Hepatocyte growth factor improved learning and memory dysfunction of microsphere‐embolized rats

Hepatocyte growth factor (HGF), an organotropic factor for regeneration and protection in various organs, has the ability to attenuate cerebral ischemia‐induced cell death. The effect of HGF on learning and memory function after cerebral ischemia, however, remains unknown. We have demonstrated that administration of human recombinant HGF (hrHGF) into the ventricle reduced prolongation of the escape latency in acquisition and retention tests of the water maze task on Days 12–28 after microsphere embolism‐induced cerebral ischemia. Treatment with hrHGF also attenuated the decrease in viable area and the density and number of perfused cerebral vessels, particularly those with a diameter smaller than 10 μm, of the ipsilateral hemisphere on Day 28 after the cerebral ischemia. We observed that treatment with hrHGF reduced the number of TUNEL‐positive cerebral endothelial cells at the early stage after the ischemia. These results suggest that hrHGF prevents learning and memory dysfunction seen after sustained cerebral ischemia by protecting against injury to the endothelial cells. HGF treatment may be a potent therapeutic strategy for cerebrovascular diseases, including cerebral infarct and vascular dementia. © 2004 Wiley‐Liss, Inc.