Pretreated Oenan the Javanica extract increases anti-inflammatory cytokines, attenuates gliosis, and protects hippocampal neurons following transient global cerebral ischemia in gerbils

Recently,we have reported that Oenanthe javanica extract(OJE)displays strong neuroprotective effect against ischemic damage after transient global cerebral ischemia.However,neuroprotective mechanisms of OJE have not been fully identified.Thus,this study investigated the neuroprotection of OJE in the hippocampal CA1 area and its anti-inflammatory activity in gerbils subjected to 5 minutes of transient global cerebral ischemia.We treated the animals by intragastrical injection of OJE(100 and 200 mg/kg)once daily for 1 week prior to transient global cerebral ischemia.Neuroprotection of OJE was observed by immunohistochemistry for neuronal nuclear antigen and histofluorescence staining for Fluoro-Jade B.Immunohistochemistry of glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 was done for astrocytosis and microgliosis,respectively.To investigate the neuroprotective mechanisms of OJE,we performed immunohistochemistry of tumor necrosis factor-alpha and interleukin-2 for pro-inflammatory function and interleukin-4 and interleukin-13 for anti-inflammatory function.When we treated the animals by intragastrical administration of 200 mg/kg of OJE,hippocampal CA1 pyramidal neurons were protected from transient global cerebral ischemia and cerebral ischemia-induced gliosis was inhibited in the ischemic hippocampal CA1 area.We also found that interleukin-4 and-13 immunoreactivities were significantly increased in pyramidal neurons of the ischemic CA1 area after OJE pretreatment,and the increased immunoreactivities were sustained in the CA1 pyramidal neurons after transient global cerebral ischemia.However,OJE pretreatment did not increase interleukin-2 and tumor necrosis factor-alpha immunoreactivities in the CA1 pyramidal neurons.Our findings suggest that pretreatment with OJE can protect neurons and attenuate gliosis from transient global cerebral ischemia via increasing expressions of interleukin-4 and-13.The experimental plan of this study was reviewed and approved by the Institutional Animal Care and Use Committee(IACUC)in Kangwon National University(approval No.KW-160802-1)on August 10,2016.

Pretreated quercetin protects gerbil hippocampal CA1 pyramidal neurons from transient cerebral ischemic injury by increasing the expression of antioxidant enzymes

Quercetin（QE; 3,5,7,3′,4′-pentahydroxyflavone）, a well-known flavonoid, has been shown to prevent against neurodegenerative disorders and ischemic insults. However, few studies are reported regarding the neuroprotective mechanisms of QE after ischemic insults. Therefore, in this study, we investigated the effects of QE on ischemic injury and the expression of antioxidant enzymes in the hippocampal CA1 region of gerbils subjected to 5 minutes of transient cerebral ischemia. QE was pre-treated once daily for 15 days before ischemia. Pretreatment with QE protected hippocampal CA1 pyramidal neurons from ischemic injury, which was confirmed by neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B histofluorescence staining. In addition, pretreatment with QE significantly increased the expression levels of endogenous antioxidant enzymes Cu/Zn superoxide dismutase, Mn superoxide dismutase, catalase and glutathione peroxidase in the hippocampal CA1 pyramidal neurons of animals with ischemic injury. These findings demonstrate that pretreated QE displayed strong neuroprotective effects against transient cerebral ischemia by increasing the expression of antioxidant enzymes.

Ethanol extract of Oenanthe javanica increases cell proliferation and neuroblast differentiation in the adolescent rat dentate gyrus

Oenanthe javanica is an aquatic perennial herb that belongs to theOenanthe genus in Apiaceae family, and it displays well-known medicinal properties such as protective effects against glu-tamate-induced neurotoxicity. However, few studies regarding effects ofOenanthe javanica on neurogenesis in the brain have been reported. In this study, we examined the effects of a normal diet and a diet containing ethanol extract ofOenanthe javanica on cell proliferation and neu-roblast differentiation in the subgranular zone of the hippocampal dentate gyrus of adolescent rats using Ki-67 （an endogenous marker for cell proliferation） and doublecortin （a marker for neuroblast）. Our results showed thatOenanthe javanica extract signiifcantly increased the number of Ki-67-immunoreactive cells and doublecortin-immunoreactive neuroblasts in the subgranular zone of the dentate gyrus in the adolescent rats. In addition, the immunoreactivity of brain-derived neurotrophic factor was signiifcantly increased in the dentate gyrus of the Oenanthe javanica extract-treated group compared with the control group. However, we did not ifnd that vascular endothelial growth factor expression was increased in theOenanthe javanica extract-treated group compared with the control group. These results indicate thatOenanthe javanica extract improves cell proliferation and neuroblast differentiation by increasing brain-de-rived neurotrophic factor immunoreactivity in the rat dentate gyrus.

