Effect of Cold Irritation on Peripheral White Blood Cells and ICAM-1, IL-1β Expression in Brain Tissue of Rat

Abstract

Background Some studies have shown that hypothermia is a neuroprotective factor for cerebral ischemic injury. The inflammation reaction plays a very important role in the pathomechanisms of neuron degeneration induced by cerebral ischemia. It is not known whether there is a relationship between cold irritation and inflammation reaction. Goals To explore the effect of cold irritation on peripheral white blood cells and intercellular adhesion molecule-1 (ICAM-1), interleukin-1 (IL-1) β expression in brain tissue of rat with cerebral ischemia. Methods Model rats were put into low temperature water (0°C) for cold irritation for 5 minutes once every day for 20 days. Rats were subjected to middle cerebral artery occlusion using an intraluminal suture method with permanent ligation of the ipsilateral common carotid artery. We assessed count of the peripheral white blood cells. The brains of all rats were cut at 1, 3, and 5 days after cerebral ischemia and the frozen brain tissues were continuously sliced and stained immunohistochemically with ICAM-1 or IL-1 antibody. Results Cold irritation model rats were associated with increased leukocyte at 1 and 3 days postischemia, increased ICAM-1-positive vessels at 1, 3, and 5 days, and increased IL-1 at 3 and 5 days. Vascular pathology of the hippocampus at electron microscopic levels showed that the blood vessels had inflammation infiltration at 1, 3, and 5 days. Conclusions These data show that cold irritation significantly increased endothelial adhesion molecular expression, leukocyte infiltration, and vascular pathology of the hippocampus in rats, and the mechanism of neuron injury may be related with the inflammation reaction induced by cold irritation.