BACKGROUND: Following ischemia, apoptosis is observed at the ipsilateral ventroposterior thalamic nucleus and substantia nigra, which are distant from, but connected to, the ischemic cerebral cortex, in animals with normotension. However, secondary brain damage in hypertension has not been clearly investigated. OBJECTIVE: The present study determined whether neuronal apoptosis is associated with neuronal loss in the ipsilateral ventroposterior thalamic nucleus and substantia nigra following cortical ischemia in adult hypertensive rats. Results should provide options for determining a time window for anti-apoptotic therapy. DESIGN, TIME AND SETTING: All experimental procedures in this randomized, controlled trial were conducted at the Neurological Laboratory of the First Affiliated Hospital of Sun Yat-sen University of China between October 2006 and July 2008.MATERIALS: Monoclonal primary antibodies specific to mouse anti-rat microtubule-associated protein 2 and glial fibrillary acidic protein were respectively purchased from Sigma Chemical, USA and BD Pharmingen, USA. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling (TUNEL) detection kits were purchased from Roche Applied Science, Switzerland and Upstate, USA, respectively.METHODS: A total of 64 male, Sprague Dawley rats, aged 60-90 days, were equally and randomly divided into middle cerebral artery occlusion and sham surgery groups. Renovascular hypertension was established in both groups by renal artery occlusion. Right distal middle cerebral artery occlusion was performed by electrocoagulation in the middle cerebral artery occlusion group. MAIN OUTCOME MEASURES: Microtubule-associated protein 2 and glial fibrillary acidic protein were detected by immunohistochemistry, and apoptotic cells were observed by TUNEL assay. The stainings were separately detected in the ipsilateral ventroposterior thalamic nucleus and substantia nigra.RESULTS: During the 4 weeks following distal middle cerebral artery occlusion in renovascular hypertensive rats, microtubule-associated protein 2 expression gradually, but significantly, decreased (P < 0.05). Expression of glial fibrillary acidic protein increased significantly in the ipsilateral ventroposterior thalamic nucleus and substantia nigra (P < 0.05) and reached a peak at 4 weeks. In addition, number of apoptotic cells was significantly increased in both areas compared with the sham controls (P < 0.05), with a peak at 2 weeks.CONCLUSION: Results suggested that neuronal loss in the ipsilateral ventroposterior thalamic nucleus and substantia nigra following distal middle cerebral artery occlusion in hypertensive rats could be a secondary event resulting from apoptosis. The temporal apoptosis profile provides options for determining a time window for anti-apoptotic therapy at 2 weeks after stroke.