Extract EGb 761 Pretreatment Limits Ubiquitin Positive Aggregates in Rabbit Spinal Cord Neurons after Ischemia-Reperfusion

TiO2-Nanowired Delivery of Chinese Extract of Ginkgo biloba EGb-761 and Bilobalide BN-52021 Enhanced Neuroprotective Effects of Cerebrolysin Following Spinal Cord Injury at Cold Environment

Military personnel during combat or peacekeeping operations are exposed to extreme climates of hot or cold environments for longer durations. Spinal cord injury is quite common in military personnel following central nervous system (CNS) trauma indicating a possibility of altered pathophysiological responses at different ambient temperatures. Our previous studies show that the pathophysiology of brain injury is exacerbated in animals acclimated to cold (5 °C) or hot (30 °C) environments. In these diverse ambient temperature zones, trauma exacerbated oxidative stress generation inducing greater blood-brain barrier (BBB) permeability and cell damage. Extracts of Ginkgo biloba EGb-761 and BN-52021 treatment reduces brain pathology following heat stress. This effect is further improved following TiO₂ nanowired delivery in heat stress in animal models. Several studies indicate the role of EGb-761 in attenuating spinal cord induced neuronal damages and improved functional deficit. This is quite likely that these effects are further improved following nanowired delivery of EGb-761 and BN-52021 with cerebrolysin-a balanced composition of several neurotrophic factors and peptide fragments in spinal cord trauma. In this review, TiO₂ nanowired delivery of EGb-761 and BN-52021 with nanowired cerebrolysin is examined in a rat model of spinal cord injury at cold environment. Our results show that spinal cord injury aggravates cord pathology in cold-acclimated rats and nanowired delivery of EGb-761 and BN-52021 with cerebrolysin significantly induced superior neuroprotection, not reported earlier.

Bradykinin and noradrenaline preconditioning influences level of antioxidant enzymes SOD, CuZn-SOD, Mn-SOD and catalase in the white matter of spinal cord in rabbits after ischemia/reperfusion

The aim of present work is to assess the effects of bradykinin (Br) or noradrenaline (Nor) preconditioning to the levels of antioxidant enzymes: superoxide dismutase (SOD), copper, zinc superoxide dismutase (CuZn-SOD), manganese superoxide dismutase (Mn-SOD) and catalase in ischemia/reperfusion (I/R) model in the rabbit spinal cord white matter as well as effect on glial fibrillary acidic protein (GFAP) and ubiquitin immunoreaction in glial cells. Rabbits were preconditioned by intraperitoneal single dose of Br or Nor 48 h prior to 20 min of ischemia followed by 24 or 48 h of reperfusion. White matter of L3-L6 spinal cord segments was used for comparison of antioxidant enzyme levels in sham control, ischemic groups and four preconditioned groups. The total SOD level in the Br or Nor preconditioned groups after 48 h of reperfusion was increased vs Br or Nor preconditioned groups after 24 h of reperfusion. The comparison among the ischemic group vs Br preconditioned (P<0.05), and Nor preconditioned (P<0.001) groups after 48 h of reperfusion, showed statistically significant decrease of Mn-SOD activity. Tissue catalase level activity was significantly decreased in the Br preconditioned group after 48 h of reperfusion (P<0.05) and Nor preconditioned groups after 24 h of reperfusion (P<0.001) and also after 48 h of reperfusion (P<0.001), in comparison to ischemic group after 48 h of reperfusion. Significantly decreased tissue catalase activity (P<0.05) in both Nor preconditioned groups after 24 or 48 h of reperfusion was measured vs Br preconditioned group after 48 h of reperfusion. According to our results, in the white matter, activation of stress proteins in glial cells, as well as antioxidant enzymes levels, were influenced by pharmacological preconditioning followed by 20 min of ischemia and 24 or 48 h of reperfusion. These changes contribute to ischemic tolerance acquisition and tissue protection from oxidative stress during reperfusion period.

