The Neuroprotective Effects Of Kukoamine A On Radiation Brain Injury Of Rats And Its Possible Mechanisms

Objective:Kukoamine A(KuA)is a pure-spermine alkaloid extracted from the traditional Chinese herb cortex lycii radicis.We previously reported that KuA could inhibit oxidative stress and apoptosis both in vitro and in vivo.Additionally,KuA could alleviate the inflammatory response in X-ray irradiated BV-2 cells.Based on these results,the aim of this study was to investigate whether KuA would prevent radiation-induced brain injury(RIBI)of rats and its possible mechanisms.Methods:For this study,male Wistar rats were received either sham irradiation or whole brain irradiation(30 Gy single dose of X-rays)followed by the immediate injection of either KuA or vehicle intravenously.The dose of KuA was 5,10 and 20 mg/kg respectively.The protective effects of KuA were assessed by Nissl staining.The levels of oxidative stress marker and antioxidants activities were assayed by kits.TUNEL staining was performed to detect the level of apoptosis in hippocampal neurons.The expression of apoptosis-related proteins as well as the brain-derived neurophic factor(BDNF)was evaluated by western blot.The levels of proinflammatory cytokines were assayed by ELISA kits.The newborn neurons were detected by bromodeoxyuridine(BrdU)/neuronal nuclei(NeuN)double immunofluorescence.Microglial activation was measured by Iba-1 immunofluorescence.The expression of COX-2 as well as NF-κB,AP-1,CREB and PPARδ were evaluated by western blot.Results:WBI led to the neuronal abnormality and it was alleviated by KuA.KuA decreased malondialdehyde(MDA)level,increased glutathione(GSH)level,superoxide dismutase(SOD)and catalase(CAT)activities,as well as alleviated neuronal apoptosis by regulating the expression of cleaved caspase-3,cytochrome C,Bax and Bcl-2.WBI led to a significant increase in the level of TNF-α,IL-1β and COX-2 and it was alleviated by KuA administration.KuA attenuated microglial activation in rat hippocampus after WBI.Neurogenesis impairment induced by WBI was ameliorated by KuA.Additionally,KuA alleviated the increased translocation of NF-κB p65 subunit and phosphorylation of c-jun induced by WBI,and elevated the expression of PPARδ.Additionally,KuA increased the expression of BDNF and p-CREB after WBI.Conclusions:These data indicate that KuA has neuroprotective effects against RIBI through inhibiting neuronal oxidative stress and apoptosis.KuA could ameliorate the neuroinflammatory response and protect neurogenesis after WBI,partially through regulating the expression of NF-κB,AP-1 and PPARδ.Thus,KuA could be further investigated as a potential agent for radio-neuroprotection.