Histological and biochemical serum effects of alpha-tocopherol on ischemia/reperfusion-related injuries induced in the pelvic limb of rats

Alprostadil attenuates inflammatory aspects and leucocytes adhesion on renal ischemia and reperfusion injury in rats

PURPOSE

To evaluate the effects of alprostadil in an experimental model of ischemia and reperfusion injury (IRI) in rat renal tissue.

METHODS

Adult male Wistar rats were randomized into three groups Vehicle-treated group(Veh), Alprostadil-treated(Al), and sham(Sh) group. Veh and Al groups had suprarenal aorta occluded for 30 minutes and reperfused for 60 minutes. Saline or 20 µg/kg of Alprostadil was intravenously infused immediately before declamping. Sh group animals underwent similar procedure without aortic occlusion. Left nephrectomy and blood sampling were performed after 60 minutes of reperfusion. Renal ICAM-1 expression and histological analysis were performed to estimate inflammatory response and tissue disarrangement. Serum biochemical markers for IRI were also measured. Kruskal-Wallis test was used to assess differences between the groups.

RESULTS

There was lower expression of ICAM-1 in groups Veh and Sh. On histologically evaluation, inflammation and necrosis in the Veh group was significantly higher (grades III/IV) than Al group (Veh>Al=Sh; p = 0.025), as well as CPK levels (Veh>Al=Sh; p = 0.03).

CONCLUSION

Alprostadil attenuates the immunohistochemical and histological repercussions in the renal tissue of rats submitted to a post-ischemic reperfusion with supra-renal aortic clamping.

Collateral circulation of the rat lower limb and its significance in ischemia-reperfusion studies

PURPOSE

Rats are the most commonly used animal model for studies of acute lower limb ischemia-reperfusion. The ischemia induced by arterial clamping may cause milder damage than the application of a tourniquet if the presence of a possible collateral system is considered.

METHODS

Male Wistar rats were randomized into three groups: in group A, the muscle weight affected by ischemia was measured; in group B, the severity of muscle damage caused by the application of a tourniquet and by infrarenal aortic occlusion was examined. Blood and muscle samples were taken from group B to assess the serum necroenzyme, potassium and TNF-α levels, as well as the muscle fiber viability and for histological examinations. In group C, the identification of the lower limb collateral system was performed using corrosion casting.

RESULTS

Tourniquet application affected the lower muscle mass and resulted in significantly more severe injury compared to infrarenal aortic occlusion. This difference was reflected in the serum necroenzyme, potassium and TNF-α levels. The histological examination and viability assay confirmed these findings. The corrosion casts showed several anastomoses capable of supplying the lower limb.

CONCLUSION

Tourniquet application proved to be capable of inducing absolute lower limb ischemia, in contrast to infrarenal aortic ligation, where a rich collateral system is considered to help mitigate the injury.

Alpha-tocopherol ameliorates oxidative renal insult associated with spinal cord reperfusion injury

Ischemic-reperfusion procedures targeting a specific organ often results in remote multiple organ injuries mediated possibly by heightened oxidative stress levels. As the kidney is one of the most vulnerable organs for ischemic oxidative stress, the aim of the present study was to confirm the occurrence of renal complication secondary to spinal cord ischemic-reperfusion injury (SC-IRI) induced by aortic clamping. The study also investigated the possible prophylactic effect of long-term administration of α-tocopherol (α-TOL) against high level of renal oxidative stress and inflammatory processes induced by SC-IRI. In this study, a total of 60 male Sprague-Dawley rats were randomly divided into five equal groups: C group underwent no surgery; CE group received α-TOL 600 mg/kg intramuscular twice weekly for 6 weeks; S group were subjected to laparotomy without clamping of the aorta; SE group were handled as S group and treated with α-TOL as group CE; SC-IRI group were subjected to laparotomy with clamping of the aorta just above the bifurcation of the aorta for 45 min, then the clamp was released for 48 h for reperfusion. SC-IRIE group was subjected to IRI as in group SC-IRI and was injected with α-TOL in the same dose and route as α-TOL-treated control group. SC-IRI resulted in increases in serum creatinine, blood urea nitrogen, plasma nitrite/nitrate level, serum tumor necrosis factor alpha, renal tissue homogenate level for malondialdehyde, superoxide dismutase and prostaglandin E2. Long-term prophylactic treatment with α-TOL resulted in amelioration of the renal functional disturbances and all measured parameters of oxidative stress and inflammation. Ischemic reperfusion injury of the spinal cord induced some remote renal functional disturbances although some of the observed changes may have resulted from decreased renal blood flow due to the hypotension induced during the procedure. Prophylactic long-term α-TOL administration guards against the renal function disturbances an effect that can be attributed, at least partially, to improvement of the renal pro-oxidant/antioxidant balance and inhibition of the inflammatory processes.

Effects of kinesiotherapy in ischemic lesion and reperfusion in rats

OBJECTIVE

To investigate the effect of kinesiotherapy on the functionality of the pelvic limb of rats after ischemic and reperfusion injury.

METHODS

10 rats were divided into two groups, GI (control) and GII (kinesiotherapy). All the animals underwent ischemia for a period of three hours, followed by tissue reperfusion. In Group GII, non-resistive systemic kinesiotherapy was performed (swimming) in three weekly sessions of 50 minutes, over a period of four weeks, while the GI animals remained at rest. Functional analysis of motor behavior was evaluated weekly. The animals were then sacrificed, and the soleus and gastrocnemius muscles and the sciatic nerve removed for histopathological analysis.

