Effects of Pretreatment with a Xanthine Oxidase Inhibitor on Free Radical Levels during Carotid Endarterectomy

Two episodes of remote ischemia preconditioning improve motor and sensory function of hind limbs after spinal cord ischemic injury

Objectives: To investigate the effect of one and two remote ischemia preconditioning episodes (1-RIPC or 2-RIPC, respectively) on neuro-protection after spinal cord ischemic injury (SCI) in rats. Design: Experimental animal study. Setting: College of Medicine, King Khalid University, Abha, KSA. Interventions: Male rats (n = 10/group) were divided into control, sham, SCIRI, 1-RIPC + SCIRI, and 2-RIPC + SCIRI. SCI was induced by aortic ligation for 45 min and each RIPC episode was induced by 3 cycles of 10 min ischemia/10 min perfusion. The two preconditioning procedures were separated by 24 h. Outcome measures: after 48 h of RIPC procedure, Tarlov's test, withdrawal from the painful stimulus and placing/stepping reflex (SPR) were used to evaluate the hind limbs neurological function. SC homogenates were used to measure various biochemical parameters. Results: Motor and sensory function of hind limbs were significantly improved and levels of MDA, AOPPs, PGE2, TNF-α, and IL-6, as well as the activity of SOD, was significantly decreased in SC tissue in either 1 or 2 episodes of RIPC intervention. Concomitantly, levels of total nitrate/nitrite and eNOS activity were significantly increased in both groups. Interestingly, except for activity of SOD, eNOS and levels of nitrate/nitrite, the improvements in all neurological biochemical endpoint were more profound in 2-RIPC + SCIRI compared with 1-RIPC + SCIRI. Conclusion: applying two preconditioning episodes of 3 cycles of 10 min ischemia/10 min perfusion, separated by 24 h, boost the neuro-protection effect of RIPC maneuver in rats after ischemic induced SCI in rats.

Antioxidant enzymes expression in lymphocytes of patients undergoing carotid endarterectomy

To remedy carotid artery stenosis and prevent stroke surgical intervention is commonly used, and the gold standard being carotid endarterectomy (CEA). During CEA cerebrovascular hemoglobin oxygen saturation decreases and when this decrease reaches critical levels it leads to cerebral hypoxia that causes neuronal damage. One of the proposed mechanism that affects changes during CEA and contribute to acute brain ischemia (ABI) is oxidative stress. The increased production of reactive oxygen species and reactive nitrogen species during ABI may cause an unregulated inflammatory response and further lead to structural and functional injury of neurons. Antioxidant activity are involved in the protection against neuronal damage after cerebral ischemia. We hypothesized that neuronal injury and poor outcomes in patients undergoing CEA may be results of oxidative stress that disturbed function of antioxidant enzymes and contributed to the DNA damage in lymphocytes.

Effect of N-acetylcysteine and allopurinol combination to protect spinal cord ischemia/reperfusion injury induced by aortic cross-clamping in rat model

Purpose

The aim of this experimental study was to determine whether combination of N-acetylcysteine and allopurinol can reduce the ischemia/reperfusion injury of spinal cord in a rat model.

Methods

Twenty-seven Spraque Dawley rats, all male, weighing between 220 to 370 (mean 325) gr were used in the study. 27 rats were divided into three groups: sham group, control group and experimental group. Abdominal aortic occlusion between the renal arteries and iliac bifurcations was carried out for 60 min with proximal and distal clip in control and experimental groups. Hindlimb motor functions were evaluated at 24, and 48 h using the Tarlov Scale. Besides, spinal cord samples were taken for determination of superoxide dismutase, and catalase activities as antioxidant enzymes, and malondialdehyde as an indicator of lipid peroxidation and xanthine oxidase levels as source hydroxyl radical for biochemical studies. Also, histopathological evaluation was made from cord tissue samples.

Results

The experimental group subjects had better neurological functions than control group subjects. In experimental group; superoxide dismutase and catalase levels increased, while malondialdehyde and xantine oxidase levels decreased as compared with control group. Histopathological examination showed that experimental group had less cell degeneration, hemorrhage, edema and inflammation loss than control group.

Conclusions

This study offers that combined use of N-acetylcysteine and allopurinol might help protect the spinal cord against ischemia/reperfusion injury.

Evaluation effects of allopurinol and FSH on reduction of ischemia-reperfusion injury and on preservation of follicle after heterotopic auto-transplantation of ovarian tissue in mouse

Purpose

Allopurinol and FSH injection are applied to reduce ischemia-reperfusion injury and to increase survival rate for ovarian follicles after ovarian heterotopic autotransplantation in mice.

Methods

Ovarian tissues from 6-week-old mice were grafted into back muscle then collected after 3 weeks. A total of five groups were included in this experiment as follows: control group (n = 5), sham-operated group (n = 5), allopurinol treatment group (AP) (n = 5), follicle stimulating hormone (FSH) treatment group (n = 5), as well as, allopurinol and FSH treatment group (APF) (n = 5). We investigated survival, number and development of follicles, vaginal cytology along with plasma malondialdehyde (MDA) concentration in grafted ovary.

