Effects of exogenous vitamin D on endoplasmic reticulum stress-related factors in the vitamin D deficiency rats with cerebral ischemia

•Vitamin D deficiency aggravated cerebral ischemia.•The 25(OH)D level in brain tissue was related to cerebral ischemia.•It seemed that extracranial 25-VD3 level was not clearly related to cerebral ischemic stroke.•Relation between cerebral ischemia and vitamin D was associated with GRP78 and CHOP levels. We observed the potential neuroprotective effect of exogenous vitamin D on cerebral ischemia in vitamin D deficiency rats and explored its mechanism. Sixty Sprague Dawley rats were randomly divided into three groups including control (CON) group, vitamin D deficiency (VDD) group and vitamin D deficiency combined with exogenous vitamin D (VDD + VD) group, with 20 rats in each group. The rats in the CON group were fed with normal diet, while the rats in the VDD and VDD + VD groups with vitamin D-deficient diet for 8 weeks, and then underwent middle cerebral artery occlusion (MCAO). Six hours later, exogenous 25-hydroxyvitaminD (25-VD3) was intravenously injected into the rats of the VDD + VD group every 24 h for 4 times. Motor behaviors were significantly better and 25-VD3 level in the left brain tissue was significantly higher in the CON group than in the VDD and VDD + VD groups 102 h after MCAO (all P 0.05). GPR78 was significantly higher, but apoptosis and CHOP significantly lower in the VDD + VD group than in the VDD group (all P