Neuronal injury and tumor necrosis factor-alpha immunoreactivity in the rat hippocampus in the early period of asphyxia-induced cardiac arrest under normothermia

Low survival rate occurs in patients who initially experience a spontaneous return of circulation after cardiac arrest（CA）. In this study, we induced asphyxial CA in adult male Sprague-Daley rats, maintained their body temperature at 37 ± 0.5°C, and then observed the survival rate during the post-resuscitation phase. We examined neuronal damage in the hippocampus using cresyl violet（CV） and Fluore-Jade B（F-J B） staining, and pro-inflammatory response using ionized calcium-binding adapter molecule 1（Iba-1）, glial fibrillary acidic protein（GFAP）, and tumor necrosis factor-alpha（TNF-α） immunohistochemistry in the hippocampus after asphyxial CA in rats under normothermia. Our results show that the survival rate decreased gradually post-CA（about 63% at 6 hours, 37% at 1 day, and 8% at 2 days post-CA）. Rats were sacrificed at these points in time post-CA, and no neuronal damage was found in the hippocampus until 1 day post-CA. However, some neurons in the stratum pyramidale of the CA region in the hippocampus were dead 2 days post-CA. Iba-1 immunoreactive microglia in the CA1 region did not change until 1 day postCA, and they were activated（enlarged cell bodies with short and thicken processes） in all layers 2 days postCA. Meanwhile, GFAP-immunoreactive astrocytes did not change significantly until 2 days post-CA. TNF-α immunoreactivity decreased significantly in neurons of the stratum pyramidale in the CA1 region 6 hours post-CA, decreased gradually until 1 day post-CA, and increased significantly again 2 days post-CA. These findings suggest that low survival rate of normothermic rats in the early period of asphyxia-induced CA is related to increased TNF-α immunoreactivity, but not to neuronal damage in the hippocampal CA1 region.

Neuroprotective effects of ischemic preconditioning on hippocampal CA1 pyramidal neurons through maintaining calbindin D28k immunoreactivity following subsequent transient cerebral ischemia

Ischemic preconditioning elicited by a non-fatal brief occlusion of blood flow has been applied for an experimental therapeutic strategy against a subsequent fatal ischemic insult. In this study, we investigated the neuroprotective effects of ischemic preconditioning（2-minute transient cerebral ischemia） on calbindin D28k immunoreactivity in the gerbil hippocampal CA1 area following a subsequent fatal transient ischemic insult（5-minute transient cerebral ischemia）. A large number of pyramidal neurons in the hippocampal CA1 area died 4 days after 5-minute transient cerebral ischemia. Ischemic preconditioning reduced the death of pyramidal neurons in the hippocampal CA1 area. Calbindin D28k immunoreactivity was greatly attenuated at 2 days after 5-minute transient cerebral ischemia and it was hardly detected at 5 days post-ischemia. Ischemic preconditioning maintained calbindin D28 k immunoreactivity after transient cerebral ischemia. These findings suggest that ischemic preconditioning can attenuate transient cerebral ischemia-caused damage to the pyramidal neurons in the hippocampal CA1 area through maintaining calbindin D28k immunoreactivity.

Delayed hippocampal neuronal death in young gerbil following transient global cerebral ischemia is related to higher and longer-term expression of p63 in the ischemic hippocampus

The tumor suppressor p63 is one of p53 family members and plays a vital role as a regulator of neuronal apoptosis in the development of the nervous system. However, the role of p63 in mature neuronal death has not been addressed yet. In this study, we first compared ischemia-induced effects on p63 expression in the hippocampal regions （CA1-3） between the young and adult gerbils subjected to 5 minutes of transient global cerebral ischemia. Neuronal death in the hippocampal CA1 region of young gerbils was significantly slow compared with that in the adult gerbils after transient global cerebral ischemia, p63 immunoreactivity in the hippocampal CA1 pyramidal neurons in the sham-operated young group was significantly low compared with that in the sham-operated adult group, p63 immunoreactivity was apparently changed in ischemic hippocampal CA1 pyramidal neurons in both ischemia-operated young and adult groups. In the ischemia-operated adult groups, p63 immunoreactivity in the hippocampal CA1 pyramidal neurons was significantly decreased at 4 days post-ischemia; however, p63 immunoreactivity in the ischemia-operated young group was significantly higher than that in the ischemia-operated adult group. At 7 days post-ischemia, p63 immunoreactivity was decreased in the hippocampal CA1 pyramidal neurons in both ischemia-operated young and adult groups. Change patterns of p63 level in the hippocampal CA1 region of adult and young gerbils after ischemic damage were similar to those observed in the immunohistochemical results. These findings indicate that higher and longer-term expression of p63 in the hippocampal CA1 region of the young gerbils after ischemia/reperfusion may be related to more delayed neuronal death compared to that in the adults.