RESULTS

There was a significant recovery of motor behavior with kinesiotherapeutic treatment during the four weeks of treatment. However, the histological examination of the tissues showed no morphological changes of cell injury and repair.

CONCLUSION

It was not possible to affirm that the exercise was effective in cell repair, because neither of the groups (control and experimental) showed any histological difference. On the other hand, systemic kinesiotherapy showed a beneficial effect on functional rehabilitation after ischemia and reperfusion. Level of evidence III, Case-Control Study .

Inhibitory activity of α-tocopherol on apoptosis in the rat bladder wall subjected to androgen deprivation

Alpha-tocopherol (2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-chromon-8-ol) is used in many previous urological studies. Thus to add to this knowledge in this study we studied the potential inhibitory activity on oxidative stress and process apoptosis on bladder wall in male rats subjected to androgen deprivation. A causal relationship between lower testosterone levels and apoptosis, as a component of castration-induced muscle atrophy, has been shown. Male Wistar rats (250-300 g) were used in this experiment, divided into four groups: control (sham operation; n=10); castration (n=10); castration, with alpha-tocopherol supplementation over preceding four weeks (n=10); and castration, with alpha-tocopherol supplementation over preceding four weeks and subsequent eight weeks (n=10). Activated caspase-3 was detected using a previously described technique, with analysis using stereological methodology. Nonparametric methods were used to test statistical significance, taking a significance level of P<0.005. This study was approved by the ethics committee of the university where the project was developed. The serum testosterone concentrations before castration were less than 20 pg/ml. Analysis of 8-isoprostane showed statistical significance (P<0.0003). The volumetric density of caspase-3 showed significant differences between the groups. There was no statistical significance regarding caspase-3 between sham and alpha-tocopherol plus castration or between the groups that received alpha-tocopherol supplementation. The observations showed that there was greater apoptosis in the group with castration alone than in the groups with alpha-tocopherol supplementation. This finding, together with the induced androgen deprivation and higher 8-isoprostane levels, corroborates the hypothesis that alpha-tocopherol supplementation has an important protective effect under conditions of oxidative stress, thereby avoiding the apoptotic process, especially regarding aging.

A potential protective effect of alpha-tocopherol on vascular complication in spinal cord reperfusion injury in rats

Background

Paraplegia remains a potential complication of spinal cord ischemic reperfusion injury (IRI) in which oxidative stress induced cyclooxygenase activities may contribute to ischemic neuronal damage. Prolonged administration of vitamin E (α-TOL), as a potent biological antioxidant, may have a protective role in this oxidative inflammatory ischemic cascade to reduce the incidence of paraplegia. The present study was designed to evaluate the preventive value of α-TOL in IRI of spinal cord.

Methods

For this study, 50 male Sprague-Dawley rats were used and divided into five experimental groups (n = 10): Control group (C); α-TOL control group (CE) which received intramuscular (i.m.) α-TOL injections (600 mg/kg); Sham operated group (S), IRI rats were subjected to laparotomy and clamping of the aorta just above the bifurcation for 45 min, then the clamp was released for 48 hrs for reperfusion; and IRIE rats group, received 600 mg/kg of α-TOL i.m. twice weekly for 6 weeks, followed by induction of IRI similar to the IRI group. At the end of the experimental protocol; motor, sensory and placing/stepping reflex evaluation was done. Plasma nitrite/nitrate (NOx) was measured. Then animals' spinal cord lumbar segments were harvested and homogenized for measurement of the levels of prostaglandin E₂ (PGE₂), malondialdehyde (MDA) and advanced oxidation products (AOPP), while superoxide dismutase (SOD) and catalase (CAT) activity were evaluated.

Results

Induction of IRI in rats resulted in significant increases in plasma levels of nitrite/nitrate (p < 0.001) and spinal cord homogenate levels of PGE₂, MDA, advanced oxidation protein products AOPP and SOD with significant reduction (p < 0.001) in CAT homogenate levels. Significant impairment of motor, sensory functions and placing/stepping reflex was observed with IRI induction in the spinal cord (p < 0.001). α-TOL administration in IRIE group significantly improved all the previously measured parameters compared with IRI group.

Conclusions

α-TOL administration significantly prevents the damage caused by spinal cord IRI in rats with subsequent recovery of both motor and sensory functions. Alpha-tocopherol improves the oxidative stress level with subsequent reduction of the incidence of neurological deficits due to spinal cord IRI conditions.

Effect of different periods of hyperbaric oxygen on ischemia-reperfusion injury of rat skeletal muscle

The effect of hyperbaric oxygen (HBO) on ischemia-reperfusion injury of skeletal muscle, applied during different periods, was studied in 56 male rats. Animals were subjected to 6-h ischemia by a tourniquet over the major femoral trocanter and 4 (A) or 24 (B) h of reperfusion. HBO was carried out during 1 h in an acrylic chamber at a pressure of 2.0 ATA (100% oxygen): in the last 60 min of ischemia (II), after ischemia, during 1-h reperfusion time (III), and during the last hour of ischemia plus 1-h reperfusion (IV). Group I was the control group. After 4- or 24-h reperfusion, samples of the soleus muscle were stained by H&E and analyzed immunohistochemically. No interstitial hemorrhage, neutrophil infiltrate, or cellular necrosis were induced by HBO. The apoptosis index did not differ among the groups. HBO reduced morphologic alterations and promoted better results when administered in the ischemia plus reperfusion period (GIV).