Long-term Effect of Telmisartan on Alzheimer's Amyloid Genesis in SHR-SR After tMCAO

Telmisartan is expected to reduce not only the level of blood pressure but also neuroinflammation and neurotoxicity via pleiotrophic effects as a metabo-sartan. We examined the effects of telmisartan on Alzheimer's disease (AD) pathology in spontaneously hypertensive rat stroke resistant (SHR-SR) after transient middle cerebral artery occlusion (tMCAO) by giving either telmisartan at 0 (vehicle), 0.3 mg/kg/day (low dose, with no reduction of blood pressure), or 3 mg/kg/day (high dose, with a significant reduction of blood pressure) p.o. from 3 months (M) of age, and performed immunohistological analysis at 6, 12, and 18 M of age. The numbers of amyloid beta (A beta)-positive neurons in the cerebral cortex and hippocampus and senile plaque (SP) in the ipsilateral cerebral cortex progressively increased with age until 18 M in the SHR-SR after tMCAO. On the other hand, low-dose telmisartan significantly reduced the number of A beta-positive neuron as well as SP at 6, 12, and 18 M. High-dose telmisartan showed further reductions of the above AD pathology. The present study suggests that telmisartan reduced both intracellular A beta and extracellular SP accumulations after tMCAO in SHR-SR, with a further improvement by combined BP lowering. Such a strong effect of telmisartan could provide a preventative approach for AD in post-stroke patients with hypertension.