Effect of ischemic preconditioning on antioxidant status in the gerbil hippocampal CA1 region after transient forebrain ischemia

Ischemic preconditioning（IPC） is a condition of sublethal transient global ischemia and exhibits neuroprotective effects against subsequent lethal ischemic insult.We,in this study,examined the neuroprotective effects of IPC and its effects on immunoreactive changes of antioxidant enzymes including superoxide dismutase（SOD） 1 and SOD2,catalase（CAT） and glutathione peroxidase（GPX） in the gerbil hippocampal CA1 region after transient forebrain ischemia.Pyramidal neurons of the stratum pyramidale（SP） in the hippocampal CA1 region of animals died 5 days after lethal transient ischemia without IPC（8.6%（ratio of remanent neurons） of the sham-operated group）;however,IPC prevented the pyramidal neurons from subsequent lethal ischemic injury（92.3%（ratio of remanent neurons） of the sham-operated group）.SOD1,SOD2,CAT and GPX immunoreactivities in the sham-operated animals were easily detected in pyramidal neurons in the stratum pyramidale（SP） of the hippocampal CA1 region,while all of these immunoreactivities were rarely detected in the stratum pyramidale at 5 days after lethal transient ischemia without IPC.Meanwhile,their immunoreactivities in the sham-operated animals with IPC were similar to（SOD1,SOD2 and CAT） or higher（GPX） than those in the sham-operated animals without IPC.Furthermore,their immunoreactivities in the stratum pyramidale of the ischemia-operated animals with IPC were steadily maintained after lethal ischemia/reperfusion.Results of western blot analysis for SOD1,SOD2,CAT and GPX were similar to immunohistochemical data.In conclusion,IPC maintained or increased the expression of antioxidant enzymes in the stratum pyramidale of the hippocampal CA1 region after subsequent lethal transient forebrain ischemia and IPC exhibited neuroprotective effects in the hippocampal CA1 region against transient forebrain ischemia.

Monocarboxylate transporter 4 plays a significant role in the neuroprotective mechanism of ischemic preconditioning in transient cerebral ischemia

Monocarboxylate transporters（MCTs）, which carry monocarboxylates such as lactate across biological membranes, have been associated with cerebral ischemia/reperfusion process. In this study, we studied the effect of ischemic preconditioning（IPC） on MCT4 immunoreactivity after 5 minutes of transient cerebral ischemia in the gerbil. Animals were randomly designated to four groups（sham-operated group, ischemia only group, IPC ＋ sham-operated group and IPC ＋ ischemia group）. A serious loss of neuron was found in the stratum pyramidale of the hippocampal CA1 region（CA1）, not CA2/3, of the ischemia-only group at 5 days post-ischemia; however, in the IPC ＋ ischemia groups, neurons in the stratum pyramidale of the CA1 were well protected. Weak MCT4 immunoreactivity was found in the stratum pyramidale of the CA1 in the sham-operated group. MCT4 immunoreactivity in the stratum pyramidale began to decrease at 2 days post-ischemia and was hardly detected at 5 days post-ischemia; at this time point, MCT4 immunoreactivity was newly expressed in astrocytes. In the IPC ＋ sham-operated group, MCT4 immunoreactivity in the stratum pyramidale of the CA1 was increased compared with the sham-operated group, and, in the IPC ＋ ischemia group, MCT4 immunoreactivity was also increased in the stratum pyramidale compared with the ischemia only group. Briefly, present findings show that IPC apparently protected CA1 pyramidal neurons and increased or maintained MCT4 expression in the stratum pyramidale of the CA1 after transient cerebral ischemia. Our findings suggest that MCT4 appears to play a significant role in the neuroprotective mechanism of IPC in the gerbil with transient cerebral ischemia.

Pretreated Glehnia littoralis Extract Prevents Neuronal Death Following Transient Global Cerebral Ischemia through Increases of Superoxide Dismutase 1 and Brain-derived Neurotrophic Factor Expressions in the Gerbil Hippocampal Cornu Ammonis 1 Area

