lead to physiological and biochemical alterations. Leporinus macrocephalus, known as piavuçu, is a migratory species that may be exposed to variations in dissolved oxygen levels. Studies evaluating oxidative changes undergone by this species in these conditions are scarce. Therefore, this investigation aimed at evaluating oxidative alterations in L. macrocephalus exposed to different oxygen levels for 96xa0h: 6.12xa0±xa00.18, 3.99xa0±xa00.17, 3.22xa0±xa00.17, 2.47xa0±xa00.30 and 0.710xa0±xa00.07xa0mgxa0L−1. At the end of the experimental period, fish were euthanized and livers used to determine lipid hydroperoxides, thiobarbituric acid reactive substances, catalase, glutathione-S-transferase, superoxide dismutase and thiol groups, which are an indirect measure of reduced glutathione. Results indicated a decrease in the studied parameters in hypoxic situations, suggesting a possible metabolic depression.

Effects of high-velocity, low-amplitude manipulation on catalase activity in men with neck pain.

OBJECTIVEnThe aim of this study was to identify the influence of high-velocity, low-amplitude (HVLA) manipulation on lipid peroxidation and catalase activity in subjects with neck pain who answered the Neck Disability Index and quadruple visual scale questionnaires.nnnMETHODSnTwenty-two men (mean age, 38 years) with neck pain were recruited through radio and newspaper advertisements in the local media. Every patient received 6 sessions of HVLA manipulation, 3 times a week for 2 weeks. Blood samples were drawn from the cubital vein before treatment in the first session and after the third and sixth sessions. The quadruple visual scale was used with the same scheme. The Neck Disability Index questionnaire was applied before the beginning of treatment and after the last session. Catalase activity and lipoperoxidation were measured in erythrocyte samples.nnnRESULTSnResults showed no change in lipid peroxidation. Nevertheless, the catalase activity was increased by HVLA manipulation. The same treatment reduced pain perception and disability in these subjects.nnnCONCLUSIONnThe present study has shown that catalase activity of the erythrocytes, but not lipoperoxidation, increased after 6 sessions of HVLA manipulation treatment in men with neck pain. The results support the beneficial role of HVLA in the treatment of patients with neck pain.

Peripheral Oxidative Stress Blood Markers in Patients With Chronic Back or Neck Pain Treated With High-Velocity, Low-Amplitude Manipulation

OBJECTIVEnThe purpose of this study was to investigate oxidative-stress parameters in individuals with chronic neck or back pain after 5 weeks of treatment with high-velocity, low-amplitude (HVLA) spinal manipulation.nnnMETHODSnTwenty-three individuals aged 38.2 ± 11.7 years with nonspecific chronic neck or back pain verified by the Brazilian Portuguese version of the Chronic Pain Grade, with a sedentary lifestyle, no comorbidities, and not in adjuvant therapy, underwent treatment with HVLA chiropractic manipulation twice weekly for 5 weeks. Therapeutic procedures were carried out by an experienced chiropractor. Blood samples were assessed before and after treatment to determine the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx), and the levels of nitric oxide metabolites and lipid hydroperoxides. These blood markers were analyzed by paired Student t test. Differences were considered statistically significant, when P was <.05.nnnRESULTSnThere was no change in catalase but an increase in SOD (0.35 ± 0.03 U SOD per milligram of protein vs 0.44 ± 0.04 U SOD per milligram of protein; P < .05) and GPx (7.91 ± 0.61 nmol/min per milligram of protein vs 14.07 ± 1.07 nmol/min per milligram of protein; P < .001) activities after the treatment. The nitric oxide metabolites and the lipid hydroperoxides did not change after treatment.nnnCONCLUSIONnHigh-velocity, low-amplitude spinal manipulation twice weekly for 5 weeks increases the SOD and GPx activities. Previous studies have shown a relationship between pain and oxidative and nitrosative parameters; thus, it is possible that changes in these enzymes might be related to the analgesic effect of HVLA spinal manipulation.

Effect of High-Velocity, Low-Amplitude Treatment on Superoxide Dismutase and Glutathione Peroxidase Activities in Erythrocytes From Men With Neck Pain

OBJECTIVEnThis study investigates the analgesic effect of high-velocity, low-amplitude (HVLA) manipulation and antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) in erythrocytes of men with neck pain.nnnMETHODSnTwenty-two men with neck pain of mechanical origin who were aged 20 to 50 years, were nonsmokers, had a sedentary lifestyle, had no comorbidities, and were not in adjuvant therapy underwent 6 sessions of HVLA chiropractic manipulation 3 times a week for 2 weeks. Patients were treated by the same chiropractor and under the same conditions. Blood samples were collected before the beginning of the treatment and at the end of the third and last session. Erythrocytes were separated from blood and then processed to determine SOD and GPx activities. The quadruple visual scale and the Neck Disability Index were used to demonstrate the analgesic effect of treatment. The results were analyzed by repeated-measures analysis of variance followed by Bonferroni posttest. Differences were considered significant when P was less than .05.nnnRESULTSnDespite the tendency to reduction in SOD and increase in GPx activities, there was no significant change after the treatment.nnnCONCLUSIONnHigh-velocity, low-amplitude treatment for 6 sessions in men with neck pain did not affect systemic SOD and GPx activities. Despite the absence of significant changes, this study is important because it is the first to investigate the activities of SOD and GPx in patients with neck pain treated with HVLA spinal manipulation.