Cornel iridoid glycoside protects against white matter lesions induced by cerebral ischemia via activation of neuregulin-1 pathway in rats

Ischemic stroke often elicits profound white matter lesions, which results in poor neurological outcomes and impairing the recovery in post-stroke. However, few studies have focused on white matter lesions caused by cerebral ischemia. The present study was aimed to investigate the effects of cornel iridoid glycoside(CIG), a main active component extracted from Cornus officinalis, on the white matter injury induced by ischemic stroke. CIG(60 and 120 mg·kg~(-1)) were administered intragastrically 6 h after middle cerebral artery occlusion reperfusion(MCAO) surgery once a day for 7 d. A series of behavioral tests were carried out to evaluate the neurological function of MCAO rats. White matter structure was detected by luxol fast blue staining and transmission electron microscopy. Immunohistochemical staining was used to assess myelin loss, oligodendrocytes maturation and glial activation. Results showed that CIG remarkably decreased neurological deficit score, accelerated the recovery of somatosensory and motor functions, and ameliorated the memory deficit in MCAO rats. CIG alleviated white matter lesions and demyelination, increased myelin basic protein expression and the number of mature oligodendrocytes in the corpus callosum of MCAO rats. Besides, CIG inhibited the activation of microglia and astrocytes. Further data obtained by western blot analysis indicated that CIG increased the expression of brain-derived neurotrophic factor(BDNF)/p-Trk B, neuregulin-1/Erb B, and PI3 K p110α/p-Akt/p-m TOR in the corpus callosum of MCAO rats. Our findings demonstrated that CIG protected against white matter lesions induced by cerebral ischemia and the mechanisms were partially contributed to increasing BDNF and activating neuregulin-1/Erb B signaling and its downstream PI3 K/Akt/m TOR pathway in white matter.