Results

Total follicles count significantly increased in APF group compared with other treatment groups (p < 0.05). MDA concentration significantly decreased in AP group and APF treatment group compared with sham-operated group. In AP group, vaginal smears showed presence of cornified epithelial cells three-five day after surgery.

Conclusions

We demonstrated that allopurinol, as a XO inhibitor, plays an important role in order to decrease ischemia injury and to increase survival rate for follicles. Also, FSH, as a folliculogenesis and angiogenesis factor, increases development of follicles. It seems that allopurinol can cause re-establishing hypothalamus-pituitary axis and finally can restore estrous cycle earlier than for the sham operated group, so it explains the increasing survival rate for follicles.

Relationships between free radical levels during carotid endarterectomy and markers of arteriosclerotic disease

BACKGROUND

Free radical production is elevated in jugular venous blood emerging from the brain in conjunction with carotid endarterectomy. This study explores the relationships between markers for lesion progression in arteriosclerosis, production of radicals and clinical characteristics.

METHODS

The radical production during carotid endarterectomy was studied in 13 patients with an ex vivo spin trap method using OXANOH as a spin trap. MCP-1, ICAM-1, MMP-9 and oxLDL were determined in venous blood samples before, during and after clamping of the carotid artery. Principal component analysis (PCA) as well as partial least square regression analysis (PLS) was applied to interpret the data.

RESULTS

PCA and PLS analysis revealed that high values of MMP-9 and low values of ICAM-1 were associated with high radical production whereas MCP-1 and oxLDL were not correlated to radical production. MMP-9 was elevated at diabetes, high haemoglobin, high leucocyte counts and thrombocyte counts as well as at contralateral stenosis, whereas ICAM-1 showed reversed relationships to these clinical variables. MCP-1 increased during surgery.

CONCLUSIONS

The main finding in our study is that MMP-9 in plasma is asscociated with radical production during carotid endarterectomy, suggesting that this enzyme might be involved in the pathogenesis of brain damage in conjunction with ischaemia-reperfusion.

Effect of allopurinol in focal cerebral ischemia in rats: an experimental study

BACKGROUND

Allopurinol is a xanthine oxidase inhibitor that prevents the generation of free radicals and may play a role in the protection of the cells during cerebral ischemia.

METHODS

We evaluated the protective and therapeutic effect of allopurinol on reversible focal cerebral ischemia-reperfusion model in rats. Cerebral blood flow to the left hemisphere of adult Sprague-Dawley rats (n = 40) was temporarily interrupted by middle cerebral artery (MCA) and bilateral common carotid artery (CCA) occlusion for 3 hours in 5 groups of 8 rats each. Allopurinol (50 mg/kg) was given intraperitoneally 2 hours and immediately before ischemia and immediately and 2 hours after reperfusion in 4 different groups of rats, respectively. Animals were kept alive 24 hours after reperfusion. After sacrifice, infarction volumes and ratios of the brain slices were calculated, and the results were compared with those of the control group.

RESULTS

The difference between the allopurinol-administered group and the control group 2 hours before for both infarction volumes and infarction ratios achieved statistical significance. Regarding the allopurinol-administered group immediately before ischemia, infarction volumes and infarction ratios were diminished, but there was no statistically significant difference. The difference between allopurinol-administered and control group immediately after and 2 hours after reperfusion for both infarction volumes and infarction ratios achieved no statistical significance.

CONCLUSION

This study showed that allopurinol has a protective effect, but not a therapeutic effect, on cerebral ischemia.

Beneficial antipsychotic effects of allopurinol as add-on therapy for schizophrenia: a double blind, randomized and placebo controlled trial

There is a large amount of data showing that adenosine plays a role opposite to dopamine in the brain. Adenosine agonists and antagonists produce behavioral effects similar to dopamine antagonists and dopamine agonists, respectively. Allopurinol, a well-known hypouricemic drug that inhibits xantine oxidase, has been used as an add-on drug in the treatment of poorly responsive schizophrenic patients. Indeed, the neuropsychiatric effects of allopurinol in schizophrenia have been suggested to be secondary to its inhibitory effect of purine degradation, enhancing adenosinergic activity. The purpose of the present investigation was to assess the efficacy of allopurinol as an adjuvant agent in the treatment of chronic schizophrenia in an 8-week double blind and placebo controlled trial. Eligible participations in the study were 46 patients with schizophrenia. All patients were inpatients and were in the active phase of the illness, and met DSM-IV criteria for chronic schizophrenia. Patients were allocated in a random fashion, 23 to haloperidol 15 mg/day plus allopurinol 300 mg/day and 23 to haloperidol 15 mg/day plus placebo. Although both protocols significantly decreased the score of the positive, negative and general psychopathological symptoms over the trial period, the combination of haloperidol and allopurinol showed a significant superiority over haloperidol alone in the treatment of positive symptoms, general psychopathology symptoms as well as PANSS total scores. The means of Extrapyramidal Symptoms Rating Scale for the placebo group were higher than in the allopurinol group over the trial, and the differences were significant in weeks 6 and 8. A significant difference was observed between the overall mean biperiden dosages in two groups. The results of this study suggest that allopurinol may be an effective adjuvant agent in the management of patients with chronic schizophrenia. Nevertheless, results of larger controlled trials are needed, before recommendations for a broad clinical application can be made.