Cellular and molecular mechanisms underlying anesthetic actions and neurotoxicity

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Evidence suggests that most commonly used local (Propofol e.g.) and inhalation (sevoflurane, desflurane etc) anesthetic agents may exert long-term side effects leading to neurotoxicity and learning and memory deficits in animals, however a direct evidence is still lacking. My research program, supported by NSERC has been focused at defining the cellular and molecular mechanisms underlying anesthetic-induced neurotoxicity - in both snail and rat models. Notwithstanding these advances, however there remain significant gaps in our knowledge vis-à-vis:a) the potential target sites for anesthetic-induced neurotoxicity, b) how best to prevent anesthetic-induced insult to neurons, and c) to develop novel anesthetic compounds that are least toxic and more efficacious. We have four specific aims with well-defined objectives that will address these issues directly. Aim #1: To determine whether P110 peptide mitigates anesthetic-induced neuronal toxicity in cultured Lymnaea and rat neurons. We have demonstrated that anesthetics-induced neurotoxicity involves perturbation of synaptic proteins as well as mitochondrial structure and function. Whereas the neurotoxic effects were reversed with a mitochondrial fusion inhibitor Mdivi-1, this compound is however non-specific and may itself be neurotoxic if used in live animals. We now wish to demonstrate that prior exposure of cultured neurons to P110 peptide will prevent anesthetic induced cell death, suppression of neurite outgrowth and synaptic proteins structure and function. Aim #2: To demonstrate anesthetic-induced toxicity in the intact rat brain slices. We will use our newly developed and patented 3-D chip (NSERC), and the isolated hippocampal brain slices will be interfaced to monitor synaptic plasticity at the CA3-CA1 synapse. This study will provide the first direct evidence that indeed anesthetics perturb neuronal communications and synaptic plasticity in the intact brain slices. We will then use P110 peptide to block anesthetic induced toxicity. Aim #3: To demonstrate whether exposure of pregnant female rats affects learning and memory in the new born pups. We will expose either pregnant rats or their new born pups (P2-P12) to sevoflurane, desflurane, propofol etc. for 20-30 minutes and their vital signs will be monitored throughout. 4-8 weeks post exposure, we will test these animals with various learning and memory tasks (novel object recognition, water maze, fear conditioning, Morris Water maze etc). Control air or saline injected animals will be used as controls. Aim #4: To mitigate anesthetic-induced deficit in learning and memory with P110 peptide. We will seek to mitigate anesthetic-induced effects on cognition and learning and memory by pre-treating the pups with P110. We anticipate that the peptide will rescue animals from anesthetic induced cytotoxicity. Together these studies will forge novel understanding of mechanisms underlying anesthetic-induced toxicity and reveal mitigation strategies.