General Anesthesia and Alzheimer's Disease Neuropathogenesis

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DESCRIPTION (provided by applicant): Several studies have suggested that Alzheimer's disease (AD), one of the most common forms of dementia, might be facilitated by anesthesia and surgery. Our recent research showed that the commonly used inhalational anesthetic isoflurane could induce caspase activation and apoptosis, which in turn increases generation of amyloid 2-protein (A2), the key component of senile plaques in AD patients. These findings could have potential clinical importance since increased A2 generation and apoptosis by anesthesia could conceivably serve to trigger or exacerbate the development of AD. However, the up-stream underlying mechanisms and the down-stream consequences of the isoflurane- induced apoptosis and A2 generation (apoptosis/A2 generation) remain largely unknown. Consistent with the notions that excessive calcium can trigger or contribute to apoptosis and isoflurane can affect synaptic function, our preliminary studies have shown that isoflurane can 1) induce apoptosis/A2 generation, 2) enhance cytosolic calcium levels, and 3) reduce surface NMDA receptors in cortical neurons of naove mice. Thus, our main hypothesis is that isoflurane enhances cytosolic calcium levels to induce apoptosis/A2 generation, leading to synaptic NMDA receptor endocytosis. We will employ chemical and genetic tools through both in vitro and in vivo approaches to accomplish three Specific Aims: 1) to characterize effects of isoflurane on apoptosis/A2 generation; 2) to define whether the alterations in cytosolic calcium levels are associated with isoflurane-induced apoptosis/A2 generation; and 3) to determine the effects of isoflurane on synaptic NMDA receptor endocytosis. The proposed research aims to extend our recent findings that isoflurane induces apoptosis/A2 generation to further determine the underlying mechanisms and their effects on synaptic NMDA receptor endocytosis. The data generated in this project would provide novel information regarding the mechanisms of isoflurane- induced apoptosis/A2 generation and their contribution to the impairment of NMDA receptor-mediated synaptic function. The results of this study may ultimately guide researchers and clinicians to design safer anesthetics and to provide better anesthesia care for patients, particularly senior and AD patients. PUBLIC HEALTH RELEVANCE: Our recent research showed that anesthetic isoflurane induces apoptosis and increases the generation of amyloid-2 protein (A2). In the proposed research we will further characterize these effects and determine their up-stream mechanisms and down-stream consequences.