Background：Glehnia littoralis,as a traditional herbal medicine to heal various health ailments in East Asia,displays various therapeutic properties including antioxidant effects.However,neuroprotective effects of G.littoralis against cerebral ischemic insults have not yet been addressed.Therefore,in this study,we first examined its neuroprotective effects in the hippocampus using a gerbil model of transient global cerebral ischemia （TGCI）.Methods：Gerbils were subjected to TGCI for 5 min.G.littoralis extract （GLE;100 and 200 mg/kg） was administrated orally once daily for 7 days before ischemic surgery.Neuroprotection was examined by neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B histofluorescence staining.Gliosis was observed by immunohistochemistry for glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1.For neuroprotective mechanisms,immunohistochemistry for superoxide dismutase （SOD） 1 and brain-derived neurotrophic factor （BDNF） was done.Results：Pretreatment with 200 mg/kg of GLE protected pyramidal neurons in the cornu ammonis 1 （CA1） area from ischemic insult area （F=29.770,P 〈 0.05） and significantly inhibited activationsof astrocytes （F =22.959,P 〈 0.05） and microglia （F =44.135,P 〈 0.05） in the ischemic CA1 area.In addition,pretreatment with GLE significantly increased expressions of SOD1 （F =28.561,P 〈 0.05） and BDNF （F =55.298,P 〈 0.05） in CA1 pyramidal neurons of the sham-and ischemia-operated groups.Conclusions：Our findings indicate that pretreatment with GLE can protect neurons from ischemic insults,and we suggest that its neuroprotective mechanism may be closely associated with increases of SOD 1 and BDNF expressions as well as attenuation ofglial activation.

Glehnia fittoralis Extract Promotes Neurogenesis in the Hippocampal Dentate Gyrus of the Adult Mouse through Increasing Expressions of Brain-Derived Neurotrophic Factor and Tropomyosin-Related Kinase B

Background： Glehnia littoralis has been used for traditional Asian medicine, which has diverse therapeutic activities. However, studies regarding neurogenic effects of G. littoralis have not yet been considered. Therefore, in this study, we examined effects of G. littoralis extract on cell proliferation, neuroblast differentiation, and the maturation of newborn neurons in the hippocampus of adult mice. Methods： A total of 39 male ICR mice （12 weeks old） were randomly assigned to vehicle-treated and 100 and 200 mg/kg G. littoralis extract-treated groups （n = 13 in each group）. Vehicle and G. littoralis extract were orally administrated for 28 days. To examine neurogenic effects ofG. litmralis extract, we performed immunohistochemistry tbr 5-bromo-2-deoxyuridine （BrdU, an indicator for cell proliferation） and doublecortin （DCX, an immature neuronal marker） and double immunofluorescence staining for BrdU and neuronal nuclear antigen （NeuN, a mature neuronal marker）. In addition, we examined expressional changes of brain-derived neurotrophic factor （BDNF） and its major receptor tropomyosin-related kinase B （TrkB） using Western blotting analysis. Results： Treatment with 200 mg/kg, not 100 mg/kg, significantly increased number of BrdU-immunoreactive （＋） and DCX＋ cells （48.0 ±3.1and 72.0 ± 3.8 cells/section, respectively） in the subgranular zone （SGZ） of the dentate gyrus （DG） and BrdU＊/NeuN＋ cells （17.0 ±1.5 cells/section） in the granule cell layer as well as in the SGZ. In addition, protein levels of BDNF and YrkB （about 232% and 244% of the vehicle-treated group, respectively） were significantly increased in the DG of the mice treated with 200 mg/kg ofG. littoralis extract. Conclusion： G. littoralis extract promots cell proliferation, neuroblast differentiation, and neuronal maturation in the hippocampal DG, and neurogenic effects might be closely related to increases ofBDN F and TrkB proteins by G. littoralis extract treatment.

Oenanthe Javanica Extract Protects Against Experimentally Induced Ischemic Neuronal Damage via its Antioxidant Effects

Background： Water dropwort （Oenanthejavanica） as a popular traditional medicine in Asia shows various biological properties including antioxidant activity. In this study, we firstly examined the neuroprotective effect of Oenanthejavanica extract （OJE） in the hippocampal comus ammonis 1 region （CA 1 region） of the gerbil subjected to transient cerebral ischemia. Methods： Gerbils were established by the occlusion of common carotid arteries for 5 min. The neuroprotective effect of OJE was estimated by cresyl violet staining. In addition, 4 antioxidants （copper, zinc superoxide dismutase [SOD], manganese SOD, catalase, and glutathione peroxidase） immunoreactivities were investigated by immunohistochemistry. Results： Pyramidal neurons in the CA1 region showed neuronal death at 5 days postischemia; at this point in time, all antioxidants immunoreactivities disappeared in CA1 pyramidal neurons and showed 100 mg/kg, OJE protected CA 1 pyramidal neurons from ischemic damage in many nonpyramidal cells. Treatment with 200 mg/kg, not In addition, 200 mg/kg OJE treatment increased or maintained antioxidants immunoreactivities. Especially, among the antioxidants, glutathione peroxidase immunoreactivity was effectively increased in the CA 1 pyramidal neurons of the OJE-treated sham-operated and ischemia-operated groups. Conclusion： Our present results indicate that treatment with OJE can protect neurons from transient ischemic damage and that the neuroprotective effect may be closely associated with increased or maintained intracellular antioxidant enzymes by OJE.