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.

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.