A synthetic peptide rescues rat cortical neurons from anesthetic-induced cell death, perturbation of growth and synaptic assembly

Abstract

Anesthetics are deemed necessary for all major surgical procedures. However, they have also been found to exert neurotoxic effects when tested on various experimental models, but the underlying mechanisms remain unknown. Earlier studies have implicated mitochondrial fragmentation as a potential target of anesthetic-induced toxicity, although clinical strategies to protect their structure and function remain sparse. Here, we sought to determine if preserving mitochondrial networks with a non-toxic, short-life synthetic peptide—P110, would protect cortical neurons against both inhalational and intravenous anesthetic-induced neurotoxicity. This study provides the first direct and comparative account of three key anesthetics (desflurane, propofol, and ketamine) when used under identical conditions, and demonstrates their impact on neonatal, rat cortical neuronal viability, neurite outgrowth and synaptic assembly. Furthermore, we discovered that inhibiting Fis1-mediated mitochondrial fission reverses anesthetic-induced aberrations in an agent-specific manner. This study underscores the importance of designing mitigation strategies invoking mitochondria-mediated protection from anesthetic-induced toxicity in both animals and humans.

Dexmedetomidine does not compromise neuronal viability, synaptic connectivity, learning and memory in a rodent model

“…The most suitable species were chosen for this study, and data were obtained in accordance with the best existing practices that ensure the animals' welfare 32 . The protocols used in this study are essentially identical to those employed in previous studies 33,34 and were adapted suitably. All in vivo experiments was carried out in accordance to ARRIVE guidelines.…”

“…Primary rat neuronal cell culture and dexmedetomidine treatment. Sprague-Dawley rat frontal cortices were isolated and cultured as previously described 34 . Some cultures were treated with various concentrations of dexmedetomidine (10 mg; MilliporeSigma, St. Louis, MO, USA) (0.05 μM, 0.1 μM, 1 μM, 2.5 μM, 5 μM, or 10 μM) dissolved in culture media, whereas controls only had culture media.…”

“…The effects of DEX on neuronal viability were tested 3 days post-culture via the LIVE⁄DEAD Viability/Cytotoxicity Kit (Molecular Probes) as previously described 34 . In order to assess the effect at a later time point, we also analyzed the viability of the remaining alive cells at day seven post-exposure.…”

“…Fluorescence images were taken on an Olympus SD-OSR spinning-disk confocal microscope (100×/1.49 oil)) with a mounted incubator system (Olympus Corp.) and all imaging parameters were kept identical for each dish. Mitochondrial morphology was quantified as previously described 34 .…”

“…Each individual neuron was assigned a distinct mitochondrial "identifier" based on their total numbers and the morphology that was specific to any given cell. This criteria for mitochondrial morphology characterization was based on previously established studies where they are classified either as fragmented when less than 0.75 μm in length, intermediate when 0.75-3 μm in length, and fused when greater than 3 μm in length 34 . We observed that the cells exposed to DEX had hyperfused mitochondrial networks at day 4 postexposure (Fig.…”