«One Small Step for Mouse»: High CO2 Inhalation as a New Therapeutic Strategy for Parkinson's Disease

Progress on the Effects of Permissive Hypercapnia on the CNS During the Intraoperative Period: A Narrative Review

Previous experimental findings and clinical evidence have shown the important role of carbon dioxide (CO2) in regulating cerebral vascular tension. CO2 can affect the CNS through various mechanisms. With factors such as patient physiology or surgical interventions potentially causing increased arterial partial pressure of carbon dioxide (PaCO2) levels during mechanical ventilation in general anesthesia, it is important to explore the potential risks or benefits of intraoperative permissive hypercapnia on brain function. In November 2023, we conducted a thorough review of PubMed to establish the article outline. Articles that were non-English or repetitive were eliminated. We collected information on the year, topic, key findings, and opinions of each article. This review not only comprehensively summarizes the factors that contribute to the elevation of intraoperative PaCO2, but also explores the impact of fluctuations in PaCO2 levels on the CNS and the underlying mechanisms involved. At the same time, this article provides our understanding of the potential clinical significance of actively regulating PaCO2 levels. In addition, we propose that the aspects of permissive hypercapnia can be further studied to provide a reliable basis for clinical decision-making. The effects of permissive hypercapnia on the CNS remain a topic of debate. Further prospective randomized controlled studies are needed to determine if permissive hypercapnia can be safely promoted during mechanical ventilation in general anesthesia.

Carbon dioxide and MAPK signalling: towards therapy for inflammation

Inflammation, although necessary to fight infections, becomes a threat when it exceeds the capability of the immune system to control it. In addition, inflammation is a cause and/or symptom of many different disorders, including metabolic, neurodegenerative, autoimmune and cardiovascular diseases. Comorbidities and advanced age are typical predictors of more severe cases of seasonal viral infection, with COVID-19 a clear example. The primary importance of mitogen-activated protein kinases (MAPKs) in the course of COVID-19 is evident in the mechanisms by which cells are infected with SARS-CoV-2; the cytokine storm that profoundly worsens a patient's condition; the pathogenesis of diseases, such as diabetes, obesity, and hypertension, that contribute to a worsened prognosis; and post-COVID-19 complications, such as brain fog and thrombosis. An increasing number of reports have revealed that MAPKs are regulated by carbon dioxide (CO2); hence, we reviewed the literature to identify associations between CO2 and MAPKs and possible therapeutic benefits resulting from the elevation of CO2 levels. CO2 regulates key processes leading to and resulting from inflammation, and the therapeutic effects of CO2 (or bicarbonate, HCO3-) have been documented in all of the abovementioned comorbidities and complications of COVID-19 in which MAPKs play roles. The overlapping MAPK and CO2 signalling pathways in the contexts of allergy, apoptosis and cell survival, pulmonary oedema (alveolar fluid resorption), and mechanical ventilation-induced responses in lungs and related to mitochondria are also discussed. Video Abstract.

Understanding the Therapeutic Approaches for Neuroprotection

The term "neurodegenerative disorders" refers to a group of illnesses in which deterioration of nerve structure and function is a prominent feature. Cognitive capacities such as memory and decision-making deteriorate as a result of neuronal damage. The primary difficulty that remains is safeguarding neurons since they do not proliferate or regenerate spontaneously and are therefore not substituted by the body after they have been damaged. Millions of individuals throughout the world suffer from neurodegenerative diseases. Various pathways lead to neurodegeneration, including endoplasmic reticulum stress, calcium ion overload, mitochondrial dysfunction, reactive oxygen species generation, and apoptosis. Although different treatments and therapies are available for neuroprotection after a brain injury or damage, the obstacles are inextricably connected. Several studies have revealed the pathogenic effects of hypothermia, different breathed gases, stem cell treatments, mitochondrial transplantation, multi-pharmacological therapy, and other therapies that have improved neurological recovery and survival outcomes after brain damage. The present review highlights the use of therapeutic approaches that can be targeted to develop and understand significant therapies for treating neurodegenerative diseases.