Ubiquitin and endogenous antioxidant enzymes participate in neuroprotection of the rabbit spinal cord after ischemia and bradykinin postconditioning

The aim of this study was to investigate neuroprotective effect of bradykinin postconditioning on the rabbit spinal cord after 20 min of ischemia and 3 days of reperfusion. Bradykinin was administered by single i.p. application at 1, 6, 12 or 24 h after ischemia. Assessment of neurological function of hind limbs (Tarlov score) was estimated. Quantitative analysis was evaluated by Fluoro Jade B method, NeuN and ubiquitin immunohistochemistry in anterior horn neurons of the spinal cord. Histomorphologically distribution of ubiquitin and endogenous antioxidant enzymes (SOD1, SOD2, catalase) immunoreaction was described. Bradykinin postconditioning showed decreased number of degenerated neurons, increased number of surviving neurons and increase in number of ubiquitin positive neurons in all bradykinin postconditioned groups versus ischemia/reperfusion group. According to our results bradykinin postconditioning applied 24 h after ischemia significantly decreased (p < 0.001) number of degenerated neurons versus ischemia/reperfusion group. The least effective time window for bradykinin postconditioning was at 12 h after ischemia. Tarlov score was significantly improved (p < 0.05) in groups with bradykinin postconditioning applied 1, 6 or 24 h after ischemia versus ischemia/reperfusion group. Tarlov score in group with bradykinin application 12 h after ischemia was significantly decreased (p < 0.05) versus sham control group. Neuronal immunoreaction of ubiquitin, SOD1, SOD2 and catalase influenced by bradykinin postconditioning was dependent on neuronal survival or degeneration. In conclusion, bradykinin postconditioning showed protective effect on neurons in anterior horns of the rabbit spinal cord and improved motor function of hind limbs.

Bradykinin preconditioning affects the number of degenerated neurons and the level of antioxidant enzymes in spinal cord ischemia in rabbits

Bradykinin preconditioning has been used for acquisition of tolerance after spinal cord ischemia. Rabbits were preconditioned intraperitoneally with bradykinin 48 h prior to 20 min of abdominal aorta ligation followed by 24 and 48 h of reperfusion. The activities of SOD and catalase were measured and Fluoro Jade B (FJB)-positive degenerated neurons were evaluated. The outcomes of Tarlov scoring system used to assess neurological functions showed significant improvement in bradykinin groups compared to the ischemic group. The number of FJB-positive degenerated neurons was decreased in ventral horns of both bradykinin groups. Significantly decreased activities of total SOD and mitochondrial Mn-SOD were also detected in both bradykinin groups versus ischemic group while CuZn-SOD and catalase activities were significantly decreased only in the bradykinin group after 24h of reperfusion versus ischemic group. These findings suggest that one of the possibilities of the neuroprotective effect of delayed bradykinin preconditioning against spinal cord ischemic injury could be realized by mitochondrial protection and decreased synthesis of Mn-SOD as well as by promotion of neuronal survival.

Effect of noradrenalin and EGb 761 pretreatment on the ischemia-reperfusion injured spinal cord neurons in rabbits

Short term sublethal ischemia or ischemic preconditioning gives protection to the neurons against subsequent lethal ischemic attack. This so-called ischemic tolerance can also be provided by certain drugs. We examined the effect of noradrenalin and EGb 761 on the spinal cord neurons injured by 30 min occlusion of abdominal aorta in rabbits. The animals survived 48 and 72 h. Degenerated neurons were visualized by Fluoro Jade B method, viable neurons were demonstrated immunohistochemically with NeuN and ubiquitin antibodies. The rabbits with noradrenalin administration 48 h before 30 min of ischemia and 48/72 h of reperfusion, showed significant increase of degenerated Fluoro Jade B labeled neurons. Animals of both groups were paraplegic. Rabbits pretreated 7 days with EGb 761 prior to 30 min of ischemia and with 48/72 h of reperfusion revealed significant decrease of Fluoro Jade B-positive neurons when compared with the groups with 30 min of ischemia followed by 48/72 h of reperfusion. In the NeuN sections, the number of viable neurons was moderately decreased. These animals showed no paraplegia. Ubiquitin aggregates occurred in the cytoplasm of degenerated neurons in the sections of rabbits preconditioned with noradrenalin 48 h prior to 30 min of ischemia and followed by 48 h of reperfusion while after 72 h of reperfusion, shrunk light shadows without ubiquitin reaction were visible. Our results indicate that EGb 761 could be involved in protection of spinal cord neurons against ischemic injury while effect of noradrenalin is not unambiguous.