Inhibited Expression of α4β2 Nicotinic Acetylcholine Receptor in Blood Leukocytes of Chinese Patients with Vascular Dementia and in Blood Leukocytes as Well as the Hippocampus of Brain from Ischemic…

Yan Xiao, Liang Zhao, Shi-Xiang Kuang, Zhi-Zhong Guan

Our present aim was to investigate whether changes in the expression of α4β2 nicotinic acetylcholine receptor (nAChR) in patients with vascular dementia (VaD) and ischemic rats are related to cognitive scores. Blood leukocytes for 59 Chinese patients with VaD (diagnosed on the basis of clinical guidelines) and 31 cases as age-matched controls were examined, and the animal model established employing Pulsinelli's four-vessel occlusion. The levels of α4 and β2 subunit mRNA in leukocytes and the hippocampus were analyzed by real-time PCR, and the protein level in the hippocampus by Western blotting. The mini-mental state examination was utilized to characterize the intellectual capacity of the patients with reference to the DSM IV diagnosis and Hachinski Ischemic Scale score, and the Morris Water Maze test to assess the ability of learning and memory of the rats. In patients, the level of α4 mRNA, but not β2, in blood leukocytes was clearly lowered, which was significantly correlated to their clinical cognitive test scores. Smoking exerted no impact on the level of α4 mRNA in the present study. In the blood leukocytes and the hippocampus of the brains of the ischemic rats, the levels of both α4 and β2 mRNA were lowered, and the proteins of these subunits in the hippocampus were decreased. The changes of α4 and β2 mRNA in blood leukocytes, and their protein levels in the hippocampus were significantly correlated with impaired learning and memory. These findings indicate that alterations in expression of the α4β2 subtype of nAChR may be involved in the molecular mechanism(s) underlying the cognitive deficit associated with VaD.