ABSTRACT
<p><b>BACKGROUND</b>Alzheimer's disease (AD) is a neurodegenerative disorder and the leading cause of dementia in the elderly. The two hallmark lesions in AD brain are deposition of amyloid plaques and neurofibrillary tangles (NFTs). Hypercholesteremia is one of the risk factors of AD. But its role in the pathogenesis of AD is largely unknown. The aim of this study was to investigate the relationship between hypercholesteremia and tau phosphorylation or beta-amyloid (Abeta), and evaluate the effect of atorvastatin on the level of tau phosphorylation and Abeta in the brains of rats fed with high cholesterol diet.</p><p><b>METHODS</b>Sprague-Dawley (SD) rats were randomly divided into normal diet control group, high cholesterol diet group, and high cholesterol diet plus atorvastatin (Lipitor, 15 mg x kg(-1) x d(-1)) treated group. Blood from caudal vein was collected to measure total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL) and high-density lipoprotein (HDL) at the end of the 3rd and the 6th months by an enzymatic method. The animals were sacrificed 6 months later and brains were removed. All left brain hemispheres were fixed for immunohistochemistry. Hippocampus and cerebral cortex were separated from right hemispheres and homogenized separately. Tau phosphorylation and Abeta in the brain tissue were determined by Western blotting (using antibodies PHF-1 and Tau-1) and anti-Abeta40/anti-Abeta42, respectively.</p><p><b>RESULTS</b>We found that high cholesterol diet led to hypercholesteremia of rats as well as hyperphosphorylation of tau and increased Abeta level in the brains. Treatment of the high cholesterol diet fed rats with atorvastatin prevented the changes of both tau phosphorylation and Abeta level induced by high cholesterol diet.</p><p><b>CONCLUSIONS</b>Hypercholesteremia could induce tau hyperphosphorylation and Abeta production in rat brain. Atorvastatin could inhibit tau hyperphosphorylation and decrease Abeta generation. It may play a protective role in the patho-process of hypercholesteremia-induced neurodegeneration in the brain.</p>
Subject(s)
Animals , Male , Rats , Administration, Oral , Amyloid beta-Peptides , Metabolism , Antibodies, Monoclonal , Atorvastatin , Blotting, Western , Brain , Metabolism , Enzyme-Linked Immunosorbent Assay , Heptanoic Acids , Pharmacology , Therapeutic Uses , Immunohistochemistry , Phosphorylation , Pyrroles , Pharmacology , Therapeutic Uses , Rats, Sprague-Dawley , tau Proteins , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To examine the effect of estrogen on the expressions of phosphorylated Tau (P-Tau), ChAT and nerve growth factor (NGF) protein in the brain tissue of rat models of Alzheimer disease (AD).</p><p><b>METHODS</b>Rat models of AD were established by injecting Aβ1-42 protein fragments in the right lateral ventricle. Two weeks later, 17β-estradiol tablets were implanted subcutaneously at the neck of the rats and maintained for 30 days. The pathological changes in the rats' brain neurons and alterations in the expressions of P-Tau, ChAT and NGF proteins were observed using HE staining and immunohistochemistry, respectively.</p><p><b>RESULTS</b>In the AD rats, neurofibrillary tangles occurred in the brain tissue, and estrogen treatment significantly reduced the formation of neurofibrillary tangles. Estrogen treatment also resulted in lowered P-Tau expression and increased ChAT and NGF protein expressions in comparison with those in the AD model rats.</p><p><b>CONCLUSION</b>Estrogen can up-regulate ChAT and NGF and down-regulate tau protein expression, thus producing obvious therapeutic effect on AD in rats.</p>
Subject(s)
Animals , Male , Rats , Alzheimer Disease , Metabolism , Pathology , Brain , Metabolism , Disease Models, Animal , Estradiol , Pharmacology , Nerve Growth Factors , Metabolism , Neurons , Metabolism , Phosphorylation , Rats, Sprague-Dawley , tau Proteins , MetabolismABSTRACT
Objective To investigate the relationship of folates,vitamin B_(12) with tan phosphorylation and the possible mechanism in Alzhcimer's disease (AD).Method Tau protein phosphorylation was examined in hippocampns of rats of two months old and forty months old treated or untreated by folates and vitamin B_(12) using Western blot and immunohistochemistry with phosphorylation dependent and independent tau antibodies.Results We found that tau phosphorylation in aged rat brain showed a significant higher level than that in the two-month olds.Folates combined with vitamin.B_(12) could decrease tau phosphorylation by 27% at the site of Ser396/404 of hippoeampus in aged rats.Conclusion It suggests folates and vitamin B_(12) may play an important role in preventing the neurodegenerative change via effeeting tau phosphorylation in AD brain.